Hierarchical 13X zeolite/reduced graphene oxide porous material for trace Pb (II) capturing from drinking water

The removal of lead in drinking water has attracted considerable attention of researchers in recent years, especially, the trace characteristic of lead is a challenge to water treatment. Herein, 13X zeolite/reduced graphene oxide composite material (13X-rGO) with hierarchically porous structure was successfully prepared using graphene oxide (GO) and 13X zeolite via a chemical reduction method and presented great performance for removing trace Pb(II) from drinking water. The influence of some important parameters including adsorbent dosage, contact time, initial lead concentration, coexisting competing ions, solution pH value, etc. on the removal of Pb(II) was systematically investigated. The composite material showed better adsorption properties compared with a single component and their physical mixture, confirming the synergistic effect of rGO and 13X zeolite on Pb(II) adsorption. The effluent lead concentration could be decreased to the level permitted by World Health Organization (WHO) (<10 ppb) within 30 s under calcium content of 20 ppm and initial lead concentration of 150 ppb. Simultaneously, the as-prepared 13X-rGO performed excellent adsorption capacity meeting WHO standard (6.07 mg/g), which was about 2.23 times that of single 13X zeolite (2.72 mg/g). In the presence of interfering ions, the lead concentration could still be reduced to safe drinking water standard. Moreover, the adsorbent could be effectively regenerated by saturated sodium chloride solution. Therefore, 13X-rGO can be introduced as a promising adsorption material for the purification of drinking water contaminated with trace lead owing to rapid adsorption, low cost and recycling potential.