Littérature scientifique sur le sujet « Preatreatments »

Abstrak. Saat ini untuk menentukan kadar lemak pada biji kakao dilakukan dengan mengekstrak biji kakao menggunakan pelarut tertentu yang memakan waktu cukup lama, sehingga metode penentuan mutu secara cepat dan tepat diperlukan untuk menghasilkan komoditas kakao standar mutu tinggi yang dapat diwujudkan dengan metode near infrared reflectance spectroscopy (NIRS). Tujuan yang ingin dicapai dari penelitian ini membandingkan data spektrum antar pretreatment mean normalization (MN) dan de-trending dan (DT) dalam mengkoreksi spektrum NIRS yang dihasilkan serta mengembangkan metode non-destruktif NIRS dalam menduga kandungan lemak pada bubuk biji kakao. Penelitian ini dilakukan di Laboratorium Instrumentasi dan Energi Program Studi Teknik Pertanian pada bulan Maret sampai Mei 2016. Hasil penelitian yang diperoleh bahwa metode NIRS menggunakan preatreatment de-trending dan mean normalization pada panjang gelombang 2300-2400 nm merupakan panjang gelombang yang paling relevan untuk menduga kadar lemak pada bubuk biji kakao. Pendugaan PLS yang didukung pretreatment telah menghasilkan pendugaan yang tergolong good model performance. Pada pendugaan kadar lemak PLS yang sangat baik dalam meningkatkan kinerja PLS pada cross validation adalah de-trending. Abstract. determining fat content in cocoa beans is generally performed by extracting cocoa beans using certain solvent extraction which takes a long time. Determining quality method quickly and exactly required to produce the commodity of high quality standard cocoa that is realized by of near infrared reflectance spectroscopy (NIRS) method. The aim of this research is to compare the spectral data pretreatment mean normalization (MN) and de- trending and (DT) in correcting the NIRS spectrum which is namely and to develop of non-destructive NIRS method in predicting the fat content in cocoa powder. This research was conducted in Instrumentation Laboratory and Energy of Agriculture department from March to May 2016. the results of the research obtained that the NIRS method used de-trending and mean normalization spectra correction methods at a wave-length range of 2300-2400 nm, found to be the most relevant to estimate the fat content in cocoa powder. The estimation of PLS been produced a of good model performance.

High temperature CO2 electroreduction of one of the most promising technologies for converting CO2 to fuels. Electroreduction can typically result in various reduced products but interms of energy efficiency a electrolytic reduction to CO followed by Fischer Tropsch (along with H2) based conversion to hydrocarbon fuels is most preferred. Nickel-Yttria Stabilized Zirconia cermet (Ni/YSZ) is one of the most common electrodes used in solid oxide fuel cells. Lately, various groups have essentially repurposed the same electrode for CO2 electrolysis. However, it suffers from catalyst degradation and poor activity. Successful operation of these electrodes requires presence of H2 in the CO2 stream. In presence of hydrogen CO2 undergoes reverere water gas shift reaction leading to production of CO (non electrochemically) in combination with electrochemical water splitting. Using operando Raman and online Mass Spectroscopy we have followed the evolution of catalyst from preatreatment in various atmospheres to its performance under conditions of operation. The mentioned electrodes were operated at current densities between 100-400 mA/cm2. The operando studies show that Ni active sites oxidize to NiOx in the presence of pure CO2. The poor electronic conductivity of NiO adversely affects the activity of the electrode. The failure is rather drastic at higher current densities. Apart from this, mass spectroscopy confirmed the formation of coke during CO2 electrolysis through Bouduard reaction. The absence of any Raman signal for carbon indicated that the reaction only proceeds to a small extent and the primary deactivation occurs through oxidation of Ni. Small amounts of H2 (~5%) in the mixture prevented the deactivation, but the reaction seemed to proceed through Reverse Water Gas Shift reaction followed by Water electrolysis. Furthermore, we have explored the performance of Ni(Mx)/YSZ type cathodes for CO2 reduction. The electrode performances were compared using three electrode configuration based measurements. Our results indicate that catalysts development in situ is drastically different for mixed metal oxides often resulting in different type of spatial distribution of the metals compared to the pure Ni/YSZ. Many electrodes show promising behavior in terms of both enhanced activity and catalyst stability. Figure 1

Abstrak.Near Infrared Reflectance Spectroscopy (NIRS) telah menjadi salah satu metode non-destruktif yang paling menjanjikan dan dapat digunakan untuk analisis dalam berbagai bidang, termasuk dibidang pertanian. Kandungan kadar lemak pada biji kakao merupakan komponen termahal dari biji kakao. Tujuan yang ingin dicapai dalam penelitian ini adalah membandingkan data spektrum antar pretreatment baseline shift dan derivatif-2 dalam mengkoreksi spektrum NIRS yang dihasilkan serta mengembangkan metode non-destruktive NIRS dalam menduga kandungan lemak pada bubuk biji kakao. Penelitian ini dilakukan di Laboratorium Instrumentasi dan Energi Program Studi Teknik Pertanian pada bulan Maret sampai Mei 2016. Penelitian menggunakan Baseline Shift dan Derivatif-2 sebagai metode koreksi spektrum dan Partial least Square (PLS) sebagai metode pengolah spektrum. Hasil penelitian yang diperoleh bahwa metode NIRS menggunakan preatreatment baseline shift dan derivatif-2 pada panjang gelombang 2300-2400 nm merupakan panjang gelombang yang relevan untuk menduga kadar lemak pada bubuk biji kakao. Pendugaan PLS yang didukung pretreatment telah menghasilkan pendugaan yang tergolong good model performance. Pada pendugaan kadar lemak yang sangat baik dalam meningkatkan kinerja PLS pada validasi silang adalah baseline shift. Kata kunci :Biji kakao, NIRS, Kadar lemak, Metode Nondestruktif Abstract. Near Infrared Reflectance Spectroscopy (NIRS) has become one of the non-destructive method which is the most engagement and can be used to analyze in a variety sectors, including the agriculture sector. The content of the fat content in cocoa beans is one of the most important component than others. The aim of this research was to compare the spectral data between baseline shift and 2nd derivative method in correcting the NIRS spectrum produced and to deloved non-destructive NIRS method in predicting the fat content of cocoa powder. This research is conducted in the Laboratory Instrumentation and Energy of Agriculture Department from March until May 2016. The research uses Baseline Shift and 2nd Derivatives as a method of correction spectrum and Partial least square (PLS) as a regression method. The results of research showed that the NIRS method uses pretreatment baseline shift and 2nd derivative on the wavelength of 2300-2400 nm is a wavelength that is relevant to estimate fat levels in cocoa beans powder. The estimation of PLS that is supported pretreatment has been resulted the estimation that is included a good performance models. In the estimation of fat content is the best in improving PLS performance on cross-validation is a baseline shift. Keywords: Cocoa beans, NIRS, levels of fat, non-destructive method

In 2016, the household waste production in EU-28 amounted to about 215 million tons. As for the most industrialized countries, the annual generation overtakes 500 kg per capita with organic residues representing the predominant fraction (European Commission, 2018a). In Italy, in 2016, domestic waste production reached 30 million tons and the content of Organic Fraction of Municipal Solids Waste (OFMSW) accounted for approximately 20% (ISPRA, 2017). According to future predictions, this percentage is estimated to increase due to the improvement of separate collection systems. Achieving high rates of separation requires a strengthening of the recovery of the OFMSW (Ranieri et al., 2018). In response, the recent European environmental policy is twofold: reduction of landfill disposal and valorisation of organic residues. European and national legislations have focused on diverting OFMSW from landfilling due to potential environmental impacts and risks (i.e. odour and greenhouse gas emissions, groundwater contamination by leachate) and promoting of technologies able to transform a waste to be disposed of in a valuable product. These are the milestones of the European Union action plan for the circular economy (European Commission, 2015) aiming at developing a sustainable future built on alternative sources of energy and materials. A world where products at the end of their life are turned into resources for new purposes (Webster, 2013). In this context, the biorefinery concept fits well with this perspective. A biorefinery is a facility where biomass is converted into bioenergy, biofuels or bioproducts for further industrial or commercial applications (Alibardi and Cossu, 2016). Due to the production of energy and bioproducts (digestate), Anaerobic Digestion (AD) is considered one of the first examples of biorefinery (Sawatdeenarunat et al., 2016). AD has been in use for many decades. To date, it has been primarily aimed at stabilising organic waste, ranging from high solid feedstocks (i.e. animal manure, food waste and agro-industrial biomass), as well as municipal wastewaters. Nowadays, a more open mind is required to look beyond these original applications. According to the biorefinery concept, AD is not regarded as a final disposal treatment but is considered the centrepiece of a larger process with multiple functions such as the production of energy, fuels, heat and biobased materials (i.e.: biopolymers and agricultural fertilizers) and the remediation and stabilization of organic waste (Surendra et al., 2015). The aim of the present work is to overcome the traditional AD of the OFMSW through the study of two lines of research: the application of substrate pretreatments and the adoption of a two-stage digestion technology. Pretreatments of OFMSW can be used to solubilize organic matter prior to AD in order to improve the overall process in terms of faster rates and degree of substrate degradation, thus increasing methane production (Cesaro and Belgiorno, 2014). Several methods have been assessed including mechanical, chemical, biological, thermal, hydrothermal and microwave treatments (Ariunbaatar et al., 2014). The present research focuses its attention on these two latter methods. Autoclaving (A) was tested since is able to release the cellulosic materials enmeshed in lignin resulting in an increase of smaller molecules available for further processing (Heerah et al., 2008; Papadimitrou et al., 2010). Similarly, Microwaving (MW) is an optimal method to solubilize organic solids and as such is a suitable candidate to treat OFMSW (Shahriari et al., 2013). With the aim to further improve AD efficiency, the two-stage process has been identified as a promising method because it allows a better reduction of organic load and increases the overall energy conversion efficiency by generating two gases with high combustion power (Liu et al., 2013). The traditional AD is separated into two reactors connected in series. While the first fermentative phase produces a hydrogen rich biogas and releases volatile fatty acids (VFAs) in the liquid solution, the second phase converts VFAs and the residual biodegradable matter into methane and carbon dioxide (De Gioannis et al., 2013). European Union (European Commission, 2003) promotes hydrogen production, as it is a sustainable energy source with no greenhouse gases emissions from its combustion and high-energy yield. Moreover, the significant generation of organic acids during the fermentative stage can be used to produce polyhydroxyalkanoates (PHAs), a class of bio-polyesters completely biodegradable. Their chief property is the mechanical behaviour that make them comparable to common plastics (Colombo et al., 2017). The dissertation consists of four main chapters. Chapter 1 provides a background of the current OFMSW disposal, introduces the concepts of circular economy and anaerobic biorefinery and defines the objectives of the research. Chapter 2 and Chapter 3 are the core elements of the dissertation since they respectively present the study on substrate pretreatments and the study on the two-stage technology. In these chapters, the state of the art of the two lines of research, the materials and methods used, the results and their discussion are provided. Both investigations follow a scale up strategy. Laboratory batch tests play the role of preliminary experiments where process parameters are varied in order to find the optimum condition to be tested on pilot scale semi-continuous trials. Chapter 4 is the final section where conclusions and future developments of the research are stated. The dissertation summarizes the work of three years of research where laboratory equipment changed and evolved over time. The first year (2016) was dedicated to the study of substrate pretreatments. The second and the third year (2017 and 2018) were devoted to the study of the two-stage process and the composition of the doctorate thesis. This line of research was supported by the Bio2Energy project (Pecorini et al., 2017), a project funded by MIUR-Regione Toscana DGRT 1208/2012 and MIUR-MISE-Regione Toscana DGRT 758/2013 PAR FAS 2007-2013 in sub-programme FAR-FAS 2014 (Linea d’Azione 1.1), which provided new equipment to deeply study the topic.