Adsorption and kinetic studies of chromium (VI) removal using Ag2Cu2O3 nanoparticles

This study reports the removal of chromium (VI) from waste aqueous medium using disilver-dicopper oxide nanoparticles (Ag2Cu2O3 NPs) as adsorbent, which were synthesized by adopting reduction route of chemical method and stabilized by emulsifier (sodium dodecyl sulfate [SDS]). Synthesized nanoparticles were further characterized using different analysis techniques such as UV-Vis for the detection of NPs via ?(max) and their point-zero charge (pzc) determination also done. Whereas, FTIR and XRD were done to determine the functional groups, crystal plane (tetragonal) and crystallite size (15.19 nm) of Ag2Cu2O3 NPs respectively. SEM was used with EDX for morphology and elemental confirmation respectively. The synthesized nanoparticles were then employed for the adsorptive removal of chromium (VI) (Cr(VI)). Different parameters including pH, temperature, agitation time, adsorbate and adsorbent's concentration were also studied. At optimized conditions, 0.5 g adsorbent, 40 ppm concentration of Cr(VI) solution along with 1 h agitation time were studied. Maximum observed adsorption and chromium removal efficiency was 96.66319 %. Four adsorption isotherms namely; Freundlich, Langmuir, Temkin and Harkins-Jeura were employed from which Freundlich adsorption model gives best fitting on experimental results. The kinetic modelling had shown that adsorption process follows second order kinetics. The thermodynamic studies of the adsorptive removal of Cr(VI) also evaluated. The Ag2Cu2O3 NPs adsorbent's reusability were also determined. The study had proven that Ag2Cu2O3 nanoparticles are efficient adsorbents for the removal of Cr(VI).