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Hydrothermal liquefaction (HTL) of wet spent coffee grounds was performed in a batch reactor for bioenergy production. The effects of spent coffee grounds to water ratio, temperature and reactor vo...

In this study, cotton stalk (CS) biochar was used as a sorbent for the removal of malachite green from wastewater. Batch sorption experiments revealed that dye removal increases along with rise in initial dye concentration, temperature of the sorption process, and sorbent weight. Dye removal was observed in the range of 35–40 mg/g for 100 mg/L initial dye concentration. Freundlich and Temkin isotherm models were used for modelling the sorption process. Furthermore, thermodynamic study indicated that the process is endothermic and that the spontaneity of sorption gradual rise with temperature. The changes in enthalpy and entropy were determined to be 57,697.25 J/mol and 177.768 J/mol, respectively. Pseudo-second-order kinetics was found to be suitable for the sorption process. Dynamic study revealed that film diffusion is the governing diffusion in the sorption process. Additionally, microwave-assisted heating was employed to regenerate the spent CS biochar, and a yield of 21–76% was obtained depending on the power of the microwave. It was observed that high-power regeneration distorts the pores; thereby, lowering the dye sorption capacity of the regenerated biochar.

Depolymerisation of lignin produces concoction of aromatic compounds, such as, phenols, dihydroxybenzenes, alkylphenols, methoxyphenols, alkyl-methoxy substituted phenols, and diaryl ethers. This review presents an introduction on lignin, phenolic compounds and its value-added products, namely, cyclohexanols, cyclohexanones, and cyclohexanes obtained via hydrodeoxygenation/-hydrogenation reaction. The prior-art of catalytic interventions for selective preparation of cyclohexanols (a potential polymer and fuel intermediates) from lignin-based phenolic compounds are discussed. For this process, in-depth evaluation of nature of catalytic support, effect of reaction conditions (temperature and H2 pressure)/medium, active metallic sites, and mechanistic paths are performed.

This study focuses on the conversion of groundnut shell into activated carbons via chemical activation using H3PO4, ZnCl2 and KOH. 100 g of groundnut shell was used for activation at 1:1 impregnation ratio (feedstock to the activating agent). The yield (wt%) of activated carbon was in the range of 87–90 wt%. Highest BET surface area was obtained for KOH activated carbon sample (691.69 m2/g). In line with this, methylene blue number was higher in case of KOH activated carbon sample (332.20 mg/g) as compared to H3PO4 (270.20 mg/g) and ZnCl2 (291.20 mg/g) samples. Thermo-gravimetric analysis reveals that all activated carbon samples were thermal stable up to ~ 850 °C. FTIR spectrum shows appearances of minor functional groups in the activated carbons.

Biomass is among the potential viable energy resources that are used to produce electricity globally. Biomass-based electrification is a clean and safe way to utilize biomass resources. India has remarked the third position on the generation of biomass globally. This is the stimulus because of which biomass can contribute to electricity generation in India. The current chapter focuses on the feasibility of biomass-based electrification using different conversion technologies. Thermochemical conversion is one of the well-recognized technologies to valorize biomass. The utilization of biomass with different technologies has been discussed in this chapter. Special emphasis is placed on the Indian scenario of biomass-based electrification along with its future prospects and challenges.

The demand for biomass utilization is increasing because of the depletion of fossil resources that are non-renewable in nature. Lignin is the second most renewable organic carbon source, but currently it has limited scope for application in the chemical and fuel industries. Lignin is a side product of the paper and pulp, sugar, and 2G bioethanol industries. Many research groups are working on the value-addition of lignin. Among the lignin depolymerization methods, catalytic hydropyrolysis is gaining attention and is playing a crucial role in developing biorefinery. The hydropyrolysis of lignin was conducted at a higher temperature in the presence of H2. The hydropyrolysis of lignin results in the selective formation of non-oxygenated cyclic hydrocarbons in a shorter reaction time. It is possible to use the cyclic hydrocarbons directly as a fuel or they can be blended with conventional gasoline. This review focuses on the prior art of pyrolysis and hydropyrolysis of lignin. Possible products of lignin hydropyrolysis and suitable synthetic routes to obtain non-oxygenated cyclic hydrocarbons are also discussed. The influence of various process parameters, such as type of reactor, metal catalyst, nature of catalytic supports, reaction temperature, and H2 pressure are discussed with regard to the hydropyrolysis of lignin to achieve good selectivity of cyclic hydrocarbons.

Oxidative fast pyrolysis of sawdust was performed in a pilot scale fluidized bed system (3 kg/h) under stabilized experimental conditions (0.20 equivalence ratio and 550 °C). Experiments were performed in non-catalytic and catalytic (ZSM-5) mode. During non-catalytic fast pyrolysis, bio-oil (∼38 wt%), bio-char (∼12 wt%) and pyro-gas (∼50 wt%) were obtained; in contrast, for catalytic fast pyrolysis bio-oil, bio-char and pyro-gas yields were ∼44 wt%, ∼4 wt% and ∼52 wt% respectively. The obtained bio-oil was characterized through CHNSO, NMR (1H and 13C NMR), FT-IR and GC–MS techniques. GC–MS analysis of the bio-oil shows it is a mixture of ∼21 chemical compounds. Furthermore, NMR (1H and 13C NMR) and FT-IR results indicates presence of hydrocarbon, alcohol, phenol and aldehyde in the bio-oil. The TGA of bio-char shows that it is stable up to 950 °C. The activation energies (Ea) of sawdust and bio-char are found to be 112.3 kJ/mol and 46.92 kJ/mol respectively. FT-IR analysis of bio-char clearly revealed removal of functionalized organic compounds during devolatilization of sawdust. In addition, GC analysis of pyro-gas suggests that it is a mixture of N2 (35.55 vol%), CO (34.49 vol%), CO2 (16.80 vol%), H2 (4.54 vol%), O2 (4.25 vol%), and CH4 (4.41 vol%).

Spent coffee grounds are composed of lipid, carbohydrates, carbonaceous, and nitrogen containing compounds among others. Using n-hexane and n-hexane/isopropanol mixture highest oil yield was achived during soxhlet extraction of oil from spent coffee grounds. Alternatively, supercritical carbon dioxide can be employed as a green solvent for the extraction of oil. Using advanced chemical and biotechnological methods, spent coffee grounds are converted to various biofuels such as, biodiesel, renewable diesel, bioethanol, bioethers, bio-oil, biochar, and biogas. The in-situ transesterification of spent coffee grounds was carried out in a large scale (4 kg), which led to 80-83% biodiesel yield. In addition, a large number of value added and diversified products viz. polyhydroxyalkanoates, biosorbent, activated carbon, polyol, polyurethane foam, carotenoid, phenolic antioxidants, and green composite are obtained from spent coffee grounds. The principles of circular economy are applied to develop a sustanaible biorefinery based on valorisation of spent coffee grounds.

Lipases namely Mucor miehei, Pseudomonas cepacia, Rhizopus delemar, Geotrichum candidum, Candida rugosa, Porcine pancreas-II, Pseudomonas fluorescence, and Candida antarctica lipase-B (Novozyme-435) were employed for biodiesel synthesis from spent coffee oil. Around 96% oil-to-biodiesel conversion was obtained using Novozyme-435 as a catalyst at 1:5 oil-to-methanol molar ratio and 40oC. Total spent coffee grounds generated at the North-West University, Potchefstroom Campus (NWU PC) was estimated which could be used to produce 162 L of biodiesel. A waste valorization strategy was devised for converting organic wastes produced at the NWU PC to bioenergy.

Biodiesel from spent coffee grounds and food waste was prepared using sulphuric acid immobilised on silica gel (H2SO4–SiO2) as a catalyst. Reactions were carried out under reflux conditions using 15 mmol methanol. Food waste lipid and spent coffee oil gave 97% and 92% of biodiesel, respectively, after 24 h of reaction. After completion of the reaction, the immobilised acidic catalyst was separated by gravity filtration. Subsequently, the catalyst was reused for three consecutive cycles. At the end of three cycles, a 22% decrease in catalytic activity was observed for reactions involving spent coffee oil, whereas a 13% decrease in activity was observed during the use of food waste lipid as a starting material

Bulk fuel was produced from spent coffee grounds (SCG) using different oil extraction and fuel production methods. The highest oil yield (30.2%) and energy efficiency (50%) from continuous hydrothermal liquefaction (CHTL) of the SCG, in water as a solvent, also had the lowest calorific value (37.4 MJ/kg). Oil from traditional hexane oil extraction had the highest calorific value (HHV) (38.7 MJ/kg). Renewable diesel yields through hydrotreatment of extracted oils were consistently higher than biodiesel yields through enzymatic transesterification of the same oils. The highest renewable diesel yield (15.8%) from batch HTL derived bio-oil had the highest calorific value (46.2 MJ/kg). However, the highest kerosene yield (9%) was obtained from in situ renewable diesel production through direct hydrotreatment of the SCG. The study showed that hydrothermal liquefaction was more efficient in producing oil from SCG than traditional solvent extraction but at the cost of losing valuable phytosterols present in the feedstock. As a bulk fuel, renewable diesel had a higher energy value than biodiesel, making it easier to blend into existing transportation fuels. The study provides useful information for the development of a sustainable waste-based bio-refinery in terms of attainable yields and processing options

Baobab (Adansonia digitata) is a promising bio-resource distributed across Africa. A variety of biofuels such as biodiesel, bioethanol, bio-oil and biogas can be prepared from feedstock derived from baobab. In this vein, different parts of baobab plant, for instance oil, fruit shells, and seed cakes can be utilized for biofuel synthesis. In this study, novozyme-435 (CAL-B) was used as a biocatalyst for biodiesel production. Oil to biodiesel conversion of 91.8±2.6% was obtained within 6 h reaction time at 50 °C when the molar ratio of oil to methanol was maintained at 1: 3. Biocatalysts are non-toxic and biodegradable, therefore sustainable for the process. The results showed potential use of baobab oil as a feedstock for biodiesel production.

Oil obtained from the seeds of Manilkara zapota (L.) was transesterified with methanol using lipases as biocatalysts. Four commercially available lipases, such as, porcine pancreas, Candida rugosa, Pseudomonas cepacia and Candida antarctica-B were used for biodiesel preparation. Novozyme-435 (C. antarctica lipase-B immobilized on acrylic resin) and CLEA (cross-linked enzyme aggregate) of C. antarctica lipase-B were compared for their biodiesel production potential. Under optimized reaction conditions, Novozyme-435 gave 96% biodiesel yield in 12 h; whereas, CLEA of C. antarctica-B gave 84% yield of biodiesel. Novozyme-435 was reused for six cycles and 72% biodiesel was formed at the end of 6th cycle. The deactivated Novozyme-435 was regenerated by incubating it in soybean oil, 2-butanol and tert-butanol.

Noodle waste contains significant amounts of starch, lignocellulosic material and oil. Pretreatment involving extraction followed by centrifugation is necessary to separate the oil from the starch and lignocellulosic mixtures. The isolated oil is subjected to a separation process to make it water and solvent free. Then, using esterification and transesterification reactions, the oil is converted to biodiesel by chemical (97.8–98.5% yield) and enzymatic (95.4% yield) methods. The residual starch and lignocellosic mixtures are hydrolyzed enzymatically to form small sugar units, such as glucose and fructose. The obtained hydrolysate is then fermented to produce bioethanol (conversion rate 96.8%). The hydrolysate can also be used as a nutrient for growing microorganisms for the production of lipids, enzymes and pigments. Additionally, noodle waste can be converted to animal feed.

Waste cooking oil is discarded into sewage and waste bins in various developing countries. In China, the discarded oil is scooped illegally from drains by smugglers. After collection, the obtained waste oil is reprocessed; the resulting substance is popularly called gutter oil. Gutter oil and its mixture with fresh vegetable oils are sold in food markets at lower prices. This created panic among the general public because of food safety concerns. 1H NMR (proton nuclear magnetic resonance), MALDI-MS (matrix-assisted laser desorption/ionization-mass spectrometry) and HPLC (high-performance liquid chromatography) are used for the detection of gutter oil. Currently, sustainable utilization of gutter oil for biofuel production is being explored using chemical and enzymatic methods. Furthermore, trial runs by Boeing company shows that gutter oil can be blended with normal jet fuel for use in aviation industry. Annually, around 1.8 billion L (476 million gallons) of biofuels can be produced from gutter o...

Waste oil was extracted from lollipop effluent stream using a mixture of organic solvents viz. n-hexane and ethyl acetate. Lollipop effluent samples found to contain ~ 10-18 wt.% oil. Subsequently, the oil was subjected to biodiesel synthesis under solvent free condition using chemical and enzymatic catalysts. Among the base catalysts used, KOH catalyzed reaction gave highest biodiesel yield (99 %) in 20 minutes. Furthermore, nine different lipases were screened as catalysts for biodiesel preparation from lollipop effluent oil. The screening experiments revealed that Novozyme-435 was best among the lipases which gave 94 % biodiesel in 18 h at 40 0C.

Depletion of fossil fuels, environmental damage due to pollution and energy security have intensified research on alternative liquid biofuels. A major portion of municipal solid waste is food waste. Huge quantities of food waste is generated worldwide and currently its disposal is becoming a challenge. Food waste contain carbohydrates, lipids, phosphates, vitamins and amino acids. Carbohydrate, lipid and carbon containing materials present in food waste can be converted to bioethanol, biodiesel and biooil. Lipid extracted from food waste is converted to biodiesel in 95–97% yield. On the other hand, 92–96% bioethanol obtained by fermentation of food waste. Along this line, pyrolysis of food waste can be performed to obtain biooil and biochar. In this paper, technical feasibility, prospects and policies for liquid biofuel preparation from food waste was evaluated. Also, limitations of using food waste as a resource for biofuel production is discussed.

Fossil fuel shortage is a major challenge worldwide. Therefore, research is currently underway to investigate potential renewable energy sources. Biodiesel is one of the major renewable energy sources that can be obtained from oils and fats by transesterification. However, biodiesel obtained from vegetable oils as feedstock is expensive. Thus, an alternative and inexpensive feedstock such as waste cooking oil (WCO) can be used as feedstock for biodiesel production. In this project, techno-economic analyses were performed on the biodiesel production in Hong Kong using WCO as a feedstock. Three different catalysts such as acid, base, and lipase were evaluated for the biodiesel production from WCO. These economic analyses were then compared to determine the most cost-effective method for the biodiesel production. The internal rate of return (IRR) sensitivity analyses on the WCO price and biodiesel price variation are performed. Acid was found to be the most cost-effective catalyst for the biodiesel production; whereas, lipase was the most expensive catalyst for biodiesel production. In the IRR sensitivity analyses, the acid catalyst can also acquire acceptable IRR despite the variation of the WCO and biodiesel prices.

Lipases from Candida rugosa, Pseudomonas cepacia, and Candida antarctica-B (Novozym-435) were used for the transesterification of crude Pongamia oil with methanol. The Candida antarctica lipase-B catalyzed transesterification gave 91% conversion in 60 h during the stepwise addition of methanol to crude Pongamia oil.

Research on different alternative liquid fuels is rapidly growing because of the environmental concerns and depletion of fossil fuels. As the world confronts a reported food shortage and rising fuel prices, researchers are engaged in developing biofuels that would not convert food crops into energy. In addition, it is apparent that the demand for biodiesel is expected to rise over the coming years. To date, many edible oils are used for biodiesel production. Thus, increasing demand of biodiesel will have a direct impact on food shortage. This underlines the need to use waste materials for biodiesel preparation. In this regard, lipid fraction which can be obtained after hydrolysis of food waste with an enzyme system accumulated in the solid state fungal culture is considered inedible and can be used as a potential source to produce biodiesel.

High yield and selectivity in the intramolecular synthesis of the macrocyclic lactone oxacyclohexadecan-2-one were achieved via a straightforward biocatalytic synthesis utilising non-conventional solvents: supercritical carbon dioxide (scCO2), ethane, fluoroform and 1,1,1,2-tetrafluoroethane. Batch and continuous syntheses were demonstrated with a higher yield attained in a continuous synthesis using in-situ product extraction by scCO2. A remarkably high yield was obtained in 1,1,1,2-tetrafluoroethane at batch conditions.

Tetrahedral aluminium was synthesized inside the TUD-1 structure with a low Si/Al ratio. The Al ion in its tetrahedral structure was stabilized by sodium as a counter cation. However, the tetrahedral aluminium species in the TUD-1 structure reverted to a mixture of hexa-, penta- and tetrahedral coordination sites after the exchange of sodium cations with protons. The Al-TUD-1 materials were found to be catalytically active for the acetal protection of benzaldehyde.

A chemoenzymatic synthesis of benzylated dihydroxyacetone phosphate precursor is described, starting from glycerol.

A new approach to enantiomerically enriched cyclic β-hydroxy ketones was developed. 3-Hydroxycyclohexanone was successfully resolved using lipase catalyzed transesterification. Among the lipases screened PFL, PCL, and PPL-II gave 57%, 39%, and 25% yield of the (R)-3-oxocyclohexyl acetate with 52%, 75%, and 91% ee. The PPL-II gave the highest E-value (32). The absolute configuration of the product was determined by comparison with the literature data.

Different acidic ionic liquids (ILs; namely, 1-methylimidazolium tetrafluoroborate, 1-methylimidazolium trifluoroacetate, N-methyl-2-pyrrolidone hydrogen sulfate, N,N,N-trioctyl-n-butanesulfonic acid ammonium hydrogen sulfate, 1-methyl-3-(3-sulfobutyl)imidazolium hydrogen sulfate) and basic ILs (namely, 1,1,3,3-tetramethylguanidinium lactate and choline hydroxide) were tested as catalysts for the aldol reaction. The choline hydroxide catalysed reaction gave high yield (94.3%) and selectivity of the 4-hydroxy-4-phenylbutan-2-one after a short reaction time (15 min) at 0 °C. This article demonstrates the potential of choline hydroxide, which is a derivative of choline and a naturally occurring water-soluble essential nutrient, as a highly active and selective green catalyst.

Benzaldehyde lyase from Pseudomonas fluorescens Biovar I [BAL; E.C.4.1.2.38] catalyzes the stereoselective formation of C–C bonds coupling aldehydes to generate alpha-hydroxy ketones. A broad range of poorly water-soluble substrates are accepted in forward and reverse reactions. In this study, the stability of BAL in aqueous–organic biphasic systems as promising reaction media was systematically investigated using methyl-tert-butylether, 2-octanone, and toluene as the organic phase. Surprisingly, a strong individual molecular toxicity of these water-immiscible solvents was observed along with the interfacial toxicity exerted by the aqueous–organic interfaces. They could be considerably reduced by covalent attachment of methoxy-poly(ethylene) glycol (mPEG750 and mPEG2000) to the enzyme surface increasing the half-life by a factor of up to 18. However, under reactive conditions solvent effects were strongly superimposed by an additional deactivating effect, possibly caused by the aldehyde substrate, and no differences between unmodified and modified BAL were detectable. For technical application of the enzyme in aqueous–organic biphasic media additional strategies for stabilization will therefore be desirable.

Non-ionic surfactants find a unique place in pharmaceutical, detergent, food, and cosmetic industries because of their ready availability from biomass, low cost, and renewability. Generally these surfactants are esters obtained from the reaction of glycerol, L-ascorbic acid, and sugar, with long or medium chain fatty acids. Problems encountered during the synthesis of these surfactants are the immiscibility of highly polar substrates in organic solvents and non-regioselective reaction. Therefore, lipases as a catalyst and t-butanol or acetone, a mixture of solvent and ionic liquid as solvents, have been used for the synthesis of ester-based surfactants. This review focuses on the uses of lipases for the synthesis of surfactants obtained from biomass derivatives viz. fats and oils, sugar and vitamin-C. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd

The kinetics of transesterification of Pongamia oil using methanol at 60�C were studied. The forward as well as the reverse rate constants of all three steps involved in the transesterification of Pongamia oil are reported for the first time. Among the forward rate constants, the one governing the conversion of TG to DG was the highest and the one for DG to MG was the lowest. A distinct feature of the present work is the direct estimation of the equilibrium constants of all three steps by measuring the concentrations of TG, DG, and MG at very long reaction times. This reduced the number of parameters to be determined from the kinetic data by one-half, thereby leading to more accurate estimation of the rate constants. The equilibrium constant of the final step involving the conversion of MG to methyl ester and glycerol was at least an order of magnitude greater than that of the first two reaction steps. A detailed comparison was made with kinetic parameters reported in literature. The trend in the relative magnitudes of the rate constants appears to be unique to Pongamia oil. Copyright � 2006 by AOCS Press.

Ascorbic acid is a naturally occurring antioxidant. Nevertheless, its primary applications as an antioxidant in the life science, food and pharmaceutical industries are limited because of its hydrophilic nature. Alternatively, ascorbyl acid esters are potential surfactants and antioxidants. Chemical methods for the synthesis of ascorbyl esters lead to the formation of side products and simultaneous decomposition of ascorbic acid due to harsh reaction conditions. In contrast, lipases are used as regioselective and mild catalysts for the synthesis of ascorbyl esters. So far, various acyl donors namely, fatty acids, fatty acid alkyl esters, fatty acid vinyl esters and triacylglycerols have been explored for the synthesis of ascorbyl fatty esters. Other compounds such as L-methyl lactate, bixin, phenyl butyric acid are also used as acyl donors. This article is focused on the recent developments of lipase-catalyzed synthesis of ascorbyl esters, their antioxidant properties and applications.

Depletion of fossil fuels and environmental problems are encouraging research on alternative fuels of renewable sources. Biodiesel is a promising alternative fuel to be used as a substitute to the petroleum based diesel fuels. However, the cost of biodiesel production is high and is attributed mainly to the feedstock used which leads to the investigation of low cost feedstocks that are economically feasible. In this paper, we report on the utilization of lipid obtained from food waste as a low-cost feedstock for biodiesel production. Lipid from food waste was transesterified with methanol using base and lipase as catalysts. The maximum biodiesel yield was 100% for the base (KOH) catalyzed transesterification at 1:10 M ratio of lipid to methanol in 2 h at 60 °C. Novozyme-435 yielded a 90% FAME conversion at 40 °C and 1:5 lipid to methanol molar ratio in 24 h. Lipid obtained from fungal hydrolysis of food waste is found to be a suitable feedstock for biodiesel production.

Demand for biofuels is rapidly growing worldwide as petroleum based fuels are finite reserves. In this context, biodiesel and bioethanol are popular biofuels that are commercially available in various countries. Biofuels can be prepared from edible biomass. However, this is already generating food versus fuel debate among the members of civil societies. Therefore, there are needs to synthesize biofuels from nonedible waste materials. Food wastes can be utilized as resources for the production of biodiesel and bioethanol since they contain significant amount of lipids and carbohydrates. In future, industrial production of biodiesel and bioethanol from food waste can contribute to resolve the waste disposal, energy scarcity and energy security problems.