Use of Eggshell-Catalyzed Biochar Adsorbents for Pb Removal from Aqueous Solution

Dongdong Liu; Zhengkai Hao; Dengqian Chen; Lipeng Jiang; Tianqi Li; Bing Tian; Cuiping Yan; Yuan Luo; Guang Chen; Hongfu Ai

doi:10.1021/acsomega.2c01957

Use of Eggshell-Catalyzed Biochar Adsorbents for Pb Removal from Aqueous Solution

ACS Omega. 2022 Jun 14;7(25):21808-21819. doi: 10.1021/acsomega.2c01957. eCollection 2022 Jun 28.

Authors

Dongdong Liu^{1

2}, Zhengkai Hao², Dengqian Chen², Lipeng Jiang², Tianqi Li², Bing Tian², Cuiping Yan², Yuan Luo², Guang Chen¹, Hongfu Ai³

Affiliations

¹ Key Laboratory of Straw Biology and Utilization, The Ministry of Education, Jilin Agricultural University, Changchun 130118, P. R. China.
² College of Engineering and Technology, Jilin Agricultural University, Changchun 130118, P. R. China.
³ College of Information Technology, Jilin Agricultural University, Changchun 130118, P. R. China.

Abstract

Eggshell is a cheap and environmentally friendly calcium source. In this study, Ca-modified biochar adsorbents (CEA) were prepared by 1:10, 1:2, and 1:1 mass ratio of the eggshell and Eupatorium adenophorum. The CEA-2 sample prepared with a 1:2 mass ratio showed a maximum Pb adsorption capacity (97.74 mg·g^-1) at the conditions of an initial pH of 7.0, an adsorbent dosage of 0.5 g·L^-1, and a contact time of 8.0 h. The kinetic and isotherm studies indicated that the adsorption process of the CEA-2 sample had monolayer adsorption characteristics, which was controlled together by intraparticle and interface diffusion. Thermodynamic studies indicated that the adsorption process of CEA-2 was spontaneous (ΔG ⁰ <0) and endothermic (ΔH ⁰ > 0). X-ray diffraction and scanning electron microscopy analyses showed a uniform distribution of Ca-Pb precipitation on the CEA-2 surface, which proved that chemical precipitation was the main adsorption mechanism. Fourier transform infrared spectra found that CEA-2 had abundant active groups, especially nitrogen-containing functional groups, which could adsorb Pb through a surface complexation reaction. The Brunauer-Emmett-Teller surface area of CEA-2 was found to be 621 m²·g^-1, and such developed pores could ensure the smooth diffusion of Pb. Finally, the effect of coexisting cation and anion experiment and the cyclic regeneration experiment indicated that CEA-2 had prominent stability and reusability for Pb adsorption.