New nano-biomaterials for the removal of malachite green from aqueous solution via a response surface methodology

The development of new biomaterials for the remove of organic contaminants from wastewater has attracted much attention over the few past years. One of the most cost-effective approaches is to produce new high value biomaterials from low value solid agricultural biowastes. In this work, sugarcane bagasse and agricultural waste rich in reducing sugars, acted as both a green bioreductant for graphene oxide (GO) and a sustainable supporter for the immobilization of Burkholderia cepacia . Therefore, this new biomaterial which contained both reduced graphene oxide (RGO) and Burkholderia cepacia , was cable of initial adsorption of malachite green (MG) and its subsequent biodegradation. After 60 h, immobilized Burkholderia cepacia degraded more MG (98.5%) than a cell cultured Burkholderia cepacia (87.7%) alone. Raman spectroscopy confirmed that GO was successfully reduced by bagasse and that consequently a composite (B-RGO) was prepared. SEM indicated that Burkholderia cepacia was well immobilized and kinetics studies showed that the adsorption of MG onto the developed composite fitted a pseudo-second order kinetics model (R 2  > 0.99). Biodegradation of MG, was confirmed by the detection of appropriate degradation products such as N, N-dimethylaniline and 4-(Dimethylamino) benzophenone using GC-MS, UV and FT-IR, and via best fit first-order biodegration kinetics. Furthermore, a response surface methodology (RSM) was applied to the removal process by varying four independent parameters using a Box-Behnken design (BBD). Optimum MG removal (99.3%) was achieved at 31.5 °C, with an initial MG concentration of 114.5 mg L −1 , initial pH of 5.85, and an adsorbent dosage of 0.11 g L −1 . The excellent removal efficiency indicated that agricultural waste derived reduced graphene oxide bio-adsorbents have significant potential for the removal of dyes such as MG from industrial wastewaters .