Development of nano-CaO2-coated clinoptilolite for enhanced phosphorus adsorption and simultaneous removal of COD and nitrogen from sewage

•First attempt to synthesize nanomaterial by impregnating CaO2 onto clinoptilolite.•Material showed synergistic effects of peroxidation, adsorption and precipitation.•Simultaneous removal of COD, TN, and TP with one treatment unit was first proposed.

Severe water pollution caused by excessive emissions of phosphorus (P) and nitrogen (N) into water bodies is a significant concern worldwide. In the present study, we synthesized a novel nano composite, nano-CaO2@clinoptilolite, for the simultaneous removal of P, COD, and N from sewage. X-ray diffraction and X-ray photoelectron spectroscopy were used to characterize the crystalline composition of the nano composite and confirm the presence of CaO2. The spatial distribution of nano CaO2 particles and the microtopography of nano-CaO2@clinoptilolite were characterized by transmission electron microscopy and energy-dispersive X-ray spectroscopy. P uptake analysis indicated that nano-CaO2@clinoptilolite was highly effective for P removal over a wide pH range of 7.0-11.0, and that phosphate precipitation induced by the solubilization of Ca2+ from CaO2 was determined to be the main mechanism of P removal. In addition, simultaneous P, COD, and N removal efficiencies of 50.4, 74.7, and 80.7%, respectively, were obtained when nano-CaO2@clinoptilolite was applied to sewage samples. The realization of synergistic peroxidation, adsorption, and precipitation by nano-CaO2@clinoptilolite provides a novel insight into the high-efficiency purification of sewage.

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