DENG Hongyan1, LI Xuelian1, LI Wenbin1, KANG Le1, ZHU Xiaohua1, MENG Zhaofu2, GAO Hui1
(1. College of Environmental Science and Engineering, China West Normal University, Nanchong Sichuan 637009, China;
2. College of Natural Resources and Environment, Northwest A&F University, Yangling Shaanxi 712100, China)
Abstract: In order to explore effects of different amendment materials on adsorption of Cu2+ on purple soil, amendment materials, activated carbon(C), maifanite(M), diatomite(D), bentonite(B) and active calcium silicate(S), were added respectively into purple soils with a mass ratio of 1% or 2% to prepare ten mixed soil samples, named as P-C1% and P-C2%(purple soil mixed with 1% and 2% activated carbon, similarly hereinafter), P-M1% and P-M2%, P-D1% and P-D2%, P-B1% and P-B2%, P-S1% and P-S2% (P as a contrast), and the batch method was used to study isothermal adsorptions and thermodynamic characteristics of Cu2+ on different mixed soil samples under different temperatures, pH values and ionic strengths. The results showed that: (1) The adsorption isotherms of Cu2+ on all mixed soil samples could be fit well with the Langmuir model, and the fitted maximum adsorption capacities were between 65.02 and 131.34 mmol/kg. The adsorption capacities of soil samples with the same amendment adding ratio to Cu2+ showed a trend of P-B > P-D > P-C > P-S > P-M, and this trend was more prominent in the scenario of 2% amendment adding. (2) When the experimental temperature increased from 20 to 40 ℃, adsorption capacities of all mixed soil samples, except P-C samples, increased. The thermodynamic parameters indicated that adsorption of Cu2+ by mixed soil samples is a spontaneous, endothermic and entropy increased process. (3) The adsorption capacities of all mixed soil samples, except P-S, increased as pH increasing within the pH range of 3 ~ 5. Adsorption capacities of all mixed soil samples increased as the ionic strength increasing until 0.1 mol/L, and then decreased.
Key words: amendment material; purple soil; Cu2+; adsorption capacity
EARTH AND ENVIRONMENT Vol.47, No.1, Tot No.327, 2019, Page 81-87