Optimized preparation of gangue waste-based geopolymer adsorbent based on improved response surface methodology for Cd(II) removal from wastewater

Chaowei Dong; Nan Zhou; Jixiong Zhang; Wanan Lai; Jianfei Xu; Junlin Chen; Runhua Yu; Yepeng Che

doi:10.1016/j.envres.2023.115246

Optimized preparation of gangue waste-based geopolymer adsorbent based on improved response surface methodology for Cd(II) removal from wastewater

Environ Res. 2023 Mar 15:221:115246. doi: 10.1016/j.envres.2023.115246. Epub 2023 Jan 16.

Authors

Chaowei Dong¹, Nan Zhou², Jixiong Zhang³, Wanan Lai⁴, Jianfei Xu⁵, Junlin Chen⁶, Runhua Yu⁷, Yepeng Che⁸

Affiliations

¹ School of Mines, China University of Mining and Technology, Xuzhou, 221116, China; Artificial Intelligence Research Institute, China University of Mining and Technology, Xuzhou, 221116, China. Electronic address: dongchaowei@cumt.edu.cn.
² School of Mines, China University of Mining and Technology, Xuzhou, 221116, China. Electronic address: 5724@cumt.edu.cn.
³ School of Mines, China University of Mining and Technology, Xuzhou, 221116, China. Electronic address: cumtzjxiong@163.com.
⁴ School of Mines, China University of Mining and Technology, Xuzhou, 221116, China. Electronic address: laiwanan2050@163.com.
⁵ School of Mines, China University of Mining and Technology, Xuzhou, 221116, China. Electronic address: cumtxjf@163.com.
⁶ Arizona College of Technology, Hebei University of Technology, Tianjin, 300401, China. Electronic address: 2080133690@qq.com.
⁷ Jiangsu Provincial Academy of Environmental Science, Nanjing, 210036, China. Electronic address: yrh17718150868@163.com.
⁸ China Coal Energy Xinjiang Tianshan Coal Power Co., Ltd, Xinjiang, 831200, China. Electronic address: Cypxzmk@163.com.

PMID: 36657595
DOI: 10.1016/j.envres.2023.115246

Abstract

Resource utilization of gangue solid waste has become an essential research direction for green development. This study prepared a novel gangue based geopolymer adsorbent (GPA) for the removal of Cd(II) from wastewater using pretreatment gangue (PG) as the main raw material. The ANOVA indicated that the obtained quadratic model of fitness function (R² > 0.99, P-value <0.0001) was significant and adequate, and the contribution of the three preparation conditions to the removal of Cd(II) was: calcination temperature > Na₂CO₃:PG ratio > water-glass solid content. The hybrid response surface method and gray wolf optimization (RSM-GWO) algorithm were adopted to acquire the optimum conditions: Na₂CO₃:PG ratio = 1.05, calcination temperature of 701 °C, solid content of water glass of 22.42%, and the removal efficiency of Cd(II) by GPA obtained under the optimized conditions (GPAC) was 97.84%. Adsorption kinetics, adsorption isotherms and characterization by XRD, FTIR, Zeta potential, FSEM-EDS and BET were utilized to investigate the adsorption mechanism of GPAC on Cd(II). The results showed that the adsorption of Cd(II) from GPAC was consistent with the pseudo-second-order model (R² = 0.9936) and the Langmuir model (R² = 0.9988), the adsorption was a monolayer adsorption process and the computed maximum Cd(II) adsorption (50.76 mg g^-1) was approximate to experimental results (51.47 mg g^-1). Moreover, the surface morphology of GPAC was rough and porous with a specific surface area (SSA) of 18.54 m² g^-1, which provided abundant active sites, and the internal kaolinite was destroyed to produce a zeolite-like structure where surface complexation and ion exchange with Cd(II) through hydroxyl (-OH) and oxygen-containing groups (-SiOH and -AlOH) were the main adsorption mechanisms. Thus, GPAC is a lucrative adsorbent material for effective Cd(II) wastewater treatment, complying with the "high value-added" usage of solid wastes and "waste to cure poison" green sustainable development direction.

Keywords: Adsorption mechanism; Gangue waste utilization; Geopolymer adsorbents; Gray wolf optimization algorithm; Response surface method.

Publication types

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

MeSH terms

Adsorption
Cadmium
Hydrogen-Ion Concentration
Kaolin
Kinetics
Temperature
Wastewater*
Water Pollutants, Chemical* / analysis

Substances

Wastewater
Cadmium
Water Pollutants, Chemical
Kaolin