Showing papers in "Biomass Conversion and Biorefinery in 2020"
TL;DR: In this paper, the shells of three important food nuts, walnut, almond, and pine nut, were studied in view of valorization as residues, and the shells differed chemically: walnut shells had 10.6% extractives, 30.1% lignin, and 49.7% polysaccharides.
Abstract: The shells of three important food nuts, walnut, almond, and pine nut, were studied in view of valorization as residues. The shells differed chemically: walnut shells had 10.6% extractives, 30.1% lignin, and 49.7% polysaccharides; almond shells 5.7% extractives, 28.9% lignin, and 56.1% polysaccharides; and pine nut shells 4.5% extractives, 40.5% lignin, and 48.7% polysaccharides. The polysaccharide composition also differed, e.g., glucose/xylose ratio of 1.12, 0.94, and 2.29 for walnut, almond, and pine nut shells, respectively. Walnut and almond shells have a SG lignin (S/G 1.6 and 1.0, respectively) and pine nut shell a G lignin. The lipophilic extracts contained mostly saturated and unsaturated alkanoic acids. The ethanol-water extracts contained total phenolics, flavonoids, and condensed tannins. The antioxidant activity was moderate (IC50 15.2, 7.9, and 8.2 μg/mL for walnut, almond, and pine nut). The three nut shells fractured easily with little formation of fines.
95 citations
TL;DR: In this paper, a review of bio-hydrogen production using organic waste materials through fermentation, biophotolysis, microbial electrolysis cell and gasification is discussed and analyzed from a technological perspective.
Abstract: The ever-increasing world energy demand drives the need for new and sustainable renewable fuel to mitigate problems associated with greenhouse gas emissions such as climate change. This helps in the development toward decarbonisation. Thus, in recent years, hydrogen has been seen as a promising candidate in global renewable energy agendas, where the production of biohydrogen gains more attention compared with fossil-based hydrogen. In this review, biohydrogen production using organic waste materials through fermentation, biophotolysis, microbial electrolysis cell and gasification are discussed and analysed from a technological perspective. The main focus herein is to summarise and criticise through bibliometric analysis and put forward the guidelines for the potential future routes of biohydrogen production from biomass and especially organic waste materials. This research review claims that substantial efforts currently and, in the future, should focus on biohydrogen production from integrated technology of processes of (i) dark and photofermentation, (ii) microbial electrolysis cell (MEC) and (iii) gasification of combined different biowastes. Furthermore, bibliometric mapping shows that hydrogen production from biomethanol and the modelling process are growing areas in the biohydrogen research that lead to zero-carbon energy soon.
83 citations
TL;DR: In this article, the authors systematically summarized the preparation of activated biochar, characterisation, and analytical techniques of activated Biochar based on more than 150 literatures published in the last 10 years.
Abstract: The biochar produced from agricultural crop residues through thermochemical processes helps in crop waste management. Biochar has paid more attention due to its distinctive features such as high organic carbon content, stable structure, large surface area, and cation exchange capacity. The biochar obtained from crop residues can be readily converted into activated biochar. This review paper systematically summarised the preparation of activated biochar, characterisation, and analytical techniques of activated biochar based on more than 150 literatures published in the last 10 years. The physicochemical properties of activated biochar varies according to the type of feedstock, pyrolysis condition, and mode of activation. The selection of the activation method mainly depends on its further end environmental application. Physical activation or steam purging at high temperature creates pores inside biochar. Gas purging increases the surface area and pore volume, although steam activation is not much suitable to improve the BC surface functionality as compared to chemical and impregnation activation. Sulphuric and oxalic acid–modified biochar was found to be most suitable for the soil amendment. Alkaline activation enhances the surface area and oxygen-containing functional group in activated biochar. Metal oxide–modified biochar had better surface functionalities than did physical- and chemical-activated biochar and better sorption of organic and inorganic contaminants from potable water and waste water. In summary, activated biochar has a wide environmental prospect in remediation.
74 citations
TL;DR: In this paper, the authors reveal a better surface treatment method to achieve improved mechanical, thermal and fatigue properties of a Caryota fiber epoxy composite system using hand layup method and post cured at 120°C for 48h.
Abstract: Epoxy biocomposites were prepared using acid-, base- and silane-treated novel Caryota urens natural fibres (CUFs). The primary aim of this research is to reveal a better surface treatment method to achieve improved mechanical, thermal and fatigue properties of Caryota fibre epoxy composite system. The composites were prepared using hand layup method and post cured at 120 °C for 48 h. The tensile, flexural and impact results show that the silane surface–treated Caryota urens fibre–reinforced epoxy composite possesses improved mechanical properties than the base- and acid-treated Caryota urens fibres in the epoxy composite. Similarly, the inter-laminar shear strength (ILSS) of silane-treated Caryota urens–reinforced epoxy composite gives the highest value of 28 MPa. The TGA shows a large mass loss for both acid- and base-treated Caryota urens epoxy composites whereas the silane-treated Caryota urens in epoxy composite retains the thermal stability. The fatigue behaviour of silane surface–modified Caryota urens epoxy composite shows the highest fatigue life cycle of 18,315 for 25% of maximum tensile stress. The SEM micrographs show improved adhesion for silane-treated CUF than those treated with acid and base. This Caryota urens fibre–reinforced epoxy composite could be used in automobile body parts, domestic appliances, defence products and lightweight mini-aircrafts.
60 citations
TL;DR: In this paper, the degradation behavior of 11 model compounds including carbohydrates and furfural derivatives, within water and various pure organic solvents as reaction media was studied, and it was shown that the formed α-carbonyl aldehydes and α,β-unsaturated aldehyde should be the primary precursors for the formation of humins.
Abstract: Humins are undesired solids formed during the hydrothermal degradation of carbohydrates. In order to reveal the mechanism of formation of humins, we studied the degradation behavior of 11 model compounds including carbohydrates and furfural derivatives, within water and various pure organic solvents as reaction media. All the studied carbohydrates could generate solid humins in both water and studied organic solvents except ethanol, while the furfural derivatives could generate solid humins in only water. The results could be explained by regarding the formed α-carbonyl aldehydes and α,β-unsaturated aldehydes as primary precursors for formation of humins. Furfural derivatives could generate chain α-carbonyl aldehydes (for example, 6-hydroxy-2,5-dioxohexanal from 5-hydroxymethylfurfural and 2-oxopentanedial from furfural) through hydrolytic ring opening reaction; thus, water is essential for these furfural derivatives to generate humins. As for carbohydrates, they could generate α-carbonyl aldehydes and α,β-unsaturated aldehydes through simple step of β-elimination in all solvents; thus, they could form humins in both water and studied organic solvents except ethanol. Ethanol could react with α-carbonyl aldehydes by acetalization; thus, the condensation between α-carbonyl aldehydes was suppressed in ethanol, leading to few humins formation from carbohydrates. Based on the above analysis, we proposed that the formed α-carbonyl aldehydes and α,β-unsaturated aldehydes should be the primary precursor of humins.
58 citations
TL;DR: In this article, the effect of biomass components on the yield of slow pyrolysis products (char, bio-oil and syngas) is investigated using a validated ASPEN Plus® model.
Abstract: Prior information on the pyrolysis product behaviour of biomass components-cellulose, hemicellulose and lignin is critical in the selection of feedstock as components have a significant influence on the pyrolysis products yield. In this study, the effect of biomass components on the yield of slow pyrolysis products (char, bio-oil and syngas) is investigated using a validated ASPEN Plus® model. The model is simulated at a temperature of 450 °C, a heating rate of 10 °C/min and a solid residence time of 30 min. The results indicated that at the given conditions, lignin contributed 2.4 and 2.5 times more char yield than cellulose and hemicellulose. The hemicellulose contributed 1.33 times more syngas yield than lignin while the cellulose and hemicellulose contributed 8.67 times more bio-oil yield than lignin. Moreover, the cost involved in the production of char using lignin (110 $/ton) is significantly economical than using cellulose (285 $/ton) and hemicellulose (296 $/ton). The net CO2 emission of lignin pyrolysis is 4.14 times lower than cellulose pyrolysis and 3.94 times lower than hemicellulose pyrolysis. It can be concluded that lignin pyrolysis is more advantageous than cellulose and hemicellulose pyrolysis. In the selection of feedstock for the slow pyrolysis, the feedstock with more lignin content is preferred.
55 citations
TL;DR: The present review focuses on the state-of-the-art development of biofuel production by mixed consortium and also recent strategies to improve biofuel yield including the metabolic pathway construction.
Abstract: Global environmental protection is of immediate concern that can only be achieved by avoiding the use of fossil fuels and tailpipe emissions. In addition, investment on waste disposal is not economical; however, recycling of the same waste for renewable energy production is favorable in the economic and social development of the society in an eco-friendly manner. Utilization of biodegradable wastes, such as agricultural and forestry residues, and non-edible plant matter for value-added bioproducts is a promising, inexpensive, and abundant clean substitute of fossil fuels. There has been extensive research on the conversion of lignocellulosic materials to biofuels over the past few decades. The recalcitrance of lignin in crop residues, however, impedes polysaccharide accessibility and its transformation into commercially significant choice of value-added products. Traditional physiochemical and thermal methods are hampered by high-cost processing steps in pretreatment and saccharification, and also require additional maintenance and care due to the generation of eco-unfriendly compounds. Recent advances in novel consolidated bioprocessing through mixed consortium are promising choices to reduce both the number of operational steps and the production of inhibitors with higher conversion efficiency. Although biofilm-based technologies have been successfully applied for wastewater and solid waste treatment, their potential application in biofuel production has been unexplored. The present review focuses on the state-of-the-art development of biofuel production by mixed consortium and also recent strategies to improve biofuel yield including the metabolic pathway construction.
55 citations
TL;DR: In this paper, the authors focused on the biodiesel production from waste beef tallow rendered from subcutaneous and intramuscular wastes discarded from leather tanneries and slaughterhouses.
Abstract: Presently, biodiesel is considered as an effective alternate fuel owing to its high sustainability and robustness. This paper concentrates on the biodiesel production from waste beef tallow rendered from subcutaneous and intramuscular wastes discarded from leather tanneries and slaughterhouses. The maximum fat content was estimated to be 92.5% and 3.05%, whereas maximum rendering efficiency was determined to be 92% and 75% for subcutaneous and intramuscular wastes, respectively. The rendered waste tallow was converted into biodiesel using ethanol as a solvent and l-valine amido ethyl methyl imidazolium bromide ([l-Vaemim]Br) as a novel ionic liquid catalyst. The most optimised reaction parameters are as follows: molar ratio of 1:7.5, catalyst concentration of 20 wt% of tallow, reaction temperature of 75 °C and reaction time of 160 min. Properties of the produced biodiesel have been tested in accordance with ASTM Standards, where the results were found to be within the permissible range. The engine characteristics of biodiesel exhibited increased heat release rate and maximum cylinder pressure, reduced emission levels than compared to ordinary diesel; in addition, its performance characteristics were similar to diesel, thereby making it a suitable replacement for existing fossil fuel.
55 citations
TL;DR: In this article, a review of literature based on optimization of the catalyst performance varying various parameters like type of active metal, support, promoters, and catalyst synthesis procedure has been cited.
Abstract: Dry (CO2) reforming of methane with its commercial application of syngas production also serves in utilization of greenhouse gases like carbon dioxide and methane. Though the process is well studied, still, there are areas that are being explored in optimizing the process. One of the key areas of research is enhancing the activity and stability of the catalysts used in the reforming reactions. Activity of catalyst depends upon particle size, dispersion on support, support type, synthesis method, etc., whereas deactivation of catalyst is due to carbon deposition and sintering of metal precursor. With noble metals like Rh, Ru, Pt, and Pt providing more stability but are not economical, commercialization of dry reforming process has been achieved using Ni-based catalysts. Literature based on optimization of the catalyst performance varying various parameters like type of active metal, support, promoters, and catalyst synthesis procedure has been cited in this review. Review also extends towards various structured catalysts like foams, zeolites, and their performance-enhancing characteristics. With active metals like Ni showing excellent dispersion on well-structured supports like layered double hydroxides; enhanced performance by addition of a second metal usually a noble metal; use of promoters like lanthanides, which induce gasification of carbon species, thus inhibiting deactivation; and methods of introducing promoters, such as controlled adsorption, these catalysts can serve as strong candidates in commercial applications.
51 citations
TL;DR: In this article, a hybrid multi-criteria decision-making (MCDM) model based on the weight obtained from analytical hierarchy process (FAHP) has been utilized for ranking.
Abstract: In the current period of energy development, it is very complex to produce energy from agricultural wastes due to the involvement of multiple criteria such as social, economical and environmental factors. In this study, a hybrid multi-criteria decision-making (MCDM) model based on the weight obtained from analytical hierarchy process (FAHP) has been utilized for ranking. Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Evaluation based on Distance from Average Solution (EDAS) are proposed to evaluate the possibilities of utilizing locally available biomass. For this purpose, a number of criteria are defined from the viewpoint of yielding maximum bio-oil during pyrolysis. The proposed methods are having excellent agreement with each other, and they are exactly matched with the experimental results. This study consists of seven biomass alternatives with seven evaluation criteria. Out of seven selected biomass materials, sugarcane bagasse is ranked top. The experimental results confirmed the prediction with maximum bio-oil yield of 48.5 wt% obtained from sugarcane bagasse. At the end of the study, the obtained bio-oil from top ranked biomass material was analysed for physical, elemental and chemical compositions using Fourier-transform infrared (FTIR) spectroscopy and gas chromatography (GC) for its utility assessment. This study gives new insights into decision-making, specifically thermochemical conversion process.
48 citations
TL;DR: This review paper describes the technical developments, industrial scenario, environmental issues, and range of diversified products from 3G biorefineries on the exploration of algal biomass into fuels and biochemicals via multidisciplinary technological routes.
Abstract: Sustainable transformation of biomass into a wide range of valuable chemicals, fuels, and materials is the eventual goal of a biorefinery. Algal feedstock (microalgae and macroalgae) is a principal component of third-generation (3G) biorefinery empowering the bio-renewables industry. While first-generation (1G) biorefineries are commercially viable, products (fuels and commodity chemicals) from second-generation (2G) and 3G biorefinery are not yet commercially competitive due to the gross technical challenges, scalable and production cost issues. Because of the inherently diversified nature of feedstock used in 3G biorefineries, a myriad of specific bioproducts can be produced. Furthermore, stable food/feed supply, environmental concerns, climate change, and geopolitical issues have necessitated the exploration of 3G feedstocks into fuels and renewable chemicals. Considerable success has been seen in research laboratories in the last two or three decades which led to mature technical developments in algal biomass conversion. However, the scale-up issues are still posing a big challenge for the commercial exploitation of algal feedstock into fuels and chemicals. Nevertheless, various products such as nutraceuticals, pharmaceuticals, and cosmetics are successfully being produced from algal feedstock. This review paper describes the technical developments, industrial scenario, environmental issues, and range of diversified products from 3G biorefineries. Specially, we focus on the exploration of algal biomass into fuels and biochemicals via multidisciplinary technological routes.
TL;DR: In this paper, Musa acuminata banana trunk ash (MBTA) was utilized as a waste biomass-derived heterogeneous catalyst for transesterification of soybean oil to biodiesel at ambient temperature.
Abstract: Due to the world wide attention regarding depletion of non-renewable resources, detrimental effect of toxic chemicals to the environment and uncontrollable up surge of waste materials, scientific community is showing substantial focus on valorization of waste into various significant products. In this study, Musa acuminata banana trunk ash (MBTA) was utilized as a waste biomass–derived heterogeneous catalyst for transesterification of soybean oil to biodiesel at ambient temperature. To characterize the solid catalyst, different analytical and spectroscopic techniques were adopted that enabled to investigate its chemical composition and morphology. EDX, XRF, and XRD analysis revealed the presence of several oxides of alkali metals and alkaline earth metals besides carbon in the ash sample. A high conversion of biodiesel (98.39%) was achieved under our optimized reaction conditions using the waste biomass catalytic system. The catalyst was recoverable up to 5 times without much depreciation in its catalytic activity. The catalyst being a waste-material is therefore cheap, easily-to-prepare, biodegradable, recyclable, and environmentally benign which makes it a prospective candidate for “green catalyst” in biodiesel synthesis.
TL;DR: In this article, a hybrid fiber-metal laminate was reinforced into SiC-toughened epoxy resin for making high performance structural material for automobile and aircraft applications.
Abstract: High toughness and high-impact damage resistance fibre-metal hybrid laminate epoxy composites were prepared and characterized In this present research, a hybrid fibre-metal laminate was reinforced into SiC-toughened epoxy resin for making high performance structural material for automobile and aircraft applications Novel natural fibre caryota urens and silicon carbide (SiC) particles were surface-treated using 3-aminopropyltriethoxysilane (APTES) whereas the aluminium foil was sandblasted The hybrid fibre-metal laminate with different stacking sequenced epoxy composites were prepared using vacuum bag moulding followed by post curing A highest strength factor of 97 is observed for composite designation CAC1, which contains 05 vol% of SiC The drop load impact toughness of ACA1 composite gives the highest energy absorption of 206 J Similarly, the CAC1 composite designation gives fracture toughness of 321 MPa
$$ \sqrt{\mathrm{m}} $$
and energy release rate of 1557 mJ/m2 The scanning electron microscope images revealed highly reacted phase of surface-treated reinforcements with epoxy resin matrix
TL;DR: In this article, the authors estimate the bioenergy potential of pistachio shell and study its degradation kinetics which are necessary for the efficient design and optimization of thermochemical processes for bioenergy generation.
Abstract: The research work aims to estimate the bioenergy potential of pistachio shell and study its degradation kinetics which is necessary for the efficient design and optimization of thermochemical processes for bioenergy generation. Initial characterizations (proximate, ultimate, higher heating value, and compositional analysis), kinetic study, and thermodynamic analysis accompanied by reaction mechanism are investigated. Physicochemical characterization results confirmed high volatile matter (~ 79.8 wt%) and high heating value (16.85 MJ/kg) of pistachio shell. Thermogravimetric analysis (TGA) is performed at four different heating rates of 10, 20, 30, and 40 °C/min under nitrogen gas flow rate from ambient temperature to 900 °C. TGA results show the three-stage pyrolysis reaction which involves removal of moisture and light volatiles, degradation of cellulose and hemicellulose, and decomposition of lignin. The result also reveals that maximum degradation occurred in the temperature range of 200–400 °C. For calculating the kinetic (activation energy and pre-exponential factor) and thermodynamic parameters (enthalpy, entropy, and Gibbs free energy), different iso-conversional models, i.e. Flynn-wall-Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink, and Friedman, are employed which gives the average value of activation energy as 168.86, 165.80, 166.29, and 190.10 kJ/mol, respectively and the pre-exponential factor values lie in the range of 107-1021 s−1. The average values of Gibbs free energy calculated for FWO, KAS, Starink, and Friedman methods are 182.09, 182.15, 182.13, and 181.42 kJ/mol, respectively. Criado method and Z plot are showing complex reaction mechanism. The results of kinetics and thermodynamic study reveal pistachio shell is an efficient biomass for bioenergy production.
TL;DR: In this paper, the use of pretreatment methods that can be applied as an alternative to the usage of residual biomass is investigated, highlighting the efficiency of the processes as well as possible weaknesses, which are associated with high energy and reagent consumption, low yields, and possible secondary impacts.
Abstract: A number of industries currently produce many tons of agroindustrial wastes with significant consequences on the environment and human and animal health. In recent years, increasing emphasis has been placed on reducing this negative impact. This review article aims to investigate the use of pretreatment methods that can be applied as an alternative to the usage of residual biomass. In addition, we seek to highlight the efficiency of the processes as well as possible weaknesses, which are associated with high energy and reagent consumption, low yields, and possible secondary impacts. Generally, the waste chemical composition consists mainly of cellulose, hemicellulose, and lignin; these can be fractionated, extracted, and purified to produce different value-added products, such as biofuels, organic acids, enzymes, biopolymers, and chemical additives. Despite the multiple possibilities to produce different products from lignocellulosic biomass, further research is still required to enhance the efficiency of the methods used nowadays and find new procedures.
TL;DR: In this paper, a comprehensive review of photo-fermentation biohydrogen production is presented, which highlights the advantages of this approach over other methods and various pretreatment procedures of potential lignocellulosic biomass feedstocks.
Abstract: Photo-fermentation biohydrogen production is an eye-catching and environmentally friendly route that can be excellently performed at ambient conditions. Nevertheless, light conversion efficacy and photo-fermentation hydrogen production performance are still low, and hence, numerous approaches are explored to enhance biohydrogen production. This review is intended at describing comprehensive characteristics and general mechanism of photo-fermentation biohydrogen production and highlights the advantages of this approach over other methods. Moreover, various pretreatment procedures of potential lignocellulosic biomass feedstocks for enhanced photo-fermentation biohydrogen production including physical, chemical, physical-chemical, and biological methods were elaborated thoroughly. Several crucial factors affecting photo-fermentation biohydrogen production such as the impact of pH, mixing, stirring, and lighting conditions, substrate concentration, different pretreatment conditions, and diverse fermentation modes were also discussed comprehensively. This aims to emphasize the recent advances in this field for further enhancement of biohydrogen production via photo-fermentation of lignocellulosic biomass. Additionally, the major challenge and prospects are also included to uncover the unexplored criteria of an effective and greener photo-fermentation biohydrogen production.
TL;DR: In this paper, a review summarizes the influences of biomass-derived low-cost biochar on agriculture and environmental health, crop responses, nutrient dynamics, and soil biological parameter-related issues as well as how biochar can helpful for agriculture and environment management.
Abstract: Biochar production from agro-environmental waste biomass is attracting huge interest as a low-cost amendment due to its potential numerous benefits to agriculture and environment, as well as its ability to store soil water. This review summarizes the influences of biomass-derived low-cost biochar on agriculture and environmental health, crop responses, nutrient dynamics, and soil biological parameter–related issues as well as how biochar can helpful for agriculture and environment management. Besides, biochar safety issues and human health in agro-environment have also been discussed. Application of biochar in agro-environment exerts measurable changes in physico-chemical and biological properties as well as carbon balance. Mechanistic evidences of biochar’s potential for enhancing crop productivity, soil water availability, biochar co-composting, and nutrient use efficiency are also discussed. The review also identifies several knowledge gaps and future research directions for large-scale use of biochar. Hence, this information in the form review is new of its kind which is useful to the broad spectrum of readers. Thus, the biochar addition in agro-environment emerges as a “win-win strategy” for sustainable soil health and environmental ecofriendly assets. But some technical and practical barriers are reported in biochar application in large quantities, which are a major concern today.
TL;DR: In this paper, the authors discuss about the potential of biochar in soil biology, systemic resistance, carbon mineralization kinetics and N2-fixation, and mycorrhizal colonization.
Abstract: Till date there is not much concrete data available linking valorization of biomass-derived engineered biochar for soil, plant, water system, and microbial dynamics under changing climatic conditions. This review article deals with the abovementioned burning topic by collection of world literature. It summarizes the conversion of biomass into biochar, their characterization, and pyrolysis influence on composition. Besides it discusses about biomass through biochar which can help to establish a relationship with soil, plant, and water to manage soil fertility–related issues and microbe interactions. Biochar addition exerts measurable changes in carbon footprint, physicochemical and biological soil properties, nutrient sorption-retention, water retention, crop production, and nutrient leaching. Mechanistic evidences of biochars’ potential on soil biology, systemic resistance, carbon mineralization kinetics and N2-fixation, and mycorrhizal colonization were mentioned in this review article. The recalcitrance, pore space, surface morphology, and pH of biochar on soil, plant, water system, and microbes are found to be controlled by biomass type, pyrolysis temperature, biotic interactions, etc. Biochar with fertilizer integration offers an improved soil management strategy, and therefore, biomass valorization through its application in soil, plant, water, and microbial dynamics comes out as a “win-win strategy” for adequate climate change mitigation and environmental eco-friendly technology.
TL;DR: In this paper, a simple, low-cost, and environment friendly method to obtain high-fluorescence carbon dots and activated carbon via a one-step hydrothermal process using banana peels was introduced.
Abstract: We introduce a simple, low-cost, and environment friendly method to obtain high-fluorescence carbon dots and activated carbon via a one-step hydrothermal process using banana peels. The dispersion of carbon dots generated strong, bright-blue photoluminescence (average diameter 3–6 nm), which could be further used in biosensing, electronics, and catalysis applications research. Moreover, the precipitation accumulated at the bottom of the hydrothermal process contained activated carbon with a highly porous structure and large specific surface area (294.6 m2 g−1), which could be used as a supercapacitor electrode. The three-electrode cell exhibited excellent capability and stability of the activated carbon as the working electrode in various aqueous electrolytes, with a high specific capacitance (199 F g−1) in an aqueous electrolyte (1-M KOH) and a high energy density of 54.15 Wh kg−1 at a current density of 0.5 A g−1. Thus, based on the excellent characteristics of the carbon dots and the strong electrochemical properties of the activated carbon as an electrode material, the banana peels, as an abundant bioresource, can provide two excellent produces.
TL;DR: In this article, the authors presented the first attempt to focus on the cocoa shell pyrolysis in terms of kinetic triplet, thermodynamic parameters, and evolved volatile analysis using the TGA-FTIR technique.
Abstract: This study presents the first attempt to focus on the cocoa shell pyrolysis in terms of kinetic triplet, thermodynamic parameters, and evolved volatile analysis using the TGA-FTIR technique. For reliable interpretation of the multistep pyrolysis of cocoa shell, the multiple kinetic triplets were adequately estimated by a combined kinetic procedure using five independent parallel reactions with the Vyazovkin isoconversional method, the compensation effect, and the master plot method. According to the results, the multiple kinetic triplets were able to describe the pyrolysis behavior of the cocoa shell with an accuracy of R2 > 0.9446 and the pyrolysis mechanisms exhibited different reaction models (n-order and contracting cylinder). Evolved volatile analysis suggested the presence of high-energy compounds (aromatic) and useful chemicals (aldehyde, ketone, esters, ether, and alcohols). The pre-exponential factors for the five pseudo-components of cocoa shell pyrolysis ranged from 2.56 × 1011 to 8.66 × 1016 min−1 (derived from the compensation effect method), while the values of Ea ranged from 99 to 271 kJ mol−1. From a comparative analysis, it was found that the results from the compensation effect method ensured the overall kinetic expression to be consistent with the experimental cocoa shell pyrolysis behavior. In contrast, the overall kinetic expression using pre-exponential factors derived from Kissinger’s method failed to match the experimental curves. The pyrolytic conversion of cocoa shell into bioenergy appeared as potentially viable (Ea – ΔH ≤ 5.5 kJ mol−1). The promising findings on the cocoa shell pyrolysis can expand the use of this residue in bioenergy applications, consisting of a great attempt toward its valorization.
TL;DR: In this paper, the feasibility use of Musa acuminata bract as (MAB) biosorbent towards the removal of hexavalent chromium from synthetic wastewater was evaluated.
Abstract: The present study is undertaken to evaluate the feasibility use of Musa acuminata bract as (MAB) biosorbent towards the removal of hexavalent chromium from synthetic wastewater. Chromium is a potential pollutant to all forms of life and therefore efficient way of treatment is necessary even towards lower chromium concentration removal. The objectives of the present research include optimizing parameters influencing biosorption of hexavalent chromium, pH, dosage of the MAB, influent Cr(VI) concentration, and time. The MAB was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) analysis, to examine the surface functional group and structural assessments of the MAB. Optimum pH for the effective biosorption was found to be 2.0, and the biosorption capacity was found to be 36.84 mg/g with 87.55% of Cr(VI) removal. Further experiments were carried out at the optimized pH for other parameters influence on the Cr(VI) biosorption. Langmuir isotherm shows better fit than the rest of the models because of the higher R2 value. The data were analyzed using pseudo-first-order, pseudo-second-order, intra-particle diffusion, and Elovich models. Higher degree of coefficient of determination was obtained for the pseudo-second-order kinetic model. The results of the present study suggested that MAB could be used beneficially in treating industrial effluents containing hexavalent chromium through further research study of column biosorption.
TL;DR: In this article, the authors summarized various pyrolysis variants used for biochar production from rice husk, modification of biochar and its environmental application, and indicated that the choice of suitable pyrotechnic variant and biochar modification method is vital to improve the adsorption capacity and nutrient release potential of the rice hulls biochar.
Abstract: Biochar produced from various biomass has been widely used in environmental applications owing to its ability to immobilize or remove the contaminants from soil, water and air. The present work summarizes various pyrolysis variants used for biochar production from rice husk, modification of biochar and its environmental application. The high volatile matter content (70.2–78.5%) and carbon content (35.2–44.7%) favoured production of biochar from rice husk through pyrolysis. Microwave-assisted hydrothermal carbonization showed highest biochar yield from rice husk (57.9%) compared to other process variants, whereas wet pyrolysis produced biochar with the highest carbon content (71.2%). Steam activation of rice husk biochar resulted in a broader pore size distribution with the presence of significant micropores compared to CO2 activation. A substantial improvement in surface area and microporous volume was observed with alkali activation compared to that of acid activation, whereas metal impregnation caused a reduction in surface area. Rice husk biochar with/without modification has been employed for adsorption of pollutants such as cations, dyes, nutrients and tetracycline. The nutrient-loaded rice husk biochar improved the soil fertility and cation exchange capacity. The studies indicated that the choice of suitable pyrolysis variant and biochar modification method is vital to improve the adsorption capacity and nutrient release potential of the rice husk biochar.
TL;DR: In this article, the authors investigated the effect of the carbon composition on the carbon mass balance in a dual fluidized bed reactor system with limestone as a bed material for the thermochemical conversion of biomass into a valuable nitrogen-free product gas.
Abstract: Especially carbon-intensive industries are interested in a decarbonization of their processes. A technology, which can contribute to a significant reduction of the carbon footprint, is the so-called sorption enhanced reforming process. The sorption enhanced reforming process uses a dual fluidized bed reactor system with limestone as a bed material for the thermochemical conversion of biomass into a valuable nitrogen-free product gas. This product gas can be used for further synthesis processes like methanation. The dependency of the product gas composition on the gasification temperature is already a well-known fact. Nevertheless, detailed investigations and models of the effect on elemental balances (especially carbon) of the process are missing in the literature and are presented in this work. Therefore, previously published data from different pilot plants is summarized and is discussed on a mass balance. Based on this information, investigations on the product gas equilibrium composition are presented and conclusions are drawn: it can be shown that the sorption enhanced reforming process can be divided into two sub-processes, namely “carbonation dominated sorption enhanced reforming” and “water-gas shift dominated sorption enhanced reforming.” The sub-process carbonation dominated SER is characterized by a high deviation from the water-gas shift equilibrium and a nearly constant CO content in the product gas over gasification temperature (< 700 °C). The sub-process water-gas shift dominated SER can be identified by a steep increase of the CO content in the product gas over temperature and nearly equilibrium state of the water-gas shift reaction (700–760 °C).
TL;DR: In this paper, a microwave-assisted extraction of Hibiscus sabdariffa has been carried out by using Citric acid-based deep eutectic solvents, where a hydrogen bond donor (HBD) (glycerol and ethylene glycol) with a certain molar ratio (1/4) were used.
Abstract: In the current study, Hibiscus sabdariffa has been extracted by microwave-assisted extraction (MAEX). Citric acid-based deep eutectic solvents (DES) have been specially designed, where a hydrogen bond donor (HBD) (glycerol and ethylene glycol) and a hydrogen bond acceptor (HBA) (citric acid) with a certain molar ratio (1/4) were used. After the best DES (citric acid/ethylene glycol) has been decided to extract the bioactive ingredients, operation conditions (power of microwave, volume of solvent water and content in the DES) of the MAEX for the relevant plant material have been optimized through Box-Behnken design (BBD) of response surface approach (RSA). The maximum yields of total phenolics (TP), total anthocyanins (TAA) and antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) have been found as 31.897 mg-GAE/g-DH, 2.961 mg-C3G/g-DH and 95.887% under the optimal conditions (35 mL DES including 50% water (v/v) at 550 W power of microwave). The differences between the experimental and estimated findings were lower than 2%. Three replicate test results obtained by in vitro experiments were also statistically analysed by using one-way analysis of variance (ANOVA) test.
TL;DR: In this paper, the effect of pyrolysis conditions on biochar yield obtained from Chlorella vulgaris was examined statistically using a thermogravimetric analyzer.
Abstract: In the present work, the effect of pyrolysis conditions on biochar yield obtained from Chlorella vulgaris was examined statistically and the pyrolysis kinetics was determined using a thermogravimetric analyzer. For the production of biochar from microalgae, pyrolysis was carried out at the temperatures of 300, 500, and 700 °C, with the heating rates of 5, 15, and 25 °C/min, retention time of 0, 15, and 30 min, and nitrogen flow rate of 100 ml/min. For the examination of pyrolysis kinetic parameters, dried microalga was heated up to 900 °C at four different heating values of 5, 10, 25, and 50 °C/min at a constant nitrogen flow rate of 40 ml/min. Optimum pyrolysis conditions and the most suitable pyrolysis kinetic model were determined for Chlorella vulgaris. According to the obtained results, it was seen that Chlorella vulgaris could be easily evaluated in thermal conversion processes. Also, these results provide valuable information for optimization of biochar production, and modeling and designing of new pyrolysis systems using microalgal biomass.
TL;DR: In this article, three model-free models were used to predict the pyrolysis kinetics of Madhuca longifolia (mahua, MH) seeds to produce renewable fuel via thermocatalytic conversion.
Abstract: The present study was focused on the bioenergy potential of Madhuca longifolia (mahua, MH) seeds to produce renewable fuel via thermocatalytic conversion. The physicochemical characterization of MH seed confirmed its bioenergy potential. Three model-free models were used to predict the pyrolysis kinetics of MH. The thermodynamic and kinetic analysis showed that MH has complex reaction kinetics which depends on the reaction rate as well as reaction order. Mahua seed was pyrolyzed in a semi-batch cylindrical shaped reactor with (CuO, Al2O3, and NaOH) and without catalysts. The yield of pyrolytic liquid during thermal pyrolysis was 51.2 wt%, whereas the use of catalysts decreased the liquid yield slightly at various biomass to catalyst ratios. Further, characterization results revealed that the use of catalysts improved the properties of pyrolytic oil by reducing viscosity, oxygenated compounds and with increasing heating value and acidity. FTIR spectra of pyrolytic oil confirmed the existence of phenols, aromatics, water, and acids which was also supported by the 1H NMR analysis. Further, GC-MS analysis confirmed reduction in oxygenated compounds and increase in alcohol.
TL;DR: In this article, a response surface methodology was employed to optimize pyrolysis conditions for production of rice husk char with maximum yield, fixed carbon content, and with minimum ash content from Uganda's New Rice for Africa (NERICA) 1 Rice husk variety.
Abstract: Response surface methodology was employed to optimize pyrolysis conditions for production of char with maximum yield, fixed carbon content, and with minimum ash content from Uganda’s New Rice for Africa (NERICA) 1 rice husk variety. The aim was to obtain rice husk char with more suitable properties as an activated carbon precursor. Mathematical models were developed to explain the relationships between the experimental responses and the pyrolysis parameters of temperature (400–600 °C), heating rate (10–25 °C min−1), and heating period (60–120 min). The optimized rice husk char was further characterized for elemental and proximate compositions, thermal behavior, specific surface area, as well as surface functional groups. Results from the analysis of variance (ANOVA) revealed that the quadratic model best fits each of the responses. Pyrolysis temperature had the greatest influence on each of the responses, followed by heating period, and lastly heating rate. Optimum pyrolysis conditions were found to be temperature (406 °C), heating rate (10 °C min−1), and heating period (60 min), resulting in char yield, fixed carbon, and ash contents of 35.26, 55.39, and 35.01% dry basis, respectively. Compared to raw rice husk, the resulting rice husk char was found more suited as activated carbon precursor, due to its enriched carbon content (60.35%) and specific surface area (123.9 m2 g−1). Thermogravimetric analysis of the rice husk char revealed that thermal activation temperatures higher than 400 °C may be required to considerably devolatilize the char, forming a more porous activated carbon.
TL;DR: In this paper, a review aims to summarize the updated state-of-the-art effort dedicated to phenolic compounds extraction from various bioresources using choline chloride-based deep eutectic solvents (Ch-DESs).
Abstract: As the demand for phenolic compounds in pharmaceutical, food, nutraceutical, and cosmetic production is escalating, recovery of phenolic compounds from bioresources has been receiving great concerns from the scientific community. Renewable, environmentally benign, and biocompatible choline chloride–based deep eutectic solvents (Ch-DESs) are considered potential alternatives to conventional solvents in phenolic compound extraction. In the past 2 years, numerous innovative studies centered on phenolic compound extraction using Ch-DESs and process variable optimization have been explored. Thus, this review aims to summarize the updated state-of-the-art effort dedicated to phenolic compounds extraction from various bioresources using Ch-DESs. Furthermore, impact factors, kinetic modeling, and chemical mechanisms of the process are thoroughly analyzed and discussed. Finally, prospects and challenges in commercialization of phenolic compound extraction from bioresources using Ch-DESs are indicated and extensively discussed.
TL;DR: In this paper, the physicochemical properties, hydrophobicity, and mechanical properties of torrefied soybean straw and pine wood pellets were investigated, and the optimal temperature for torrefaction was found to be 250 and 300°C, respectively.
Abstract: In this study, soybean straw pellets (SSP) and pine wood pellets (PWP) were used as materials for torrefaction at 200–350 °C. Impacts of torrefaction temperature on the physicochemical properties, hydrophobicity, and mechanical properties of the pellets were investigated. Results showed that some oxygen-containing functional groups in the biomass pellets disappeared during torrefaction, and the oxygen content significantly decreased. The hydrophobic behavior of biomass is highly affected by their chemical composition. A significant decrease in hemicellulose content was observed in torrefied pellets. Consequently, the equilibrium moisture content of torrefied pellets decreased significantly; and the torrefied PWP remained intact even after immersion of more than 2 h in water. As the torrefaction temperature increased, the cellulose and lignin started to decompose and formed more micropores. Meanwhile, the torrefied pellets became less dense, which lowered the mechanical properties of the pellets. Optimal temperature for the preparation of high-quality torrefied SSP and torrefied PWP was found to be 250 °C and 300 °C, respectively, since higher temperatures cause excessive loss of volatiles and degradation of mechanical properties without significantly enhancing the high heating value of torrefied pellets.
TL;DR: In this paper, the influence of solved compounds in the feedwater on the formation of the hydrochar particle size and the secondary char fraction of the resulting hydrochars was investigated.
Abstract: The chemical-physical processes controlling hydrothermal carbonization (HTC) are still not completely understood. This paper focuses on two aspects: the influence on the hydrochar formation of the particle size of the feedstock and the presence of solved compounds in the feedwater. To address these, brewer’s spent grains were crushed to 250 μm proved by HPLC analysis of liquid byproducts, particularly when rPW, containing readily condensable/polymerizable intermediates, is added. This has a positive effect on the yield and carbon content of the hydrochars caused mainly by an increase in its secondary char fraction. The reaction pathways involved are discussed in detail.