Adsorption of lead ions by magnetic carbon: Comparison of magnetic carbon properties and modification methods

Magnetic biochar (MBC) is extensively used to remove contaminants from environmental media because of being easy to recover and separate. However, magnetic modification generally decreases the surface area of Biochar (BC), leading to an insignificant improvement in adsorption performance. In the present study, research was conducted on the changes in the physicochemical characteristics of the modified MBC in terms of elemental distribution, morphological characteristics, and surface functional groups based on magnetic carbon. Magnetic carbon was prepared using pine cone material and modified by four methods (ball milling, acid and oxidant modifications as well as metal impregnation). The role of contact time (0.25–8 h), initial Pb2+ concentration (5–200 mg/L), solution pH (2-7), and other process parameters in removing Pb2+ from the contaminated water was evaluated. The results showed that the maximum adsorption of Pb2+ by MBC reached up to 123.38 mg/g when time varied from 0.25 to 8 h. The proposed secondary kinetic and Langmuir isotherm models better proved the results of adsorption. The adsorption performance of ball milling modified MBC (BMBC) was evenly enhanced to varying degrees by several modification methods, especially ball milling with green and low-cost, a simple mechanical process to enhance the number and surface area of functional groups of MBC. •Modification based on magnetic biochar.•Various methods were used for modification.•The changes of physicochemical properties brought by different modification methods to the magnetic carbon were analyzed.•Great increase of adsorption capability was obtained for Pb2+.