oa South African Journal of Chemistry - Graphene oxide/zinc oxide nanocomposite : a superior adsorbent for removal of methylene blue - statistical analysis by response surface methodology (RSM) : research article
Graphene oxide (GO) was synthesized from natural graphite using the Hummers method. Graphene oxide/zinc oxide nano composite were synthesized by mixing of GO and ZnO solutions and then freeze drying. The adsorptive performance of the nano composite was investigated in the removal of methylene blue. The statistical study of the adsorption process was carried out by response surface methodology (RSM). Experimental variables such as sample pH, adsorption time, dye concentration and adsorbent dosage were considered for the optimization process. The process was optimized by response surface methodology (RSM) through Box-Benhken method. The optimum conditions, predicted by the RSM were obtained at pH, contact time, initial dye concentration and adsorbent dosage of 6, 8.5 min, 5 ppm, 0.02 g, respectively. The removal of methylene blue under optimum conditions was predicted to be 98.17%and resulted in 97% in practice. The Pareto analysis suggested that order of relative importance of the factors were as follows: adsorbent dosage > dye concentration > adsorption time > pH. Under optimized conditions, GO/ZnO nano composite showed a higher capacity than GO, carbon nanotube (CNT), ZnO and ZnO/CNT for adsorption of methylene blue. The study revealed that GO/ZnO could be a promising adsorbent for removal of industrial dyes from wastewaters.
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