Pre-treating lignocellulosic biomass is a major technological challenge. Recycling the liquid fraction may reduce chemical inputs and water use but may have lower efficiency. Seven chemical ...pre-treatments of sugarcane bagasse were compared: four acids (sulfuric, citric, phosphoric, and oxalic), two alkaline (sodium and calcium hydroxides) and an oxidative (alkaline hydrogen peroxide). The liquid fractions resulting from these pre-treatments were reused up to five times. After each pre-treatment cycle, the solid fraction was hydrolyzed with Celluclast 1.5L enzyme in a 1:10 solid-liquid ratio. Sulfuric and oxalic acids solubilized 80% of the hemicellulose over the cycles. Sodium and calcium hydroxides and hydrogen peroxide removed lignin until the fourth cycle. About 70% of lignin were removed with alkaline hydrogen peroxide. This pre-treatment lead to the highest glucose release after the enzymatic hydrolysis, above 50% in the three cycles analyzed. The best efficiency in enzymatic hydrolysis followed the order H2O2-alkaline > NaOH > oxalic acid > phosphoric acid > H2SO4 > citric acid > Ca (OH)2. With the recycling, more than 62% in reagents used in the pre-treatment of sugarcane bagasse were saved, enabling an economy in the costs at this stage of the process.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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Breaking with trends in pre-processing? Engel, Jasper; Gerretzen, Jan; Szymańska, Ewa ...
TrAC, Trends in analytical chemistry (Regular ed.),
10/2013, Volume:
50
Journal Article
Peer reviewed
•Pre-processing can make or break data analysis.•Selection of appropriate pre-processing strategies is crucial.•Three types of selection approaches seem commonly used.•All approaches have serious ...drawbacks and can provide misleading results.•Objective approaches to quality parameters are required for future research.
Data pre-processing is an essential part of chemometric data analysis, which aims to remove unwanted variation (such as instrumental artifacts) and thereby focusing on the variation of interest. The choice of an optimal pre-processing method or combination of methods may strongly influence the analysis results, but is far from straightforward, since it depends on the characteristics of the data set and the goal of data analysis. This first critical review is devoted to the selection procedure for appropriate pre-processing strategies. We show that breaking with current trends in pre-processing is essential, as all selection approaches have serious drawbacks and cannot be properly used.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
To understand the influence of the pre-treatment of bentonite with Na+ and Ca2+ on the adsorption of phosphate on zirconium-modified bentonite, three kinds of adsorbent materials including ...zirconium-modified raw, Na+-pretreated and Ca2+-pretreated bentonites were synthesized and characterized firstly, and afterward their adsorption performance and mechanism for phosphate were studied comparatively. The phosphate adsorption ability for zirconium-modified bentonite decreased after the pre-treatment of bentonite with Na+, but it increased after the pre-treatment of bentonite with Ca2+. The maximum phosphate adsorption capacity calculated from the Langmuir isotherm model for zirconium-modified Ca2+-pretreated bentonites (13.4 mg P/g) was much higher than that for the zirconium-modified raw bentonite (9.06 mg P/g). The pre-treatment of bentonite with Na+ and Ca2+ did not change the interaction type between zirconium-modified bentonite and phosphate, i.e., the coordination of phosphate to zirconium. The decreased phosphate adsorption capacity for zirconium-modified bentonite induced by the Na+ pre-treatment could be mainly attributed to the decrease of the specific surface area and the content of exchangeable Ca. The increased phosphate adsorption capacity for zirconium-modified bentonite induced by the Ca2+ pre-treatment could be mainly due to the increase in the amount of exchangeable Ca. Results of this work suggest that the zirconium-modified Ca2+-pretreated bentonite is more suitably used as an adsorbent for the removal of phosphate from wastewater than the zirconium-modified raw and Na+-pretreated bentonites.
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•Zr was used to modify bentonite (BT), and Zr-modified BT (ZrBT) was prepared.•Pre-treatment of BT with Na decreases Ca and specific surface area (SSA) of ZrBT.•Na pre-treatment reduces P sorption due to decrease in Ca content and SSA of ZrBT.•Pre-treatment of BT with Ca increases Ca amount but has no effect on SSA.•Ca pre-treatment enhances P sorption because of increase in Ca amount of ZrBT.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Sludge generated at sewage treatment plants is of environmental concern due to the voluminous production and the presence of a high concentration of emerging contaminants (ECs). This review discusses ...the fate of ECs in sewage sludge treatment with an emphasis on fundamental mechanisms driving the degradation of compounds based on chemical properties of the contaminant and process operating conditions. The removal of ECs in sewage sludge through various treatment processes of sludge stabilization, such as anaerobic digestion (AD), composting, and pre-treatment methods (thermal, sonication, and oxidation) followed by AD, are discussed. Several transformation mechanisms and remediation strategies for the removal of ECs in sludge are summarized. The study concludes that pH, sludge type, and the types of functional groups are the key factors affecting the sorption of ECs to sludge. During conventional waste stabilization processes such as composting, the degradation of ECs depends on the type of feedstock (TOC, N, P, C/N, C/P) and the initial concentration of the contaminant. In AD, the degree of degradation depends on the hydrophilicity of the compound. The estrogenicity of the sludge may sometimes increase due to the conversion to estrogenic compounds. The pre-treatment techniques can increase the partitioning of ECs in the soluble fraction resulting in enhanced biodegradation up to 10–60%. However, the formation of by-products and loss of OH· to scavenging under high organic content during advanced oxidation processes can make the process uneconomical and require further research.
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•Summarizes up to date findings on the fate of ECs in sludge treatment.•Reviews the effect of various sludge treatment techniques for removal of ECs.•Discusses the transformation products and conversion mechanism.•Features the bioremediation methods for degradation of emerging contaminants.•Identifies the key challenges and research needs in ECs removal from sludge.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Bio-oil upgrading can be achieved mainly via three types of methods that are biomass pre-treatment, catalytic upgrading and downstream bio-oil upgrading. The article aim is to review the different ...physicochemical biomass pre-treatment methods used to improve the physiochemical properties of the bio-oils produced from pyrolysis of treated biomass. Biomass pre-treatment could be classified as physical, thermal, chemical and biological methods. The physical methods, such as grinding and densification improve the biomass particle size and density, affecting the heat flow and mass transfer during pyrolysis, while thermal methods, such as torrefaction, decrease the activation energy of the pyrolysis process and increase the amount of hydrocarbons in the produced bio-oil. The chemical methods generally remove the minerals and alkali metals from the biomass, improve its calorific value and enhance other biomass properties. The biomass pre-treatment methods can be integrated with catalytic pyrolysis to enhance the total carbon yield and aromatic hydrocarbons in the bio-oil. This article provides review of the basic principles of the methods, important parameters that affect biomass properties, highlights the key challenges involved in each treatment method and suggests possible future recommendations to further understand the influence of the pre-treatment methods on bio-oil upgrading. In the last section, the effect of integrated catalytic pyrolysis and pre-treatment methods on bio-oil upgrading is provided.
•Biomass pre-treatment methods for bio-oil upgrading are thoroughly discussed.•Basic principles and key advantages of all the methods are highlighted.•Thermal methods improve the biomass structure and energy content.•Chemical treatments remove undesirable inorganic species from the biomass.•Catalytic pyrolysis with pre-treated biomass increases aromatics in the bio-oil.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
As a result of increasing coffee consumption in the world, the amount of coffee waste, which is an important environmental problem, is increasing. Due to their complex organic properties, they should ...not be discharged to landfills. At the same time, these wastes with a porous and cellulosic structure, have high acoustic and heat insulation performances in the building material they are used. In this study, commercial coffee wastes were evaluated without pre‐treatment (CW) and with microwave (MCW) and ultrasound (UCW) pre‐treatment in insulation plaster containing boron. First, the morphological, thermal, and chemical properties of coffee wastes were determined by SEM, TGA, and FTIR analyzes. CW, MCW, and UCW wastes were replaced with insulation plaster at rates of 10%, 20%, and 30%. The physical, mechanical, thermal, and acoustic properties of insulation plasters produced from coffee waste were determined by the analysis methods given in Turkish Standards. According to the results, insulation plasters obtained from pre‐treated wastes were more efficient in terms of mechanical and thermal properties. In terms of thermal and acoustic insulation, UCW30 insulation plasters showed the best performance. Thermal conductivity values were estimated by entering dosage, density, water absorption, bond strength, compressive strength, and moisture values as input dataset to artificial neural network (ANN). The developed ANN model and the experimentally obtained data were compared and it was observed that the results were in harmony. As a result, with this study, a new generation green insulation material was produced by recycling coffee wastes. In this way, a different solution has been found for an important environmental problem.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•Demineralized biomass can increase the yield of BTX in catalytic pyrolysis.•Pyrolysis of demineralized biomass gives a higher organic liquid yield.•Secondary vapor reactions influences the ...performance of catalytic upgrading.•Bio-oil from demineralized biomass presents significantly lower total acid number.
The effect of ash removal pre-treatment of lignocellulosic biomass prior to catalytic pyrolysis for producing biofuels was investigated. Non-catalytic and catalytic pyrolysis of demineralized and raw biomass was performed in Py-GC/MS and bench-scale experiments to study the performance of in-bed and ex-bed upgrading. Pre-treated biomass shows a significant increase in the organic liquid yield in experiments performed at 600 °C: from 31 to 42 wt% compared to raw biomass, as well as a significant reduction of char yield. The performance of in-bed catalytic pyrolysis of pre-treated biomass over HZSM-5 is limited compared to the corresponding raw material. However, ex-bed catalytic pyrolysis of pre-treated biomass at 600 °C results in an overall increased yield of BTX compounds. Pyrolysis vapors from pre-treated biomass present a suitable composition for catalytic upgrading after secondary vapor-phase reactions. Additionally, demineralization reduces the total acid number of derived liquids in catalytic and non-catalytic pyrolysis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This review discusses the latest trend in recovering valuable metals from spent lithium-ion batteries (LIBs) to meet the technological world's critical metal demands. Spent LIBs are a secondary ...source of valuable metals such as Li (5%–7%), Ni (5%–10%), Co (5%–25%), Mn (5–11%), and non-metal graphite. Recycling is essential for the battery industry to extract valuable critical metals from secondary sources to develop new and novel high-tech LIBs for various applications such as eco-friendly technologies, renewable energy, emission-free electric vehicles, and energy-saving lightings. LIB waste is currently undergoing high-temperature pyrometallurgical or hydrometallurgical processes to recover valuable metals, and these processes have proven to be successful and feasible. These methods, however, are not preferable due to the difficulties in controlling the process, secondary waste produced, high operational cost, and high risk of scaling up. Biotechnological approaches can be promising alternatives to pyrometallurgical and hydrometallurgical technologies in metal recovery from LIB waste. Microbiological metal dissolution or bioleaching has gained popularity for metal extraction from ores, concentrates, and recycled or residual materials in recent years. This technology is eco-friendly, safe to handle, and reduces operating costs and energy demands. The pre-treatment process (material preparation), microorganisms used in the bioleaching of LIBs, factors influencing the bioleaching process, methods of enhancing the leaching efficiency, regeneration of electrode materials, and future aspects have been discussed in detail.
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•The bioleaching process, an emerging trend for extracting valuable metals Co, Li, Ni, and Mn from Lithium-ion batteries (LIBs) is discussed.•Extensive information on the pre-treatment process, microorganisms, and their mechanisms in the bioleaching of LIBs.•Factors influencing the bioleaching process, methods for improving leaching efficiency and metal recovery, challenges, and prospects are discussed in detail.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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