Physical vapor deposition of W on grape waste-based biochar and application of the material as adsorbent for diclofenac, crystal violet, and Pb(II): Effect of deposition parameters on the material features and adsorption potential

W-coated grape waste-based biochars were prepared by tungsten deposition via magnetron sputtering at varying current powers (100–200 W). The effect of deposition conditions on the adsorbents’ features and performance in removing three classes of contaminants, including diclofenac (DCF), crystal violet (CV), and Pb(II), was investigated. Characterization analysis confirmed the successful deposition of W-thin films as tungsten oxides and the increase in tungsten content, from 0.87% to 1.68%, with an increase in current power from 100 to 200 W. Kinetic curves were well represented by the pseudo-first-order and pseudo-second-order models. The Sips model best described the equilibrium data, with increased affinity observed as tungsten content increased. The biochar obtained at a higher current power, named GWBB200W15min, achieved outstanding adsorption capacities of 798.8 mg g -1 , 766.4 mg g -1 , and 684.0 mg g -1 for DCF, CV, and Pb(II), respectively, at C 0 = 300 mg L -1 and optimal pH 7.0 for the organic contaminants and pH 5.0 for Pb(II). These results denote improvements of about 43%, 61%, and 46% compared with the raw biochar. Regeneration assays demonstrated the high reusability potential and stability of the W-coated biochar. Overall, increasing the current power led to increased W content and enhanced surface properties, associated with improved adsorption performance, in which the deposited W-thin films provided new binding sites that engendered strong interactions. These results showed that W deposition via magnetron sputtering has promising potential for obtaining adsorbents with enhanced adsorption capacity, high reusability, and multi-contaminant removal capability.