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A grafting of N1-(3-trimethoxysilylpropyl)diethylenetriamine (TMSPDETA) on natural clay was carried out to obtain an organic–inorganic hybrid clay material that was applied as an adsorbent to the uptake of Reactive Blue 19 (RB-19) and Reactive Green 19 (RG-19) dyes from aqueous wastewaters. This research demonstrates the effect of TMSPDETA contents on amino-functionalized clay materials' hydrophobic/hydrophilic behavior. The resultant material was utilized to uptake reactive dyes in aqueous solutions. The clay@TMSPDETA hybrid material was characterized by isotherm of adsorption and desorption of nitrogen, FTIR, elemental analysis, TGA, pHpzc, total acidity, total basicity groups, and hydrophilic balance. The hybrid samples were more hydrophilic than the pristine clay for ratios from 0.1 up to 0.5 due to adding amino groups to the pristine clay. FTIR spectra suggest that TMSPDETA was grafted onto the clay. The hybrid material presents a surface area 2.17-fold (42.7 m2/g) lower than pristine clay (92.7 m2/g). The total volume of pores of hybrid material was 0.0822 cm3/g, and the pristine clay material was 0.127 cm3/g, corresponding to a diminution of the total pore volume (Vtot) of 1.54 times. The kinetic data followed the pseudo-second-order (PSO) model for RB-19 and RG-19 reactive dyes. The equilibrium data were better fitted to the Liu isotherm model, displaying a Qmax as 178.8 and 361.1 mg g−1 for RB-19 and RG-19, respectively, at 20.0 °C. The main mechanism of interactions of the reactive dyes with the hybrid clay is electrostatic interaction. The clay@TMSPDETA has a very good effect on treating synthetic dye-textile wastewater. The removal percentage of simulated wastewater was up to 97.67% and 88.34% using distilled water and plastic industry wastewater as the solvents, respectively. The clay@TMSPDETA-0.1 could be recycled up to 5 cycles of adsorption and desorption of both dyes, attaining recoveries of 98.42% (RB-19) and 98.32% (RG-19) using 0.1 M HCl + 10% ethanol. [ABSTRACT FROM AUTHOR]

The transformation of recalcitrant pharmaceutical pollutants into products with diminished concerns via heterogeneous photocatalysis has gained considerable momentum over the past several years. However, practical applications of most semiconductor-based photocatalysts are severely restricted, attributed to insufficient visible light response pertaining to their wide band gap, ultrafast recombination of the photogenerated charge carriers, and issues corresponding to retrieval for persistent usage. Herein, rosette-like molybdenum disulfide (MoS2) nanoflowers are directly grown on the interpenetrating networks of graphene aerogels (GAs) through a facile one-step hydrothermal method, and the resulting lightweight, self-supporting composites are systematically assessed for the photocatalytic degradation of tetracycline (TC). Notably, after 120 min of exposure to visible light, ∼91% of TC is degraded over the MoS2/GAs, which is severalfold higher than pristine MoS2, standalone GA, and other contemporary photocatalysts. Based on the radical quenching assay, hydroxyl radicals and superoxide anions are the principal mediators of the photocatalytic dissociation of TC. Furthermore, the primary intermediates and residual products of the photocatalytic breakdown of TC are distinguished, and a conceivable disintegration pathway is proposed. Besides, these tailor-made hybrid aerogels can be recuperated easily and successfully reused over multiple cycles, suggesting their widespread consideration in photocatalytic wastewater treatment. [ABSTRACT FROM AUTHOR]

It is well-documented that accumulation of pharmaceutically active compounds (PhACs), such as antibiotics, in aquatic ecosystems is a prominent environmental hazard. Herein, a series of 2D materials–based heterojunctions, conceptualized based on the integration of graphitic carbon nitride (g-C3N4) with tungsten disulfide (WS2), was fabricated through a facile one-step calcination process, and systematically evaluated for eliminating tetracycline (TC) and sulfamethoxazole (SMX) from aqueous matrices. The microstructure, optical properties, and surface chemistry of the as-prepared composites were examined with a range of microscopy and spectroscopy techniques. In comparison with pristine g-C3N4 or bare WS2, the g-C3N4/WS2 material, with optimal WS2 loading, showed significantly improved photocatalytic activity, towards degradation of TC (84%) and SMX (96%), under visible light. Free radical scavenging experiments revealed that superoxide anions and hydroxyl radicals were predominantly responsible for the rapid breakdown of the PhACs. In addition, the dissociation intermediates and residues were identified and the plausible photocatalytic degradation pathways of TC and SMX over the as-constructed 2D/2D heterojunction were discussed. Further, the photocatalysis end products were non-toxic, as inferred via the resazurin cell viability assay, employing Escherichia coli as a model organism. Most importantly, the 2D/2D g-C3N4/WS2 architecture was structurally resilient and exhibited a fairly stable cycling performance for persistent usage in wastewater treatment. The outcomes of this study testify that 2D/2D heterojunction of g-C3N4 fragments and WS2 nanosheets holds great promise for destroying antibiotics or their metabolites, usually present in wastewaters. [ABSTRACT FROM AUTHOR]

In this work, we report fabrication of a new Zn3V2O8/g-C3N4 Z-scheme nano-heterojunction for superior photodegradation of organo-phosphorous pesticide diazinon under visible light irradiation. The crystal structure, morphology, elemental composition, photo-electrochemical response and band structure of nano-photo-catalysts were investigated using various analytical techniques. The as-synthesized photocatalyst with best optimized ratio Zn3V2O8/40 wt% g-C3N4 (ZC-40) composites led to 95.2% diazinon (DZN) degradation in 60 min exposure and maintaining high structural stability after multiple reuse cycles (10 mg L−1 initial DZN concentration, pH = 6, catalyst dosage 0.35 g L−1 and visible light intensity 180 mW cm−2). Moreover, the experiments were performed under various reaction conditions as pH conditions, co-existing electrolytes, humic acid, tap water, river water and natural solar light. The improved photocatalytic activity of the heterojunction was ascribed to the synergistic effect of Z-scheme mechanism, high visible light absorption, oxygen vacancies, charge separation and metallic redox mediator. The reduced recombination and high charge transfer capacity was confirmed by electrochemical impedance spectroscopy and photoluminescence. The Z-scheme transfer between Zn3V2O8 and g-C3N4 boosted by V5+/V3+ metallic redox mediator retains the strong redox capacity, and diminishes the recombination. LC–MS results confirm the degradation intermediates and a detailed degradation mechanism were also predicted. Superoxide radicals (●O2–) and hydroxyl radicals (HO●) were found as major oxidative species involved in the photocatalytic degradation. The ZC-40 photocatalyst exhibited high degradation of other pesticides as malathion (90.1%), glyphosate (85.4%) and chlorpyrifos (97.4%) in water system under visible light. This work provides new approaches in designing new photocatalytic heterojunctions with high efficiency and structural robustness for utilizing visible light and efficient water treatment based on advanced oxidation technology. [ABSTRACT FROM AUTHOR]

The Calophylluminophyllum species annually produces a large volume of cylindrical fruits, which accumulate on the soil because they do not have nutritional value. This study sought to enable the use of this biomass by producing activated biochar with zinc chloride as an activating agent for further application as an adsorbent in batch and fixed bed columns. Different methodologies were used to characterize the precursor and the pyrolyzed material. Morphological changes were observed with the emergence of new spaces. The carbonaceous material had a surface area of 468 m2 g−1, Dp = 2.7 nm, and VT = 3.155 × 10−1 cm3 g−1. Scientific and isothermal studies of the adsorption of the diuron were conducted at the natural pH of the solution and adsorbent dosage of 0.75 g L−1. The kinetic curves showed a good fit to the Avrami fractional order model, with equilibrium reached after 150 min, regardless of the diuron concentration. The Liu heterogeneous surface model well represented the isothermal curves. By raising the temperature, adsorption was encouraged, and at 318 K, the Liu Qmax was reached at 250.1 mg g−1. Based on the Liu equilibrium constant, the nonlinear van't Hoff equation was employed, and the ΔG° were < 0 from 298 to 328 K; the process was exothermic nature (ΔH0 = −46.40 kJ mol−1). Finally, the carbonaceous adsorbent showed good removal performance (63.45%) compared to a mixture containing different herbicides used to control weeds. The stoichiometric column capacity (qeq) was 13.30 and 16.61 mg g−1 for concentrations of 100 and 200 mg L−1, respectively. The length of the mass transfer zone was 5.326 cm (100 mg L−1) and 4.946 cm (200 mg L−1). This makes employing the leftover fruits of the Calophyllum inophyllum species as biomass for creating highly porous adsorbents a very effective and promising option. [ABSTRACT FROM AUTHOR]

A Al2O3/MnO2/TiO2 (AlMnTiO) nanocomposite was synthesized using the thermal coprecipitation method and the adsorption performance of methyl orange (MO) dye from aqueous solution was carried out. Single-parameter optimization was used to explore the properties of AlMnTiO nanocomposite parameters on dye adsorption, including dose of adsorbent, solution pH, contact duration, and starting MO concentration. The model is the appropriate adsorption isotherm for the equilibrium process using a pseudo-second-order kinetic model property. Langmuir plot had a Qmax (mg/g) of 198.4 and best fitted (R2=0.990) among different isotherm models. The relevant parameters were computed using the dual-energy binary-layer statistical physics model. The statistical physics binary-layer model yield n (stoichiometric coefficient) values of 0.410, 0.440, and 0.453, all values are below 1, demonstrating the multi-docking process. AlMnTiO nanocomposite was regenerated up to six times, making the material extremely cost-effective. Using AlMnTiO nanocomposite, MO dye was removed from wastewater both in the laboratory and on the industrial scale. [ABSTRACT FROM AUTHOR]