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In present study, lipids were extracted from unbroken microalga Chlorella vulgaris with high water content (50% microalgal solution) through three-phase partitioning (TPP). The method was found to extract around 15.9% of total lipid transformable to methyl esters (LTMEs) from unbroken microalgal cells which is two times of Bligh and Dyer method. We investigated the effects of various parameters on TPP performance and were optimised through response surface methodology. The results indicated that incubation duration, temperature and extraction time were positively correlated with LTME extraction efficiency. The optimum temperature was 60 °C, incubation duration was 120 min, extraction time was 60 min, ratio of solvent to DKP was 1:1. The FAME yield was calculated as 12.05% and major fatty acids together accounted for 71.33% which indicated the great potential of the proposed lipid extraction procedure for microalga-based biodiesel production., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Alanine is widely employed for synthesizing polymers, pharmaceuticals, and agrochemicals. Electrocatalytic coupling of biomass molecules and waste nitrate is attractive for the nitrate removal and alanine production under ambient conditions. However, the reaction efficiency is relatively low due to the activation of the stable substrates, and the coupling of two reactive intermediates remains challenging. Herein, we realize the integrated tandem electrochemical‐chemical‐electochemical synthesis of alanine from the biomass‐derived pyruvic acid (PA) and waste nitrate (NO3−) catalyzed by PdCu nano‐bead‐wires (PdCu NBWs). The overall reaction pathway is demonstrated as a multiple‐step catalytic cascade process via coupling the reactive intermediates NH2OH and PA on the catalyst surface. Interestingly, in this integrated tandem electrochemical‐chemical‐electrochemical catalytic cascade process, Cu facilitates the electrochemical reduction of nitrate to NH2OH intermediates, which chemically couple with PA to form the pyruvic oxime, and Pd promotes the electrochemical reduction of pyruvic oxime to the desirable alanine. This work provides a green strategy to convert waste NO3− to wealth and enriches the substrate scope of renewable biomass feedstocks to produce high‐value amino acids. [ABSTRACT FROM AUTHOR]

Production of γ-valerolactone (GVL) from biomass-derived platform levulinic acid (LA) via catalytic transfer hydrogenation (CTH) over renewable lignosulfonate-derived catalyst is reported herein. Lignosulfonate-derived catalysts were prepared by assembled Zr-metals with sodium lignosulfonate (LigS) derived from the industry paper waste. The resulting Zr-LigS catalyst exhibited excellent catalytic performance in 92.5% GVL yield under mild conditions. With the combination of detail catalyst characterizations, catalytic performance of the Zr-LigS catalyst, in-situ ATR-FTIR and poisoning experiments, the hydrothermal treatment of Zr4+ and LigS resulted in the formation of basic sites, which contributed significantly to the CTH reaction. Kinetic experiments demonstrated that the activation energy was as low as 41.9 kJ/mol. Furthermore, isotopic labeling experiments suggested that the β -H in isopropanol is transferred to the C O bond of LA by the formation of six-membered intermediates on the basic sites, which is the rate-determining step. [Display omitted] • Renewable Zr-LigS catalyst is prepared by hydrothermal method. • Zr-LigS catalyzes CTH with more than 90%γ-valerolactone yield under mild condition. • In-situ liquid phase FTIR was employed to study the mechanism. [ABSTRACT FROM AUTHOR]

Traditional two steps biodiesel production process generally involves corrosive sulfuric acid in the transesterification step, which is not environmentally benign. In this work, a novel procedure was presented for the direct production of biodiesel using Lewis acid deep eutectic solvent (LADES) to avoid using sulfuric acid. Synergy between the Lewis site of the LADES catalyst and the Brønsted site from biomass pretreated by Brønsted acidic deep eutectic (BADES) has resulted in the development of a bifunctional medium considered to be appropriate for high biodiesel formation and increase the FAMEs weight. The mechanism of biodiesel formation was anticipated through the experimental and computational studies of Lewis and/or Brönsted acid sites in the reaction process. The potential interference factors of the extraction process such as time of reaction, temperature, LADES catalyst concentration in methanol, and solvent volume were further optimized experimentally, followed by the Box–Behnken method. The highest amount (39.86 mg/g) of fatty acid methyl esters (FAMEs) was obtained from Chlorella pyrenoidosa biomass at 120 °C for 90 min, 5 mL solvent volume, and 5% concentration of LADES (ChCl-CrCl 3.6 H 2 O) catalyst in methanol. The predominant FAMEs were C16:0 (9.47 mg/g), C18:2 (12.42 mg/g), and C18:3 (8.68 mg/g), and obtained biodiesel qualities meet international standards. The recyclability of LADES was tested, and satisfactory results of FAME weight were observed up to three cycles, and the FTIR peaks of LADES catalyst after four cycles of reusing have shown the structure of DES remain stable. Despite the existence of sustainable, efficient, and less toxic ways for microalgae transesterification, further investigation is required to assess the scalability of these methods for large-scale use. [Display omitted] • LADES (ChCl-CrCl 3.6 H 2 0) acid catalyst, was used for biodiesel production of microalgae biomass. • Maximum, 39.86 mg/g FAME was obtained using 5% LADES catalyst. • FAME weight of the conventional sulfuric acid and LADES catalyst compared. • Direct transesterification can decrease production costs by eliminating lipid extraction step • LADES catalyst can be reused up to four cycles. [ABSTRACT FROM AUTHOR]

The biomass of Chlorella sp. was pretreated with three different aqueous deep eutectic solvents (aDESs), i.e. aqueous choline chloride-oxalic acid (aCh-O), aqueous choline chloride-ethylene glycol (aCh-EG) and aqueous urea-acetamide (aU-A). The effect of aDESs pretreatment of microalgae biomass was evaluated in terms of lipid recovery rate, total carbohydrate content, fatty acid composition, and thermal chemical behavior of biomass. Results indicated that, lipid recovery rate was increased from 52.03% of untreated biomass to 80.90%, 66.92%, and 75.26% of the biomass treated by aCh-O, aCh-EG and aU-A, respectively. However, there were no major changes observed in fatty acid profiles of both untreated and treated biomass, specifically palmitic acid, palmitoleic acid and stearic acid under various pretreatments. Furthermore, characterizations of untreated and treated biomass were carried out using Fourier transform infrared (FTIR), thermogravimetry analysis (TGA) and scanning electron microscope (SEM) to understand the enhanced lipids recovery. [ABSTRACT FROM AUTHOR]