Articles de revues : « Allophagie »

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Parfitt, R. L. « Allophane and imogolite : role in soil biogeochemical processes ». Clay Minerals 44, n^o 1 (mars 2009) : 135–55. http://dx.doi.org/10.1180/claymin.2009.044.1.135.

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AbstractThe literature on the formation, structure and properties of allophane and imogolite is reviewed, with particular emphasis on the seminal contributions by Colin Farmer. Allophane and imogolite occur not only in volcanic-ash soils but also in other environments. The conditions required for the precipitation of allophane and imogolite are discussed. These include pH, availability of Al and Si, rainfall, leaching regime, and reactions with organic matter. Because of their excellent water storage and physical properties, allophanic soils can accumulate large amounts of biomass. In areas of high rainfall, these soils often occur under rain forest, and the soil organic matter derived from the forest biomass is stabilized by allophane and aluminium ions. Thus the turnover of soil organicmatter in allophanicsoils is slower than that in non-allophanicsoils. The organic matter appears to be derived from the microbial by-products of the plant material rather than from the plant material itself. The growth of young forests may be limited by nitrogen supply but growth of older forests tends to be P limited. Phosphorus is recycled through both inorganic and organic pathways, but it is also strongly sorbed by Al compounds including allophane. When crops are grown in allophanic soils, large amounts of labile P are required and, accordingly, these soils have to be managed to counteract the large P sorption capacity of allophane and other Al compounds, and to ensure an adequate supply of labile P. Because of their physical and chemical properties, allophanic soils are excellent filters of heavy metals and pathogens.

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Parfitt, R. L., A. Parshotam et G. J. Salt. « Carbon turnover in two soils with contrasting mineralogy under long-term maize and pasture ». Soil Research 40, n^o 1 (2002) : 127. http://dx.doi.org/10.1071/sr00105.

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Total organic carbon (C) and natural 13C abundance were measured in adjacent allophanic soils (Andisols) and non-allophanic soils (Inceptisols) under maize (Zea mays L.) and ryegrass pasture (Lolium perenne L.) to assess the C turnover rate in soils of contrasting mineralogy and specific surface area. The allophanic soil contained more total C than the non-allophanic soil (139 v. 101 t C/ha in the upper 0–35 cm) but neither soil showed a significant difference in C content between pasture and maize, provided maize residue was retained and incorporated. The gross annual inputs under maize and pasture were both estimated to be about 9 t C/ha, consistent with the similar soil total C contents. Since the soil total C content did not appear to change with time, the gross C mineralisation was about 9 t C/ha each year. The proportion of old pasture C remaining in the soil after maize cropping for 25 years was about 78&percnt; in the allophanic soils and about 69&percnt; in the non-allophanic soils, reflecting the influence of both Al and allophane, with its high specific surface area, on the retention of old C. The maize C retained in 25 years was similar in both the allophanic soil and the non-allophanic soil (29 t/ha). Therefore, the higher total C content of the allophanic soil would appear to arise from stabilisation of old pasture and forest C by Al and allophane. clover, grass, New Zealand soils.

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Onodera, Yoshio, Takashi Iwasaki, Abhijit Chatterjee, Takeo Ebina, Toshio Satoh, Takashi Suzuki et Hitoshi Mimura. « Bactericidal allophanic materials prepared from allophane soil ». Applied Clay Science 18, n^o 3-4 (mars 2001) : 123–34. http://dx.doi.org/10.1016/s0169-1317(00)00038-7.

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Onodera, Yoshio, Shunji Sunayama, Abhijit Chatterjee, Takashi Iwasaki, Toshio Satoh, Takashi Suzuki et Hitoshi Mimura. « Bactericidal allophanic materials prepared from allophane soil ». Applied Clay Science 18, n^o 3-4 (mars 2001) : 135–44. http://dx.doi.org/10.1016/s0169-1317(00)00039-9.

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Perez del Villar, L., M. C. Moro et M. L. Cembranos. « Allophane in weathered zones of barite ore deposits (Vide de Alba and San Blas, Zamora, Spain) : mineralogy and genesis ». Clay Minerals 27, n^o 3 (septembre 1992) : 309–23. http://dx.doi.org/10.1180/claymin.1992.027.3.04.

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AbstractThe allophane studied occurs in the weathered zones of the barite-sulphide-bearing dolomitic levels, interbedded in the barite ore deposits of Vide de Alba and San Bias (Province of Zamora). These ore deposits are interstratified in the Silurian-Devonian sulphide bearing volcano sedimentary materials of the Alcañices Synform. The allophanic samples have been studied by polarizing microscopy, SEM, XRD, DTA, TG, IRS, EMA and chemical analyses, the last after dissolving the samples by acid (HF + HNO3 + 3HCl + H3BO3) and alkaline digestion (0·5 m NaOH). It is suggested that allophane originates from the reaction of acid solutions released during the weathering of sulphides with acid volcanoclastic rocks. Silica-alumina gels were deposited in holes formed during earlier dissolution of the dolomite associated with the barite ores. Later processes of desilication partially transform allophane to gibbsite.

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Moro, M. C., M. L. Cembranos et A. Fernandez. « Allophane-like materials in the weathered zones of Silurian phosphate-rich veins from Santa Creu d'Olorda (Barcelona, Spain) ». Clay Minerals 35, n^o 2 (avril 2000) : 411–21. http://dx.doi.org/10.1180/000985500546873.

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AbstractAllophane-like materials occur in the weathered zones of the phosphate-rich veins hosted in Silurian metasediments of the Catalonian Coastal Ranges. These metasediments also host sulphide and phosphate sedimentary mineralizations. Mineralogical and geochemical investigations of the allophanic samples indicate that they comprise Si-rich allophane, with a molar SiO2/Al2O3 ratio ranging between 1.19 and 2.23, with amorphous Al-(Ca) phosphate and hydroxylapatite as major minerals, and minor goethite and quartz. It is assumed that allophane, amorphous Al-(Ca) phosphate and hydroxylapatite come from the reaction of acid solutions, released during the weathering of sulphide interbedded in black shales, with phosphate-rich veins and volcano- sedimentary host rocks. Silica-alumina gels were deposited in fissures and cavities left by a previous dissolution of the phosphate-rich veins. Later the phosphate minerals filled the conchoidal microfractures and shrinkage microcracks of the allophane.

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Allbrook, RF. « Shrinkage of some New Zealand soils and its implications for soil physics ». Soil Research 31, n^o 2 (1993) : 111. http://dx.doi.org/10.1071/sr9930111.

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Aggregates from three New Zealand soils were used to produce shrinkage curves. Each soil had a clay mineralogy dominated by a different mineral, namely allophane, halloysite and kaolinite.The curves showed marked differences. Only the allophanic soil showed structural shrinkage, and only the halloysitic soil showed residual shrinkage. When the slope of the normal shrinkage line is about unity, this indicates the soil is liable to crack- this was only shown by the allophanic soil. The implication for soil physics is that, since all soils with at least a moderate clay content shrink, bulk densities change with moisture and this must be allowed for in such calculations as soil moisture on a volume basis.

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Chevallier, Tiphaine, Kenji Fujisaki, Olivier Roupsard, Florian Guidat, Rintaro Kinoshita, Elias de Melo Viginio Filho, Peter Lehner et Alain Albrecht. « Short-range-order minerals as powerful factors explaining deep soil organic carbon stock distribution : the case of a coffee agroforestry plantation on Andosols in Costa Rica ». SOIL 5, n^o 2 (15 novembre 2019) : 315–32. http://dx.doi.org/10.5194/soil-5-315-2019.

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Abstract. Soil organic carbon (SOC) constitutes the largest terrestrial C stock, particularly in the Andosols of volcanic areas. Quantitative information on distribution of SOC stocks is needed to construct a baseline for studying temporal changes in SOC. The spatial variation of soil short-range-order minerals such as allophane usually explains the variability of topsoil SOC contents, but SOC data for deeper soil layers are needed. We found that within a 1 km2 Costa Rican basin covered by coffee agroforestry, SOC stocks in the upper 200 cm of soil were highly variable (24 to 72 kg C m−2). Topsoil SOC stocks were not correlated with SOC stocks present in deeper layers. Diffuse-reflectance mid-infrared (MIR) spectroscopy made possible the analysis of a large number of samples (69 soil profiles, i.e. 598 soil samples) for ammonium-oxalate and sodium-pyrophosphate-extractable forms of Al, Fe, and Si, as well as SOC content and bulk density. Using the MIR spectra, we identified two different soil materials, which were identified as allophanic and halloysitic soil material. Allophanic soil occurred on top of the halloysitic soil. The thickness of the allophanic soil material, rich in SRO minerals and related to a young andic A horizon, explained the variability of SOC. This study illustrates that knowledge of topography and pedogenesis is needed to understand and extrapolate the distribution of SOC stocks at landscape scales.

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Parfitt, RL. « Surface charge in some New Zealand soils measured at typical ionic strength ». Soil Research 30, n^o 3 (1992) : 331. http://dx.doi.org/10.1071/sr9920331.

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The positive and negative surface charges of some New Zealand soils used for horticulture were measured at different pH values using 0.002 M CaCl2 solutions, Which have a similar ionic strength to soil solutions in New Zealand. The surface negative charge increased with pH for all soil samples including those containing mica and smectite. This behaviour was mainly due to the presence of organic matter and allophane both of which had an appreciable amount of variable negative charge. Allophanic soil B horizons had a higher positive charge than that of the Oxidic soils, which was less than 1 cmol kg-1 at pH 5.

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He, Ming, et Yukiya Horikawa. « Stability of allophane, allophanic clay, and allophane-halloysite floc in aqueous solutions of an anionic exocellular heteropolysaccharide (Gum Xanthan) fromXanthomonas campestris ». Soil Science and Plant Nutrition 42, n^o 3 (septembre 1996) : 603–12. http://dx.doi.org/10.1080/00380768.1996.10416329.

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Romero-Mancilla, Pablo Eduardo, José Miguel Montenegro-Cooper, Robert W. King, Pablo Lapeña-Mañero et Carmen García-Casuso. « Experimental Investigation on the Influence of Oven-Drying on the Geotechnical Properties of Volcanic Ash-Derived Residual Soils ». Applied Sciences 11, n^o 24 (9 décembre 2021) : 11708. http://dx.doi.org/10.3390/app112411708.

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For thousands of years, the volcanic activity present along the Andes Mountain range has generated a large amount of pyroclastic material. As a result, around 60 percent of the soils present in Chile have a volcanic origin, of which, we can find soils derived from volcanic ash. These correspond to soils whose origin is the weathering of volcanic ash, which generates minerals such as allophane, imogolite, and halloysite. The presence of these minerals gives these soils unique geotechnical properties, such as high plasticity, low dry unit weight, and a unique internal structure. Subjecting these soils to extreme temperatures like those needed to perform standard laboratory tests produces changes in their structures, and thus in their geotechnical behavior. These changes are important to be aware of with respect to slope stability problems, embankment conformation, surface foundations, etc. In the present study, a type of soil found in Chile originating from the weathering of volcanic ash and locally named Trumao was studied. Due to its age and formation processes, the main minerals found in the soil are allophane and imogolite, and hence it belongs to the allophanic soil type. The material was studied in its natural state (undisturbed) and, after being oven-dried using common geotechnical tests, the behaviors of both samples were compared. The study shows that some properties are affected significantly by the oven-drying process, and thus it is not recommended to expose the material to high temperatures during geotechnical laboratory testing to avoid misleading results.

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Tulin, Anabella. « Characteristics of Interlayer Materials in Non-Allophanic Volcanic Ash and Red Yellow Soils from Japan ». Science and Humanities Journal 5, n^o 1 (1 décembre 2005) : 1–23. http://dx.doi.org/10.47773/shj.1998.051.1.

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The characteristics and properties of interlayer materials from 10 non-allophanic (Melanudand) and red yellow soils (Alfisols and Ultisols) from three locations in Japan were studied by chemical extractions and x-ray diffraction (XRD) analyses. Allophane was dissolved from clay samples using 0.15 M acid oxalate solution while silicon and aluminum were dissolved using both 0.15 M acid oxalate and 0.3 M sodium citrate solutions. XRD analyses were done for the treated and untreated samples. For the chemically extracted samples, the clay samples were treated with bicarbonate citrate solution for the removal of iron oxides after the dissolution treatments then saturated with K and Mg ions for XRD analyses. Results of the XRD patternd of the untreated and treated samples indicated the interlayer materials as a hydroxy-interlayered form for vermiculite (HIV). Between the two dissolution treatments, the 0.3 M sodium citrate treatment was found to be more effective in removing the interlayer materials than the 0.15 M acid oxalate treatment by allowing interlayer expansion and collapse.

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Wang, Shun, Peixin Du, Peng Yuan, Yaqi Liu, Hongzhe Song, Junming Zhou, Liangliang Deng et Dong Liu. « Structural alterations of synthetic allophane under acidic conditions : Implications for understanding the acidification of allophanic Andosols ». Geoderma 376 (octobre 2020) : 114561. http://dx.doi.org/10.1016/j.geoderma.2020.114561.

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Close, M. E., G. N. Magesan, R. Lee, M. K. Stewart et J. C. Hadfield. « Field study of pesticide leaching in an allophanic soil in New Zealand. 1 : Experimental results ». Soil Research 41, n^o 5 (2003) : 809. http://dx.doi.org/10.1071/sr02080.

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Seven pesticides, 2,4-D, atrazine, hexazinone, picloram, procymidone, terbuthylazine, and triclopyr, were applied to a Horotiu soil (allophanic loamy silt) located near Hamilton, New Zealand, along with 2 tracer compounds, bromide and deuterated water. Their movement and persistence was monitored for about 2�years using soil sampling down to a maximum of 1 m and 9 suction cups located between 0.2 and 2.5 m down the profile. There was rapid leaching of the tracers as well as hexazinone, picloram, and, to a lesser extent, triclopyr. Procymidone was much less mobile but was very persistent. Atrazine, terbuthylazine, and 2,4-D showed low mobility and persistence at the study site. Bromide and hexazinone were observed in the underlying groundwater following winter recharge and an intensive irrigation period at the end of the study. There was slight adsorption of bromide by the allophane in the soil. The combination of both soil sampling and suction cups gave a more complete description of the leaching process and the distribution of the compound through the profile than either technique by itself. This combination is worthwhile and gives complementary information providing the strengths and limitations of both techniques are appreciated.

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Close, M. E., L. Pang, G. N. Magesan, R. Lee et S. R. Green. « Field study of pesticide leaching in an allophanic soil in New Zealand. 2 : Comparison of simulations from four leaching models ». Soil Research 41, n^o 5 (2003) : 825. http://dx.doi.org/10.1071/sr02081.

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Seven pesticides were applied to an allophanic silt loam along with a bromide tracer and their concentrations in soil and water monitored over a 2-year period. Inverse modelling was carried out using GLEAMS, LEACHM, and HYDRUS-2D to derive field-based mobility and degradation parameters. Hexazinone and procymidone were more mobile and more persistent than most literature values would suggest, whereas picloram and triclopyr were much less mobile but more persistent. The greater mobility for hexazinone, a weak base, and the reduced mobility of picloram and triclopyr, weak acids, are consistent with the effects of allophane. Mobility values for 2,4-D, atrazine, and terbuthylazine could not be determined with confidence from experimental results, but both atrazine and terbuthylazine appeared less persistent, and 2,4-D more persistent than literature values. A fourth model, SPASMO, currently under development, was used as an independent test of the optimised parameters. It performed well for the soil water concentrations but tended to overestimate the observed soil concentrations using the derived parameters. HYDRUS-2D simulations of bromide and hexazinone concentrations in the groundwater gave a good fit to observed data from 3 monitoring wells following a large recharge pulse.

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Simamora, Jupri, Purba Marpaung et Alida Lubis. « DETERMINATION TYPE OF ALLOPHANE ON ANDISOL IN DOLAT RAKYAT VILLAGE TIGA PANAH DISTRICT, REGENCY OF KARO ». Jurnal Pertanian Tropik 2, n^o 3 (1 décembre 2015) : 228–38. http://dx.doi.org/10.32734/jpt.v2i3.2916.

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The aim of the research was to determinate the type of Allophane minerals by means of Thermogram and to know the type of Allophane minerals with Allophane–Organic Matter relations. The research was done in Dolat Rakyat villages, District of Tiga Panah Karo Regency, In Soil Fertility Laboratory University of North Sumatera, and College of Chemical Industry (PTKI), Medan in June - October 2014. Soil type is Andisol. The result of the research in Dolat Rakyat Village Tiga Panah District, Regency of Karo Thermogram interpretation showed that type of Allophane minerals Andisol that is Allophane B. Allophane-Organic Matter relations showed that type of Allophane minerals is Allophane B with positive relations between Allophane-Humic Acid; negative relations between Allophane-Fulvic Acid, and Allophane-Humic Acid+Fulvic Acid.

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Filimonova, Svetlana, Stephan Kaufhold, Friedrich E. Wagner, Werner Häusler et Ingrid Kögel-Knabner. « The role of allophane nano-structure and Fe oxide speciation for hosting soil organic matter in an allophanic Andosol ». Geochimica et Cosmochimica Acta 180 (mai 2016) : 284–302. http://dx.doi.org/10.1016/j.gca.2016.02.033.

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Airlangga, Tandaditya Ariefandra, Naoto Matsue, Eko Hanudin et Erni Johan. « Phosphate Adsorption Capacity of Allophane from Two Volcanic Mountains in Indonesia ». JOURNAL OF TROPICAL SOILS 25, n^o 1 (2 janvier 2020) : 39. http://dx.doi.org/10.5400/jts.2020.v25i1.39-46.

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Allophane is known as clay mineral with high capacity of phosphate adsorption via ligand-exchange mechanism. This study aims to compare the phosphate adsorption characteristics by allophane from Mt. Merapi and Mt. Lawu in relation to its chemical and mineralogical properties. The results of X-Ray Flourescence analysis shows that both allophane samples from Merapi and Lawu have low Si/Al ratio, i.e. 1.18 and 1.16, respectively. Infrared spectral characteristics of the allophane materials indicated that the main adsorption bands appeared at the range of 2700-3700 cm-1 (due to stretching vibration of all hydroxyl (OH) groups), 1400 – 1800 cm-1 (vibration of HOH deformation), and 650 - 1200 cm-1 (vibration between the Si-O-Al). Adsorption experiment of phosphate on allophane samples were conducted at initial adsorbate concentration of up to 2.0 mM and at pH 4.0 and 8.0. Phosphate adsorption capacity of allophane shows that both allophane from Merapi and Lawu are categorized as very high in adsorbing phosphate and fit well with the Langmuir adsorption equation. Phosphate adsorption increases with decreasing pH due to the positive charge sites such as Al-OH2+ in the allophane structure increase. Another reason is the negative charge of phosphate gradually decreases from -2 to -1 with decreasing pH, and the repulsive force between the negatively charged Si-O- in the allophane structure and phosphate anions decreases.

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Al Rawi, Sara, Sophie Louvet-Vallée, Abderazak Djeddi, Martin Sachse, Emmanuel Culetto, Connie Hajjar, Lynn Boyd, Renaud Legouis et Vincent Galy. « Allophagy ». Autophagy 8, n^o 3 (19 mars 2012) : 421–23. http://dx.doi.org/10.4161/auto.19242.

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Calvelo Pereira, R., M. Camps Arbestain, F. M. Kelliher, B. K. G. Theng, S. R. McNally, F. Macías et F. Guitián. « Assessing the pore structure and surface area of allophane-rich and non-allophanic topsoils by supercritical drying and chemical treatment ». Geoderma 337 (mars 2019) : 805–11. http://dx.doi.org/10.1016/j.geoderma.2018.10.037.

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Singleton, PL, M. Mcleod et HJ Percival. « Allophane and halloysite content and soil solution silicon in soils from rhyolitic volcanic material, New Zealand ». Soil Research 27, n^o 1 (1989) : 67. http://dx.doi.org/10.1071/sr9890067.

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The relationship between Si in soil solution and allophane and halloysite content was studied by using a drainage sequence of three New Zealand soils from rhyolitic volcanic alluvium. Clay mineralogy was compared with soil colour and drainage. Allophane and halloysite contents of two morphologically similar soils from rhyolitic volcanic ash were also studied and possible reasons for differences in mineralogy were determined. Allophane was estimated by acid oxalate and pyrophosphate dissolution. The Al/Si ratio of the allophane was determined and the allophane content of the soil was estimated from the Si extracted in acid-oxalate. Halloysite was estimated by differential thermal analysis of the whole soil. Soil samples were centrifuged with a dense water-immiscible organic liquid to displace the soil solution from between soil particles. The Si in soil solution was then determined by spectrophotometry. Allophane was predominant when Si in soil solution was <10gm-3, and halloysite was predominant when Si in soil solution was >10gm-3. Low Si in soil solution and the presence of allophane was associated with well drained horizons which could be identified by their ochreous colour. High Si in soil solution, the absence of allophane and predominance of halloysite, was associated with poorly drained horizons. These horizons could be identified by their pale colour (chroma <2). In two morphologically similar soils, the change from allophane dominance in one soil to hahoysite dominance in the other soil also corresponded to an increase in Si in soil solution. This was probably the result of slightly slower horizon permeability which increased Si in soil solution to a level favouring halloysite formation.

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Singh, Jagrati, S. Saggar, D. L. Giltrap et Nanthi S. Bolan. « Decomposition of dicyandiamide (DCD) in three contrasting soils and its effect on nitrous oxide emission, soil respiratory activity, and microbial biomass—an incubation study ». Soil Research 46, n^o 7 (2008) : 517. http://dx.doi.org/10.1071/sr07204.

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The objective of this work was to study the degradation kinetics of a nitrification inhibitor (NI), dicyandiamide (DCD), and evaluate its effectiveness in reducing nitrous oxide (N2O) emissions in different types of soils. Three soils contrasting in texture, mineralogy, and organic carbon (C) content were incubated alone (control) or with urine at 600 mg N/kg soil with 3 levels of DCD (0, 10, and 20 mg/kg). Emissions of N2O and carbon dioxide (CO2) were measured during the 58-day incubation. Simultaneously, subsamples were collected periodically from the incubating soils (40-day incubation) and the amounts of DCD, NH4+, and NO3− were determined. Our results showed that the half-life of DCD in these laboratory incubating soils at 25°C was 6–15 days and was longer at the higher rate of DCD application. Of the 3 soils studied, DCD degradation was fastest in the brown loam allophanic soil (Typic orthic allophanic) and slowest in the silt loam non-allophanic soil (Argillic-fragic Perch-gley Pallic). The differences in DCD degradation among these soils can be attributed to the differences in the adsorption of DCD and in the microbial activities of the soils. Among the 3 soils the highest reduction in N2O emissions with DCD from the urine application was measured in the non-allophanic silt loam soil followed by non-allophanic sandy loam soil and allophanic brown loam soil. There was no adverse impact of DCD application on soil respiratory activity or microbial biomass.

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Rois, Ibnu, Pranoto Pranoto et Sunarto Sunarto. « APLIKASI ALOFAN DALAM TANAH ANDISOL SEBAGAI ADSORBEN UNTUK MENURUNKAN BAKTERI Coliform LIMBAH CAIR DOMESTIK ». EnviroScienteae 14, n^o 2 (15 octobre 2018) : 99. http://dx.doi.org/10.20527/es.v14i2.5475.

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Research on allophane has been done as an adsorbent to decrease MPN Coliform in domestic wastewater. The purpose of this study was to look for natural adsorbent materials that can be used to decrease MPN Coliform. Natural allophane was identified from andisol soil by pH analysis of NaF, FTIR, XRD, and SAA. The result of the analysis showed that there was allophane on andisol soil with pH 11,73. The diameter of empty space or alloy pores of 5 nm with a hole/pore size of 0.5 nm. Testing of MPN Coliform is done by method of Most Probable Number (MPN) variety 5: 5: 5. Based on the result of the research, allophane adsorbent can decrease MPN Coliform by 60.9%.

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He, N., T. L. Barr et J. Klinowski. « ESCA and solid-state NMR studies of allophane ». Clay Minerals 30, n^o 3 (septembre 1995) : 201–9. http://dx.doi.org/10.1180/claymin.1995.030.3.04.

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AbstractThe surface/near-surface chemistry of allophane has been studied by X-ray photoelectron spectroscopy (ESCA) and the bulk material by 27A1 and 29Si solid-state NMR and other techniques. The surface/near-surface Si/Al ratio of allophane is c.1.0, similar to that for kaolinite, zeolite Na-A and sodalite. The core level binding energies for kaolinite and allophane are almost identical, but quite different from those for zeolite Na-A and sodalite, both framework aluminosilicates. The nature and size of these differences is consistent with the differences between the chemistry of sheet and framework silicates. The small variations in the Si(2p) spectra for kaolinite and allophane are discussed in terms of bonding of the tetrahedral units in the two materials.

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Hashizume, H., et B. K. G. Theng. « Adsorption of DL-alanine by allophane : effect of pH and unit particle aggregation ». Clay Minerals 34, n^o 2 (juin 1999) : 233–38. http://dx.doi.org/10.1180/000985599546190.

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AbstractThe adsorption of DL-alanine at pH 4, 6 and 8 by a soil allophane has been determined. Two sets of experiments were carried out: (1) in which the allophane had been kept in a moist state throughout; and (2) in which the mineral had previously been dried at 50°C. In both instances, the adsorption isotherms showed three distinct regions as the concentration of alanine in solution was increased: (1) an initial, nearly linear, rise at low equilibrium concentrations; (2) a levelling off to a plateau at intermediate concentrations; and (3) a steep linear increase at high concentrations. For comparable concentrations of alanine in solution, adsorption decreased in the order pH 6 > pH 8 > pH 4. Irrespective of pH, however, more alanine was adsorbed by the ‘wet’ allophane than by its ‘dry’ counterpart. These observations are interpreted in terms of the morphology and aggregation of allophane unit particles together with the pH-dependent charge characteristics of allophane and alanine. The results are compared with published data on the adsorption of alanine by montmorillonite.

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Cichota, R., I. Vogeler, N. S. Bolan et B. E. Clothier. « Cation influence on sulfate leaching in allophanic soils ». Soil Research 45, n^o 1 (2007) : 49. http://dx.doi.org/10.1071/sr06070.

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We have examined the influence of the ionic composition of the soil solution on the movement of sulfate and calcium in 2 New Zealand soils with differing allophane content. For this study, we have carried out a series of miscible displacement experiments using repacked and intact soil columns, in which sulfate was applied in the presence of either calcium or potassium as the accompanying cation. Our results showed that sulfate leaching was significantly retarded in the soil with higher allophane content when applied with calcium. On the other hand, no effects were observed for all studied soils when potassium was used as the accompanying cation. In addition, in soils with high allophane content, calcium also had its retention increased when sulfate was present. The increase in sulfate adsorption was accompanied by corresponding increase in calcium adsorption. These findings evidenced the presence of co-adsorption, or ion-pair adsorption (IPA), in allophane-containing soils. The extent of this adsorption is dependent on the soil pH, the accompanying cation, and the allophane content of the soil.

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Silva-Yumi, Jorge, Roberto Cazorla Martínez, Carlos Medina Serrano et Gabriela Chango Lescano. « Allophane, a natural nanoparticle present in andisols of equatorial Ecuador, properties and applications ». Characterization and Application of Nanomaterials 5, n^o 1 (17 avril 2022) : 89. http://dx.doi.org/10.24294/can.v5i1.1689.

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Allophane is a natural nanoparticle present in soils of volcanic origin such as andisols, which are distributed around the world in countries with volcanic activity. In Ecuador, andisols constitute 30% of the territory in high and humid areas of the northern highlands. Allophane can be obtained from andisols through physical and chemical processes, or it can be synthesized. This nanomaterial has multiple properties for various applications in different areas. There is a lot of research on these nanoparticles and this type of soils, but they have not been studied yet in Ecuador. In this article, the structural characteristics, properties, formation, isolation, synthesis and uses of allophane are presented, with the ﬁnish of generating knowledge and encouraging research on these soils that are the source of the aforementioned nanoparticle. The literature search was performed in Science Direct and Google Scholar databases, and high impact articles related to natural or synthetic allophane research were used. The particular characteristics that allophane has allows it to be used as an environmental remediator, bactericide, anti-inﬂammatory, flame retardant, enzyme support, but in addition it has been studied in catalysis, photocatalysis and electrocatalysis. Considering the area covered by allophane in the Ecuadorian territory and its availability, it can be used for research based on international studies that have been developed to take advantage of it in the environmental and medical areas.

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Hojamberdiev, Mirabbos, Yuki Makinose, Kenichi Katsumata, Toshihiro Isobe, Nobuhiro Matsushita et Kiyoshi Okada. « Hydrothermal Synthesis and Visible-Light-Driven Photocatalytic Activity of Allophane – Wakefieldite-(Ce) Composite ». Advanced Materials Research 896 (février 2014) : 545–48. http://dx.doi.org/10.4028/www.scientific.net/amr.896.545.

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In this study, highly adsorptive mechanically-mixed and as-synthesized allophane–wakefieldite-(Ce) composites were prepared by mechanical mixing and hydrothermal synthesis, respectively. The results from X-ray diffraction and Raman spectroscopy analyses show that the mechanically-mixed composite has higher crystallinity than the as-synthesized composite. The nanoparticles of wakefieldite-(Ce) were homogenously distributed with allophane in the as-synthesized composite. The specific surface areas of the mechanically-mixed and as-synthesized composites are 164 m2/g and 191 m2/g, respectively. The photocatalytic activity of the samples was evaluated for the degradation of acetaldehyde (AcH) gas under visible light. Both composites demonstrated higher photocatalytic activity than individual wakefieldite-(Ce) and allophane because allophane in the composites played an important role in the adsorption of acetaldehyde gas molecules and the mediation between the gas phase and the wakefieldite-(Ce) surface.

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Calabi Floody, M., B. K. G. Theng, P. Reyes et M. L. Mora. « Natural nanoclays : applications and future trends – a Chilean perspective ». Clay Minerals 44, n^o 2 (juin 2009) : 161–76. http://dx.doi.org/10.1180/claymin.2009.044.2.161.

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AbstractBecause of their large potential for agricultural, industrial and medicinal applications, nanomaterials have been the focus of much research during the past few decades. Nanoclays are natural nanomaterials that occur in the clay fraction of soil, among which montmorillonite and allophane are the most important species. Montmorillonite is a crystalline hydrous phyllosilicate (layer silicate). Organically-modified montmorillonites or ‘organoclays’, formed by intercalation of quaternary ammonium cations, have long been used as rheological modifiers and additives in paints, inks, greases and cosmetics and as carriers and delivery systems for the controlled release of drugs. Perhaps the largest single usage of organoclays over recent years has been in the manufacture of polymer-clay nanocomposites. These organic–inorganic hybrid materials show superior mechanical, thermal and gas-barrier properties. Organoclays are also useful in pollution control and water treatment. Allophane is a non-crystalline aluminosilicate derived from the weathering of volcanic ash. A large proportion of the agricultural land in Chile is covered by volcanic soils,the clay fraction of which is dominated by allophane. Consisting of nanosize (3.5–5.0 nm) hollow spherules, allophane is a suitable support material for enzyme immobilization. Allophane is also effective at adsorbing phenolic compounds and colour from kraft mill effluents and phosphate from water and wastewater.

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Nakayama, Chieko, et Yoshinori Tanaka. « Adsorption of nitrate as a groundwater pollutant by soil particles ». Journal of Nepal Geological Society 34 (9 octobre 2006) : 141–46. http://dx.doi.org/10.3126/jngs.v34i0.31890.

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This study discusses nitrogen adsorption in several soil samples of the Kanto loam collected from two locations in the Kanto plain. Their chemical properties were assessed on each of the soil samples as well as on pure allophane clay by instrumental analysis using batch and soil column tests. Nitrogen-nitrate adsorption by soil samples was determined by a 10-hour batch test using a nitric acid solution of 0.14 mmol. A saturation column test was conducted to obtain a breakthrough curve and calculate the coefficients of dispersion and retardation. The extent of nitrate adsorption in soil samples was confirmed by percolation with 0.14 mmol nitric acid through columns packed with the soil sample and silicate sand. In the batch test, it was found that the amount of nitrate adsorption was greater in allophane-rich volcanic ash soils with the amount of nitrate adsorption increasing under conditions of low pH. The breakthrough curve determined by the column test showed that the coefficient of retardation increased in allophane-rich soils. Adsorption of nitrates by Kanto loam soils was thus found to be dependent upon the content of allophane and amorphous material in the soil. Since the positive charge of allophane has the potential to reduce the nitrate content in groundwater, it can be effectively applied to reduce nitrate contamination in groundwater.

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Baskaran, S., N. S. Bolan, A. Rahman et R. W. Tillman. « Pesticide sorption by allophanic and non‐allophanic soils of New Zealand ». New Zealand Journal of Agricultural Research 39, n^o 2 (juin 1996) : 297–310. http://dx.doi.org/10.1080/00288233.1996.9513189.

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Parfitt, RL. « Allophane in New Zealand - a review ». Soil Research 28, n^o 3 (1990) : 343. http://dx.doi.org/10.1071/sr9900343.

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Studies of allophanes from New Zealand are reviewed, and a definition of the allophane group of minerals is suggested. Three types of allophane are identified, and their structures are discussed under headings Al-rich soil allophanes, Si-rich soil allophanes and stream deposit allophanes. Examples from New Zealand soils and tephras are discussed in relation to properties, identification and weathering processes.

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Duwig, C., B. Prado, A. J. Tinet, P. Delmas, N. Dal Ferro, J. P. Vandervaere, H. Denis, P. Charrier, A. Gastelum Strozzi et F. Morari. « Impacts of land use on hydrodynamic properties and pore architecture of volcanic soils from the Mexican Highlands ». Soil Research 57, n^o 6 (2019) : 629. http://dx.doi.org/10.1071/sr18271.

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Volcanic soils are important resources because of their unique mineralogical and physical characteristics, and allophanic Andosols represent some of the world’s most fertile soils. However, their unique properties can be lost when cultivated. Most soils in the Central Valley, Mexico, are derived from volcanic materials. This valley encompasses one of the largest water supply systems in the world by volume, but is affected by soil degradation and deforestation. Sustainably managing volcanic soils requires understanding how land use affects their hydrodynamic properties. Gas adsorption and mercury intrusion porosimetry, water retention curves, tension infiltrometry and X-ray tomography were used to describe pore structure characteristics. Two volcanic soils (one Andosol and one derived from indurated tuff – Tepetates), three land uses (maize monoculture, maize–wheat rotation and fallow) and two horizons (Ap and A2 for maize monoculture and maize–wheat rotation) were studied. Tillage affected topsoil by increasing the sand fraction by 38% and decreasing total porosity and macroporosity by 23% and 40% respectively. Macropore size was reduced and the number of isolated macropores was higher in the tilled layer under maize, compared with untilled subsoil. The plot under maize–wheat rotation had lower allophane content, and saturated hydraulic conductivity was reduced by nearly an order of magnitude and water retention by half, compared with maize and fallow plots. Compared with Andosols, Tepetates showed differences in mineralogical composition with lower contents of amorphous compounds and in its porous network characteristics with twice the total and percolating macroporosity compared with the maize plot. Its high content of organic carbon (3.5%) seemed beneficial for its hydrodynamic properties. Sustainable agricultural management of these volcanic soils requires reducing mechanised tillage, avoiding periods when soil is bare, not applying maize–wheat rotation and applying maize–fallow rotation allowing natural vegetation growth.

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Childs, C. W., K. Inoue, H. Seyama, M. Soma, B. K. G. Theng et G. Yuan. « X-ray photoelectron spectroscopic characterization of Silica Springs allophane ». Clay Minerals 32, n^o 4 (décembre 1997) : 565–72. http://dx.doi.org/10.1180/claymin.1997.032.4.07.

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AbstractA range of allophane samples (atomic AI/Si bulk ratios 1.1-1.9) from Silica Springs, New Zealand, has been characterized by X-ray photoelectron spectroscopy (XPS). Binding energies of Si 2s, Si 2p, Al 2p, O 1s, C 1s, and N 1s electrons, together with the kinetic energies of Al KL23L23 Auger electrons, at or near the surface of allophane aggregates, have been derived. The values for Al, Si and O electrons are similar to those for kaolinite but also to those for some framework silicates (feldspars) having 4-coordinate Al. Values for N electrons suggest that N occurs in organic structures. Comparison of XPS and bulk Al/Si ratios shows an enrichment of Al at or near the surface of allophane aggregates. The same is true for C and N. Extraction with citrate-dithionite-bicarbonate (CDB) reagent leaves the surfaces depleted in Al. The CDB extracts have higher Al/Si ratios than the bulk allophanes. Similarly, CDB treatment reduces the degree of surface enrichment of C and N. Small increases in the binding energies of Si electrons following CDB treatment suggest partial dissolution of the bulk structure though a concomitant removal of a separate phase or species cannot be ruled out. The results may be accounted for in terms of the structure previously suggested for the primary spherules of Silica Springs allophane (Childs et al., 1990) though the composition of the spherules at or near the surface of the allophane aggregates is different from those of the bulk.

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Ohashi, F., S. I. Wada, M. Suzuki, M. Maeda et S. Tomura. « Synthetic allophane from highconcentration solutions : nanoengineering of the porous solid ». Clay Minerals 37, n^o 3 (septembre 2002) : 451–56. http://dx.doi.org/10.1180/0009855023730052.

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AbstractThe amorphous aluminosilicate allophane was synthesized by rapid mixing of inorganic solutions with high initial concentrations (10 – 100 mmol/l) followed by hydrothermal treatment. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed homogeneous products having a hollow spherical amorphous structure with a particle diameter of 3 – 5 nm. The amorphous products had a high BET specific surface area (490 – 552 m2/g) in comparison with natural allophane and had a narrow pore-size distribution (2 – 5 nm in diameter). The results of water vapour adsorption isotherm studies showed a gradual increase over the range of relative water vapour pressure of 0.6 – 0.9 and reached a maximum of ∼85 wt.%. The synthetic allophane shows promise as an adsorbent material because of its high adsorption-desorption capacity and its unique structure.

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Addison, B., M. Boyes et P. L. Singleton. « Differences in particle density between field-moist and oven-dry samples from Allophanic Soils ». Soil Research 37, n^o 5 (1999) : 965. http://dx.doi.org/10.1071/sr98116.

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Particle density is used to calculate total soil porosity and related measurements such as macroporosity and water storage capacity. Methods for measuring particle density often advise using dry samples. This study measured particle density by displacement of water using both field-moist and oven-dry samples from 4 New Zealand Allophanic Soils. There were significant differences in particle density between the 2 methods. Oven-dry samples under-estimated particle density by up to 0.33 Mg/m 3 and as a result, calculations of porosity were under-estimated by up to 0.05 m 3/m 3 . Under-estimation of porosity can result in incorrect interpretation of a soil's aeration and water holding status. Allophanic Soils are known to undergo irreversible physical changes on drying and it is likely that these changes caused the difference in measurements. Only field-moist samples should be used to determine particle density of Allophanic Soils to ensure accurate calculation of soil porosity.

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Liu, Q., P. Loganathan, M. J. Hedley et M. F. Skinner. « Root processes influencing phosphorus availability in volcanic soils under young Pinus radiata plantations ». Canadian Journal of Forest Research 36, n^o 8 (1 août 2006) : 1913–20. http://dx.doi.org/10.1139/x06-083.

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Phosphorus (P) availability was investigated in rhizosphere soils under 4- to 5-year-old, second-rotation Pinus radiata D. Don and understorey grass (browntop, Agrostis capillaris L.) in two P-deficient Andosols (a Pumice Soil and an Allophanic Soil). Pinus radiata rhizosphere had more soil organic matter, greater mycorrhizal hyphal length density, higher acid phosphatase activity, and more concentrated dissolved organic carbon than bulk soil or the rhizosphere of grass species in one or both soils. Concentrations of resin P and organic P in the P. radiata rhizosphere were higher than those in the grass rhizosphere and bulk soils, suggesting that P. radiata rhizosphere processes have a greater potential to accumulate organic P and mobilize soil P than understorey grass rhizosphere processes. This effect was less marked in the Allophanic Soil than in the Pumice Soil, probably because of the higher P-fixing capacity and lower plant-available P concentrations in the Allophanic Soil.

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Hashimoto, Yohey, Jihoon Kang, Nobuhiko Matsuyama et Masahiko Saigusa. « Path Analysis of Phosphorus Retention Capacity in Allophanic and Non-allophanic Andisols ». Soil Science Society of America Journal 76, n^o 2 (mars 2012) : 441–48. http://dx.doi.org/10.2136/sssaj2011.0196.

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Ito, Kiyoshi, Tadashi Takahashi et Masami Nanzyo. « Aluminum toxicity of synthetic aluminum–humus complexes derived from non-allophanic and allophanic Andosols and its amelioration with allophanic materials ». Soil Science and Plant Nutrition 55, n^o 1 (février 2009) : 35–41. http://dx.doi.org/10.1111/j.1747-0765.2008.00328.x.

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Calderon, Edward H. Jiménez, Marco Rosero et Magdalena Diaz. « Use of Allophane as Face Mask Filter for Coronaviruses (Sars-Cov-2) ». Key Engineering Materials 878 (mars 2021) : 62–72. http://dx.doi.org/10.4028/www.scientific.net/kem.878.62.

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The traditional mouth cover masks can be made by hand. But with the arrival of the Coronavirus pandemic, these masks have special requirements and we will have to use these until at least 2022. Therefore, the current technological problem is what must be the appropriate filter nanomaterial (cuprum, zinc, zeolite or Allophane) to absorb and/or destroy coronaviruses. In addition, the preparation of this specific purpose mask must be certified, easy to manufacture and inexpensive. Taking these requirements into account, there is a suitable nanomaterial called Allophane, which has active centers of silicon and aluminum (Si / Al), which rapidly absorb micro droplets and nanodrops of water [3, 5] nm. Coronaviruses are microscopically embedded in water droplets. To build an absorbent filter that also destroys coronaviruses, we can use some organic surfactant in optimal proportions and that works cooperatively with Allophane. The physicochemical properties of natural Allophane were studied. For the characterization, analytical techniques were used: Fourier transform infrared spectroscopy (FTIR), BET surface area, X-ray diffraction (XRD), Chemisorption and Atomic Force Microscopy (AFM). In addition, the Navier Stokes 3D equations were studied, which allow us studying molecular dynamics contributing substantively to chemical kinetics describing the process of absorption of water and decomposition of water + coronavirus.

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Taylor, T. S., J. C. Hughes et L. W. Titshall. « Mineralogy of volcanically derived alluvial soils at Moshi, Tanzania ». Soil Research 54, n^o 8 (2016) : 926. http://dx.doi.org/10.1071/sr15252.

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Despite intensive commercial agriculture in the rift zone of Tanzania, mineralogical studies on the soils influenced by volcanic parent materials are scarce. A mineralogical investigation of the soils and two buried ash layers from an irrigated sugar estate was undertaken using X-ray diffraction, transmission electron microscopy and measurements of extractable iron, aluminium and silicon and the specific surface area (SSA) of the clay fraction. The dominant mineral in the sand and silt fractions was sanidine. The clay fractions contained mainly high-defect kaolin, illite and K-feldspar, with small amounts of calcite, talc and gibbsite in some samples. Electron microscopy revealed the presence of tubular and spheroidal halloysite and <0.5µm kaolinite crystals, as well as nanocrystalline material, probably allophane, and volcanic glass. The amounts of ferrihydrite (0.34–1.84%) and allophane (0.52–6.84%) were low in the soils but higher in the buried ash layers. The surface areas of the clay fractions were high (up to 145m2g–1) and it was calculated that 5% allophane constituted 22% of the total SSA. Although all soils were dominated by halloysite and small kaolinite particles, it is likely that the small amounts of allophane with high SSA has a strong effect on their physical and chemical properties.

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Jiménez Calderón, Edward Henry, Ana Emperatriz Paucar Tipantuña, Paulina Fernanda Herrera Mullo, Daniel Alejandro Hidalgo Cháfuel, Washington Ruiz, Ullrich Stahl et José Bermudez. « Natural and Activated Allophane Catalytic Activity Based on the Microactivity Test in Astm Norm 3907/D3907M-2019 ». Applied Sciences 10, n^o 9 (27 avril 2020) : 3035. http://dx.doi.org/10.3390/app10093035.

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The optimal conditions of the catalytic activation of allophane were evaluated for possible use as a catalyst within a fluidized bed catalytic cracking unit (FCC). The physicochemical properties of natural allophane and activated allophane were studied by using an alkaline activating agent, followed by a hydrothermal treatment. For the characterization, analytical techniques were used: Fourier transform infrared spectroscopy, particle size, (BET) surface area, thermogravimetry (TGA), X-ray diffraction (XRD), chemisorption, X-ray fluorescence (XRF), atomic force microscopy (AFM), and chromatography. The catalytic evaluation was determined by the (MAT) micro activity test equipment constructed according to ASTM D-3907/D3907M-2019. In addition, the Navier–Stokes 3D equations (nonlinear partial derivatives) were studied, which allow studying molecular dynamics contributing substantively to chemical kinetics describing the process of decomposition of crude oil in thermal cracking, determining the maximum temperature at which it retains its properties through the action of heat.

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Cardinale, Anna Maria, Cristina Carbone, Marco Fortunato, Bruno Fabiano et Andrea Pietro Reverberi. « ZnAl-SO4 Layered Double Hydroxide and Allophane for Cr(VI), Cu(II) and Fe(III) Adsorption in Wastewater : Structure Comparison and Synergistic Effects ». Materials 15, n^o 19 (4 octobre 2022) : 6887. http://dx.doi.org/10.3390/ma15196887.

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Owing to their structure, layered double hydroxides (LDHs) and allophane are nowadays considered as promising materials for application in different fields. The goal of this work is to compare the efficacy of allophane and ZnAl-SO4 LDH to remove, by adsorption, some cationic and anionic pollutants from industrial wastewater. Both compounds were synthesized via the co-precipitation route (direct method) followed by hydrothermal treatment, obtaining nanoscopic crystallites with a partially disordered turbostratic (ZnAl-SO4 LDH) or amorphous (allophane) structure. The characterization of the obtained compounds was performed by means of powder x-ray diffraction (PXRD), thermal gravimetry analysis (TGA), field emission scanning electron microscopy analysis (FESEM), and Fourier-transform infrared spectroscopy (FT-IR). The sorbents were tested using wastewater produced by a real metalworking plant and containing ionic species such as Cu(II), Fe(III) and Cr(VI), whose concentration was measured by means of inductively coupled plasma-optical emission spectrometry (ICP-OES). This investigation represents an alternative procedure with respect to standard protocols based on customarily made and artificially lab-produced wastewaters. Both sorbents and their combination proved to be efficient in Cr(VI) removal, irrespective of the presence of cations like Cu(II) and Fe(III). A synergistic effect was detected for Cu(II) adsorption in a mixed allophane/LDH sorbent, leading to a Cu(II) removal rate of 89.5%.

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Wilson, M. A., S. A. McCarthy et P. M. Fredericks. « Structure of poorly-ordered aluminosilicates ». Clay Minerals 21, n^o 5 (décembre 1986) : 879–97. http://dx.doi.org/10.1180/claymin.1986.021.5.03.

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AbstractThe structure of synthetic aluminosilicates prepared at pH 6 has been investigated by 29Si and 27Al high-resolution solid-state nuclear magnetic resonance (NMR) spectroscopy. Fourier transform infrared (FTIR) spectroscopy and electron microscopy have also been used to characterize the products. The amount of Si and Al in protoimogolite, disordered allophane and other structures has been measured. There is a fair correlation between the intensity of the 349 cm−1 band in the FTIR spectra and the proportion by weight of protoimogolite Si measured by NMR. It is shown that disordered allophanes have similar structures to those proposed by van Reeuwijk and de Villiers (Soil Sci. Soc. Am. Proc. 32 (1968) 238–240), i.e. octahedral Al surrounding a tetrahedral core. Moreover, it is clear that at high Al:Si ratios (⩾1:1), protoimogolite can compete with disordered allophane precursors for aluminum. The driving forces for formation of protoimogolite rather than allophane appear to be long range Al-Al repulsive forces through oxygen.

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Schwertmann, U., J. Friedl, H. Stanjek et D. G. Schulze. « The effect of clay minerals on the formation of goethite and hematite from ferrihydrite after 16 years’ ageing at 25°C and pH 4 – 7 ». Clay Minerals 35, n^o 4 (septembre 2000) : 613–23. http://dx.doi.org/10.1180/000985500547034.

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AbstractIn soils and other weathering environments, hematite and goethite are usually formed in the presence of clay minerals. Two-line ferrihydrite was aged in the presence of six different clay minerals in aqueous suspension at 25°C and pH 4, 5, 6 and 7 for 16 years. The transformation into hematite/goethite mixtures was complete in the systems with gibbsite, kaolinite, illite and smectite, but incomplete in those with soil smectite and allophane. Soil smectite and allophane, as well as increasing pH, favoured hematite over goethite. The grainy and multi-domainic hematite crystals in the allophane system contained Si and Al (EDX) and showed a Si – O vibration at ∼920 cm– 1 (FTIR). The unit-cell contraction due to structural Al was counteracted by structural OH, which was removed at 200°C. Heating also increased the magnetic hyperfine field at RT by 1.2 – 1.6 T. Hematite crystals with irregular shape and grainy interior have also been observed in soils.

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Nishikiori, Hiromasa, Shingo Matsunaga, Naoyuki Furuichi, Hitoshi Takayama, Koji Morita, Katsuya Teshima et Hiromi Yamashita. « Influence of allophane distribution on photocatalytic activity of allophane–titania composite films ». Applied Clay Science 146 (septembre 2017) : 43–49. http://dx.doi.org/10.1016/j.clay.2017.05.026.

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Pranoto, Pranoto, Tri Martini et Deta Agustin Rachmawati. « Karakterisasi dan Uji Efektivitas Allophane-Like untuk Adsorpsi Ion Logam Tembaga (Cu) ». ALCHEMY Jurnal Penelitian Kimia 14, n^o 2 (3 septembre 2018) : 202. http://dx.doi.org/10.20961/alchemy.14.2.18538.202-218.

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Telah dilakukan penelitian karakterisasi dan uji efektivitas allophane-like untuk adsorpsi ion logam tembaga (Cu). Allophane-like dibuat dengan mencampurkan larutan Tetraethyl Orthosilicate (TEOS) dan Aluminum Nitrate Nonahydrate [Al(NO3)3.9H2O] dengan perbandingan 0,5; 0,75; 1; 1,25 dan 1,5. Proses pencampuran dilakukan penambahan NaOH secara bertahap dan dilakukan pengadukan serta pemanasan. Penambahan NaOH dilakukan dengan membuat perbandingan NaOH dan Campuran TEOS dan Al(NO3)3.9H2O 3:1. pH campuran larutan yang diperoleh diukur dan pH larutan dibuat menjadi asam (pH 3-4). Allophane-like dikarakterisasi dengan spektroskopi infra merah (FTIR), XRD, keasaman, dan luas permukaan. Uji adsorpsi terhadap ion logam tembaga (Cu) dilakukan pada variasi perbandingan TEOS dan Al(NO3)3.9H2O 0,5; 0,75; 1; 1,25 dan 1,5, pH larutan tembaga (Cu) 3-7 serta waktu kontak 30-120 menit dengan sistem batch. Hasil penelitian diketahui bahwa allophane-like memiliki gugus fungsi yang sama dengan allophane-alam yang ditunjukkan dengan data FTIR yaitu memiliki puncak yang sama pada 3431-3252; 1631; 1071; 785; dan 562-457 cm-1. Hasil analisa XRD, keasaman dan luas permukaan menunjukkan karakteristik yang berbeda. Kondisi adsorpsi ion logam tembaga (Cu) terjadi pada variasi perbandingan TEOS dan Al(NO3)3.9H2O 1,5, pH 6, waktu kontak 120 menit, persentase penyerapan 41,79% dan kapasitas adsorpsi 0,97865 mg/g.Characterization and Effectivity of Allophane-Like in the Adsorption of Metal Ion of Copper (Cu). The characterization and effectivity testing of allophane-like for adsorption copper (Cu) metal ion has been studied. Allophane-like was prepared by mixing a solution of Tetraethylorthosilicate (TEOS) and Aluminum Nitrate nonahydrate [Al(NO3)3.9H2O] using ratio of 0.5; 0.75; 1; 1.25 and 1.5. The mixing process was done gradually adding NaOH and stirring and heating. The addition of NaOH was done by making a comparison between NaOH and mixture of TEOS dan Al(NO3)3.9H2O in 3:1. The pH of the mixture solution was measured and made acidic solution (pH 3-4). Allophane-like was characterized by infrared spectroscopy (FTIR), XRD, acidity, and surface area. The adsorption evaluation of copper (Cu) metal ion was done on the variation of the composition of TEOS dan Al(NO3)3.9H2O in 0.5; 0.75; 1; 1.25 and 1.5, the pH of a solution of copper (Cu) 3-7 and contact time of 30-120 minutes in batch system. The results revealed that the allophane-like has the same functional group with nature allophane indicated by the FTIR data that has the same peak at 3431-3252; 1631; 1071; 785; and 562-457 cm-1. XRD analysis results, acidity and surface area showed different characteristics. The best conditions adsorption of copper (Cu) metal ion occured at the composition of TEOS dan Al(NO3)3.9H2O in 1.5, pH 6, the contact time of 120 minutes, the absorption percentage of 41.79% and adsorption capacity of 0.97865 mg/g.

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Oh, Young-Mi, Paul V. Nelson et Dean L. Hesterberg. « 256 Evaluation of Phosphate Desorption Characteristics of Clay Minerals for Soilless Root Media ». HortScience 34, n^o 3 (juin 1999) : 486C—486. http://dx.doi.org/10.21273/hortsci.34.3.486c.

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Soilless root media retain very little phosphate. This characteristic necessitates continual application of phosphate, which leads to excessive application and leaching. The phosphate desorption characteristics of synthetic hematite (a-Fe2O3), goethite (a-FeOOH), allophane (Si3Al4O12*nH2O), and a commercial alumina (Al2O3), previously determined for their maximum adsorption capacities, were evaluated to determine their potential for providing a low, constant soil solution phosphate supply with low phosphate leaching from soilless root media. The desorption isotherms of the clay minerals were obtained by introducing 10 mM KCl solution at 0.2 ml/min flow rate into a stirred flow reaction chamber loaded with clay adsorbed with phosphate at maximum adsorption capacity. The suspension in the reaction chamber was held at pH 6.4 during desorption. Effluent solutions were collected for phosphorus analysis until the equilibrium concentration of phosphorus in solution reached 0.05 mg•L-1. Adsorbed phosphorus at 0.05 mg•L-1 equilibrium concentration in solution was in the order allophane (19 mg•g-1) > alumina™ goethite (8 mg•g-1) > hematite (1.3 mg•g-1). The equilibrium concentration of phosphorus in solution over time showed that allophane releases phosphate for a longer time than the other clay minerals at a desirable soil solution concentration for plants, less than 5 mg•L-1. Among the clay minerals tested, allophane showed the most favorable potential to supply phosphate to plants in soilless root media.

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Takahashi, J., et T. Higashi. « Sulphate retention : a simplified method for categorizing soils into allophanic and non-allophanic Andosols ». European Journal of Soil Science 66, n^o 1 (1 décembre 2014) : 65–73. http://dx.doi.org/10.1111/ejss.12211.

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Sparling, G. P., L. Barton, L. Duncan, A. McGill, T. W. Speir, L. A. Schipper, G. Arnold et A. Van Schaik. « Nutrient leaching and changes in soil characteristics of four contrasting soils irrigated with secondary-treated municipal wastewater for four years ». Soil Research 44, n^o 2 (2006) : 107. http://dx.doi.org/10.1071/sr05084.

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Land treatment is the preferred option for the disposal of wastewater in New Zealand. We applied secondary-treated municipal wastewater to 4 contrasting soils (a Gley, Pumice, Recent, and Allophanic Soil) at the rate of 50 mm per week, for 4 years. Amounts of N and P in applied wastewater, leachates, and removed in herbage were measured every 1–4 weeks, and a range of soil chemical, biochemical and physical characteristics measured by destructive sampling after 2 and 4 years. After 4 years, leaching losses amounted to 290–307 kg N on the Gley and Recent Soils, representing approximately 22% of the N applied. Leaching losses from the Allophanic and Pumice Soils were 44 and 69 kg N/ha, respectively, representing <5% of that applied. More than half of the N leached was in organic forms. Leaching losses of P were <5 kg P/ha on the Pumice and Allophanic Soils (< 1% of that applied), 41 kg P/ha from the Recent Soil and 65 kg P/ha from the Gley Soil (8% and 13% of that applied, respectively). After 4 years, the total C and microbial C content in the A horizon of the irrigated Recent Soil were, respectively, 47% and 44% less than non-irrigated cores. All irrigated soils showed a rise in pH of up to 1 unit, and all had a marked increase in the exchangeable Na+ which reached 4–22% ESP. After 4 years, the saturated and near saturated hydraulic conductivity of the Gley Soil had declined from 567 and 40 mm/h to 56 and 3 mm/h, respectively. Allophanic and Pumice Soils are to be preferred over the Recent and Gley Soils for effective treatment of wastewater and to minimise the loss of nutrients to the wider environment.

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