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[Display omitted] • Pretreatment is a critical process for biohydrogen production from biomass. • A distinction should be made between the initial pH and the pH of the process. • Dissolved bio-H 2 concentrations are not always in equilibrium with the gas phase. • The combined fermentation methods offer advantages compared to dark fermentation. • Iron catalysts are attractive due to high abundance and relatively low toxicity. Biohydrogen is a green energy carrier with the potential to reduce our dependency on fossil fuels. The production of biohydrogen from lignocellulosic materials may be low cost, but commercial production has not been realized. The issues to be addressed include screening and construction of microorganisms that meet industrial requirements, optimization of bioreactor designs, and novel hybrid fermentation systems such as combining dark fermentation (DF) with methanogenic systems and doping nanomaterials to increase biohydrogen yield. This paper focuses on the biohydrogen production, highlighting various fermentative bioreactor types, influential factors in dark fermentation, and pretreatment techniques. Besides, current strategies to produce biohydrogen, including synthetic biology approaches and metabolic engineering, are assessed for their potential to contribute to net zero carbon emission. Pretreatment of biomass using dilute acids is the most common technique to destroy the complicated structure of lignocellulosic biomass. Mesophilic temperatures (37 °C), HRT of 72 h, and pH near 7.0, are recurrent parameters of biomass fermentation. The combined approach of electro-fermentation and dark fermentation produces a higher yield of biohydrogen compared to the single dark fermentation. Furthermore, additives (mainly iron-based materials) have been investigated to improve the efficiency of biomass pretreatment as well as biohydrogen production. Finally, this paper points out that the vigorous development of novel engineered strains is an important part of achieving commercial-scale production of biohydrogen. Overall, considerable efforts are needed from both technical and managing aspects to achieve a full-scale application of biohydrogen production to make this technology economical, efficient and sustainable. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microwave-assisted pyrolysis is a promising method for biomass/waste valorisation. • Life cycle analysis shows reduced energy consumption, low global warming potential. • Innovations in reactor design and operation parameters aids in cost reduction. Microwave-assisted pyrolysis (MAP) has been perceived as a promising technology for biomass and waste conversion due to its distinctive features, including fast, even, and precise heating. This results in higher energy efficiency when compared to conventional pyrolysis via thermal heating. However, the scaling up of MAP of biomass and waste poses challenges, with investigations ongoing to uncover not only the technological aspect, but also both the environmental impacts and economic feasibility associated with this process/technology. The possible environmental impacts associated with MAP processes can be analyzed through systematic life-cycle assessment (LCA), while the economic feasibility can be evaluated via techno-economic analysis (TEA). This paper presents an overview of the current research trend in MAP and the products produced, as well as the LCA and TEA of the pyrolysis technologies. The LCA study reported a 2.5 folds reduction in energy consumption and up to 62% reduction in global warming potential. TEA study revealed that conventional pyrolysis has a greater profit for long-term assessment due to a higher maturity and less complexity technology; however, MAP may be more economically feasible in the future owing to the increased maturity and more established technology. Finally, the challenges and future perspectives for LCA and TEA in MAP are elucidated. [ABSTRACT FROM AUTHOR]

[Display omitted] • A review on developing carbon neutral wastewater treatment based on EAOPs. • Recent advances on EAOPs for wastewater treatment are summarized. • Strategies for carbon neutral wastewater treatment based on EAOPs are summarized. • Renewable energy generation is key to carbon neutrality in wastewater treatment. • Mineralization remains one of the greatest challenges for CO 2 abatement. Electrochemical advanced oxidation processes (EAOPs) have been widely studied in efficient wastewater treatment for achieving high degradation efficiency of pollutants even at the expense of high electric energy consumption and carbon emissions. This development is inconsistent with the initiative of carbon neutrality. Despite the growing numbers of published papers on EAOPs, there is still a lack of guidelines regarding carbon neutral wastewater treatment, thus hampering efforts to achieve sustainable development of EAOPs and attain carbon neutrality. This review systematically summarized recent advances of EAOPs and the potential strategies for developing carbon neutral wastewater treatment. The mechanisms, performance, and defects of recent developed EAOPs via improving electrodes, catalysts and processes were discussed systematically. The effective strategies including energy conservation, material savings, carbon dioxide reduction reaction (CO 2 RR), and mineralization mitigation were presented in detail. To conserve energy, the review also investigated the power supply capacity, degradation efficiency and costs in transforming renewable energy into electric energy for EAOPs operation. The wind turbines and photovoltaic cells (PVCs) could performe better than fuel cells and triboelectricity nanogenerators (TENGs). Furthermore, the review explored the carbon offset potential of EAOPs by combining with CO 2 RR. The carbon offset factor ranged from <1% to ∼88%. In addition, specific strategies and challenges in developing carbon neutral EAOPs were summarized and discussed. This review was expected to constitute a baseline for the development of EAOPs towards carbon neutral wastewater treatment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Separation mechanisms including adsorption via COF-based membranes are investigated. • The latest synthesis methods and application of COF-based membranes are highlighted. • Pioneering perspectives about existing challenges of COF-based membranes are proposed. • Theoretical guidance for designing high-performance COF-based membranes is presented. With the accelerating steps of urbanization, the freshwater scarcity has been emerging as a serious threat to sustainable economic and social development. Under this circumstance, increasing attention is shifting to alternative water sources, such as wastewater and seawater, to harvest the embedded freshwater for supplement. Membrane technology has been predominately applied in this scenario due to its huge advantages in separation efficiency and economic investment. However, the application, especially with polyamide (PA) composite membranes, is significantly limited by the unsatisfied water flux when reclaiming high-quality freshwater. Recently, covalent organic framework (COF)-based membranes with pure COF or COF-incorporated PA as the selective layer exhibited great promise in alleviating this current dilemma benefiting from its tunable aperture, regular channels and desirable hydrophilicity. Unfortunately, relative research works were mainly focusing on the structure–function relationship between COF and the resultant membrane. In the meantime, the accompanied reviews were derived mainly from summarizing membrane preparation processes and practical applications while paid insufficient attention in the separation mechanisms of the COF-based membranes, which are highly desired for directionally optimizing membrane performance from the theoretical perspective. Herein, the mechanisms involved in water purification through COF-based membranes are systematically investigated, especially in a novel view of adsorption. In addition, the up-to-date synthesis strategies of high-performance COF-based membranes are highlighted. Besides, the latest advances in structure-performance relationship of emerging COF-based membranes for wastewater purification and saltwater desalination are also described in this paper. This review aims to provide theoretical guidance and potential methods for design and preparation of next-generation COF-based membranes with higher-performance for high-quality recovery of freshwater. [ABSTRACT FROM AUTHOR]

[Display omitted] • An innovative bioinspired CO 2 sorbent was synthesized by pyrocatechol and HMDA; • Outstanding CO 2 capture of 7.28 mmol/g was achieved under 4% humidified CO 2 at RT; • Easy functionalization for higher CO 2 capture and lower energy penalty regeneration. • Mussel-inspired coatings were completely stable over 50 adsorption/desorption cycles; • Our coating approach can be potentially applied to a plethora of surfaces. Nowadays, finding innovative technologies to efficiently adsorb/desorb CO 2 over several cycles with low energy consumption is a pressing environmental concern. In this work, a new bioionspired coating based on the copolymerization of benzene-1,2-diol and hexamethylenediamine, with a CO 2 uptake of 7.28 mmol/g under humidified conditions with an outstanding chemical stability and regenerability process is reported. Further functionalization with glycidyltrimethylammonium chloride increases the uptake capacity up to 9.96 mmol/g while lowering the desorption temperature down to 50 °C for 20 min. Moreover, the coating shows strong adhesion on cotton and paper, without modifying their intrinsic permeability and mechanical properties, allowing for the recycling of fully available and environmentally friendly biomass. These results demonstrate the competitive advantages of this bioinspired coating compared with current technologies to capture CO 2 while accomplishing the resource efficiency of bioeconomy policies. [ABSTRACT FROM AUTHOR]

• Process simulation is combined with life cycle assessment and life cycle costing. • Instant coffee has >2 times higher impacts and costs than ground coffee. • Light roasts have lower impacts and costs due to lower losses and energy use. • The coffee industry emits 863–894 kt CO 2 eq./y, or 1.3% of total from UK food sector. • This could be reduced by 4.9% through process and packaging improvements. With around two billion cups consumed daily worldwide, the coffee industry faces pressures to improve its sustainability. Focusing on the UK as the fifth largest coffee consumer in Europe, this paper presents for the first time a life cycle environmental and economic sustainability assessment of coffee production at the product and sectoral levels. Both gate-to-gate and cradle-to-gate system boundaries are considered to identify opportunities for improvements in the manufacturing process and along the supply chain. Process design and simulation are combined with life cycle assessment and life cycle costing to evaluate the sustainability of the production of ground and instant coffee roasted to different levels. Based on the functional unit of 1 tonne of coffee produced, instant coffee has higher impacts and costs than ground coffee for both system boundaries because it requires double the amount of green coffee beans and 7–11 times more energy. For gate-to-gate, roasting and packaging are the main contributors to the impacts and costs; for cradle-to-gate, cultivation of coffee beans and packaging are the hotspots. Light roasts generally have lower impacts and costs due to lower material losses and energy requirements. At the sectoral level, the coffee industry emits 863–894 kt CO 2 eq. annually, contributing 1.3% to the GHG emissions from the UK food and drinks sector. Key opportunities for improvements include switching to lighter roast and pouch packaging, as well as using air recirculation roasters and silverskin as fuel. These results will be of interest to the coffee industry, policy makers and consumers. [ABSTRACT FROM AUTHOR]

[Display omitted] • The role and impacts of OVs in the catalysis of gaseous pollutants is illustrated. • Methods for regulating the generation of OVs in catalysts are summarised. • The characterisation of OVs is concluded by classification. • Potential research directions and challenges are emphasized. Environmental problems, especially increasing atmospheric pollution, are urgently prompting new strategies to assist in sustainable development. Many studies have demonstrated that oxygen vacancies (OVs) play an important role in the degradation of gaseous pollutants by modulating the surface and electronic structure of catalysts. To clarify the oxygen vacancy effect, this paper reviews recent research advances in improving the performance of catalysts for the degradation of gaseous pollutants based on controlling OVs. The constitutive relationship between OVs and performance in the degradation of typical gaseous pollutants is elucidated. Various approaches for generating and characterizing OVs in catalysts are also summarized. Finally, some perspectives on the challenges and future opportunities for the development of oxygen-deficient catalysts are discussed. This review is significant for the study of the reaction mechanism of OVs with gaseous pollutants and the design of efficient catalysts. [ABSTRACT FROM AUTHOR]

• NC has emerged as a potential candidate for fabricating highly efficient membranes. • The aim of this article is to provide a comprehensive review of NC-based membranes. • The structural design, separation performances and mechanisms are provided. • The review focuses on the state-of-the-art NC membranes for molecular separation. Nanocellulose (NC), a family of most promising natural nanomaterials, has emerged as a potential candidate for the fabrication of highly efficient separation membranes owing to its unique one-dimensional nanostructure, hydrophilic property, easily designed surface chemistry as well as outstanding mechanical strength. In this paper, we review the latest advancements on the state-of-the-art NC-based membranes for molecular separation in water treatment, chemical industries, seawater desalination and battery fields. Based on the function of NC, NC-based membranes are classified as NC-assembled membranes, NC/2D nanomaterial composite membranes, functional NC membranes, thin-film nanocomposite membranes, and thin-film composite membranes with NC as an interlayer. Their preparation methods, physicochemical structures, separation performances and separation mechanisms are summarized to elucidate the role of NC. A summary and perspective are further provided on the opportunities and challenges in this arising field. The aspects discussed may promote green development of advanced membranes, considering the growing concerns about sustainable resource. [ABSTRACT FROM AUTHOR]

[Display omitted] • One monolayer Janus bio-nanocomposite film with stimulus response is developed. • Janus structure and bonding intensity is obtained by incorporating nanocellulose into PVA. • Asymmetric structure, good mechanical properties, and water-resistance are realized. • Janus bio-nanocomposite film exhibits a smart and controllable responsiveness to salts. • Janus bio-nanocomposite film based actuators are controllably designed and explored. Stimuli-responsive materials have been increasingly explored to construct actuators and develop soft robots. Herein, one strategy via regulating lignin-containing cellulose nanofibrils (LCNF) distribution in PVA network followed by alkaline treatment (AT) and pre-stretching to fabricate bio-nanocomposite derived Janus films with stimulus response is proposed. LCNF/PVA-AT film displays obvious asymmetric structure, good mechanical properties, and water-resistance. Based on Janus structure and Hofmeister effect of PVA in salt solution, the applied pre-stretching treatment further enables the as-prepared LCNF/PVA-AT film with an excellently smart and controllable responsiveness to salt solutions. In addition, by adjusting some factors including length–width ratio of the film, salt type and concentration, the deformation degree and response/recovery time of LCNF/PVA-AT film and its based actuators can be controllably designed. The study will enrich the development of green, sustainable and biodegradable polymers derived Janus films, and expand their wide potential applications in multifunctional actuators. [ABSTRACT FROM AUTHOR]