ZnAl2O4/BiPO4 composites as a heterogeneous catalyst for photo-Fenton treatment of textile and pulping wastewater

New breakthrough in rapid degradation of lignin derivative compounds · A novel high stable and reusable green organic photocatalyst

The pulp and paper sectors are thriving yet pose significant environmental threats to water bodies, mainly due to the substantial release of pollutants. Lignin-derived compounds are among the most problematic of these contaminants. To address this issue, we present our initial results on utilizing organic semiconductor photocatalysis under visible light for treating lignin-derived compounds. Our investigation has been centered around creating a green and cost-effective organic semiconductor photocatalyst. This catalyst is designed using a structure of bagasse cellulose spheres to support PM6 (poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene))-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)-benzo[1,2-c:4,5-c']dithiophene-4,8-dione))]: MeIC (3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-cyclopentane-1,3-dione[c]-1-methyl-thiophe))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']-dithiophene)). This photocatalyst demonstrates remarkable efficiency, achieving over 91 % degradation of lignin-derived compounds. The superior photocatalytic performance is attributed to three main factors: (1) The ability of PM6 to broaden MeIC's absorption range from 300 to 800 nm, allowing for effective utilization of visible light; (2) the synergistic interaction between PM6 and MeIC, which ensures compatible energy levels and a vast, evenly spread surface area, promoting charge mobility and extensive donor/acceptor interfaces. This synergy significantly enhances the generation and transport of carriers, resulting in a high production of free radicals that accelerate the decomposition of organic materials; (3) The deployment of PM6:MeIC on biomass-based carriers increases the interaction surface with the organic substances. Notably, PM6: MeIC showcases outstanding durability, with its degradation efficiency remaining between 84 % and 91 % across 100 cycles. This study presents a promising approach for designing advanced photocatalysts aimed at degrading common pollutants in papermaking wastewater.

Fabrication of an effectual, stable and reusable Mg-doped CdAl2O4 nanoparticles for photodegradation of toxic pollutants under visible light illumination

The water contamination caused by discharging extensive organic dyes stuff into water bodies is one of the utmost significant concerns disturbing the environment and human life. CdAl₂O₄ spinel materials have been excellent in the elimination of emerging pollutants by the photocatalysis route. These materials, when altered through methods namely doping with Mg ions, have benefits over CdAl₂O₄, especially reduced energy gap and light absorbed in the visible region. The XRD established the creation of space group R 3‾ with no other phase step being found. The photoluminescence outcomes indicated that Mg-doped CdAl₂O₄ nanoparticles had the preventing e^--h⁺ recombination possibility, which was favorable for the photocatalytic process. The Mg (0.075 M)-doped CdAl₂O₄ catalyst had higher photocatalytic performance with 94 and 96% removal of two azo (BB and BG) dyes under a mere 90 min visible light irradiation, which indicated enhanced Photodegradation behaviors when compared to other Mg (0.025, 0.050 M)-doped and pure CdAl₂O₄ materials. More interestingly, pH 5 was optimum for the Mg (0.075 M)-doped CdAl₂O₄ samples photodegradation of both dyes, and the optimum catalyst amount was 5 mg/100 mL. The doped Mg ions influenced the elimination of both dyes by inducing the manufacture of more active species. The Mg (0.075 M)-doped CdAl₂O₄ samples is reusable and highly stable with only a 5% reduction in degradation rate after six cycles. Based on the quencher and ESR investigations, the ^.OH^- and h⁺ are described as active species in the removal reaction. We hope our present examinations highlight the possibility of using Mg (0.075 M)-doped CdAl₂O₄ product for a broad range of photodegradation applications, also it may be applied for several ecological remediations, surface cleaning devices, foods and pharmaceutical industry applications.

Functionalized Regulation of Metal Defects in ln2S3 of p-n Homojunctions

The introduction of metal vacancies into n-type semiconductors could efficiently construct intimate contact interface p-n homojunctions to accelerate the separation of photogenerated carriers. In this work, a cationic surfactant occupancy method was developed to synthesize an indium-vacancy (V_In)-enriched p-n amorphous/crystal homojunction of indium sulfide (A/C-IS) for sodium lignosulfonate (SL) degradation. The amount of V_In in the A/C-IS could be regulated by varying the content of added cetyltrimethylammonium bromide (CTAB). Meanwhile, the steric hindrance of CTAB produced mesopores and macropores, providing transfer channels for SL. The degradation rates of A/C-IS to SL were 8.3 and 20.9 times higher than those of crystalline In₂S₃ and commercial photocatalyst (P25), respectively. The presence of unsaturated dangling bonds formed by V_In reduced the formation energy of superoxide radicals (^•O₂^-). In addition, the inner electric field between the intimate contact interface p-n A/C-IS promoted the migration of electron-hole pairs. A reasonable degradation pathway of SL by A/C-IS was proposed based on the above mechanism. Moreover, the proposed method could also be applicable for the preparation of p-n homojunctions with metal vacancies from other sulfides.

Degradation of the residual textile mixture cetyltrimethylammonium bromide/remazol yellow gold RNL-150%/reactive blue BF-5G: evaluation photo-peroxidation and photo-Fenton processes in LED and UV-C photoreactors

This article presents a study on the degradation of a residual textile mixture composed of cationic surfactant cetyltrimethylammonium bromide (CTAB) and the remazol yellow gold RNL-150% and reactive blue BF-5G textile dyes. This was carried out by employing the photo-peroxidation and photo-Fenton processes in LED and UV-C photoreactors. The photo-Fenton process was the most efficient as regards the degradation of the CTAB and dye mixture, for both types of radiation. In the kinetic study, degradations of 99% were obtained in 180 min for the chromophore groups using both types of radiation. The degradation of the CTAB and aromatic groups was, meanwhile, an average of 25% when employing LED radiation. The behavior of the degradation reaction was pseudo-first-order. Toxicity tests indicated that the solutions were better able to grow seeds and bacteria after treatment with the photo-Fenton process, using both types of radiation. The photo-Fenton processes carried out by employing LED and UV-C photoreactors were able to degrade the CTAB and dye mixture, thus highlighting the efficiency of LED radiation when its power (three times smaller) is compared to that of UV-C radiation. This process, therefore, represents an alternative for use in textile wastewater treatment systems.

Effluents detoxification from pulp and paper industry using microbial engineering and advanced oxidation techniques

Due to the high demand of paper and related items, pulp and paper industry is flourishing day by day. With increased production, come the hazards associated with the toxic elements present in the effluents. Various microorganisms are currently employed in the remediation of these toxic effluents. In addition, various techniques like ozonation, electrocoagulation, UV treatment, Fenton's reagent, and photo-Fenton based techniques are used in advanced oxidation processes to reduce these toxins from effluents. This review highlights various above mentioned advanced techniques and innovative processes along with the biological remediation of these toxic effluents with the help of some potential microbial consortia or their combinatory effects. Moreover, the present review will also disclose the ideas on utilizing the tools of metabolic engineering, systems biology, and artificial intelligence towards microbial engineering for relatively better bioremediation processes. In the future, these techniques might be helpful in increasing the capability of microbial consortia towards detoxification of effluents to make them environmentally safe. Finally, this review gives well-synchronized approaches to get more insights into these innovative methodologies and techniques and their use for various industrial applications.

VS2 and its doped composition: Catalytic depolymerization of alkali lignin for increased bio-oil production

VS₂ spheres and VS₂ sheets with doped compositions (Mo, Ag and graphite) were successfully prepared by one-step hydrothermal method and characterized by different techniques including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N₂ adsorption isotherms. Catalysts were applied for the depolymerization of alkali lignin. VS₂ spheres exhibited lower yield of degraded lignin and bio-oil than those with VS₂ sheets and VS₂ flowers heated to 250 °C and held for 1.5 h with 2.0 MPa H₂. The catalytic depolymerization performance was markedly affected by the dopant in the VS₂ sheets, with the highest degraded lignin yield of 81.22%, achieved over 5 wt% Ag-VS₂ at 290 °C under 2.0 MPa H₂ for 1.5 h, yielding 61.23% bio-oil. The VS₂-based catalysts show excellent selectivity in the interruption of the lignin structure and target production of bio-oil. The bio-oil showed that the relevant contents of a phenolic-type compound changes significantly according to the dopant in the VS₂ catalyst.