Sustain. Chem., Volume 2, Issue 1 (March 2021) – 12 articles

This study compared the yield of biodiesel produced from tall oil fatty acids (TOFA) via (i) homogeneous catalyst (sulfuric acid) and (ii) a heterogeneous catalyst (Amberlyst^® BD20, together with Ambersep BD 19 (Midcontinental Chemical Co., Olathe, KS, USA)^® using a batch reactor. The effect of operation conditions including temperature, catalyst concentration, methanol: oil ratio and reaction time on esterification yield were investigated. Gas chromatographic data showed that the major fatty acids present in the TOFA are oleic acid (C18:1n9) and linoleic acid (C18:2n6). Homogenous catalysis yielded 96.76% biodiesel compared to 90.24% for heterogeneous catalysis. Optimized conditions for homogenous catalysis were at a catalyst concentration of 0.5 w/w%, 15:1 methanol: oil mass ratio at 55 °C for 60 min. FTIR results also showed that the homogeneous catalyst yielded a more complete reaction toward biodiesel production in a shorter time (60 min) compared to the heterogeneous catalyst (4.7 h). For heterogeneous catalysis, the highest yield and the lowest acid value were achieved after a second recycling because the reactants were not fully in contact with the catalyst during the first recycling. The catalyst did not show a reduction in catalytic activity even after the fourth recycling. However, the acid value was higher than that for ASTM standards for biodiesel. Full article

The rapid growth, demand, and production of batteries to meet various emerging applications, such as electric vehicles and energy storage systems, will result in waste and disposal problems in the next few years as these batteries reach end-of-life. Battery reuse and recycling are becoming urgent worldwide priorities to protect the environment and address the increasing need for critical metals. As a review article, this paper reveals the current global battery market and global battery waste status from which the main battery chemistry types and their management, including reuse and recycling status, are discussed. This review then presents details of the challenges, opportunities, and arguments on battery second-life and recycling. The recent research and industrial activities in the battery reuse domain are summarized to provide a landscape picture and valuable insight into battery reuse and recycling for industries, scientific research, and waste management. Full article

Proteins are bioactive compounds with high potential to be applied in the biopharmaceutical industry, food science and as biocatalysts. However, protein stability is very difficult to maintain outside of the native environment, which hinders their applications. Fluorinated ionic liquids (FILs) are a promising family of surface-active ionic liquids (SAILs) that have an amphiphilic behavior and the ability to self-aggregate in aqueous solutions by the formation of colloidal systems. In this work, the protein lysozyme was selected to infer on the influence of FILs in its stability and activity. Then, the cytotoxicity of FILs was determined to evaluate their biocompatibility, concluding that the selected compounds have neglected cytotoxicity. Therefore, UV–visible spectroscopy was used to infer the FIL-lysozyme interactions, concluding that the predominant interaction is the encapsulation of the lysozyme by FILs. The encapsulation efficiency was also tested, which highly depends on the concentration and anion of FIL. Finally, the bioactivity and thermal stability of lysozyme were evaluated, and the encapsulated lysozyme keeps its activity and thermal stability, concluding that FILs can be a potential stabilizer to be used in protein-based delivery systems. Full article

Supercritical CO₂ (ScCO₂) emulsion has attracted lots of attention, which could benefit both climate control via CO₂ storage and industry revenue through significantly increased oil recovery simultaneously. Historically, aqueous soluble surfactants have been widely used as stabilizers, though they suffer from slow propagation, relatively high surfactant adsorption and well injectivity issues. In contrast, the CO₂-soluble surfactants could improve the emulsion performance remarkably, due to their CO₂-philicity. Here, comprehensive comparison studies are carried out from laboratory experiments to field scale simulations between a commercially available aqueous soluble surfactant (CD 1045) and a proprietary nonionic CO₂-philic surfactant whose solubility in ScCO₂ and partition coefficient between ScCO₂/Brine have been determined. Surfactant affinity to employed oil is indicated by a phase behavior test. Static adsorptions on Silurian dolomite outcrop are conducted to gain the insights of its electro-kinetic properties. Coreflooding experiments are carried out with both consolidated 1 ft Berea sandstone and Silurian dolomite to compare the performances as a result of surfactant natures under two-phase conditions, while harsher conditions are examined on fractured carbonate with presence of an oleic phase. Moreover, the superiorities of ScCO₂ foam with CO₂-philic surfactant due to dual phase partition capacity are illustrated with field scale simulations. ScCO₂ and WAG injections behaviors are used as baselines, while the performances of two types of CO₂ emulsions are compared with SAG injection, characterized by phase saturations, CO₂ storage, oil production, CO₂ utilization ratio and pressure distribution. A novel injection strategy, named CO₂ continuous injection with dissolved surfactant (CIDS), which is unique for a CO₂-philic surfactant, is also studied. It is found that the CO₂-soluble surfactant displays much lower oil affinity and adsorption on carbonate than CD 1045. Furthermore, in a laboratory scale, a much higher foam propagation rate is observed with the novel surfactant, which is mainly ascribed to its CO₂ affinity, assisted by the high mobility of the CO₂ phase. Field scale simulations clearly demonstrate the potentials of CO₂ emulsion on CO₂ storage and oil recovery over conventional tertiary productions. Relative to traditional aqueous soluble surfactant emulsion, the novel surfactant emulsion contributes to higher injectivity, CO₂ storage capability, oil recovery and energy utilization efficiency. The CIDS could further reduce water injection cost and energy consumption. The findings here reveal the potentials of further improving CO₂ storage and utilization when applying ScCO₂-philic surfactant emulsion, to compromise both environmental and economic concerns. Full article

The task-specific design of ionic liquids (ILs) has emerged in several industrial and pharmaceutical applications. The family of ILs with fluorine tags equal to or longer than four carbon atoms, the fluorinated ionic liquids (FILs), combine the best properties of ILs with the ones of perfluorinated compounds, and are being designed for several specific purposes. In the pharmaceutical field, there is an urgency to search for novel antibacterial agents to overcome problems associated to antimicrobial resistances. Then, the main purpose of this work is to evaluate the environmental impact and the ability of FILs to be used as antibacterial agents against Pseudomonas stutzeri bacteria. Beyond its rare pathogenicity, these bacteria are also used as a bioremediation agent to treat several contamination sites. Then, it is important to determine which FILs have antibacterial properties, and which do not impact the bacterial growth. The biocompatibility of FILs was also evaluated through their hemolytic activity and represent a step forward the application of FILs in pharmaceutical applications. The results proved that high concentrations of FILs can have a reduced ecotoxicity and a high biocompatibility. [C₈C₁Im][CF₃SO₃] was identified as the most promising compound to be used as an antibacterial agent since it prevents the growth of bacteria at concentrations compatible with the red blood cells’ viability. Full article

Enzyme-induced carbonate precipitation (EICP) is a relatively new bio-cementation technique for ground improvement. In EICP, calcium carbonate (${\mathrm{CaCO}}_3$) precipitation occurs via urea hydrolysis catalysed by the urease enzyme sourced from plants. EICP offers significant potential for innovative and sustainable engineering applications, including strengthening of soils, remediation of contaminants, enhancement of oil recovery through bio-plugging and other in situ field applications. Given the numerous potential applications of EICP, theoretical understanding of the rate and quantity of ${\mathrm{CaCO}}_3$ precipitation via the ureolytic chemical reaction is vital for optimising the process. For instance, in a typical EICP process, the rate and quantity of ${\mathrm{CaCO}}_3$ precipitation can depend significantly on the concentration, activity and kinetic properties of the enzyme used along with the reaction environment such as pH and temperature. This paper reviews the research and development of enzyme-catalysed reactions and its applications for enhancing ${\mathrm{CaCO}}_3$ precipitation in EICP. The paper also presents the assessment and estimation of kinetic parameters, such as the maximal reaction velocity (${\mathrm{V}}_{\max }$) and the Michaelis constant (${\mathrm{K}}_{\mathrm{m}}$), that are associated with applications in civil and geotechnical engineering. Various models for evaluating the kinetic reactions in EICP are presented and discussed, taking into account the influence of pH, temperature and inhibitors. It is shown that a good understanding of the kinetic properties of the urease enzyme can be useful in the development, optimisation and prediction of the rate of ${\mathrm{CaCO}}_3$ precipitation in EICP. Full article

The review will discuss the methods that have been optimized so far for the enzymatic hydrolysis of soapstock into enriched mixtures of free fatty acids, in order to offer a sustainable alternative to the procedure which is currently employed at the industrial level for converting soapstock into the by-product known as acid oil (or olein, i.e., free fatty acids removed from raw vegetable oil, dissolved in residual triglycerides). The further biocatalyzed manipulation of soapstock or of the corresponding acid oil for the production of biodiesel and fine chemicals (surfactants, plasticizers, and additives) will be described, with specific attention given to processes performed in continuous flow mode. The valorization of soapstock as carbon source in industrial lipase production will be also considered. Full article

Ionic liquids are critical reagents for science and technical processes nowadays. Metals are the most used reagents in the industry. It is crucial to have a deeper understanding of how ionic liquids and metals could interact. In this article the interaction of those two families of compounds is accessed. The dissolution (reaction) of metals with ionic liquids is studied, namely the influence of temperature, redox potential, and availability of an oxidant in the process. The final state achieved by the iron metal samples was also addressed by Mössbauer spectroscopy. Full article

In this study, chitosan-based composite films blended with a dextran like exopolysaccharide derived from lactic acid bacteria were prepared using the solvent casting method. Later, these composite films were plasticized with 1,3-propanediol (1,3-PDO) produced biologically using biodiesel derived crude glycerol. Further, their physical properties, such as tensile strength, water vapor barrier, thermal behavior, and antioxidant properties, were tested. In comparison to the control chitosan-exopolysaccharide films, 1,3-PDO plasticized films increased tensile strengths (20.08 vs. 43.33 MPa) with an elongation percentage (%E) of 20.73, which was two times more than the control films. As a polymer composite, the Fourier transform infrared (FTIR) spectrum displayed the characteristic peaks at 1000 cm⁻¹, 1500 cm⁻¹, and 3000–3500 cm⁻¹ to describe the functional groups related to chitosan, exopolysaccharide, and 1,3-PDOThe thermogravimetric analysis displayed a significant three-step degradation at 100–105 °C, 250–400 °C, and 600 °C, where 100% of the films were degraded. The plasticized films were observed to have enhanced water solubility (51%) and rate of moisture absorption (193%). The plasticized films displayed enhanced physico-chemical properties, anti-oxidant properties, and were100% biodegradable. Full article

This study has developed novel fully bio-based resorcinol epoxy resin–diatomite composites by a green two-stage process based on the living character of the cationic polymerization. This process comprises the photoinitiation and subsequently the thermal dark curing, enabling the obtaining of thick and non-transparent epoxy-diatomite composites without any solvent and amine-based hardeners. The effects of the diatomite content and the compacting pressure on microstructural, thermal, mechanical, acoustic properties, as well as the flame behavior of such composites have been thoroughly investigated. Towards the development of sound absorbing and flame-retardant construction materials, a compromise among mechanical, acoustic and flame-retardant properties was considered. Consequently, the composite obtained with 50 wt.% diatomite and 3.9 MPa compacting pressure is considered the optimal composite in the present work. Such composite exhibits the enhanced flexural modulus of 2.9 MPa, a satisfying sound absorption performance at low frequencies with Modified Sound Absorption Average (MSAA) of 0.08 (for a sample thickness of only 5 mm), and an outstanding flame retardancy behavior with the peak of heat release rate (pHRR) of 109 W/g and the total heat release of 5 kJ/g in the pyrolysis combustion flow calorimeter (PCFC) analysis. Full article

Pine as a softwood and poplar as a hardwood pretreated with hydrochloric acid (HCl), phosphoric acid (H₃PO₄), and hypophosphorous acid (H₃PO₂) are studied for the pyrolytic properties and products in thermogravimetry (TG) and fixed bed reactor. The pyrolysis performances are pronouncedly distinguished due to the compositional and structural changes induced by the acid pretreatments. Reduction in the mineral content in the biomass feedstocks by pretreatment with the acids results in significant changes in the pyrolytic products. The residual P in the H₃PO₂-pretreated biomass apparently catalyzed the biomass deeper dehydration in pyrolysis compared to the other two mineral acids. TG analysis shows a shift of the temperature of maximum mass loss (T_max) by more than 40 °C to lower temperature in the decomposition of the H₃PO₂-pretreated biomass from that of the untreated and the HCl- and H₃PO₄-pretreated biomass. Inspired by the striking differences in TG profiles of biomass pretreated by the three acids, thermal pyrolysis of pretreated biomass was carried out in a fixed bed reactor aimed at producing biochemicals at low temperatures (330 °C and 400 °C). The liquid products obtained from the fixed bed reactor show remarkably different major anhydrosugars as a result of pretreatment by the three acids. While phenolics dominate in the collected pyrolysis liquid from untreated biomass samples, biomass pretreated with all three acids results in substantially reduced phenolics in the bio-oils. The reduction in phenolic compounds in the bio-oil may be attributed to the reduction in mineral content in the feedstock. Consequently, the yields of anhydrosugars, mainly levoglucosan (LG) and levoglucosenone (LGO) are increased. LG yields of 20.9–28.5% from the cellulose content are obtained from HCl- and H₃PO₄-pretreated pine/poplar, with very low LGO yield (less than 1.7%). However, H₃PO₂-pretreated biomass is selective to produce LGO, especially at 330 °C. LGO yields of 7.4% and 6.7% are obtained from H₃PO₂-pretreated pine and poplar, respectively. Full article

The Co4Cat^TM process is a simple, surfactant-free method to produce colloidal dispersions of precious metal nanoparticles in alkaline mono-alcohols. The synthesis is performed in low-boiling-point solvents and is relevant for industrial production. The robustness of the process is demonstrated by using three different commercial spirits as solvents to obtain Pt nanoparticles. The results demonstrate that careful control of the solvent purity is not needed to achieve the synthesis of stable 2 nm platinum nanoparticle colloids readily active electrocatalysts for energy conversion reactions like the methanol oxidation. Full article