Composite materials based on biochar from coffee husk origin and nano zero-valent type Fe/Cu: Potential for treatment of water sources contaminated with As(V)

Abstract

In this study, a composite material, Gr–Fe/Cu@BC (CPS), was synthesized using biochar derived from coffee husks and Fe/Cu bimetallic zero-valent nanoparticles for the treatment of water contaminated with As(V). The Fe/Cu bimetallic zero-valent nanoparticles were synthesized via a green chemical method employing concentrated Camellia sinensis extract as a reducing agent for metal salts. A Box–Behnken experimental design identified optimal conditions for As(V) removal, including a pH range of 5–7, metal/C ratio of approx.imately 12–13 %, CPS/As mass ratio from 1000 to 1250 and reaction time of around 180 min. The maximum As(V) removal efficiency reached 91.64 % with a maximum adsorption capacity (qmax) of 2.86 mg g-1. The adsorption kinetics of As(V) on CPS followed a pseudo-second-order model, with a rate constant (K2) of 5.96 g mg-1 h-1. Furthermore, the structural and surface properties of CPS were characterized using advanced analytical techniques such as SEM, TEM, BET, XRD and EDS, confirming the successful integration of Fe/Cu nanoparticles onto the biochar matrix via complexation bonds. These findings highlight the potential of CPS as an environmentally friendly, cost-effective material for the treatment of As(V)-contaminated water and other heavy metal pollutants.