Effective adsorption of Pb(ii) from wastewater using MnO2 loaded MgFe-LD(H)O composites: adsorption behavior and mechanism

Yongxiang Huang; Xiangping Luo; Chongmin Liu; Shaohong You; Saeed Rad; Litang Qin

doi:10.1039/d3ra03035k

Effective adsorption of Pb(ii) from wastewater using MnO₂ loaded MgFe-LD(H)O composites: adsorption behavior and mechanism

RSC Adv. 2023 Jun 26;13(28):19288-19300. doi: 10.1039/d3ra03035k. eCollection 2023 Jun 22.

Authors

Yongxiang Huang^{1

2}, Xiangping Luo^{1

2}, Chongmin Liu^{1

2}, Shaohong You^{1

2}, Saeed Rad^{1

2}, Litang Qin^{1

2}

Affiliations

¹ College of Environmental Science and Engineering, Guilin University of Technology Guilin 541004 China chongmin@glut.edu.cn youshaohong@glut.edu.cn.
² Guangxi Key Laboratory of Theory & Technology for Environmental Pollution Control, Guilin University of Technology Guilin 541004 China.

Abstract

Pb(ii) adsorption by MnO₂/MgFe-layered double hydroxide (MnO₂/MgFe-LDH) and MnO₂/MgFe-layered metal oxide (MnO₂/MgFe-LDO) materials was experimentally studied in lab-scale batches for remediation property and mechanism analysis. Based on our results, the optimum adsorption capacity for Pb(ii) was achieved at the calcination temperature of 400 °C for MnO₂/MgFe-LDH. Langmuir and Freundlich adsorption isotherm models, pseudo-first-order and pseudo-second-order kinetics, Elovich model, and thermodynamic studies were used for exploring the Pb(ii) adsorption mechanism of the two composites. In contrast to MnO₂/MgFe-LDH, MnO₂/MgFe-LDO_{400 °C} has a stronger adsorption capacity and the Freundlich adsorption isotherm model (R² > 0.948), the pseudo-second-order kinetic model (R² > 0.998), and the Elovich model (R² > 0.950) provide great fits to the experimental data, indicating that the adsorption occurs predominantly via chemisorption. The thermodynamic model suggests that MnO₂/MgFe-LDO_{400 °C} is spontaneously heat-absorbing during the adsorption process. The maximum adsorption capacity of MnO₂/MgFe-LDO_{400 °C} for Pb(ii) was 531.86 mg g^-1 at a dosage of 1.0 g L^-1, pH of 5.0, and temperature of 25 °C. Through characterization analysis, the main mechanisms involved in the adsorption process were precipitation action, complexation with functional groups, electrostatic attraction, cation exchange and isomorphic replacement, and memory effect. Besides, MnO₂/MgFe-LDO_{400 °C} has excellent regeneration ability in five adsorption/desorption experiments. The above results highlight the powerful adsorption capacity of MnO₂/MgFe-LDO_{400 °C} and may inspire the development of new types of nanostructured adsorbents for wastewater remediation.