Deep eutectic solvents (DESs) are an emerging class of mixtures characterized by significant depressions in melting points compared to those of the neat constituent components. These materials are promising for applications as inexpensive "designer" solvents exhibiting a host of tunable physicochemical properties. A detailed review of the current literature reveals the lack of predictive understanding of the microscopic mechanisms that govern the structure-property relationships in this class of solvents. Complex hydrogen bonding is postulated as the root cause of their melting point depressions and physicochemical properties; to understand these hydrogen bonded networks, it is imperative to study these systems as dynamic entities using both simulations and experiments. This review emphasizes recent research efforts in order to elucidate the next steps needed to develop a fundamental framework needed for a deeper understanding of DESs. It covers recent developments in DES research, frames outstanding scientific questions, and identifies promising research thrusts aligned with the advancement of the field toward predictive models and fundamental understanding of these solvents.

Deep Eutectic Solvents: A Review of Fundamentals and Applications.

Anaerobic digestion is a versatile biotechnology for conversion of organic wastes to valuable biogas Anaerobic digestion of manure is making the most of it, as the process allows simultaneous bio-energy generation, production of nutrient rich soil amendment, reduced emission of greenhouse gases and odor control; it is thus in line with climate friendly farming practices Despite the enumerated advantages, the potential of manure for biogas production is not fully utilized due to the low and imbalance carbon to nitrogen (C/N) ratio in animal manures To satisfy the anaerobic digestion requirements and to compensate the carbon deficiency of manure, there should be another carbon-rich substrate to be co-digested with manure to improve its characteristics for anaerobic digestion; lignocellulosic biomass residues seem promising for this purpose This work presents a review on anaerobic co-digestion of animal manure and lignocellulosic feedstock for biogas production Several research studies conducted on co-digestion of these organic wastes are described and reviewed The impact of numerous parameters including temperature, pH, organic loading rate (OLR), hydraulic retention time (HRT), C/N ratio, alkalinity and concentration of volatile fatty acids (VFAs) on the performance and stability of the co-digestion process is extensively discussed The influence of various pretreatment methods including physical, chemical and biological pretreatments on providing well-prepared substrate for anaerobic co-digestion and thus enhancement of biogas production is discussed An overview of the most significant factors and intermediates which can inhibit or even cease the process is also presented

Anaerobic co-digestion of animal manures and lignocellulosic residues as a potent approach for sustainable biogas production

Ionic liquids (ILs) and deep eutectic solvents (DESs) have been suggested as eco-friendly alternatives to organic solvents. A trace amount of water is often unavoidable as impurity, and water is also added on purpose to reduce their problematically high viscosity and lower their high price. Understanding the distinct effects of water on the properties of ILs/DESs is highly important. In this review, we collect published experimental and theoretical results for IL/DES–H2O systems at varied water concentrations and analyze them. Results from mechanistic studies, thermodynamic modelling and advanced experiments are collected and critically discussed. Six commonly studied IL/DES–H2O systems were selected to map experimental observations onto microscopic results obtained in mechanistic studies. A great variety of distinct contours of the excess properties can be observed over the entire compositional range, indicating that the properties of IL/DES–H2O systems are highly unpredictable. Mechanistic studies clearly demonstrate that the added H2O rapidly changes the heterogeneous 3D structures of pure ILs/DESs, leading to very different properties and behaviour. There are similarities between aqueous electrolytes and IL/DES solutions but the bulky and asymmetric organic cations in ILs/DESs do not conform to the standard salt dissolution and hydration concepts. Thermodynamic modelling previously assumes ILs/DESs to be either a neutral ion-pair or completely dissociated ions, neglecting specific ion hydration effects. A new conceptual framework is suggested for thermodynamic modelling of IL/DES–H2O binary systems to enable new technologies for their practical applications.

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The peculiar effect of water on ionic liquids and deep eutectic solvents

Pretreatment Strategies for Enhanced Biogas Production From Lignocellulosic Biomass

Resource recovery and circular economy from organic solid waste using aerobic and anaerobic digestion technologies.

Globally, there is increasing awareness that renewable energy and energy efficiency are vital for both creating new economic opportunities and controlling the environmental pollution. AD technology is the biochemical process of biogas production which can change the complex organic materials into a clean and renewable source of energy. AcoD process is a reliable alternative option to resolve the disadvantages of single substrate digestion system related to substrate characteristics and system optimization. This paper reviewed the research progress and challenges of AcoD technology, and the contribution of different techniques in biogas production engineering. As the applicability and demand of the AcoD technology increases, the complexity of the system becomes increased, and the characterization of organic materials becomes volatile which requires advanced methods for investigation. Numerous publications have been noted that ADM1 model and its modified version becomes the most powerful tool to optimize the AcoD process of biogas production, and indicating that the disintegration and hydrolysis steps are the limiting factors of co-digestion process. Biochemical methane potential (BMP) test is promising method to determine the biodegradability and decomposition rate of organic materials. The addition of different environmentally friendly nanoparticles can improve the stability and performance of the AcoD system. The process optimization and improvement of biogas production still seek further investigations. Furthermore, using advanced simulation approaches and characterization methods of organic wastes can accelerate the transformation to industrializations, and realize the significant improvement of biogas production as a renewable source and economically feasible energy in developing countries, like China. Finally, the review reveals, designing and developing a framework, including various aspects to improve the biogas production is essential.

Anaerobic co-digestion process for biogas production: Progress, challenges and perspectives

Molar enthalpy of mixing and refractive indices of choline chloride-based deep eutectic solvents with water

The molar enthalpies of mixing for binary systems of choline chloride (chcl)/urea deep eutectic solvents (mole ratios of 1:1.5, 1:2, and 1:2.5) with water were measured at 308.15 and 318.15 K under atmospheric pressure with an isothermal calorimeter. The binary mixture of (chcl/urea (1:2.5) + water) showed endothermic behavior over the entire range of compositions, while the binary mixtures of (chcl/urea (1:1.5) + water) and (chcl/urea (1:2) + water) showed endothermic behavior first and then was changed to be exothermic with increasing content of deep eutectic solvents. The Redlich–Kister (RK) equation and the nonrandom two-liquid (NRTL) model were used to fit experimental molar enthalpies of mixing. The NRTL model with the fitted parameters was further used to predict the vapor pressure for the three systems and was compared with the experimental data from literature. For the binary mixtures of (chcl/urea (1:2) + water), the predicted vapor pressure agreed well with the experimental data only when the t...

Molar Enthalpy of Mixing for Choline Chloride/Urea Deep Eutectic Solvent + Water System

Surface ligands play critical roles in nano-synthesis and thus it is of great importance in expanding the scope of suitable ligands. In this work, we explore phenynyl ligands in modulating the Au-Au interface when growing Au domains on Au seeds. A patchy growth mode is observed where the emerging islands are flat-laying with holes and branches. This growth mode is distinctively different from the conventional facet-controlled growth using weak ligands, and the non-wetting island growth using strong ligands. Through manipulating the molecular structure and the packing of the phenynyl ligands on the Au seeds, the overgrown Au domains are continuously tuned, from patches to islands, extending the plasmon absorption peak into the near-infrared spectral range. We believe that the new ligand with intermediate affinity and the unusual growth mode would expand the control in both synthesis and application. 

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The patchy growth mode: Modulation of the Au-Au interface via phenynyl ligands

Bimetallic Janus structures are of great importance as their fantastic properties arise from the physical separation and the synergistic effects of the composed materials. Currently, the effective control of the Janus structure still remains a challenge compared to that of the conventional core–shell configuration and thus is highly desired. In this work, strong thiol ligands were used for tuning the interfacial energy between the Au seeds and the Cu deposit to induce the transformation of the Au–Cu core–shell to the asymmetric Janus structures. As a result of effective ligand control, a series of Au–Cu Janus structures using Au nanospheres, Au nanorods, and triangular Au nanoplates as seeds were successfully obtained. Most importantly, the Janus degree of the Au–Cu Janus structures can be readily tuned by varying the molecular structure and the amount of thiol ligands. We believe that the effective strong ligand-mediated interfacial energy control achieved in the Au–Cu system could tune bimetallic Janus structures with different metal–metal combinations, which would help in the precise control of bimetallic nanostructures. In addition, further exploration of the strong ligand control in multicomponent systems may open new doors toward the design and synthesis of sophisticated functional nanomaterials with promising properties. 

Jianpeng Zong

Papers

Anaerobic co-digestion process for biogas production: Progress, challenges and perspectives

Molar enthalpy of mixing and refractive indices of choline chloride-based deep eutectic solvents with water

Molar Enthalpy of Mixing for Choline Chloride/Urea Deep Eutectic Solvent + Water System

The patchy growth mode: Modulation of the Au-Au interface via phenynyl ligands

Tuning Au–Cu Janus Structures through Strong Ligand-Mediated Interfacial Energy Control