• Energy Research

Critical metals are key to lithium-ion batteries (LIB), but metal mining has inflicted many socio-environmental harms. Recovering metals from spent LIBs can partially overcome this challenge, but existing recovery and recycling techniques such as pyrometallurgy and hydrometallurgy are either energy intensive or require toxic chemicals. Solvometallurgy, using biodegradable deep eutectic solvents (DESs), has emerged as a greener option, but full life cycle sustainability of DESs remains unclear. Here, using an integrated assessment framework we show that, compared with pyrometallurgy and hydrometallurgy, the weak solubility of metal compounds in hydrogen bond donors (HBDs) and acceptors (HBAs) and their non-recoverability in chemical precipitation routes of the DES approach result in 3.1 times more CO2 eq, ∼5 times more ozone depletion, and 6.5–7.3 times higher costs. Although alternative electrodeposition routes can minimize HBA loss and alleviate chemical impacts, high energy consumption associated with HBDs exacerbates global warming potential. In situ repairing/regeneration of crystalline compounds in cathode materials could offer a more sustainable application for DESs.

Abstract Response surface methodology was used to optimize the xylose production from pinewood sawdust through dilute-phosphoric-acid hydrolysis. The effects of independent variables on xylose yield were investigated, including reaction temperature (75–175 °C), reaction time (0–7.2 h), solution-to-feed ratio (4–20 mL/g), and phosphoric-acid concentration (0–6.67 wt%). Results indicated that the individual factor H3PO4 concentration and the interacting factors including temperature × time, temperature × H3PO4 concentration, and solution-to-feed ratio × H3PO4 concentration were all significant factors. Long reaction time (>5.4 h) and high phosphoric-acid concentration (>5%) showed little effect. Xylose yield increased with increasing temperature up to 125 °C. Higher phosphoric-acid concentration and larger solution-to-feed ratio also increased xylose yield. The coefficient of determination, corresponding analysis of variance, and parity plot indicated that the fitted model was appropriate for the acid-hydrolysis process. The maximum xylose production of 90.95% could be obtained with the reaction temperature of 106.7 °C, reaction time of 4.57 h, phosphoric-acid concentration 4.49 wt%, and solution-to-feed ratio of 12.51 mL/g.

Abstract An ever increasing demand for animal protein products has posed serious challenges for managing the increasing quantities of livestock manure. The choice of treatment technologies is still a complicated task and considerable debates over this issue still continue. To build a clearer picture of manure treatment framework, this study was conducted to review the most frequently employed manure management technologies from their state of the art, challenges, sustainability, environmental regulations and incentives, and improvement strategies perspectives. The results showed that most treatment technologies have focused on the solid fraction of manure while the liquid fraction still remains a potential environmental threat. Compared to other waste to energy solutions, anaerobic digestion is the most mature technology to upgrade manure's organic matter into renewable energy, however the problems associated with high investment costs, operating parameters, manure collection, and digestate management have hindered its developments in rural areas in developing countries. Bio-oil production through hydrothermal liquification is also a promising solution, as it can directly convert the wet manure into biofuel. However, lipid-poor nature of manure, operational difficulties, and the need for downstream process to remove nitrogenous compounds from the final product necessitate further research. Livestock manure management (both solid and liquid fractions) under biorefinery approach seems an inevitable solution for future sustainable development to meet circular bioeconomy requirements. Much research is still required to establish a systematic framework based on regional requirements to develop an integrated manure nutrient recycling and manure management planning with minimum environmental risks and maximum profit.

Glucose isomerization to fructose is one of the most important reactions in the field of biomass valorization. We demonstrate wood waste valorization with MgCl2 salt to synthesize an environment-fr...

We describe the selective hydrogenation of furfural (FAL) into tetrahydrofurfuryl alcohol (THFA) under mild conditions (30 °C) in aqueous media using a Rh-loaded carbon (Rh/C) catalyst in a one-pot fashion.

Abstract Biomass resources have been considered as one of the most promising renewable feedstocks to replace fossil resources. However, valorization of biomass is still challenging due to concerns about environmental sustainability and low efficiency of conversion processes. Mechanical ball milling technology, which has emerged as an efficient and environmentally sound alternative to traditional method, can overcome this obstacle to facilitate biomass valorization. Mechanical energy in the ball milling process can induce chemical reactions of biomass in solvent-less/-free conditions. This work reviews the latest advances in the mechanochemical conversion of biomass into chemicals and carbon materials. The initial pretreatment of biomass, catalytic transformation process of biomass, and synthesis of biomass-derived carbon materials (ordered mesoporous carbons, hierarchically porous carbons, carbon/metal composites, etc.) are discussed in detail. Mechanisms, development history, key influencing factors, and technology readiness level of ball milling on biomass valorization are also elucidated. Limitations and opportunities associated with this green technology are highlighted for future research directions.

The current review explores the potential application of algal biomass for the production of biofuels and bio-based products. The variety of processes and pathways through which bio-valorization of algal biomass can be performed are described in this review. Various lipid extraction techniques from algal biomass along with transesterification reactions for biodiesel production are briefly discussed. Processes such as the pretreatment and saccharification of algal biomass, fermentation, gasification, pyrolysis, hydrothermal liquefaction, and anaerobic digestion for the production of biohydrogen, bio-oils, biomethane, biochar (BC), and various bio-based products are reviewed in detail. The biorefinery model and its collaborative approach with various processes are highlighted for the production of eco-friendly, sustainable, and cost-effective biofuels and value-added products. The authors also discuss opportunities and challenges related to bio-valorization of algal biomass and use their own perspective regarding the processes involved in production and the feasibility to make algal research a reality for the production of biofuels and bio-based products in a sustainable manner.

This review lays great emphasis on production and characteristics of biochar through gasification. Specifically, the physicochemical properties and yield of biochar through the diverse gasification conditions associated with various types of biomass were extensively evaluated. In addition, potential application scenarios of biochar through gasification were explored and their environmental implications were discussed. To qualitatively evaluate biochar sustainability through the gasification process, all gasification products (i.e., syngas and biochar) were evaluated via life cycle assessment (LCA). A concept of balancing syngas and biochar production for an economically and environmentally feasible gasification system was proposed and relevant challenges and solutions were suggested in this review.