Synthesis and physicochemical evaluations of a novel MIL-101(Fe)-PMA-Biochar triple composite photocatalyst activated through visible-light and utilized toward degradation of organic pollutants: optimal operations and kinetics investigations.

A triple photocatalytic composite of biochar, metal-organic framework, and phosphomolybdic acid was prepared through hydrothermal treatment of iron (III) chloride hexahydrate, terephthalic acid, lavandulifolia-derived biochar, and phosphomolybdic acid. It was characterized and utilized for photodegradation of Rhodamine-B (RhB) dye under visible-light irradiation. Investigations of reaction variables confirmed that, the highest yield of 96.2% was achieved at ambient temperature using 0.07 g of catalyst at pH of 7, and a dye concentration of 10 ppm. Under these optimum conditions, Methyl Orange (MO) dye was also degraded to yield 93% removal. In addition, the kinetic and thermodynamic parameters for RhB were determined. It was revealed that the photodegradation of RhB followed a pseudo-first-order kinetics with no mass transfer limitations. A corresponding chemical mechanism for this process was also suggested. Adsorption isotherms were investigated for rate of adsorption as well as adsorption capacity of the catalyst under dark conditions. Notably, the catalyst could have been reused for five cycles with a loss of around 20% activity.

Investigations of the ODS process utilizing CNT- and CNF-based WO3 catalysts for environmental depollution: experimental and theoretical aspects.

In this contribution, CoW/X materials (X = CNT or CNF) were utilized as oxidative desulfurization (ODS) catalysts for the removal of dibenzothiophene (DBT) from a model fuel (n-decane), incorporating the H2O2 as an efficient oxidant. Different operating conditions were investigated. Both compounds revealed high desulfurization efficiency using milder operating conditions leading to low levels of the DBT compound since only 1 h while using a low ratio of H2O2/S = 6. Among synthesized compounds, the CoW (15)/CNT showed superior DBT conversion through the ODS process. In other words, the highest sulfur removal efficiency of 100% for a feed sulfur content of 500 ppm was determined in a 40-min duration under optimum conditions. This was satisfyingly more effective than a recently reported CoW (20)/rGO catalyst. The characterization of synthesized catalysts was performed in order to evaluate their physicochemical properties. Moreover, product identification of the oxidation desulfurization process was performed using the GC-Mass, FTIR, and NMR techniques where it was found that this process was that of a single product. These experimental studies were complemented with density functional theory (DFT) investigations, which indeed shed important light on understanding the adsorption mechanisms as well as electronic properties of the system undertaken.

Preparation of novel and highly active magnetic ternary structures (metal-organic framework/cobalt ferrite/graphene oxide) for effective visible-light-driven photocatalytic and photo-Fenton-like degradation of organic contaminants.

Herein, MIL-101(Fe), CoFe2O4, novel binary (MIL-101(Fe)/CoFe2O4, MIL-101(Fe)/GO and CoFe2O4/GO), and ternary (MIL-101(Fe)/CoFe2O4/(3%)GO and MIL-101(Fe)/CoFe2O4/(7%)GO) magnetic composites based upon the MIL-101(Fe) were synthesized. The XRD, FESEM, TEM, EDX, BET-BJH, FTIR, VSM, DRS, PL, EIS and other electrochemical analyses were applied to characterize samples. The MIL/CoFe2O4/(3%)GO demonstrated the best performance compared to other samples for visible light photocatalytic and photo-Fenton-like degradation of Direct Red 23 (DtR-23), Reactive Red 198 (ReR-198) dyes as well as Tetracycline Hydrochloride (TC-H) antibiotic. Degradation of dyes using the ternary composite after 70 min of visible light irradiation was greater than that of 99%. The presence of the optimum GO as a strong electron acceptor in MIL/CoFe2O4/(3%)GO not only led to the effective separation of charge carriers and thus reduction of their recombination but also increased the absorption of visible light. The composite possessed good durability in terms of stability and reusability. The PL, EIS and electrochemical analyses indicated that the MIL/CoFe2O4/(3%)GO improved the optical properties and photocatalytic performance.

Study of Molecular Conformation and Activity-Related Properties of Lipase Immobilized onto Core-Shell Structured Polyacrylic Acid-Coated Magnetic Silica Nanocomposite Particles.

A facile approach for the preparation of core-shell structured poly(acrylic acid) (PAA)-coated Fe3O4 cluster@SiO2 nanocomposite particles as the support materials for the lipase immobilization is reported. Low- or high-molecular-weight (1800 and 100,000, respectively) PAA molecules were covalently attached onto the surface of amine-functionalized magnetic silica nanoacomposite particles. The successful preparation of particles were verified by scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), zeta potential measurement, and Fourier-transform infrared (FTIR) techniques. Once lipase is covalently immobilized onto the particles with an average diameter of 210 ± 50 nm, resulting from high binding sites concentrations on the low- and high-molecular-weight PAA-coated particles, high lipase immobilization efficiencies (86.2% and 89.9%, respectively), and loading capacities (786 and 816 mg g(-1), respectively) are obtained. Results from circular dichroism (CD) analysis and catalytic activity tests reveal an increase in the ß-sheet content of lipase molecules upon immobilization, along with an enhancement in their activities and stabilities. The lipases immobilized onto the low- and high-molecular-weight PAA-coated particles show maximum activities at 55 and 50 °C, respectively, which are ∼28% and ∼15% higher than that of the free lipase at its own optimum temperature (40 °C), respectively. The immobilized lipases exhibit excellent performance at broader temperature and pH ranges and high thermal and storage stabilities, as well as superior reusability. These prepared magnetic nanocomposite particles can be offered as suitable support materials for efficient immobilization of enzymes and improvement of the immobilized enzymes properties.