The effect of diverse metal oxides in graphene composites on the adsorption isotherm of gaseous benzene

Abstract

The effective removal technique is necessary for the real world treatment of a hazardous pollutant (e.g., gaseous benzene). In an effort to develop such technique, the adsorption efficiency of benzene in a nitrogen stream (5 Pa (50 ppm) at 50 mL atm min(-1) flow rate and 298 K) was assessed against 10 different metal oxide/GO composite materials (i.e., 1: graphene oxide Co (GO-Co (OH)(2)), 2: graphene oxide Cu (GO-Cu(OH)(2)), 3: graphene oxide Mn (GO-MnO), 4: graphene oxide Ni (GO-Ni(OH)(2)), 5: graphene oxide Sn (GO-SnO2), 6: reduced graphene oxide Co (rGO-Co(OH)(2)), 7: reduced graphene oxide Cu (rGO-Cu(OH)(2)), 8: reduced graphene oxide Mn (rGO-MnO), 9: reduced graphene oxide Ni (rGO-Ni(OH)(2)), and 10: reduced graphene oxide Sn (rGO-SnO2)) in reference to their pristine forms of graphene oxide (GO) and reduced graphene oxide (rGO). The highest adsorption capacities (at 100% breakthrough) were observed as similar to 23 mg g(-1) for both GO-Ni(OH)(2) and rGO-SnO2, followed by GO (similar to 19.1 mg g(-1)) and GO-Co(OH)(2) (similar to 18.8 mg g(-1)). Therefore, the GO-Ni(OH)(2) and rGO-SnO2 composites exhibited considerably high capacities to treat streams containing > 5 Pa of benzene. However, the lowest adsorption capacity was found for GO-MnO (0.05 mg g(-1)). Alternately, if expressed in terms of the 10% break-through volume (BTV), the five aforementioned materials showed values of 0.50, 0.46, 0.40, 0.44, and 0.39 L g(-1), respectively. The experimental data of target sorbents were fitted to linearized Langmuir, Freundlich, Elovich, and Dubinin-Radushkevich isotherm models. Accordingly, the non-linear Langmuir isotherm model revealed the presence of two or more distinct sorption profiles for several of the tested sorbents. Most of the sorbents showed type-III isotherm profiles where the sorption capacity proportional to the loaded volume.