Adsorption performance of phosphate in water by mixed precursor base geopolymers

Wentao Zhou; Tian Lan; Gaofei Shang; Jianhong Li; Jianjian Geng

doi:10.1016/j.jconhyd.2023.104166

Adsorption performance of phosphate in water by mixed precursor base geopolymers

J Contam Hydrol. 2023 Apr:255:104166. doi: 10.1016/j.jconhyd.2023.104166. Epub 2023 Feb 28.

Authors

Wentao Zhou¹, Tian Lan², Gaofei Shang³, Jianhong Li⁴, Jianjian Geng⁵

Affiliations

¹ School of Land Science and Technology, China Agricultural University, Beijing 100193, China.
² School of Land Science and Technology, China Agricultural University, Beijing 100193, China; School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: tlan@tsinghua.edu.cn.
³ School of Economics and Management, Inner Mongolia University of Technology, Hohhot 010051, Inner Mongolia, China.
⁴ Biochar Engineering Technology Research Center of Guangdong Province, School of Environmental and Chemical Engineering, Foshan University, Foshan 528000, China.
⁵ Yunnan Institute of Tropical Crops, Jinghong 666101, China.

PMID: 36871363
DOI: 10.1016/j.jconhyd.2023.104166

Abstract

Design of low-cost and high-removal efficiency phosphate adsorbents is of great significance for the control of eutrophication. In this study, fly ash and metakaolin were used as raw materials to evaluate the capability of phosphate adsorption and to investigate the mechanism of phosphate adsorption. The results of comparing the adsorption effect of geopolymers prepared with different modulus of alkali activator showed that the removal efficiency of phosphate in water at 0.8 M was on average 30.33% higher than 1.2 M. Therefore, FA + MK-0.8 had the maximum removal efficiency of 94.21% for phosphate in water with the maximum adsorption capacity of 36.02 mg/kg. In addition, the adsorption of phosphate could be well fitted by pseudo-second-order model and the process was mainly controlled by film diffusion. The alkali activation process can destroy the octahedral structure of the raw material, so the geopolymer are mainly tetrahedral in structure. Interestingly, new zeolite structures were formed in the mineral crystal phase of FA + MK-0.8, which may facilitate the adsorption of phosphate by geopolymers. Furthermore, the combined FTIR and XRD analysis results indicated that the underlying mechanisms of phosphate adsorption were electrostatic gravitation, ligand exchange, and surface complexation. This research not only synthesizes low-cost and high removal efficiency wastewater purification materials, but also provides a promising application for the elimination and resource utilization of industrial solid waste.

Keywords: Fly ash; Geopolymers; Metakaolin; Phosphate; Water treatment.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adsorption
Coal Ash / chemistry
Phosphates / chemistry
Water Pollutants, Chemical* / analysis
Water*

Substances

Water
Phosphates
Coal Ash
Water Pollutants, Chemical