Brazilian Journal of Chemical Engineering最新文献

Enzyme immobilization allows the reuse of the biocatalyst more than once without excessive loss of its catalytic activity and conveys operational and storage stability. In this work, β-glucosidase produced extracellularly by the filamentous fungus Moniliophthora perniciosa was immobilized by adsorption on Celite, silica, and chitosan. Celite was the chosen carrier for immobilization due to the high activity yield and maintenance of 65% ± 1.9 of its initial activity after seven reuses. The activity of the immobilized β-glucosidase peaked at pH 4 at a temperature of 60 °C. Moreover, the immobilized enzyme retained 23.7% ± 4.85 of the initial activity when incubated at a temperature of 90 °C during 60 min. Additionally, it retained more than 70% of the initial activity after 20 min of incubation at 50–70 °C.

The ultraviolet light combined with hydrogen peroxide (UV/H₂O₂) was applied to break down mono-ethanolamine (MEA) in an aqueous solution. The coupled UV/H₂O₂ advanced oxidation process (AOP) was primarily responsible for the breakdown of MEA, with pseudo-first-order reaction kinetics. It was discovered that the reaction factors like MEA and H₂O₂ initial dosages affected reaction rates and MEA removal efficiency. The maximum removal efficiency was determined to be 77.35%. The hydroxyl ion (•OH) radical is primarily accountable for breaking down MEA in an aqueous environment. The energy consumed per reaction order calculations are performed by considering of the concentration factor of maximum degradation, in conjunction with the intensity of UV light. Overall, this work provides useful kinetic data that may be applied to the creation of an effective remediation strategy for MEA effluents.

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This study aimed to optimize two cell disruption methods, i.e., high-speed homogenization (Ultra-turrax) and cold plasma, to efficiently recover microbial lipids from Rhodotorula mucilaginosa CCT 7668. A previously optimized medium composed of agro-industrial byproducts (70 g/L sugarcane molasses and 3.4 g/L corn steep liquor) was used for producing lipids at 25 °C, 180 rpm for 144 h. Different pretreatments of biomass (wet, dry, and/or frozen) were evaluated; 7.0% of lipid content and 0.50 g/L total lipids resulted from the use of dry and frozen biomass. An experimental design methodology was applied to study the following variables: biomass:solvent ratio (0.3:100–1.2:100), operation time (0.6–7.4 min) and rotation speed (9280–22,720 rpm), when high-speed homogenization was used. Lipid contents ranged from 9.6 to 35.2% while total lipids ranged from 0.80 to 2.96 g/L. Regarding the cold plasma technology, biomass (0.5–0.7 g), operation time (20–40 min) and power (8–14 W) were evaluated. Lipid contents ranged from 20.6 to 34.9% while total lipids ranged from 1.81 to 3.06 g/L. Therefore, this study defined optimal conditions to efficiently produce microbial lipids with low toxicity, which represent potential sources that may be applied to food and pharmaceutical industries.

Structural and functional properties of a membrane describe its quality necessary to achieve the defined performance. Preparation of mixed matrix membrane (MMM) was performed considering the non-solvent induced phase separation (NIPS) method, relied immersion precipitation technique using dimethylformamide (DMF) and tetrahydrofuran (THF) solvents. Nanoclay particles (NCPs) at a certain weight were dispersed within the PVC polymer. Four different membranes were structurally characterized using FTIR, XRD, and EDS methods. Further analyses were on surface morphology using FESEM, and AFM. Nanofiltration experiment was conducted and functionality of the novel membranes was evaluated in terms of flux of water permeation (FWP), hydrophilicity character (contact angle determination), and salt rejection (SR) behavior. With use of 2 wt% NCPs, porosity and hydrophilicity characteristics of the resultant membrane increased by 15%, and 17%, respectively. Crystallinity nature of the composite membrane did not change considerably (XRD results). Pure water flux (PWF) and calculated salt rejection were 118.35 kg m⁻² h⁻¹, and 95%, respectively.

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The synthesis of pure titanium dioxide (TiO₂) nanomaterials from naturally occurring ilmenite (FeTiO₃), which is present in black sands, is highly desirable due to its numerous industrial and technological applications. In this study, nanostructured rutile nanorods were synthesized using Egyptian ilmenite concentrate through a simple mechanical/chemical route, comprising two stages: the first stage involved the reduction of ilmenite by activated carbon as a reducing agent during milling, while the second stage involved the decomposition of FeTiO₃/carbon and the selective dissolution for iron and silica using a mixture of HCl/H₂O₂ and NH₄F/HF, respectively. The results indicated that the optimal conditions for hydrothermal leaching of the milled ilmenite/carbon are achieved at a solid/liquid ratio of 167 g/L, 4 h at 170 °C. The amorphous titanium dioxide could be converted to ~ 95% pure rutile-phase nanorods by annealing at 700 °C followed by additional leaching processes to simply remove silica from the synthesized rutile.

This article focuses on synthesizing dual-functional adsorption-ion exchange material (Fe-Ca/225H) by precipitation method on 225H cation exchange resin for the treatment of phosphate and hardness in water. Materials were analyzed through methods such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction studies (XRD), and scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). For the phosphate adsorption, suitable conditions were experimentally found to include reaction time (48 h), pH (6.5), adsorbent dosage (10 g/L), and HCO₃⁻ ions as the most impact ion on the phosphate adsorption. When calcium and magnesium were present in a solution containing phosphate, the phosphate adsorption capacity increased by 1.24 times. This was due to the combination of calcium and magnesium with phosphate on the surface of the material, which improves the adsorption efficiency. Besides, when compared with materials containing only iron (Fe/225H), the adsorption capacity of Ca-Fe/225H materials is still higher in both synthetic wastewater and domestic wastewater. The durability of the material after 10 regenerations was still over 80% effective. The material is effective in simultaneously treating both phosphate and hardness in the solution, with a much higher hardness treatment efficiency than amphoteric resin on the market (MB6SR).

Propionic acid (PA) is industrially produced using raw materials derived from petroleum. In search of more sustainable processes, this work investigated the production of propionic acid (PA) by fermentation using whey permeate (WP) and corn steep water (CSL), with the strain Propionibacterium freudenreichii subsp ATCC 6207. Two strategies of fermentation were compared: one in batch and the other fed batch, carried out in a 5 L bioreactor at 30 °C, with pH control. Furthermore, in fed-batch fermentation, lactose concentration was controlled. The study revealed that batch fermentation was more efficient in producing propionic acid (PA). After 72 h, the concentration reached 13.10 g L⁻¹, with a yield of 0.335 g g⁻¹ and productivity of 0.182 g L⁻¹ h⁻¹. The research addressed the PA purification by ion exchange chromatography, using cryogels functionalized with taurine (Tau-cryogel). Tests at different pH (4 to 7) showed greater PA adsorption on the cryogel at pH 4 (256.13 mg g⁻¹), with recovery of 59.7% and lower adsorption of acetic acid (29.34 mg g⁻¹), indicating promising selectivity in purification. This study shows the feasibility of using byproducts such as WP and CSL in the production of PA and the potential of applying ion exchange cryogels in its purification.

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