Littérature scientifique sur le sujet « Zinc-based activator »

Galvanizing is most often used to protect against corrosion. In repair production zinc coverings are used for protection against corrosion of fastening details and restoration of landing surfaces of lightly loaded details. Electroplating is the process of applying metal to the surface of parts by crystallizing it from an aqueous solution of the corresponding salts (electrolyte) when a direct current passes through them. An electrical circuit is closed by an electrolyte between two conductors called electrodes. The electrode to which the conductor of the external circuit with a plus is attached is called the anode, and with a minus – the cathode. The repaired part, on which the metal is built up, serves as the cathode, and the anode – plates, copper, lead, zinc, cadmium and other metals. In electrolysis, soluble and insoluble anodes are used. In practice, soluble lead is most often used, and insoluble lead is used only for chromium plating. The preparation of the surface of the part before coating (machining, degreasing, digestion) is important for the quality of the coating. The paper identifies the advantages and disadvantages of the method of updating parts of agricultural machinery with galvinic coatings based on zinc. This makes it possible to analyze the results of experiments and evaluate the effectiveness of using this method of restoring parts. The article presents the technological process of restoration of parts by galvinic galvanizing using an activator and the results of experiments using graphs of the dependence of the rate of coating on the current density and the speed of the activator. Determine whether the use of an experimental activator will increase the speed and quality of coating on parts.

The efficiency of sulfur vulcanization reaction in rubber industry is generally improved thanks to the combined use of accelerators (as sulphenamides), activators (inorganic oxides), and co-activators (fatty acids). The interaction among these species is responsible for the formation of intermediate metal complexes, which are able to increase the reactivity of sulfur towards the polymer and to promote the chemical cross-links between the rubber chains. The high number of species and reactions that are involved contemporarily in the process hinders the complete understanding of its mechanism despite the long history of vulcanization. In this process, ZnO is considered to be the most efficient and major employed activator and zinc-based complexes that formed during the first steps of the reaction are recognized to play a main role in determining both the kinetic and the nature of the cross-linked products. However, the low affinity of ZnO towards the rubber entails its high consumption (3–5 parts per hundred, phr) to achieve a good distribution in the matrix, leading to a possible zinc leaching in the environment during the life cycle of rubber products (i.e., tires). Thanks to the recent recognition of ZnO ecotoxicity, especially towards the aquatic environment, these aspects gain a critical importance in view of the urgent need to reduce or possibly substitute the ZnO employed in rubber vulcanization. In this review, the reactivity of ZnO as curing activator and its role in the vulcanization mechanism are highlighted and deeply discussed. A complete overview of the recent strategies that have been proposed in the literature to improve the vulcanization efficiency by reducing the amount of zinc that is used in the process is also reported.

Abstract Concern about the release of eco-toxic zinc species from rubbers into the environment leads to an increasing interest in potential substitutes. Although alternative metal oxides and zinc compounds as activators for sulfur vulcanization have been studied thoroughly, at present no viable alternative has been found to eliminate ZnO completely from rubber compounds, without significantly jeopardizing processing as well as performance characteristics. In this paper, the application of a new activator for sulfur vulcanization will be discussed. This activator is developed based on the assumption that an increase in the availability of Zn2+-ions could lead to a considerable reduction of ZnO in rubber compounds. Montmorillonite clay was used as carrier material and loaded with Zn2+-ions via an ion-exchange process. Application in a wide range of natural and synthetic rubbers has been explored. Results clearly demonstrate that this Zn-Clay can substitute conventional ZnO, retaining the curing and physical properties of the rubber products but reducing the zinc concentration with a factor 10 to 20. Model Compound Vulcanization studies have been used to gain an insight into the mechanism of this activator. It can be concluded that systems with Zn2+-ions on a support represent a new and novel route to reduce the zinc level, and therefore to minimize its environmental impact significantly.

Background: Rubber vulcanization is a consolidated chemical process to enhance the mechanical properties of the polymeric material by sulfur crosslinking of the polymer chains, such as rubber. Vulcanization Activators are important rubber processing additives that activate sulfur cure and improve the efficiency of sulfur-based cure systems. The most common activator is zinc fatty acid ester that is often formed in-situ by the reaction of fatty acid with zinc oxide. Although zinc is one of the less harmful heavy metals, according to European Council Directive 2004/73/EC, the reduction of zinc level in the environment has become an important task because of its toxic effect on aquatic organisms. : The current study reviews the research achievements in the field of reducing the consumption of micronutrients of ZnO particles based on the use of nanoparticles instead of them in the polymer industry. Among the proposed methods, due to the less environmental effects of magnesium oxide, the use of MgO nanoparticles instead of zinc oxide has also achieved good results. Objective: The aim of this paper is considering suggested different methods on the reduction of using ZnO particles in related industries, the use of ZnO nanoparticles has had better results than its particles. In addition, due to the less environmental effects of magnesium oxide, magnesium oxide nanoparticles can be used instead of micronutrients of zinc oxide. Overall, the results of various investigations show that reducing the diameter of the zinc oxide particles reduces the amount required for curing the rubber and thus reduces its toxic effects. Also, the use of magnesium oxide nanoparticles instead of zinc oxide in different concentrations is investigated.

Leucine-rich repeat-containing 8 (LRRC8) volume-regulated anion channels (VRACs) play important physiological roles in diverse cell types and may represent therapeutic targets for various diseases. To date, however, the pharmacological tools for evaluating the druggability of VRACs have been limited to inhibitors, as no activators of the channel have been reported. We therefore performed a fluorescence-based high-throughput screening (HTS) of 1,184 Food and Drug Administration-approved drugs for compounds that increase VRAC activity. The most potent VRAC potentiator identified was zinc pyrithione (ZPT), which is used commercially as an antifouling agent and for treating dandruff and other skin disorders. In intracellular Yellow Fluorescent Protein YFP(F46L/H148Q/I152L)-quenching assays, ZPT potentiates the rate and extent of swelling-induced iodide influx dose dependently with a half-maximal effective concentration (EC50) of 5.7 µM. Whole cell voltage-clamp experiments revealed that coapplication of hypotonic solution and 30 µM ZPT to human embryonic kidney 293 or human colorectal carcinoma 116 cells increases the rate of swelling-induced VRAC activation by approximately 10-fold. ZPT potentiates swelling-induced VRAC currents after currents have reached a steady state and activates currents in the absence of cell swelling. Neither ZnCl2 nor free pyrithione activated VRAC; however, treating cells with a mixture of ZnCl2 and pyrithione led to robust channel activation. Finally, the effects of ZPT on VRAC were inhibited by reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) and NAD(P)H oxidase inhibitor diphenyleneiodonium chloride, suggesting the mechanism of action involves ROS generation. The discovery of ZPT as a potentiator/activator of VRAC demonstrates the utility of HTS for identifying small-molecule modulators of VRAC and adds to a growing repertoire of pharmacological tool compounds for probing the molecular physiology and regulation of this important channel.

Background: Metal oxide or metal oxide composite nanoparticles are attaining tremendous importance due to their catalytic activities for various organic transformations. Objective: To report the one-pot synthesis of xanthene derivatives prepared by ZnS-Fe2O3-Ag composite under solvent-free conditions. Method: To prepare nanocomposite by a facile and simple hydrothermal approach. Results: The prepared composite is smaller (17.56 nm) in size and can be easily separable, recycled and reused six times without any significant loss of catalytic activity with excellent yields. In short reaction time, great catalytic activity was perceived with no co-catalyst and any other activator. Conclusion: In conclusion, ZnS-Fe2O3-Ag composite provides a simple, economical, efficient and greener method for the synthesis of one-pot multicomponent reaction of aldehyde with 1,3-diketones under solvent free conditions for the synthesis of 1,8-dioxooctahydro xanthenes. In short reaction time, great catalytic activity was perceived with no co-catalyst and any other activator.

In order to improve adsorption of macromolecular contaminants and promote the growth of microorganisms, active carbon for biological wastewater treatment or follow-up processing requires abundant mesopore and good biophile ability. In this experiment, biophile mesopore active carbon is produced in one-step activation with orange peel as raw material, and zinc chloride as activator, and the adsorption characteristics of orange peel active carbon is studied by static adsorption method. BET specific surface area and pore volume reached 1477 m2/g and 2.090 m3/g, respectively. The surface functional groups were examined by Fourier transform infrared spectroscopy (FT-IR). The surface of the as-prepared activated carbon contained hydroxyl group, carbonyl group, and methoxy group. The analysis based on X-ray diffraction spectrogram (XRD) and three-dimensional fluorescence spectrum indicated that the as-prepared activated carbon, with smaller microcrystalline diameter and microcrystalline thickness and enhanced reactivity, exhibited enhanced adsorption performance. This research has a deep influence in effectively controlling water pollution, improving area water quality, easing orange peel waste pollution, and promoting coordinated development among society, economy, and environment.

Zinc oxide performs as the best cure activator in sulfur-based vulcanization of rubber, but it is regarded as a highly toxic material for aquatic organisms. Hence, the toxic cure activator should be replaced by a non-toxic one. Still, there is no suitable alternative industrially. However, binary activators combining ZnO and another metal oxide such as MgO can largely reduce the level of ZnO with some improved benefits in the vulcanization of rubber as investigated in this research. Curing, mechanical, and thermal characteristics were investigated to find out the suitability of MgO in the vulcanization of rubber. Curing studies reveal that significant reductions in the optimum curing times are found by using MgO as a co-cure activator. Especially, the rate of vulcanization with conventional 5 phr (per hundred grams) ZnO can be enhanced by more than double, going from 0.3 Nm/min to 0.85 Nm/min by the use of a 3:2 ratio of MgO to ZnO cure activator system that should have high industrial importance. Mechanical and thermal properties investigations suggest that MgO as a co-cure activator used at 60% can provide 7.5% higher M100 (modulus at 100% strain) (0.58 MPa from 0.54 MPa), 20% higher tensile strength (23.7 MPa from 19.5 MPa), 15% higher elongation at break (1455% from 1270%), 68% higher fracture toughness (126 MJ/m3 from 75 MJ/m3), and comparable thermal stability than conventionally using 100 % ZnO. Especially, MgO as a co-cure activator could be very useful for improving the fracture toughness in rubber compounds compared to ZnO as a single-site curing activator. The significant improvements in the curing and mechanical properties suggest that MgO and ZnO undergo chemical interactions during vulcanization. Such rubber compounds can be useful in advanced tough and stretchable applications.

Alkali activation of fly ash can a promising alternative of the system to improve adsorption capability of fly ash. In finding the best chemical composition of the activator solution, geopolymer has been synthesized using molar ratios of Na2O/SiO2 0.16, 0.3, and 0.5 (Gr1, Gr3, Gr5). The results indicated that the geopolymer synthesized with a ratio molar of Na2O/SiO2 0.3 (Gr3) improved the adsorption properties of fly ash substantially. Gr3 was characterized by BET, XRD, and FTIR. The batch experiment was conducted at the different duration and initial concentrations. The equilibrium sorption data were fitted for the Langmuir and Freundlich equations. The maximum sorption capacities calculated from Langmuir isotherm was 54 mg g-1 and 47 mg g-1 for Cu (II) and Zn (II) respectively. The kinetic data reveal that the pseudo-second order model was appropriate for a description of the kinetic performance.

In recent years, the use of sacrificial anodes for cathodic protection in reinforced concrete structures has increased, reflecting ease of installation, low-maintenance requirements, as well as desirability in prestressed concrete structures where the naturally controlled protection potential decreases the risk of hydrogen embrittlement. Zinc-based alloys have been among the most evaluated galvanic materials for concrete structures, especially in the United States, in many applications: thermal spray, superficial metal/mesh with and without hydrogel adhesive, embedded in concrete (point anodes) with or without salt activator, etc. However, the protection capacity lifetime of zinc alloys as used has been questioned based both on laboratory and on field application studies. Aluminum alloys have also been evaluated, sometimes showing better results as anode materials than zinc alloys. However, both zinc and aluminum alloy anodes may experience limited applicability in concrete structures exposed only to atmospheric conditions, as opposed to those in immersed, tidal, and splash zone service. This paper presents a review of the research work in the literature to date for both laboratory and field evaluations, toward identifying technically relevant situations where the use of sacrificial anodes may or may not be a practical option for reinforcement protection in concrete structures.

I nanocompositi di gomma (NC) sono materiali comunemente usati nell’industria degli pneumatici. Le proprietà meccaniche dipendono sia dall’aggiunta delle nanoparticelle (NP) di filler rinforzanti e dal processo di vulcanizzazione. La reazione di vulcanizzazione a base zolfo si basa sulla formazione di un reticolo chimico tra le catene di polimero attraverso ponti mono-, bi- e poli-sulfurei. L’incremento della velocità di reazione e dell’efficienza di reticolazione è consentito da un complesso sistema catalitico, composto da acceleranti (ad esempio sulfenammidi), attivatori (ossidi metallici) e co-attivatori (acidi grassi). L’ossido di zinco (ZnO) è il principale attivatore usato industrialmente; un ruolo fondamentale è assegnato agli ioni zinco, in grado di influenzare aspetti cinetici e meccanicistici, come il processo di accorciamento dei ponti sulfurei nei prodotti di reticolazione (associato a maggiori densità di reticolo). Ciononostante, la bassa dispersione dell’ossido di zinco, dovuta ad una bassa affinità verso il polimero, porta ad un uso ingente di ZnO nelle gomme (3-5 parti per cento di gomma) e a problemi ambientali, connessi al rilascio dello zinco durante il ciclo di vita degli pneumatici. In questo quadro, lo scopo del progetto di dottorato è stato lo sviluppo di attivatori innovativi a base zinco per il processo di vulcanizzazione, per ridurre il quantitativo di ZnO micro-cristallino nel processo industriale e diminuire il rilascio di zinco, mantenendo un’elevata efficienza del processo. A tal scopo, l’introduzione di siti reattivi di zinco è stata indagata. Partendo da NP di ZnO ancorate sulla superficie della silice (ZnO/SiO2), siti singoli di zinco (Zn/SiO2) dispersi su silice sono stati sintetizzati, sfruttando i vantaggi derivanti da una maggiore dispersione dello zinco nel composito e incrementando la reattività e disponibilità dell’attivatore nella reazione. Inizialmente, la sintesi dei due materiali e le loro proprietà sono state studiate, tramite analisi strutturali, morfologiche e di superficie. NP di ZnO amorfe, con dimensioni e percentuali di carico su silice variabili, sono state sintetizzate utilizzando una procedura ottimizzata di tipo sol-gel, basata sul fenomeno di idrolisi e condensazione di un precursore di zinco in ambiente basico. Inoltre, centri isolati di zinco (II) sono stati preparati in una reazione a due fasi, in cui la silice è pre-funzionalizzata con un agente ancorante (3-amminopropil)trietossisilano, APTES) e in seguito fatta interagire con un precursore di zinco. La caratterizzazione sperimentale ha suggerito che ogni centro di zinco isolato fosse coordinato con due gruppi amminici e due gruppi labili (idrossidi o nitrati), che potessero promuovere una maggiore reattività. I test in NC di gomma, comparati con NC preparati con ZnO micro-cristallino, hanno dimostrato maggiori efficienze di vulcanizzazione, migliorate proprietà meccaniche, elevate densità di reticolo e maggiore rinforzo in presenza dei due attivatori, usando metà del quantitativo tradizionale di ZnO. La cinetica di reazione è stata studiata tramite un approccio modello (Model Compound Vulcanization, MCV), evidenziando una migliore cinetica di processo e differenti meccanismi di reazione per ZnO/SiO2 e Zn/SiO2. Inoltre, i centri di zinco isolati hanno dimostrato di comportarsi da siti catalitici eterogenei, con una potenziale riduzione del rilascio di zinco e conseguenze dirette sulla distribuzione della reticolazione nel composito vulcanizzato, evidenziato tramite analisi avanzate di tipo morfologico e meccanico. Infine, la modulazione dei parametri strutturali degli attivatori e il loro uso in sistemi non convenzionali, che includono compositi rinforzati da filler anisotropici e polimeri modificati organicamente, hanno dimostrato la possibile regolazione della reattività e l’alta versatilità dei due attivatori per applicazioni in diversi sistemi.
Rubber nanocomposites (NCs) are commonly used materials in tyres industries. Their mechanical properties are the combined result of the addition of reinforcing filler nanoparticles (NPs) and the vulcanization process. Sulphur vulcanization reaction is based on the formation of a chemical cross-link between polymer chains through mono-, bi- and poly-sulphide bridges. The enhancement of the vulcanization rate and cross-linking efficiency is achieved thanks to a complex catalytic system, composed of accelerators (as sulphenamides), activators (metal oxides) and co-activators (fatty acids). Zinc oxide (ZnO) is the primary industrial activator and a main role is recognized to zinc ions, able to influence both kinetic and mechanistic aspects of the reaction, through the shortening of sulphur bridges in the products (associated to higher cross-linking densities). Nevertheless, some drawbacks are connected to the low dispersion of ZnO, because of the low affinity with the rubber, such as the use of high ZnO amount in rubber (3-5 parts per hundred rubber) and environmental issues, due to zinc release during the lifecycle of tyres. In this scenario, the aim of the PhD project is the development of innovative zinc-based activators for rubber vulcanization process, to reduce the amount of microcrystalline ZnO used in the industrial process and to decrease the zinc leaching during the preparation and use of the material, keeping a high vulcanization efficiency. Thus, the introduction of more active zinc species in the form of reactive sites has been proposed. Starting from nanosized ZnO particles anchored onto surface silica particles (ZnO/SiO2), single zinc sites (Zn/SiO2) dispersed on silica were synthesized, to exploit the advantages derived from the higher distribution, while increasing the availability and reactivity of the activator towards the other vulcanization reagents. In the first part, the syntheses of the materials were studied and their properties deeply investigated, through structural, morphological and surface analyses. The formation of amorphous ZnO NPs with tunable zinc loading and size on silica was achieved exploiting an optimized sol-gel procedure, based on hydrolysis and condensation of a zinc precursor in a basic environment. Besides, isolated zinc(II) centres anchored to silica were synthesized in a two-step reaction, in which silica was pre-functionalized with a grafting agent ((3-aminopropyl)triethoxysilane, APTES) and then reacted with a zinc precursor. The experimental characterization suggested the coordination of each zinc isolated centres to two amine groups and two labile groups (hydroxide or nitrate), promoting a higher reactivity. Both ZnO/SiO2 and Zn/SiO2 were tested as activators in rubber NCs and compared to microcrystalline ZnO; higher vulcanization efficiencies and improved mechanical properties were achieved, with increased cross-linking densities, using half of the conventional amount of ZnO. Lately, the kinetic of the vulcanization reaction was studied thanks to a model approach, called “Model Compound Vulcanization” (MCV). This study highlighted that the vulcanization process proceeded with an improved kinetic and following different reaction mechanisms. In particular, Zn centres were proved to behave as heterogeneous catalytic sites during the reaction, with a potential impact on the reduction of zinc leaching from rubber NCs and a direct consequence on the cross-linking distribution of the vulcanized rubber NCs, evidenced through advanced morphological and mechanical analyses. Finally, the modulation of the structural parameters of the activators and the use into non-conventional systems, including anisotropic NPs reinforced NCs and organically modified polymers, demonstrated the possible modulation of their reactivity and the high versatility of the materials for applications into different systems.

碩士
國立臺灣大學
應用力學研究所
102
In this research, a novel volatile organic compound (VOC) sensing layer was fabricated. The advantage of the fabrication is the low cost and the simple equipment. We use the Zinc Oxide (ZnO) as the sensing material to detect the reduction gas. By the characteristic of oxidation of the surface of ZnO, the oxygen ion will become reduction when the surface is in the environment with volatile organic compound. ZnO seed layers were deposited by RF Sputter. ZnO nanowires were grown in aqueous of zinc acetate and hexamethylenetetramine. With UV pretreatment, ZnO nanowires change from flower-like to well-aligned and vertical growth nanowires. The different nanowires morphologies can be fabricated by different growth time and high temperature annealing. The ZnO films were characterized by field-emission scanning electron microscopy (FE-SEM) to illustrate the morphologies. The signal of the nanowires structure was linear with the different concentration. The nanowires structure not only enhances light absorption but also the gas sensing results. On the other hand, we use the hydrothermal method to fabricate nanowires on the metallic interdigitated electrodes and apply this technology to gas sensing area successfully.

Traditional plant breeding depends on spontaneous and induced mutations available in the crop plants. Such mutations are rare and occur randomly. By contrast, molecular breeding and genome editing are advanced breeding techniques that can enhance the selection process and produce precisely targeted modifications in any crop. Identification of molecular markers, based on SSRs and SNPs, and the availability of high-throughput (HTP) genotyping platforms have accelerated the process of generating dense genetic linkage maps and thereby enhanced application of marker-assisted breeding for crop improvement. Advanced molecular biology techniques that facilitate precise, efficient, and targeted modifications at genomic loci are termed as “genome editing.” The genome editing tools include “zinc-finger nucleases (ZNFs),” “transcription activator-like effector nucleases (TALENs),” oligonucleotide-directed mutagenesis (ODM), and “clustered regularly interspersed short palindromic repeats (CRISPER/Cas) system,” which can be used for targeted gene editing. Concepts of molecular plant breeding and genome editing systems are presented in this chapter.

Al-based alloys and mechanochemically activated aluminum powders were prepared in this study, and the regularities of their hydrolysis reaction with water were studied. Aluminum alloys were prepared by melting aluminum with additions of Ga–In–Sn eutectic (5 wt.%), bismuth (3 wt.%), antimony (3 wt.%), or zinc (3 wt.%). The temperature-dependent kinetics of their hydrolysis in a temperature range 25–70 °C was studied by using a volumetric technique. The most efficient activation of the hydrolysis process was achieved for the Al–Ga– In–Sn-Zn alloy, particularly at low temperatures (5 and 25° C). The addition of bismuth to the Al–Ga–In–Sn alloy significantly decreases the hydrolysis rate, whereas the addition of antimony has only a weak effect on the process, despite the fact that the standard electrode potentials of bismuth and antimony have rather close values. Commercially available aluminum PA-4 and ASD-1 powders were mechanochemically activated by Ga–In–Sn or Ga–In–Sn–Zn eutectic alloys (5 wt.%) and graphite (1–3 wt.%) in a mixer type ball mill. Subsequently, they were pressed (P = 4 MPa) into the pellets, which were used to generate hydrogen from water via the hydrolysis process. X-ray diffraction study of the milled PA-4 powder revealed the presence of four phases, including aluminum, graphite, and two In–Sn intermetallic compounds (In3Sn and In1–xSnx, were x ≈ 0.04). The quantitative analysis by EDX showed a uniform distribution of the activating additives over the pellet surface, while the graphite was partly aggregated. Studies on the hydrolysis kinetics when utilizing Al-based pellets demonstrated that the process readily proceeds at temperatures ≥ 5° C. At the same time, the efficiency of hydrogen generation depends on the amount of the added graphite, particle size of aluminum powders, duration and medium of their mechanochemical treatment, and the hydrolysis temperature.

Tremendous progress has been achieved in the field of gene editing in plants, such as with the use of zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR). Because of the potential advantages associated with mutant creation and crop germplasm innovation, genome editing technology has been rapidly developed and widely used in crop improvement in recent years. In this review, we aim to document some of the important recent developments and applications of genome-editing tools, especially with respect to gene knock-ins. We introduce the mechanism underlying knock-ins and different outcomes of insertion. We also discuss genome editing tools and methods developed to improve insertion efficiencies. Additionally, we review the recent trends in genetic editing biotechnologies; several strategies are being developed to further improve the efficiency of plant gene knock-ins. Undoubtedly, CRISPR/Cas technology will boost the development of new plant breeding techniques tremendously.

Abstract A large quantity of sludges resulting from the treatment of MWWTP (Municipal Wastewater Treatment Plant) effluent is generated annually following the increase of population density and acceleration of urbanization. Sludge production in Europe has been predicted by around 12 million tons in 2020. As a solid waste, appropriate disposal of Municipal Sewage Sludge (MSS) has been taken seriously due to its larger volume and toxic substances such as heavy metals. Electrokinetic remediation has more advantages in heavy metals uptake compared to other technologies, due to the ability to treat soils in-situ and to remove heavy metals from soils. In this work, it was studied the remediation of MSS by the electrokinetic remediation coupled with activated carbon (AC) as a permeable reactive barrier (PRB). It was applied an electric current of 3 V cm−1 and it was used an AC/sludge ratio of 30 g kg−1 of contaminated sludge for the preparation of the PRB. In each trial, the evolution of cadmium (Cd), lead (Pb), copper (Cu), chromium (Cr), nickel (Ni) and zinc (Zn) removal from the sludge were evaluated. Results proved that this process is perfectly suited for the removal of chromium, nickel and zinc metals from the sludge. At the end of the operation time, it was achieved a maximum removal rate of 56% for chromium, 73% for nickel and 99% for zinc, with initial concentrations of 2790 mg kg−1, 2840 mg kg−1, and 94200 mg kg−1, respectively. Based on these results, it was proved the technical viability of the proposed technology (electrokinetic with AC as a permeable reactive barrier) to treat municipal sewage sludges.

Abstract. Graphene oxide is a nanomaterial of very high adsorption capabilities due to its vast surface area. Moreover, numerous oxygen functional groups present on the surface of graphene oxide enable its modifications to be performed. The authors aimed to create adsorbents based on activated carbon impregnated with amine-modified graphene oxide. The study showed that the amino group functionalisation, both with the use of ethylenediamine (GO-EDA) and using polyaniline (GO-PANI), causes the adsorbent to remove lead, mercury, copper, and iron ions from aqueous solutions very efficiently. Both adsorbents also reduce the cadmium, nickel, zinc, and arsenic ion content, however to a lesser extent but nevertheless still significantly. The two sorbents can be applied in field water treatment to remove specific contaminants.

Abstract Thermal spraying for joining and filling of aluminum substrates under atmospheric conditions represents an enrichment in soldering technology. In a respective process, rod-, wire- or cored wire type, zinc-aluminum-based spray materials are applied for joining components or area filling of substrate and fused simultaneously. The advantages, in contrast to soldering, result from the direct application of the spray material, in particular also in constraint positions, and an uncomplex processing, which enables a conditioned inline capability and the use as a comparatively simple procedure for construction-site services or repairs. The aluminum substrate surface and spray material passivation, which would prevent a successful fusing, can be effectively suppressed by the use of a flux in the cored wires as well as straight on the substrates or a brushing activation.

Zinc production by solar carbothermic reduction of ZnO offers a CO2 emission reduction by a factor of 5 vis-a´-vis the conventional fossil-fuel-based electrolytic or Imperial Smelting processes. Zinc can serve as a fuel in Zn-air fuel cells or can be further reacted with H2O to form high-purity H2. In either case, the product ZnO is solar-recycled to Zn. We report on experimental results obtained with a 5 kW solar chemical reactor prototype that features two cavities in series, with the inner one functioning as the solar absorber and the outer one as the reaction chamber. The inner cavity is made of graphite and contains a windowed aperture to let in concentrated solar radiation. The outer cavity is well insulated and contains the ZnO-C mixture that is subjected to irradiation from the inner graphite cavity. With this arrangement, the inner cavity protects the window against particles and condensable gases and further serves as a thermal shock absorber. Tests were conducted at PSI’s Solar Furnace and ETH’s High-Flux Solar Simulator to investigate the effect of process temperature (range 1350–1600 K), reducing agent type (beech charcoal, activated charcoal, petcoke), and C:ZnO stoichiometric molar ratio (range 0.7–0.9) on the reactor’s performance and chemical conversion. In a typical 40-min solar experiment at 1500 K, 500 g of a ZnO-C mixture were processed into Zn(g), CO, and CO2. Thermal efficiencies of up to 20% were achieved.

Abstract Wastes are produced during petroleum production as well as agricultural operations. The treatment of oilfield produced water (PW) for reuse using activated carbons (ACs) derived from Elaeis Guineensis biomasses was investigated. The biomasses (palm kernel shells, PKS and empty palm bunch, EPB) were prepared and converted to biochars by pyrolysis, and then activated with 0.2M HCl at a temperature of 450°C. The ACs were characterised for pH, bulk density, iodine numbers, ash and moisture contents, particle size, specific surface area, pore volume and size. The characteristics of the adsorbents indicate that iodine numbers ranged from 700.14-1181.48mg/g for EPB; 525.10-918.93mg/g for PKS; ash content ranged from 6.20-6.80% for EPB and 2.00-2.80% PKS. The AC particle sizes were optimized, and 300µm-size for both adsorbents showed good prospects based on iodine number. For this particle size, the mean pore volume and size, and specific surface area acquired using the Quantachrome NovaWin Instruments, version 11.03, were determined as 0.1689 cc/g, 3.102nm, and 1065 m2/g, for EPB, and 0.1353cc/g, 1.956nm and 300 m2/g, for PKS. The SEM results confirmed the surface morphology of the adsorbents, while XRF results showed that the adsorbents have high percentages of compounds of silicon, potassium, carbon, and calcium, but the PKS has no magnesium and barium. The EPB has no barium but 9.6% moles magnesium. Both have very low percentages of the heavy metals, namely, iron, chromium, aluminium, cobalt, zinc, nickel and copper. This implies that the ACs can effectively treat produced water to remove these heavy metal ions.

Статья посвящена теме переработки отвалов рудника Байжансай в Туркестанской области, который, в настоящее время, является местом отходов полиметаллической руды в количестве примерно 6,5 тонн. В материале рассматривается потенциальная возможность применения данных отходов для извлечения полезных компонентов, таких как из цветных металлов - свинец и цинк, из благородных серебро и из редкоземельных - германий, индий, селен, теллур и таллий. При использовании данной переработки можно не только снизить негативное влияние отходов на окружающую среду, но и добыть полиметаллические руды, которые можно использовать в производстве стекол, оптики, в производстве высокоответственных подшипников для двигателей, для защиты антикоррозионных металлопокрытий и во многих других сферах, указанных в данной статье. Авторами было изучено технологическое решение по переработке отходов Байжансая. На основании полученных данных, была разработана технологическая модель, сочетающего в одном аппарате процессы электрохимической активации воды, флокуляции, газонасыщения и разделения микропримесей редких и рассеянных элементов (РРЭ), цветных металлов из технологических растворов и жидких техногенных отходов. Данный модуль является аналогом "классического" аппарата, но преимуществом предложенного модуля является меньшая энерго затратность, более эффективная работа по временным аспектам и по габаритам. The article is devoted to the topic of processing the dumps of the Baizhansai mine in the Turkestan region, whichis a place of waste of polymetallic ores in the amount of about 6.5 tons. The article discusses the potential use of these wastes for the extraction of useful components, such as non-ferrous metals - lead and zinc, precious silver, and rare-earth metals - germanium, indium, selenium, tellurium and thallium. With the use of this processing, it is possible not only to reduce the negative impact of waste on the environment, but also to extract polymetallic ores that can be used in the production of glass, optics, in the production of highly critical bearings for engines, to protect anti-corrosion metal coatings and in many other areas specified in this article. The authors studied the technological solution for the processing of waste from Baizhansai. Based on the data obtained, the authors of the article have developed a technological module that combines in one apparatus the processes of electrochemical activation of water, flocculation, gas saturation and separation of trace impurities of rare and trace elements (RRE), non-ferrous metals from technological solutions and liquid man-made waste. This module is analogous to the "classical" apparatus, but the advantage of the proposed module is lower energy consumption, more efficient work in terms of time and dimensions.

Citrus, like many other tropical and subtropical fruit are sensitive to chilling temperatures. However, application of a pre-storage temperature conditioning (CD) treatment at 16°C for 7 d or of a hot water brushing (HWB) treatment at 60°C for 20 sec remarkably enhances chilling tolerance and reduces the development of chilling injuries (CI) upon storage at 5°C. In the current research, we proposed to identify and characterize grapefruit genes that are induced by CD, and may contribute to the acquisition of fruit chilling tolerance, by two different molecular approaches: cDNA array analysis and PCR cDNA subtraction. In addition, following the recent development and commercialization of the new Affymetrix Citrus Genome Array, we further performed genome-wide transcript profiling analysis following exposure to CD and chilling treatments. To conduct the cDNA array analysis, we constructed cDNA libraries from the peel tissue of CD- and HWB-treated grapefruit, and performed an EST sequencing project including sequencing of 3,456 cDNAs from each library. Based on the obtained sequence information, we chose 70 stress-responsive and chilling-related genes and spotted them on nylon membranes. Following hybridization the constructed cDNA arrays with RNA probes from control and CD-treated fruit and detailed confirmations by RT-PCR analysis, we found that six genes: lipid-transfer protein, metallothionein-like protein, catalase, GTP-binding protein, Lea5, and stress-responsive zinc finger protein, showed higher transcript levels in flavedo of conditioned than in non-conditioned fruit stored at 5 ᵒC. The transcript levels of another four genes: galactinol synthase, ACC oxidase, temperature-induced lipocalin, and chilling-inducible oxygenase, increased only in control untreated fruit but not in chilling-tolerant CD-treated fruit. By PCR cDNA subtraction analysis we identified 17 new chilling-responsive and HWB- and CD-induced genes. Overall, characterization of the expression patterns of these genes as well as of 11 more stress-related genes by RNA gel blot hybridizations revealed that the HWB treatment activated mainly the expression of stress-related genes(HSP19-I, HSP19-II, dehydrin, universal stress protein, EIN2, 1,3;4-β-D-glucanase, and SOD), whereas the CD treatment activated mainly the expression of lipid modification enzymes, including fatty acid disaturase2 (FAD2) and lipid transfer protein (LTP). Genome wide transcriptional profiling analysis using the newly developed Affymetrix Citrus GeneChip® microarray (including 30,171 citrus probe sets) revealed the identification of three different chilling-related regulons: 1,345 probe sets were significantly affected by chilling in both control and CD-treated fruits (chilling-response regulon), 509 probe sets were unique to the CD-treated fruits (chilling tolerance regulon), and 417 probe sets were unique to the chilling-sensitive control fruits (chilling stress regulon). Overall, exposure to chilling led to expression governed arrest of general cellular metabolic activity, including concretive down-regulation of cell wall, pathogen defense, photosynthesis, respiration, and protein, nucleic acid and secondary metabolism. On the other hand, chilling enhanced various adaptation processes, such as changes in the expression levels of transcripts related to membranes, lipid, sterol and carbohydrate metabolism, stress stimuli, hormone biosynthesis, and modifications in DNA binding and transcription factors.