REMOVAL OF HIGH-CONCENTRATION FLUORIDE WASTEWATER BY CALCINED HYDRATED CALCIUM ALUMINATE WITH A TWO-STEP PROCESS.

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Title:	REMOVAL OF HIGH-CONCENTRATION FLUORIDE WASTEWATER BY CALCINED HYDRATED CALCIUM ALUMINATE WITH A TWO-STEP PROCESS.
Authors:	GUANGHONG SHENG¹ shenggh@ahut.edu.cn, WEIJIAN LIANG¹, SHIYU LUO¹, SHISHENG WANG¹, YIYUN LIU¹, LEPING LIU¹
Source:	Environment Protection Engineering. 2025, Vol. 51 Issue 3, p83-100. 18p.
Subject Terms:	Wastewater treatment, Adsorption (Chemistry), Calcium aluminate, Ion exchange (Chemistry), Fluorite, Electrostatic interaction, Precipitation (Chemistry)
Abstract:	Hydrated calcium aluminate for fluoride removal of high-concentration fluoride-containing wastewater was prepared by thermal activation. X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), The Fourier transform infrared spectrometry (FT-IR) were used to study the adsorption process. The results showed that the main component of the modified calcium aluminate cement (CAC) was 12CaO·7Al2O3 (C12A7), and a large amount of calcium and aluminum ions were released during the fluoride removal process. The calcination of hydrated calcium aluminate improved the removal rate of fluoride. After a two-step treatment, adsorption and pH modification, the concentration of fluoride-containing solution from 300 mg/dm3 was reduced to less than 1 mg/dm3. Fluoride removal relies primarily on adsorption at low concentrations, whereas chemical precipitation dominates at high concentrations. The process involves three mechanisms: chemical precipitation, ion exchange, and electrostatic interaction. [ABSTRACT FROM AUTHOR]
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Abstract:	Hydrated calcium aluminate for fluoride removal of high-concentration fluoride-containing wastewater was prepared by thermal activation. X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), The Fourier transform infrared spectrometry (FT-IR) were used to study the adsorption process. The results showed that the main component of the modified calcium aluminate cement (CAC) was 12CaO·7Al2O3 (C12A7), and a large amount of calcium and aluminum ions were released during the fluoride removal process. The calcination of hydrated calcium aluminate improved the removal rate of fluoride. After a two-step treatment, adsorption and pH modification, the concentration of fluoride-containing solution from 300 mg/dm3 was reduced to less than 1 mg/dm3. Fluoride removal relies primarily on adsorption at low concentrations, whereas chemical precipitation dominates at high concentrations. The process involves three mechanisms: chemical precipitation, ion exchange, and electrostatic interaction. [ABSTRACT FROM AUTHOR]
ISSN:	03248828
DOI:	10.37190/EPE/207494