Mechanical Improvement of Biochar-Alginate Composite by Using Melamine Sponge as Support and Application to Cu(II) Removal

The development of biosorbents using carbon–neutral materials is expected to contribute to a sustainable environment in water purification. In this study, the biochar-alginate composite was selected as the core material of biosorbent and Cu(II) was set as the adsorption experimental model. In particular, in order to improve the insufficient mechanical strength of alginate, a melamine sponge (MS) was applied as a support to the biochar-alginate composite. As a result, the tensile strength was significantly improved about 4.3-fold compared to the alginate foam (without MS), and it can be manufactured in the shape required in the process. The Cu(II) adsorption capacity of the biosorbent was analyzed based on the adsorption equilibrium and kinetics. As a result, the pseudo-second-order model and the Langmuir isotherm model were most suitable, and the maximum adsorption capacity of Cu(II) was estimated to be 126.58 mg/g. In conclusion, the biochar-alginate composite on melamine sponge was an excellent material as a biosorbent for removing Cu(II) from wastewater.