Cleaner Chemical Engineering最新文献

In this study, the feasibility of increasing the proportion of cashew nut shell liquid (CNSL)-based biofuels in diesel was assessed. Biofuel–diesel blends with different percentages of CNSL were prepared, and their physical properties, including the density, viscosity, and heating value, were determined. B10 (CNSL/diesel = 10:90 v/v) satisfied the diesel specifications without preheating, whereas B20 (20:80 v/v) and B30 (30:70 v/v) met the specifications only after preheating to 60 and 80 °C, respectively. To avoid preheating B20 and B30, an acetone/butanol/ethanol (ABE) mixture (30:60:10 v/v) was added to the fuel blends to improve their flow characteristics. The blends with CNSL/ABE (361)/diesel ratios of 20:10:70 and 30:30:40 (v/v) exhibited properties comparable to those of diesel and remained stable for one month of storage. These fuel blends allow up to 30 vol% CNSL and 30 vol% ABE (361) to be incorporated into diesel and can be used as alternative fuels in diesel engines.

Lactic acid synthesis from lignocelluloses can respond to the environmental concerns associated with producing this important commodity chemical for various applications, e.g., food, cosmetics, pharmaceuticals, etc. Pretreatment of palmarosa (Cymbopogon martinii) biomass with 1.0 % HNO₃ solution at 121 °C temperature and 1.03 bar pressure for 60 min under an autoclave conditions demonstrated a highly selective conversion of biomass contained hemicellulose to xylose in ∼17 wt % yield. A further hydrolytic depolymerization of pretreated biomass to liquid products was carried out via processing in the presence of anthraquinone (5 wt % loading) as a catalyst under temperature (250 °C) and pressure (15–16 bar, where, 1 bar = 10⁵ Pa) in dilute NaOH (1.5 M) solution for 60 min to afford a hydrolysate rich in carboxylic acids and small aromatics. Solvent extraction method was applied successfully to separate the aromatic compounds from the aqueous phase. The carboxylic acids were formed as the product of cellulose oxidation with good selectivity (>45 %) towards the DL-lactic acid (∼14 wt % yield with respect to substrate biomass). Small aromatics, predominantly phenol was identified as the product of depolymerized lignin.

This review paper presents state-of-the-art electrolytic-based hydrogen production technologies capable of helping to achieve the “net-zero” targets. It covers the recent advances in electrochemical water-splitting technologies, considering their maturity, durability, and operational aspects related to their near-term deployment. This paper aims to critically assess electrochemical technologies compatible with renewables, nuclear, or other clean energy sources with a high potential to be applied for green hydrogen production at scale. It also discusses the techno-economic aspects as well as the technological readiness of the potential carbon-free hydrogen production routes based on electrochemical approaches. With a comprehensive survey of the recent literature and extensive insight into current developments, the issues associated with deploying the electrolytic water splitting technologies are discussed, along with a review of their market readiness level to play a potential role in the transition journey from fossil fuel-based-economy into hydrogen-driven energy infrastructure. In addition, the paper provides insight into the legal strategies and the governmental incentives required to reach the so-called “net-zero” emission plans globally to enable green hydrogen for deep decarbonization of the industrial, transportation, and residential sectors. Near-term projects to deploy large-scale clean hydrogen production announced globally are also listed with their expected contribution toward the zero-emission targets. The result of this review shows that wind and solar photovoltaic energies, as the two most preferred renewable sources, can be used to drive Proton Exchange Membrane (PEM) and Alkaline Electrolysers (AE) at a cost range of USD 2 - 3 /kg of H₂. This figure is expected to decrease by more than 40 % until 2030 if these electrolyzers can be deployed at a large scale.

Poly(ethylene terephthalate) (PET) is a widely used polyester with several applications, including offshore platforms and mooring lines of the Oil & Gas industry. Due to the widespread use of PET and the growing concern about its environmental impact, biotechnology emerges as a potential solution to mitigate this problem. This work aims to evaluate, for the first time, the potential of Y. lipolytica IMUFRJ 50682 in the biodegradation of PET from waste mooring lines of Oil & Gas offshore platforms. In this study, the biodegradation of PET from mooring lines by the yeast Yarrowia lipolytica was investigated through submerged cultivation or solid-state fermentation. After fermentation was complete, the biodegradation of PET sampled from the culture medium was evidenced by an increase in transmittance in areas related to the ester group detected through Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) for both culture strategies and all media tested. Besides, the crystallinity of PET increased by 79% and 72% after submerged cultivation using CSL-G + DMSO medium (2% corn steep liquor, 2% glycerol, and 5% Dimethyl sulfoxide) and after solid-state fermentation, respectively. Scanning electron microscopy revealed the formation of scratches and erosions on the polymer's surface after the microbial cultivation. The presence of PET monomer, terephthalic acid (TPA) (up to 142 µmol L ^− 1), and some intermediates, such as bis(2-hydroxyethyl) terephthalate (BHET) and mono-(hydroxyethyl) terephthalate (MHET) in the medium after Y. lipolytica growth in the presence of PET proves that the polymer is being degraded. These results suggest a good biotechnological potential of Y. lipolytica for the depolymerization of PET from mooring lines.

Corrosion of metals is a major issue in various industries and the use of organic materials, especially plant extracts, as alternatives to toxic chemicals in corrosion inhibitors is gaining attention. However, the potential of animal products as corrosion inhibitors has not been fully explored. This study investigates the corrosion inhibiting potential of snail slime (SS) for mild steel in 0.5 M H₂SO₄ solution using Gravimetric and electrochemical methods, including open circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used for material characterization. The results indicate that snail slime has a high inhibition efficiency of up to 92.75%, with inhibition efficiency decreasing as temperature and immersion time increase but it increased with higher inhibitor concentrations. Adsorption studies showed that snail slime exhibited strong adherence to the Langmuir and Temkin adsorption isotherms, indicating spontaneous adsorption on mild steel. The inhibition mechanism shows typical physical adsorption and follows first-order kinetics. While the EIS analysis indicated a charge transfer-controlled corrosion process with the highest inhibition efficiency of 81.74%, the PDP analysis revealed that snail slime acted as a mixed-type inhibitor with the highest inhibition efficiency of 81.98%. FTIR reveals the functional groups responsible for the inhibition exhibited by snail slime inhibitors, including CH, OH, CO-O, CCl, and NH. SEM shows that the inhibition of corrosion is due to the formation of an insoluble stable protective film on the sample surface by an adsorption process. These findings suggest that snail slime has significant potential as an eco-friendly alternative to synthetic corrosion inhibitors in industrial applications.

In this research, the stability, specificity, and sensibility of a colorimetric detection method based on gold nanoparticles conjugated with aptamers for detection of Salmonella enterica serovar Typhimurium was investigated. The synthesis of gold nanoparticles by citrate reduction and conjugation with aptamers were studied to obtain high stability over time and to hinder inaccurate results. The reaction conducted at initial pH 5.0 and molar ratio 3.5:1 Na3Ct to HAuACl₄ produced stable, monodisperse and spherical particles, with a mean particle diameter of 18 nm. Gold nanoparticles showed stability upon salt exposure limited to 120 mmol/L, which was enhanced with aptamer conjugation to 700 mmol/L. Experiments with different microorganisms confirmed the biosensor specificity to Salmonella, with a detection limit of 10³ CFU/mL for S. Typhimurium, as well as 10⁴ CFU/mL for S. minnesota, S. heidelberg, and Salmonella spp. The assays carried out with artificially contaminated samples and environmental samples resulted in a detection time and detection limit identical to those obtained with pure samples. Results confirm that the biosensor synthesized is a great alternative for detection methods, making it possible to improve time and efficiency detection in the routine inspections as well as reduce costs.

Efforts have been concentrated on developing alternative methods of enzyme purification that are less costly and highly efficient. In this work, we evaluated three different methods for lipase purification from Yarrowia lipolytica, such as precipitation using ammonium sulfate, ethanol, or acetone; aqueous two-phase systems (ATPS) based on polyethylene glycol (PEG) and potassium phosphate; and direct immobilization. It was impossible to obtain stable precipitates of the enzyme due to the low concentration of total protein and the presence of biosurfactant produced by the microorganism. Different mixture compositions were selected for the partitioning study. Three ATPS showed selective partitioning of the target enzymes, i.e., lipase and protease migrated to opposite phases. In the ATPS composed of 13 wt% PEG-4000 and 10 wt% salts, it was possible to achieve a purification factor for lipase of 4.2. Purification by immobilization performed by lipase-lipase interactions showed three lipases of distinct sizes in the crude extract. In the immobilization method by hydrophobic supports, phenyl-agarose and butyl‑agarose were more selective in immobilizing than octyl-agarose. In the ion exchange immobilization method, only the lipases identified at 66 kDa and 41 kDa have an attraction for DEAE-agarose (anionic) and sulfopropyl-agarose (cationic) matrices.

Natural fiber reinforcement in cementitious matrices is being explored to provide an environment-friendly solution for lowering the overall carbon footprint of construction materials while giving the matrix much-needed tensile strength. Short bamboo fibers extracted from Bambusa blumeana or Kawayan tinik using 5% sodium hydroxide solution and treated with 10% aluminum sulfate solution are used to reinforce zero-cement geopolymer mortars. Bamboo fibers with varying lengths of 10 mm, 20 mm, and 30 mm are mixed with mill-scale – fly ash-based geopolymer in varying 0%, 0.5%, 1%, 1.5%, and 2% fiber loading per weight of specimen sample. Compressive strength and split tensile strength tests are administered to small cylinder samples, 50 mm in diameter by 100 mm in height, in accordance with ASTM C780. An optimum fiber length of 20 mm and fiber loading of 1.4% by weight is determined using Response Surface Methodology (RSM). The addition of bamboo fibers increased the unconfined compressive strength up to 292.41% compared to specimens without bamboo fibers. The split tensile strength also improved by up to a 355.82% increase compared to control samples. The corresponding high-strength and low-strength samples are also subjected to Fourier-transform Infrared Spectroscopy – Attenuated Total Reflectance (FTIR-ATR) to investigate and compare the stretching of bands between the raw materials and tested specimens. Scanning Electron Microscopy – Energy Dispersive X-Ray analysis (SEM-EDX) is used to show microscopic images and the elements present in the selected samples. The implications of the results on the material development of bamboo fiber-reinforced geopolymer mortar for construction are discussed.

Separation of aromatics from non-aromatic hydrocarbons was exemplified assuming the liquid-phase extraction process for methylcyclohexane−toluene model mixture separation using the newly tested 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMim][NTf₂]) ionic liquid (IL). For this process a separation unit was proposed consisting of separation part represented by a counter-current extraction column and regeneration part including a vacuum evaporator and a vacuum distillation column. Separation of feed composed of 10 mole% of toluene in methylcyclohexane was considered in the designed separation unit. Designed separation efficiency of the unit was based on the following specifications: minimum methylcyclohexane and toluene content in the product streams of 99.5 mole% and the purity of regenerated extraction solvent recycled to the extraction column above 99 mole%.

Mathematical model of a counter-current extractor was compiled and its operation was simulated in the Matlab environment. In extractor simulations, proprietary phase equilibrium data were employed. Ternary liquid–liquid equilibrium (LLE) of the methylcyclohexane−toluene−[EMim][NTf₂] system was estimated experimentally, from which the model parameters of the original NRTL equation were evauated and used for the ternary phase equilibrium description.

Aspen Plus was used to design a separation unit for the title hydrocarbons mixture separation, including the extraction solvent regeneration. Simulation of the proposed separation unit operation was focused not only on its separation efficiency but also on the evaluation of the unit energetic requirements.

Results of the unit design calculations (parameters of individual equipment, heat duties) obtained for the tested ionic liquid [EMim][NTf₂] were confronted with the simulation results obtained for two ILs recommended in the literature for the non-aromatic–aromatic hydrocarbon mixture separation, namely 1‑butyl‑3-methylimidazolium tetracyanoborate [BMim][TCB] and 1-hexyl-3-methylimidazolium tetracyanoborate [HMim][TCB]. Based on the energetic analysis, the heat integration of the suggested separation unit was carried out for ionic liquid [HMim][TCB], which appeared to be the most efficient extraction solvent among those tested in this study, The heat integration resulted in about 71% reduction of the heat demand of the proposed separation unit.

Increasing exploration of natural sources and the development of new oil-derived technologies have caused environmental contamination. Thus, among the bioremediation strategies, biostimulation and bioaugmentation techniques have been the most used in the current literature. This study aimed to build a bench-scale bioreactor to promote degradation used ship engine lubricating oil using an immobilized bacterial consortium in Salvinia sp. (SS). For this purpose, bacterial strains were isolated from the hydrocarbon-contaminated moist soil in the marginal at Guanabara Bay, Rio de Janeiro, Brazil, followed by isolation, identification of microorganisms, and biodegradation tests. Then these microorganisms were immobilized in SS biomass. The bacterial consortium underwent biodegradation tests and bioreactor biodegradation on a bench scale. According to the results, the consortium of Bacteria like Bacillus could biodegrade 52.9% of the lubricating oil and 0.027 d ^− 1 degradation rate.