Application of zeolite synthesized from coal fly ash via wet milling as a sustainable resource on lead(II) removal.

In this work, zeolite based on coal fly ash was firstly synthesized via wet milling for the adsorption of lead (Pb(II)). The effects of contact time, solid-to-liquid ratio and initial pH of solution on Pb(II) removal were investigated in detail. The experimental data showed that synthesized zeolite has high adsorption capacity of 99.082 mg of Pb(II) per gram of adsorbent. Coal fly ash zeolite synthesized by wet milling has good Pb(II) adsorption performance when the initial pH of the solution is above 5. The adsorption kinetic results demonstrated that removal of Pb(II) via the synthesized zeolite followed pseudo-second-order kinetic model. X-ray photoelectron spectroscopy results directly demonstrated the adsorption between Pb(II) and synthesized zeolite, and a possible reaction pathway was proposed. Specifically, the removing mechanism of Pb(II) from aqueous solution via the synthesized zeolite involves two stages: one is that Pb(II) in aqueous solution is absorbed on the interior of the synthesized zeolite, and the other is chemical precipitation.