Characterizations and mechanisms for synthesis of chitosan-coated Na–X zeolite from fly ash and As(V) adsorption study

Abstract

Solid waste fly ash with low aluminum of Yunnan Province in China was used as pristine material to prepared chitosan-coated Na–X zeolite, and the obtained composite material was employed as As(V) adsorbent. Then, the prepared materials were characterized by XRD, FT-IR, and XPS. And the results suggested that the low aluminum fly ash was successfully convert into Na–X zeolite, and the mineralization between Si–OH of the obtained Na–X zeolite and C–OH of chitosan was the dominated mechanism for coated chitosan over the surface of Na–X zeolite. From the batch experiments of As(V) removal, it has been found that the coated chitosan could significantly improve As(V) performance of Na–X zeolite. The optimal working pH for removal As(V) by chitosan-coated Na–X zeolite was attained at pH 2.1 ± 0.1, and the maximum adsorption capacity was 63.23 mg/g. And the adsorption data at different interval time was excellent fitted by pseudo-second-order kinetic model. From the analyze of XPS, the results suggested that As(V) uptake over adsorbent by the bond of As–N and As–O and the surface hydroxyl group of Al–OH and –NH₂ were involved in uptake As(V) from acid wastewater.

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