Different Types Of Feedstock Research Articles

Recent Advances in Additive Friction Stir Deposition: A Critical Review

Additive friction stir deposition (AFSD) is a novel solid-state additive manufacturing method developed on the principle of stirring friction. Benefits from its solid-phase properties, compared with traditional additive manufacturing based on melting–solidification cycles, AFSD solves the problems of porosity, cracks, and residual stress caused by the melting–solidification process, and has a significant improvement in efficiency. In AFSD, the interaction between feedstocks and high-speed rotating print heads suffers severe plastic deformation at high temperatures below the melting point, ending up in fine, equiaxed recrystallized grains. The above characteristics make components by AFSD show similar mechanical behaviors to the forged ones. This article reviews the development of AFSD technology, elaborates on the basic principles, compares the macroscopic formability and material flow behavior of AFSD processes using different types of feedstocks, summarizes the microstructure and mechanical properties obtained from the AFSD of alloys with different compositions, and finally provides an outlook on the development trends, opportunities, and challenges to the researchers and industrial fields concerning AFSD.

A comprehensive review on anaerobic digestion with focus on potential feedstocks, limitations associated and recent advances for biogas production.

With the escalating energy demand to accommodate the growing population and its needs along with the responsibility to mitigate climate change and its consequences, anaerobic digestion (AD) has become the potential approach to sustainably fulfil our demands and tackle environmental issues. Notably, a lot of attention has been drawn in recent years towards the production of biogas around the world in waste-to-energy perspective. Nevertheless, the progress of AD is hindered by several factors such as operating parameters, designing and the performance of AD reactors. Furthermore, the full potential of this approach is not fully realised yet due the dependence on people's acceptance and government policies. This article focuses on the different types of feedstocks and their biogas production potential. The feedstock selection is the basic and most important step for accessing the biogas yield. Furthermore, different stages of the AD process, design and the configuration of the biogas digester/reactors have been discussed to get better insight into process. The important aspect to talk about this process is its limitations associated which have been focused upon in detail. Biogas is considered to attain the sustainable development goals (SDG) proposed by United Nations. Therefore, the huge focus should be drawn towards its improvements to counter the limitation and makes it available to all the rural communities in developing countries and set-up the pilot scale AD plants in both developing and developed countries. In this regard, this article talks about the improvements and futures perspective related to the AD process and biogas enhancement.

Co-feeding biomass and municipal solid waste for enhanced hydrogen and synthetic natural gas yields employing chemical looping process

Synthetic natural gas (SNG) is a promising alternative to conventional fossil natural gas. This study proposes a chemical looping hydrogen production (CLHP)-based route for SNG synthesis and elucidates the insights and necessities of appropriately co-feeding different types of feedstocks to maximize the yields of hydrogen and subsequent SNG. A study employing microalgae (MA) and refuse-derived fuel (RDF) as biomass and municipal solid waste representatives demonstrates that blending MA with RDF in a proportion of 40 %:60 % (0.4MA-0.6RDF) eradicates oxygen carrier splitting. This boosts fuel-to-hydrogen efficiency from 74.1 % to 77.8 %, as well as subsequent thermal and exergy efficiencies of SNG production from 59.07 % and 55.8 % to 61.3 % and 57.92 %, respectively, compared to the use of MA alone. Nonetheless, blending fuels does not yield substantial economic advantages, as evidenced by the levelized cost of SNG production using pure MA and the 0.4MA-0.6RDF blend remaining at approximately 0.63 USD/Nm3.

(Corrosion Division Rusty Award for Mid-Career Excellence) Enhancing the Corrosion Resistance of Additively Manufactured Metallic Materials: The Role of Feedstock Modification

The properties of metallic materials produced through additive manufacturing (AM), including their corrosion behavior, depend on various parameters such as the type of AM technique, processing parameters, built environment, and the feedstock used [1]. These factors collectively influence the occurrence of processing defects and the microstructure of the alloy, which can be controlled through feedstock modifications. To illustrate the impact of feedstock modification on both microstructure and corrosion, two examples will be presented. These examples will compare the corrosion behavior of additively manufactured 316L stainless steel (SS) produced using three different types of feedstocks: the as-received feedstock, feedstock modified with CrN, and feedstock modified with carbon nanotubes. The feedstock modification was carried out by ball milling of commercial 316L SS powder with the selected additive [2-4]. Test coupons were produced by laser powder bed fusion of the commercial feedstock and modified feedstock. Corrosion resistance was evaluated using cyclic potentiodynamic polarization tests in NaCl solution. The pitting and repassivation potentials of the 316L SS produced by modified feedstock were significantly higher compared to those of 316L SS produced using as-received feedstock [2-4]. The mechanistic aspects of the feedstock modifications and their influence on corrosion behavior will be discussed in detail.1. V.B. Vukkum, R.K. Gupta, Review on Corrosion Performance of Laser Powder-Bed Fusion Printed 316L Stainless Steel: Processing Parameters, Manufacturing Defects, Post-Processing, Feedstock, and Microstructure, Materials & Design, 221, 110874 (2022)2. A. Nieto, V. B. Vukkum, P. Jalagam, K. Nema, J. Budan, R.K. Gupta, T.Y. Ansell, 3D Printed Carbon Nanotube Reinforced Stainless Steel via Selective Laser Melting, MRS Communications 12, 578, 20223. V.B. Vukkum, J. Christudasjustus, A.A. Darwish, S.M. Storck, R.K. Gupta, Enhanced corrosion resistance of additively manufactured stainless steel by modification of feedstock, npj Materials Degradation 6, 1 (2022)4. V.B. Vukkum, F. Ozdemir, S. Storck, R.K. Gupta, Corrosion performance of feedstock modified - Additively manufactured stainless steel. Corrosion Science, 209, 110724 (2022).

Biofuels for a sustainable future: Examining the role of nano-additives, economics, policy, internet of things, artificial intelligence and machine learning technology in biodiesel production

As the global population and economy grow, so does the energy demand. Over-reliance on non-renewable resources leads to depletion and price spikes, making renewable alternatives necessary. Biodiesel is an eco-friendly and non-toxic fuel that closely resembles traditional fossil fuels. It is produced from various sources, including animal fat, palm oil, and non-edible plant oil. Biodiesel releases fewer harmful air pollutants and greenhouse gases than fossil fuels and is simpler to manage. Despite these advantages, it cannot replace traditional diesel fuel on a large scale. This overview summarizes biodiesel production, explaining the different types of feedstock utilized and their benefits and drawbacks. Various biodiesel production methodologies are discussed. The primary objective of this article is to inform engineers, industrialists, and researchers involved in waste biodiesel, as well as to highlight waste biodiesel as a potential substitute for fossil fuels. This review article discusses the nano-additives in biodiesel and applications of internet of things, artificial intelligence, and machine learning in biofuel. This review shows that nano-additives can potentially improve biodiesel fuel properties, favorable economic and policy environments promoting biodiesel production, and internet of things, artificial intelligence, and machine learning technologies optimize the biodiesel production processes. These advances can help promote biodiesel as a cleaner, renewable energy source, lowering the consumption of fossil fuels. It also suggests further biofuel development by improving efficiency, expanding feedstock options, creating policy support, developing infrastructure, and increasing public awareness.

Potential of Rhodosporidium toruloides for Fatty Acids Production Using Lignocellulose Biomass.

Microbial lipids are ideal for developing liquid biofuels because of their sustainability and no dependence on food crops. Especially the bioprocess for microbial lipids may be made economical by using sustainable approaches, e.g., lignocellulose-based carbon sources. This demand led to a search for ideal microorganisms with the ability to utilize efficiently biomass into value-added products. Rhodosporidium toruloides species belongs to the family of oleaginous (OG) yeast, which aggregates up to 70% of its biomass to produce fatty acids which can be converted to a variety of biofuels. R. toruloides is extremely adaptable to different types of feedstocks. Among all feedstock, a lot of effort is going on to develop a bioprocess of fatty acid production from lignocellulose biomass. The lignocellulose biomass is pretreated using harsh conditions of acid, alkali, and other which leads to the generation of a variety of sugars and toxic compounds. Thus, so obtained lignocellulose hydrolysate may have conditions of different pH, variable carbon and nitrogen ratios, and other non-optimum conditions. Accordingly, a detailed investigation is required for molecular level metabolism of R. toruloides in response to the hydrolysate for producing desired biochemicals like fatty acids. The present review focuses on numerous elements and obstacles, including metabolism, biofuel production, cultivation parameters, and genetic alteration of mutants in extracting fatty acids from lignocellulosic materials utilizing Rhodosporidium spp. This review provides useful information on the research working to develop processes for lignocellulose biomass using oleaginous yeast.

Current Issues and Developments in Cyanobacteria-Derived Biofuel as a Potential Source of Energy for Sustainable Future

Biofuel production using cyanobacteria aims to maintain the sustainability of an ecosystem with minimum impact on the environment, unlike fossil fuels, which cause havoc on the environment. The application of biofuel as an alternative energy source will not only help in maintaining a clean environment and improving air quality but also decrease harmful organic matter content from aquatic bodies. Cyanobacteria are valuable sources of many novel bioactive compounds, such as lipids and natural dyes, with potential commercial implications. One of the advantages of cyanobacteria is that their biochemical constituents can be modified by altering the source of nutrients and growth conditions. Careful changes in growth media and environmental conditions altering the quality and quantity of the biochemicals and yield capacity have been discussed and analyzed. In the present review, the challenges and successes achieved to date in the commercial production of biofuel and its application in the transportation industry are discussed. The authors also focus on different types of feedstocks obtained from biomass, especially from cyanobacterial species. This review also discusses the selection of appropriate cyanobacterial species with merits and demerits in the post-harvesting process. In sum, the current review provides insight into the use of organic bioresources to maintain a sustainable environment.

Fabrication of biochar derived from different types of feedstocks as an efficient adsorbent for soil heavy metal removal

For effective soil remediation, it is vital to apply environmentally friendly and cost-effective technologies following the notion of green sustainable development. In the context of recycling waste and preserving nutrients in the soil, biochar production and utilization have become widespread. There is an urgent need to develop high-efficiency biochar-based sorbents for pollution removal from soil. This research examined the efficacy of soil remediation using biochar made from three distinct sources: wood, and agricultural residues (sunflower and rice husks). The generated biochars were characterized by SEM/SCEM, XRF, XRD, FTIR, BET Specific Surface Area, and elemental compositions. The presence of hydroxyl and phenolic functional groups and esters in wood, sunflower and rice husk biochar were noted. The total volume of pores was in the following descending order: rice husk > wood > sunflower husk. However, wood biochar had more thermally stable, heterogeneous, irregular-shaped pores than other samples. Adsorption of soil-heavy metals into biochars differed depending on the type of adsorbent, according to data derived from distribution coefficients, sorption degree, Freundlich, and Langmuir adsorption models. The input of biochars to Calcaric Fluvic Arenosol increased its adsorption ability under contamination by Cu(II), Zn(II), and Pb(II) in the following order: wood > rice husk > sunflower husk. The addition of sunflower husk, wood, and rice husk biochar to the soil led to an increase in the removal efficiency of metals in all cases (more than 77%). The increase in the percentage adsorption of Cu and Pb was 9–19%, of Zn was 11–21%. The present results indicated that all biochars functioned well as an absorbent for removing heavy metals from soils. The tailor-made surface chemistry properties and the high sorption efficiency of the biochar from sunflower and rice husks could potentially be used for soil remediation.

A comprehensive review on nanocatalysts and nanobiocatalysts for biodiesel production in Indonesia, Malaysia, Brazil and USA

Biodiesel is an alternative to fossil-derived diesel with similar properties and several environmental benefits. Biodiesel production using conventional catalysts such as homogeneous, heterogeneous, or enzymatic catalysts faces a problem regarding catalysts deactivation after repeated reaction cycles. Heterogeneous nanocatalysts and nanobiocatalysts (enzymes) have shown better advantages due to higher activity, recyclability, larger surface area, and improved active sites. Despite a large number of studies on this subject, there are still challenges regarding its stability, recyclability, and scale-up processes for biodiesel production. Therefore, the purpose of this study is to review current modifications and role of nanocatalysts and nanobiocatalysts and also to observe effect of various parameters on biodiesel production. Nanocatalysts and nanobiocatalysts demonstrate long-term stability due to strong Brønsted-Lewis acidity, larger active spots and better accessibility leading to enhancethe biodiesel production. Incorporation of metal supporting positively contributes to shorten the reaction time and enhance the longer reusability. Furthermore, proper operating parameters play a vital role to optimize the biodiesel productivity in the commercial scale process due to higher conversion, yield and selectivity with the lower process cost. This article also analyses the relationship between different types of feedstocks towards the quality and quantity of biodiesel production. Crude palm oil is convinced as the most prospective and promising feedstock due to massive production, low cost, and easily available. It also evaluates key factors and technologies for biodiesel production in Indonesia, Malaysia, Brazil, and the USA as the biggest biodiesel production supply.

Biogas Production Depending on the Substrate Used: A Review and Evaluation Study—European Examples

Biogas production is the most important and promising alternative for replacing fossil fuels in an environmentally friendly manner. Along with the many renewable energy sources available, biogas production occupies an irreplaceable position due to the undeniable availability of biomass and the need to manage agro-commercial waste. The article reviews the current state of technology used in the production of biogas for selected European examples in terms of methane fermentation efficiency and actual energy production. The novelty of the article is its description of innovative trends that have great potential to play an important role in this field in the near future. The development of the biogas industry in Europe is evident, although the dynamics vary from country to country. Different models are presented, which are based on the different types of feedstock used for biogas production and the proportion of substrates used in co-digesters. Of course, Germany is the undisputed pioneer in the use of this renewable energy source. Nevertheless, the efforts to improve energy self-reliance and environmental impacts are reflected in the growing number of operational biogas plants in other European countries, which provides hope for rapid progress toward the complete abolition of the conventional exploitation of fossil fuels.

Content of adsorbed film water and density of oxygen-containing functional groups on surface of ageing biochar in sandy spodosol

Abstract Application of different types of feedstocks and conditions of their pyrolysis can result in different properties and sustainability of biochar during changes (aging) of its properties in soils. The aim of the studies was to assess the consequences of aging of biochar in soil for a content of adsorbed film water and a density of oxygen-containing functional groups on its surface. Sampling of soil and biochar was conducted in May and July of 2021 in a plot experiment with an applied rate of biochar of 20 t.ha−1 in 2016. WP4-T dew point potentiometer was used for measurements of relationships of potentials of adsorbed film water and its content in soil and biochar. Infrared Fourier FSM 2201/2202 spectrometer was applied for determination of densities of oxygen-containing functional groups on surface of biochar in a mid-infrared spectrum. Results showed that retention capacity of adsorbed film water by soil increased from May to July, possibly because of increasing content of hydrophilic organic compounds of plant origin. Aging of biochar in soil also resulted in an increase of retention capacity of adsorbed film water on its surface. The results of infrared Fourier spectroscopy confirmed that densities of oxygen-containing functional groups on the surface of biochar increased from May to July at spectra of wavenumbers of 1,600–1,400 cm−1 and 1,400–1,100 cm−1.

A machine learning model to predict the pyrolytic kinetics of different types of feedstocks

An in-depth knowledge of pyrolytic kinetics is vital for understanding the thermal decomposition process. Numerous experimental studies have investigated the kinetic performance of the pyrolysis of different raw materials. An accurate prediction of pyrolysis kinetics could substantially reduce the efforts of researchers and decrease the cost of experiments. In this work, a model to predict the mean values of model-free activation energies of pyrolysis for five types of feedstocks was successfully constructed using the random forest machine learning method. The coefficient of determination of the fitting result reached a value as high as 0.9964, which indicates significant potential for making a quick initial pyrolytic kinetic estimation using machine learning methods. Specifically, from the results of a partial dependence analysis of the lignocellulose-type feedstock, the atomic ratios of H/C and O/C were found to have negative correlations with the pyrolytic activation energies. However, the effect of the ash content on the activation energy strongly depended on the organic component species present in the lignocellulose feedstocks. This work confirms the possibility of predicting model-free pyrolytic activation energies by utilizing machine learning methods, which can improve the efficiency and understanding of the kinetic analysis of pyrolysis for biomass and fossil investigations.

Biofuel Generation by Macro and Micro Algae as a Renewable Energy Source: A Systematic Review

Recently, the fossil fuel consumption is increasing owed to industrial revolution which leads to serious human health and environmental problems. For sustainable energy generation and survival of human life and earth planet biofuel is an alternative source of energy. Non-renewable energy causes environmental effects which results in environmental degradation, to overcome these problems biofuel is the best environmental friendly option. Biofuel can be generated from different types of biomass, among these algae have potential to produce considerable amount of biofuel. But it is very difficult task to produce algal biofuel from specific type of algae. The present review compares and discusses the different types of feedstock, methods of oil production and improvement of method for biodiesel production and their utilization. This review mainly focuses on the cultivation and methodology for biofuel generation and recovery from algae for sustainable development.

Plastic packaging substitution in industry: variability of LCA due to manufacturing countries

The raising environmental concerns related to fossil fuel-based plastic packaging resulted in policy efforts for reducing their use and introducing bio-based materials. However, the availability of bio-based material suppliers may be currently limited. At the industrial level, Life Cycle Assessment (LCA) can provide decision support to companies willing to substitute fossil fuel-based with bio-based plastic packaging. In this context, a detailed modelling of the plastic supply chain can markedly alter the LCA results and the consequent interpretation. The present work is based on preliminary results from the Italian project “Plastic New Deal”, which aims to support small enterprises on substituting fossil fuel-based plastic with other materials. The goal of this study is to investigate the variability of LCA results related to the substitution of fossil fuel-based low-density polyethylene (LDPE) with bio-based LDPE (bio-LDPE) and polylactic acid (PLA), used as film for packaging. A total of 11 scenarios was built, modelling the country of plastic manufacturing and type of feedstock. LCA results of bio-based plastics by country vary up to +165% and -95% with respect to the average, which is much higher than the one of fossil fuel-based LDPE across all the impact categories considered in the study. This is due to the additional variability in the cultivation and conversion processes, originated from different types of feedstocks. Uncertainties on End-of-Life (EoL) treatment processes of plastic packaging and on accounting for life cycle biogenic carbon dioxide exchanges might further alter the LCA results for the climate change total category. The present paper attempts to highlight potential issues associated to a generic LCA which does not sufficiently account for the company context, empowering the accuracy of LCA as decision support tool and opening a discussion on how to improve the reliability of practical LCA recommendations.

A comprehensive study of the promoting effect of manganese on white rot fungal treatment for enzymatic hydrolysis of woody and grass lignocellulose

BackgroundThe efficiency of biological systems as an option for pretreating lignocellulosic biomass has to be improved to make the process practical. Fungal treatment with manganese (Mn) addition for improving lignocellulosic biomass fractionation and enzyme accessibility were investigated in this study. The broad-spectrum effect was tested on two different types of feedstocks with three fungal species. Since the physicochemical and structural properties of biomass were the main changes caused by fungal degradation, detailed characterization of biomass structural features was conducted to understand the mechanism of Mn-enhanced biomass saccharification.ResultsThe glucose yields of fungal-treated poplar and wheat straw increased by 2.97- and 5.71-fold, respectively, after Mn addition. Particularly, over 90% of glucose yield was achieved in Mn-assisted Pleurotus ostreatus-treated wheat straw. A comparison study using pyrolysis gas chromatography mass spectrometry (Py-GC/MS) and two-dimensional 1H–13C heteronuclear single quantum coherence (2D HSQC) nuclear magnetic resonance (NMR) spectroscopy was conducted to elucidate the role of Mn addition on fungal disruption of the cross-linked structure of whole plant cell wall. The increased Cα-oxidized products was consistent with the enhanced cleavage of the major β-O-4 ether linkages in poplar and wheat straw lignin or in the wheat straw lignin–carbohydrate complexes (LCCs), which led to the reduced condensation degree in lignin and decreased lignin content in Mn-assisted fungal-treated biomass. The correlation analysis and principal component analysis (PCA) further demonstrated that Mn addition to fungal treatment enhanced bond cleavage in lignin, especially the β-O-4 ether linkage cleavage played the dominant role in removing the biomass recalcitrance and contributing to the glucose yield enhancement. Meanwhile, enhanced deconstruction of LCCs was important in reducing wheat straw recalcitrance. The findings provided not only mechanistic insights into the Mn-enhanced biomass digestibility by fungus, but also a strategy for improving biological pretreatment efficiency of lignocellulose.ConclusionThe mechanism of enhanced saccharification of biomass by Mn-assisted fungal treatment mainly through Cα-oxidative cleavage of β-O-4 ether linkages further led to the decreased condensation degree in lignin, as a result, biomass recalcitrance was significantly reduced by Mn addition.Graphic abstract

Determination of Nitrogen and Sulphur Mineralization in Batch and Semi-Continuous Anaerobic Digestion Using an Artificial Fiber Bag Technique

In the biogas industry, feedstock plans are used to estimate methane production and nutrient content in the digestate, however, these predictions do not consider the mineralized nitrogen fraction of the feedstock, which is useful when determining the quality of the digestate. In this study, the artificial fiber bag technique, which is commonly used to study feedstock degradation in ruminants, was implemented in anaerobic digestion to quantify mineralization of N and S. The artificial fiber bags were used to enclose substrates but with access to inoculum because of small pores in the bags, thereby enabling digestion. The content of the bags was analyzed before and after digestion to quantify residual mass as well as N and S concentration in the substrate. The method was validated through batch anaerobic digestion of a single substrate with and without bags, where the bags showed little influence on methane production and degradation. Semi-continuous anaerobic digestion experiments showed higher substrate degradation and higher N and S release at thermophilic conditions using four different types of feedstocks and proved useful for solid feedstocks but less so for semi-solid feedstock. For N, most of the mineralization occurred during the first 15 days over a trial of 30 days.

The impact of blending with poplar wood on the co-pyrolysis characteristics of waste particleboards

Waste particleboards are largely generated from discarded furniture, floor, and other building materials, which can to be efficiently utilized as energy source by pyrolysis technologies. However, due to the existence of the adhesives and ash inside, waste particleboards are relatively hard to be pyrolyzed and form certain amounts of nitrogenous compounds. In order to improve the pyrolysis reactivity and tune the pyrolytic products, wood is proposed to be blended with waste particleboards for the co-pyrolysis treatment. In this study, the pyrolysis characteristics and chemical composition of pyrolytic vapors of samples with different blending ratios were studied using the TGA and Py-GC-MS analyses. The results showed as increasing the weight percentage of poplar wood, the pyrolysis activation energy and char residue content of the blends were gradually reduced, which was almost a linear correlation. Nevertheless, the chemical composition and distribution of pyrolytic vapors products of the samples was varied nonlinearly with blending ratio, and poplar wood exhibited a significant influence on the production of pyrolytic compounds from waste particleboards. The yields of most pyrolysis products reached the highest when the ratio of poplar wood was 50%, which probably indicated the existence of a synergy effect during the co-pyrolysis of different types of feedstock. It is believed that the results of this study are beneficial to the pyrolysis conversion of waste wood-based materials.

A concise review on alternative route of biodiesel production via interesterification of different feedstocks

Environmental challenges and decreasing fossil reserves due to increased utilization of fossil fuels have propagated the importance of alternative energy sources. Increased biodiesel production promoted excess waste crude glycerol leading to environmental issues, thereby inhibiting the sustainability of the process. This review paper discusses the different types of feedstocks utilized to produce glycerol-free biodiesel by reacting with methyl acetate via interesterification. Methyl acetate is used as an advantageous alternative to methanol in biodiesel production to overcome the environmental challenge associated with excess waste glycerol. The by-product, triacetin from the interesterification reaction, has shown excellent qualities as a fuel additive, thereby making the process cleaner and more sustainable as a result of not separating the triacetin from biodiesel. The resulting product referred to as biodiesel fuel (BDF) has been found to exhibit useful properties and applications as fatty acid methyl esters (FAME). The promising environmental and sustainability merits of the process far outweigh the slow interesterification kinetics demerits of the process, which can be overcome by suitable processing conditions. The prospects associated with biodiesel production by interesterification are also pointed out.

Hydrothermal Treatment of Vegetable Oils and Fats Aiming at Yielding Hydrocarbons: A Review

According to the International Air Transport Agency (IATA), the aviation industry causes 2% of GHG emissions. As a result, goals such as improving aircraft efficiency by 1.5% per year and achieving carbon-neutral growth by 2020 were established. In this circumstance, fuels produced from biomass seem to be a promising route. There are many routes available to convert biomass into renewable fuels such as pyrolysis, hydroprocessing, transesterification, hydrothermal processes, and steam reforming. In this study, one reports a review of hydrothermal technologies. This review reports recent information about hydrothermal processes using water in sub- and supercritical states. This article introduces some concepts of the hydrothermal processes, advantages, and different types of feedstock adopted. The parameters which have an influence on hydrothermal processes such as temperature, pressure, particle size, catalyst, biomass/water ratio, and reaction time are illuminated. Water characteristics in sub- and supercritical conditions are discussed as a highly reactive medium to increase the affinity for the extraction of value-added compounds. Additionally, this review splits and details the reaction schemes that take place under hydrothermal conditions. Finally, it introduces recent research and development (R&D) trends in the hydrothermal process of fatty acids and triglycerides.

Multi-objective optimization of operation of lignocellulosic acetone-butanol-ethanol fermentation with ex situ butanol recovery (ESBR)

This study proposes a multi-objective operation strategy for a continuous acetone-butanol-ethanol (ABE) fermentation process with ex situ recovery by adsorption (termed “lignocellulosic ESBR-by-adsorption system”), which is used to produce biobutanol from lignocellulosic biomass. In this study, a model-based cyclic steady state (CSS) optimization of the lignocellulosic ESBR-by-adsorption system is performed to find the best operating conditions and gain better understandings of its dynamic behavior. To gain insights into the relationships between operating conditions and performance of the system, key operating variables are optimized with respect to three different objective functions: maximizing productivity, maximizing yield, and minimizing substrate loss. In addition, an optimization study is conducted for two different types of feedstocks to investigate the effect of feedstock type on system performance. Furthermore, an open-loop sensitivity analysis is performed to identify the most influential parameters and operating conditions that provide more stable system behavior when uncertainties are present.