Reduced graphene oxide nanosheets decorated with ZnS and ZnS-Ag nanoparticles are successfully prepared via a facile one-step chemical approach consisting of reducing the metal precursors on a rGO surface. Prepared rGO-ZnS nanocomposite is employed as an adsorbent material against two model dyes: malachite green (MG) and ethyl violet (EV). The adsorptive behavior of the nanocomposite was tuned by monitoring some parameters, such as the time of contact between the dye and the adsorbent, and the adsorbent dose. Experimental data were also simulated with kinetic models to evaluate the adsorption behavior, and the results confirmed that the adsorption of both dyes followed a pseudo 2nd order kinetic mode. Moreover, the adsorbent was also regenerated in a suitable media for both dyes (HCl for MG and ethanol for EV), without any significant loss in removal efficiency. Ag doped rGO-ZnS nanocomposite was also utilized as a photocatalyst for the degradation of the selected organic contaminant, resorcinol. The complete degradation of the phenolic compound was achieved after 60 min with 200 mg of rGO-ZnS-Ag nanocomposite under natural sunlight irradiation. The photocatalytic activity was studied considering some parameters, such as the initial phenol concentration, the photocatalyst loading, and the pH of the solution. The degradation kinetics of resorcinol was carefully studied and found to follow a linear Langmuir–Hinshelwood model. An additional advantage of rGO-ZnS and rGO-ZnS-Ag nanocomposites was antibacterial activity against Gram-negative bacterium, E. coli, and the results confirmed the significant performance of the nanocomposites in destroying harmful pathogens.

Poly(N-isopropylacrylamide/2-acrylamido-2-methylpropane sulfonic acid) microgel was prepared and fabricated with silver nanoparticles to design a material for dual functions of catalyst and sensor.

Clay minerals can effectively adsorb contaminants from aqueous effluents due to their good adsorption and high cation exchange capacity. However, naturally occurring clay materials possessing hydrophilic features are not especially effective for the removal of organic pollutants. Therefore, in the present work the issue of hydrophilicity is tackled by modification of the clay (Pakistan origin) to prepare organoclays. Hexadecylpyridinium chloride, cetyltrimethylammonium bromide, and sodium dodecyl sulfate were used as clay modifiers. Changes in the basal spacing of clay layers after modification with surfactants were determined through XRD analysis. Chemical compositions of the clay and organoclays were determined by FTIR spectroscopy. Surface morphology of the as-prepared organoclays was assessed from SEM analysis. The modified clays (organoclays) were tested for their ability as potential adsorbents for three dyes from water: brilliant green, ethyl violet and allura red. All three modified clays showed high adsorption characteristics by removing (>90 %) of all three dyes with an adsorption capacity ranging from 35 to 85 mg/g. The time-dependent adsorption experiments showed that the rates of adsorption of dyes on organoclays were fast, adsorbing maximum amounts of dyes ranging from 15 to 80 mins of contact time. The adsorption kinetic study revealed that the dye removal process is mainly governed by a pseudo-1st order mechanism. Thus, surfactant-modified clays are an excellent choice as cost-effective and efficient adsorbents for the purification of water from dye contaminants.