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Abstract: Nanoparticles (NPs) of PTFE (polytetrafluoroethylene) in suspension form were reported as very efficient extreme pressure (EP) additive in 150 N API Group II oil in our earlier work. The less stability of a nanosuspension due to agglomeration of NPs beyond 3 wt%, however, was a major issue, which needed to be addressed for its possible industrial exploitation in lubricants. Using another additive, eg polyisobutylene succinimide (PIBSI), as a dispersant appeared to be a plausible solution. Its inclusion (1 wt%) increased the stability of the oil by a factor of 4. It was necessary to investigate, however, whether it influenced other properties synergistically or antagonistically. The present paper highlights the positive and negative aspects of inclusion of PIBSI on the tribo‐performance (EP and anti‐wear) of the nano‐PTFE‐based oils. A series of nano‐PTFE oils (1%‐6%) stabilised with PIBSI (1%) were developed and evaluated for EP and anti‐wear performance. The PIBSI‐PTFE combination clearly showed antagonistic behaviour due to competition for film formation on the surfaces. However, with an increase in concentration of NPs, the film formation mechanism was dominated by them. Scanning electron microscopy, atomic force microscopy, and X‐ray photoelectron spectroscopy were used for the examination of the topography and surface chemistry of the protective films formed on the steel specimens. [ABSTRACT FROM AUTHOR]

TiO2 nanoparticles of average size about 20–30 nm were hydrothermally synthesized from TiCl4 under mild acidic conditions. The nanoparticles were mixed with dispersant and base oil to give a partially transparent concentrate with 1.5 wt% of Ti content. The concentrate was dispersed in hexane and base oil to characterize, respectively, by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The concentrate was diluted with base oil to a parts per million level of Ti containing dispersion blends that were evaluated for wear and friction control performance. Nano TiO2 containing fully formulated oil blend showed excellent load-bearing capability in Swingung, Reibung, Verschleiβ (SRV; oscillation, friction, wear) tests. Four-ball test results show that the wear scar diameter was considerably reduced to 0.30 mm for TiO2-added blend compared to neat base oil (0.60 mm). The performance of TiO2-added blend was comparable to secondary zinc dialkyl dithiophospate (ZDDP)-added blend under identical condition. Raman spectra of the worn surface on the tested ball revealed the presence of ilmenite (FeTiO3) and no deposits of pure TiO2. [ABSTRACT FROM AUTHOR]

The positive interaction between Clostridium sp. and lactic acid-producing bacteria (Lactobacillus sp) is commonly seen in various high-rate hydrogen production systems. However, the exact role of the hydrogen production ability of Lactobacillus sp in a dark fermentation production system is rarely studied. Lactobacillus delbrueckii was herein used for the first time, to the best of the author's knowledge, to demonstrate biohydrogen production under anaerobic conditions. At first, the pH condition was optimized, followed by the addition of nanoparticles for enhanced biohydrogen production. Under optimized conditions of pH 6.5, substrate concentration 10 g/L, and 100 mg/L of NiO/Fe 2 O 3 , the maximum hydrogen yield (HY) of 1.94 mol/mol hexose was obtained, which is 18 % more than the control. The enhanced H 2 production upon the addition of nanoparticles is supported via the external electron transfer (EET) mechanism, which regulates the metabolic pathway regulation with increased production of acetate and butyrate and reduced formation of lactate., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

Repurposed used cooking oil is a sustainable alternative to other feedstocks for biodiesel production offering enviro-economic benefits. Residual crude glycerol (RCG) from such biodiesel production plants is difficult to utilize due to presence of numerous toxic impurities with various inhibitory effects on biological fermentative reforming process. However, it is a new industrial feedstock for bio-based production of 1,3-propanediol. In this work, a new Clostridium butyricum strain L4 was isolated from biogas reactor leachate after rigorous adaption and 35 subcultures under increasing stress conditions and studied for green production of 1,3-propanediol (PDO) from RCG and further process development. Evaluation of fermentative reforming kinetics was performed and the optimal reaction conditions are pH 7.0, temperature 30 °C, 2 g yeast extract/L and 15 g ammonium sulphate/L. Glycerol-glucose co-fermentation (10:1) enhanced cell growth and thus, PDO output by 11.6 g/L. In comparison to batch fermentation (24.8 g PDO/L; 0.58 mol PDO/mol glycerol) there was 2.8-fold improvement with fed-batch process resulting in accumulation of 70.1 g PDO/L (Yield = 0.65 mol PDO/mol glycerol) using the studied biocatalyst in 150 h. In order to predict yields under different operational conditions a multiple linear regression model was developed (r 2  = 0.783) with six independent variables (p < 0.05), where biomass (g/L) and temperature ( o C) were forecasted as top contributors to PDO yield. Finally, this biocatalyst appears as a potential candidate for industrial use due to its non-pathogenic nature, ability to grow in wide pH and temperature conditions, tolerance to high substrate and product concentration, insignificant generation of by-products and Coenzyme B12 independent biotransformation. The study can add value to bio-utilization of RCG to produce green 1,3-propanediol., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The pulp and biorefining industries produce their waste as lignin, which is one of the most abundant renewable resources. So far, lignin has been remained severely underutilized and generally burnt in a boiler as a low-value fuel. To demonstrate lignin's potential as a value-added product, we will review market opportunities for lignin related applications by utilizing the thermo-chemical/biological depolymerization strategies (with or without catalysts) and their comparative evaluation. The application of lignin and its derived aromatics in various sectors such as cement industry, bitumen modifier, energy materials, agriculture, nanocomposite, biomedical, H 2 source, biosensor and bioimaging have been summarized. This comprehensive review article also highlights the technical, economic, environmental, and socio-economic variable that affect the market value of lignin-derived by-products. The review shows the importance of lignin, and its derived products are a platform for future bioeconomy and sustainability., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Lignin is produced as a byproduct in cellulosic biorefinery as well in pulp and paper industries and has the potential for the synthesis of a variety of phenolics chemicals, biodegradable polymers, and high value-added chemicals surrogate to conventional petro-based fuels. Therefore, in this critical review, we emphasize the possible scenario for lignin isolation, transformation into value addition chemicals/materials for the economic viability of current biorefineries. Additionally, this review covers the chemical structure of lignocellulosic biomass/lignin, worldwide availability of lignin and describe various thermochemical (homogeneous/heterogeneous base/acid-catalyzed depolymerization, oxidative, hydrogenolysis etc.) and biotechnological developments for the production of bio-based low molecular weight phenolics, i.e. polyhydroxyalkanoates, vanillin, adipic acid, lipids etc. Besides, some functional chemicals applications, lignin-formaldehyde ion exchange resin, electrochemical and production of few targeted chemicals are also elaborated. Finally, we examine the challenges, opportunities and prospects way forward related to lignin valorization., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Sustainable production of solar-based chemicals is possible by mimicking the natural photosynthetic mechanism. To realize the full potential of solar-to-chemical production, the artificial means of photosynthesis and the biological approach should complement each other. The recently developed hybrid microbe-metal interface combines an inorganic, semiconducting light-harvester material with efficient and simple microorganisms, resulting in a novel metal-microbe interface that helps the microbes to capture energy directly from sunlight. This solar energy is then used for sustainable biosynthesis of chemicals from CO 2 . This review discusses various approaches to improve the electron uptake by microbes at the bioinorganic interface, especially self-photosensitized microbial systems and integrated water splitting biosynthetic systems, with emphasis on CO 2 bioelectrosynthesis., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Tandem bio-inorganic platform by combining efficient light harvesting properties of nano-inorganic semiconductor cadmium sulfide (CdS) with biocatalytic ability of electro-active bacteria (EAB) towards carbon dioxide (CO 2 ) conversion is reported. Sulfur was obtained from either cysteine (EAB-Cys-CdS) or hydrogen sulfide (EAB-H 2 S-CdS) and experiments were carried out under similar conditions. Anchoring of the nano CdS cluster on the microbe surface was confirmed using electronic microscope. Bio-inorganic hybrid system was able to produce single and multi-carbon compounds from CO 2 in visible spectrum (λ > 400 nm). Though, acetic acid was dominant (EAB-Cys-CdS, 1.46 g/l and EAB-H 2 S-CdS, 1.55 g/l) in both the microbe-CdS hybrids, its concentration as well as product slate varied significantly. EAB-H 2 S-CdS produced hexanoic acid and less methanol fraction, while the EAB-Cys-CdS produced no hexanoic acid along with almost double the concentration of methanol. Due to easy harvesting process, this bio-inorganic hybrid represents unique sustainable approach for solar-to-chemical production via CO 2 transformation., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Impact of gas diffusion electrodes (GDEs) was evaluated in enhancing the CO 2 bio-availability for its transformation to C4-organics, especially to alcohols using selective mixed culture. Observed current density was more stable (9-11 A/m 2 ) than submerged experiments reported and significantly varied with pH and respective CO 2 solubility. Uncontrolled operating pH (starting with 8.0) showed its impact on shifting/triggering alternate metabolic pathways to increase the carbon length (butyric acid) as well as producing more reduced end products, i.e. alcohols. During the experiments, CO 2 was transformed initially to a mixture of volatile fatty acids dominated with formic and acetic acids, and upon their accumulation, ethanol and butanol production was triggered. Overall, 21 g/l of alcohols and 13 g/l of organic acids were accumulated in 90 days with a coulombic efficiency (CE) of 49%. Ethanol and butanol occupied respectively about 45% and 16% of total products, indicating larger potential of this technology., (Copyright © 2018. Published by Elsevier Ltd.)

Electro-biocatalytic reactor was operated using selectively enriched mixed culture biofilm for about 320 days with CO 2 /bicarbonate as C-source. Biocathode consumed higher current (-16.2 ± 0.3 A/m 2 ) for bicarbonate transformation yielding high product synthesis (0.74 g/l/day) compared to CO 2 (-9.5 ± 2.8 A/m 2 ; 0.41 g/l/day). Product slate includes butanol and butyric acid when CO 2 gets transformed but propionic acid replaced both when bicarbonate gets transformed. Based on electroanalysis, the electron transfer might be H 2 mediated along with direct transfer under bicarbonate turnover conditions, while it was restricted to direct under CO 2 . Efficiency and stability of biofilm was tested by removing the planktonic cells, and also confirmed in terms of Coulombic (85-97%) and carbon conversion efficiencies (42-48%) along with production rate (1.2-1.7 kg/m 2 electrode) using bicarbonate as substrate. Selective enrichment of microbes and their growth as biofilm along with soluble CO 2 have helped in efficient transformation of CO 2 up to C4 organic molecules., (Copyright © 2017. Published by Elsevier Ltd.)

An insight into the properties of cell wall of mustard stalk (MS) pretreated by five ionic liquids (ILs) revealed ILs interaction with cellulose, hemicellulose and lignin components. Differential Scanning Calorimetry (DSC) showed increased pore size coupled with increased population of pores evoked by certain ILs in better facilitating enzymatic accessibility. Interestingly, all the five ILs predominantly increased the propensity of two pore sizes formation; 19 and 198 nm, but remarkable difference in the pore volumes of pretreated MS suggested the supremacy of [OAc] - based ILs, resulting in higher glucose yields. Cellulose I to II transition in pretreated MS was supported by the reduced total crystallinity index (TCI), lateral order index (LOI) values. Strong inverse correlation existed between the said parameters and residual acetyl content with enzymatic hydrolysis (R 2  > 0.8). An inverse relationship between hydrogen bond basicity, LOI and TCI suggested it to be a good indicator of IL pretreatment efficiency., (Copyright © 2017 Elsevier Ltd. All rights reserved.)