Green algae Ulva lactuca-derived biochar-sulfur improves the adsorption of methylene blue from water.

The present investigation explores the efficacy of green algae Ulva lactuca biochar-sulfur (GABS) modified with H2SO4 and NaHCO3 in adsorbing methylene blue (MB) dye from aqueous solutions. The impact of solution pH, contact duration, GABS dosage, and initial MB dye concentration on the adsorption process are all methodically investigated in this work. To obtain a thorough understanding of the adsorption dynamics, the study makes use of several kinetic models, including pseudo-first order and pseudo-second order models, in addition to isotherm models like Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich. The findings of the study reveal that the adsorption capacity at equilibrium (qe) reaches 303.78 mg/g for a GABS dose of 0.5 g/L and an initial MB dye concentration of 200 mg/L. Notably, the Langmuir isotherm model consistently fits the experimental data across different GABS doses, suggesting homogeneous adsorption onto a monolayer surface. The potential of GABS as an efficient adsorbent for the extraction of MB dye from aqueous solutions is highlighted by this discovery. The study's use of kinetic and isotherm models provides a robust framework for understanding the intricacies of MB adsorption onto GABS. By elucidating the impact of various variables on the adsorption process, the research contributes valuable insights that can inform the design of efficient wastewater treatment solutions. The comprehensive analysis presented in this study serves as a solid foundation for further research and development in the field of adsorption-based water treatment technologies.

A novel tertiary magnetic ZnFe2O4/BiOBr/rGO nanocomposite catalyst for photodegrading organic contaminants by visible light.

A novel tertiary magnetic ZnFe2O4/BiOBr/rGO visible light-driven photocatalytic system was successfully synthesized from graphite, bismuth nitrate pentahydrate, iron (III) nitrate, and zinc nitrate precursors. The produced materials were characterized regarding micro-structure, chemical composition and functional groups, surface charge properties, photocatalytic characteristics such as band gap energy (Eg), recombination rate of charge carriers, and magnetic properties. ZnFe2O4/BiOBr/rGO heterojunction photocatalyst exhibited a saturation magnetization of 7.5 emu/g, and a visible light response (Eg = 2.08 eV). Thus, under visible light, these materials could generate effective charge carriers responsible for forming free hydroxyl radicals (HO•) for degrading organic pollutants. ZnFe2O4/BiOBr/rGO also exhibited the lowest charge carriers recombination rate compared to all individual components. The construction of ZnFe2O4/BiOBr/rGO system resulted in 1.35 to 2.55 times higher in photocatalytic degradation of DB 71 compared to individual components. At the optimal conditions (0.5 g/L catalyst load and pH 7.0), the ZnFe2O4/BiOBr/rGO system could completely degrade 30 mg/L DB 71 after 100 min. DB 71 degradation process was best described by the pseudo-first-order model, with the coefficient of determination within the range of 0.9043-0.9946 for all conditions. HO• radicals were mainly responsible for degrading the pollutant. The photocatalytic system could be effortlessly regenerated, very stable, which showed an efficiency of >80.0 % after 5 repetitive runs regarding the DB 71 photodegradation. The photocatalyst was easily recovered by a magnet. This research provides a novel approach for producing an effective and practical photocatalyst that can be applied in real organic pollutants-containing waste water treatment systems.

Novel N,C,S-TiO2/WO3/rGO Z-scheme heterojunction with enhanced visible-light driven photocatalytic performance.

Novel N,C,S-TiO2/WO3/rGO Z scheme photocatalyst was successfully synthesized from graphite, TIOT, and ammonium metatungstate precursors. Material characteristics such as crystal structure, surface morphology, functional groups, specific surface area, elemental composition, band gap energy, and electron-hole recombination were characterized by XRD, TEM, BET, SEM/EDX, FT-IR, UV-VIS, and PL methods. The as-synthesized novel N,C,S-TiO2/WO3/rGO Z-scheme heterojunction photocatalyst exhibited visible light-driven photocatalytic activity (the band gap energy = 2.24 eV), could generate both effective electrons and holes, and presented the lowest electron-hole recombination rate compared to all individual components. Different factors impacting the photocatalytic decomposition of Direct Blue 71 (DB 71) by the N,C,S-TiO2/WO3/rGO system were studied. The results showed that pH of the solution, catalyst load, DB 71 initial concentration, and reaction time affected the DB 71 photocatalytic degradation efficiency. The DB 71 degradation completed after 100 min with a typical efficiency of over 91%, which was much better than other photocatalytic systems. The DB 71 degradation process followed the pseudo-first-order kinetics model with coefficients of determination > 0.95 for all conditions. The photocatalyst was easily regenerated, and exhibited a very good stability, with a photocatalytic degradation efficiency of over 83.0% after 3 cycles.

The superior photocatalytic activity of Nb doped TiO2/g-C3N4 direct Z-scheme system for efficient conversion of CO2 into valuable fuels.

In this study, we firstly aimed to use Nb as dopant to dope into the TiO2 lattice in order to narrow band gap energy or enhance photocatalytic activity of the Nb-TiO2. Then, the prepared Nb-TiO2 was combined with g-C3N4 to establish Nb-TiO2/g-C3N4 direct Z-scheme system for superior reduction of CO2 into valuable fuels even under visible light. The obtained results indicated that the band gap energy of the Nb-TiO2 (2.91 eV) was lower than that of the TiO2 (3.2 eV). In the successfully established Nb-TiO2/g-C3N4 direct Z-scheme system, the photo-excited e- in the CB of the Nb-TiO2 combined with the photo-excited h+ in the VB of the g-C3N4 preserving the existence of e- in the CB of the g-C3N4 and h+ in the VB of Nb-TiO2, and thereby, the system produced numerous amount of available e-/h+ pairs for the reduction of CO2 into various valuable fuels. In addition, the produced e- of the Nb-TiO2/g-C3N4 existing in the CB of the g-C3N4, which the potential energy is approximately -1.2 V, would be strong enough for the reduction of CO2 to generate not only CH4 and CO but also HCOOH. Among established Nb-TiO2/g-C3N4 materials, the 50Nb-TiO2/50 g-C3N4 material was the best material for the CO2 reduction.