Adsorption characteristics and mechanisms of Pb2+ and Cd2+ by a new agricultural waste–Caragana korshinskii biomass derived biochar

• Published in: Environmental science and pollution research international 2021-03, Vol.28 (11), p.13800-13818
• Main Authors: Wang, Tongtong, Zheng, Jiyong, Liu, Hongtao, Peng, Qin, Zhou, Huoming, Zhang, Xingchang
• Format: Article
• Language: English
• Subjects: Adsorption; Agricultural wastes; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biomass; Cadmium; Caragana korshinskii; Cellulose; Charcoal; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Heavy metals; Lead; Lignin; Optimization; Pollution control; Pyrolysis; Research Article; Surface chemistry; Waste Water Technology; Water Management; Water pollution; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-020-11571-9

In order to explore the comprehensive utilisation and recycling technology of Caragana korshinskii resources, a new agricultural biomass waste, 15 kinds of Caragana korshinskii biochar (CB) were prepared by controlling the pyrolysis temperature and time at the anaerobic environment. Moreover, we pay more attention to deriving the adsorption mechanisms and exploring the difference in adsorption characteristics of Pb 2+ and Cd 2+ . The optimal preparation conditions and the batch adsorption experiments were evaluated, and the adsorption characteristics and mechanisms were discussed using 8 theoretical adsorption models and multiple characterisation methods. The results showed that the CB prepared at 650 °C for 3 h presented the best performance. The Langmuir and Freundlich models can well simulate the isotherm adsorption process of CB for Pb 2+ and Cd 2+ , respectively. The adsorption kinetics of CB for Pb 2+ and Cd 2+ were best fitted by the pseudo-second-order model. The adsorption equilibrium for Pb 2+ and Cd 2+ was reached within 3 h, and their maximum adsorption capacity reached 220.94 mg g −1 and 42.43 mg g −1 , respectively. In addition, the best addition amount was 3 g L −1 and 2.2 g L −1 for Pb 2+ and Cd 2+ , respectively. The optimum pH range was 3–6 for Pb 2+ and 6–7.5 for Cd 2+ . The adsorption mechanisms of CB for Pb 2+ and Cd 2+ were physicochemical composite adsorption processes, mainly including physical sorption on surface sites, intraparticle diffusion, electrostatic adsorption, ion/ligand exchange, cationic-π interactions, surface complexation and precipitation. Furthermore, the ash of CB also presented a positive effect on the adsorption of Pb 2+ . Compared with other cellulose- and lignin-based biomass materials, CB showed low cost and efficient performance without complicated modification conditions. Therefore, this study demonstrates that CB is a promising raw material in water pollution control to immobilise heavy metals.