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In TiO2 photocatalysts have been interested in the world thanks to many advantages in handling toxic compounds, with great potential for practical application at low cost. However, the electron-hole recombination rate is still high and can not be processed under visible light, which is a major limitation of this material. Modification of TiO2 by W6+ is a possible solution, however there is still little research and the optimal W6+ ratio in small amounts is still low. The material was synthesized by a one-stage solvothermal method at 200 ºC for 10 hours, without using any surfactants or post-reaction calcination with doped W molar ratios of 0.5%, 1%, and 1.5%. The result was that the TiW-1.5% catalyst sample had the highest specific surface area of 175 m2/g, higher than pure TiO2 of 160.0 m2/g. The W6+ ion successfully replaced Ti4+ in the TiO2 crystal lattice, reducing the band gap energy of the catalytic sample to 2.88 eV with the TiW-1.5% sample. For TiW-0%, the formaldehyde decomposition ability is 53.50%. Doping W into TiO2 increased catalytic efficiency, with a material sample with an optimal modified W content of 1.5% mol W having a formaldehyde decomposition efficiency of 71.98%. Research results show that W modification can improve the activity of TiO2 and increase the efficiency of volatile organic compound treatment. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The production of highly efficient and reusable adsorbents that can be used in pigment treatment has been of great scientific interest. Metallic organic frameworks (MOFs) are considered a new type of material with extremely diverse structures and can be used as adsorbents to remove environmental pollutants. The selected Co/Fe-MOF material was synthesized in this study by using the solvent-thermal method. Then, the effects of several influencing factors such as adsorbent dosage, pH, initial concentration of MO, and exposure time on the adsorption capacity of methyl orange (MO) dyes by Co/Fe-MOF were evaluated. Under acidic conditions (pH 4), the effective removal of MO from aqueous solution reached equilibrium after 60 min upon exposure to MO at the concentration of 200 mg/L, and the adsorption capacity was 137.6 mg/g. The two models of adsorption isotherms, Freundlich and Langmuir, showed good compatibility with the experimental data, and the calculated correlation coefficients (R2) were both greater than 0.96. The MO adsorption efficiency was proposed to fit the pseudo-quadratic and pseudo-first-order kinetic models. Therefore, MOF materials can be considered as a potential agent for wastewater treatment, thereby providing a possible solution to solve water pollution.

For the first time, activated carbon from a durian shell (ACDS) activated by H2SO4 was successfully synthesized in the present study. The fabricated ACDS has a porous surface with a specific surface area of 348.0017 m2·g−1, average capillary volume of 0.153518 cm3·g−1, the average pore diameter of 4.3800 nm; ash level of 55.63%; humidity of 4.74%; density of 0.83 g·cm−3; an iodine index of 634 mg·g−1; and an isoelectric point of 6.03. Several factors affecting Methylene Blue (MB) adsorption capacity of ACDS activated carbon was investigated by the static adsorption method, revealing that the adsorption equilibrium was achieved after 90 min. The best adsorbent pH for MB is 7 and the mass/volume ratio is equal to 2.5 g·L−1. The MB adsorption process of ACDS activated carbon follows the Langmuir, Freundlich, Tempkin, and Elovich isotherm adsorption model, which has determined the maximum adsorption capacity for MB of ACDS as qmax = 57.47 mg·g−1. The MB adsorption process of ACDS follows the of pseudo-second-order adsorption kinetic equation. The Weber and Morris Internal Diffusion Model, the Hameed and Daud External Diffusion Model of liquids have been studied to see if the surface phase plays any role in the adsorption process. The results of thermodynamic calculation of the adsorption process show that the adsorption process is dominated by chemical adsorption and endothermic. The obtained results provide an insight for potential applications of ACDS in the treatment of water contaminated by dyes.

In this study, we report on the preparation of copper oxide/strontium titanate/multi-walled carbon nanotube (CuO/STO/MWCNTs) nanocomposites and their photocatalytic activity for degradation of dye under visible light. The crystalline structures of the nanocomposites were investigated by an X-ray diffraction (XRD) technique, which explored the successful fabrication of CuO/STO/MWCNTs nanocomposites, and the cubic STO phase was formed in all samples. For the morphological study, the transmission electron microscope (TEM) technique was used, which had proved the successful preparation of CuO and STO nanoparticles. The energy dispersive X-ray spectroscopy (EDX), dark field scanning transmission electron microscope (DF-STEM-EDX mapping), and X-ray photoelectron spectra (XPS) analysis were performed to evidence the elemental composition of CuO/STO/MWCNTs nanocomposites. The optical characteristics were explored via UV–Vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) techniques. These studies clearly indicate the effect of the presence of CuO and MWCNTs on the visible absorption of the CuO/STO/MWCNTs nanocomposites. The photocatalytic activity of CuO/STO/MWCNTs nanocomposites was evaluated by the degradation of methylene blue (MB) dye under visible light irradiation, following first-order kinetics. Among the different x% CuO/STO/MWCNTs nanocomposites, the 5 wt.% CuO/STO/MWCNTs nanocomposites showed the highest photocatalytic efficiency for the degradation of MB dye. Moreover, the 5% CuO/STO/MWCNTs showed good stability and recyclability after three consecutive photocatalytic cycles. These results verified that the optimized nanocomposites can be used for photocatalytic applications, especially for dye degradation under visible light.

A CuO-loaded SrTiO3 catalyst showed highly photocatalytic activity for H2 evolution. This catalyst was prepared by an impregnation method and characterized by XRD, TEM, BET, XPS, Uv-vis DRS and PL techniques. Under optimum conditions, the best rate of H2 evolution of the CuO-loaded SrTiO3 catalyst is 5811 µmol h−1g−1, whereas it is a mere 34 µmol h−1g−1 for the pure SrTiO3. High efficiency, low cost and good stability are some of the merits that underline the promising potential of CuO-loaded SrTiO3 in the photocatalytic hydrogen.

In this study, activated carbon derived from mangosteen peel (abbreviated as ACMP) was successfully fabricated. This as-prepared ACMP possessed graphite and had a porous structure with a specific surface area of 419.8554 m2/g. Investigations of the influencing factors on the ciprofloxacin (CIP) adsorption capability of the ACMP based on the static adsorption method showed that: adsorption equilibrium can be achieved in 60 min, the optimal pH for CIP adsorption was a pH of 6, and the optimal ratio between the material mass and solution volume was 3 g/L. The CIP adsorption process of the ACMP follows the Langmuir, Freundlich, Tempkin, Elovich, and Redlich–Peterson isotherm adsorption models. The maximum adsorption capacity calculated according to the Langmuir isothermal adsorption model for the CIP of the ACMP was (qmax = 29.76 mg/g). The CIP adsorption process of the ACMP followed the apparent quadratic kinetic equation, as well as spontaneous, endothermic, physical, and chemical adsorption. The adsorption rate was governed by membrane diffusion.

In TiO2 photocatalysts have been interested in the world thanks to many advantages in handling toxic compounds, with great potential for practical application at low cost. However, the electron-hole recombination rate is still high and can not be processed under visible light, which is a major limitation of this material. Modification of TiO2 by W6+ is a possible solution, however there is still little research and the optimal W6+ ratio in small amounts is still low. The material was synthesized by a one-stage solvothermal method at 200 °C for 10 hours, without using any surfactants or post-reaction calcination with doped W molar ratios of 0.5%, 1%, and 1.5%. The result was that the TiW-1.5% catalyst sample had the highest specific surface area of 175 m²/g, higher than pure TiO2 of 160.0 m²/g. The W6+ ion successfully replaced Ti4+ in the TiO2 crystal lattice, reducing the band gap energy of the catalytic sample to 2.88 eV with the TiW-1.5% sample. For TiW-0%, the formaldehyde decomposition ability is 53.50%. Doping W into TiO2 increased catalytic efficiency, with a material sample with an optimal modified W content of 1.5% mol W having a formaldehyde decomposition efficiency of 71.98%. Research results show that W modification can improve the activity of TiO2 and increase the efficiency of volatile organic compound treatment. [ABSTRACT FROM AUTHOR]

In this study, we investigated the adsorption process of organic Congo red (CR) by M/Fe-MOF (M=Co, Ni) materials. The results of the study show that the optimal adsorption capacity of the materials under the optimal conditions is as follows: Adsorbent weight 0.1 g/L and pH8 for all 3 materials. At the concentration of colorant CR 75 mg/L, the adsorption capacity reached 530 mg/g for Co/Fe- MOF materials; for Ni/Fe-MOF materials, the adsorption capacity reached 560 mg/g, at the colorant concentration CR 140 mg/L; for Fe-MOF materials, the adsorption capacity reached 523 mg/g, at the colorant concentration CR 120 mg/L. The experimental data are consistent with Langmuir and PSO models for both M/Fe-MOF materials (M=Co, Ni). Research results on the reuse process of M/Fe-MOF (M=Co, Ni) materials show that the material is reused 4 times. With this result, it can be considered as the first step to improve the efficiency of pigment adsorption in the current water pollution treatment problem. [ABSTRACT FROM AUTHOR]