Synthesis of graphene oxide using tea-waste biochar as green substitute of graphite and its application in de-fluoridation of contaminated water

Abstract

In the present study, pyrolysis of domestic tea waste was carried out to yield bio-char. The biochar obtained was further used as a substitute for graphite in synthesis of graphene oxide (GO) in the conventional process. GO obtained was further applied for fluoride removal from simulated effluents. The prepared adsorbent was characterized using SEM, XRD and FTIR analysis. Effect of different experimental parameters on the de-fluoridation efficiency of the reported adsorbent was investigated. Data obtained was further used for determination of process isotherms, kinetics and thermodynamics. The regeneration potential of the reported adsorbent was also determined. The experimental results suggested that equilibrium adsorption data was strongly guided by the Langmuir isotherm and pseudo-second-order kinetics. Analysis of process thermodynamics also revealed that the adsorption reaction was spontaneous chemisorption in nature. Significant process parameters including GO dosage, ambient temperature and contact time were optimized using Response surface methodology (RSM) and artificial neural network (ANN). Results of RSM and ANN analysis indicated good correlation between experimentally recorded and theoretically predicted % fluoride removals. Under optimized conditions, fluoride removal efficiency was found to be 98.31%. Therefore, it can be inferred that tea waste derived biochar may be accepted as a sustainable alternative of graphite for GO synthesis. Moreover GO so obtained has immense potential for de- fluoridation of effluents in highly reduced dosage and treatment time.