Fabrication of porosity-enhanced MgO/biochar for removal of phosphate from aqueous solution: Application of a novel combined electrochemical modification method.

A novel combined electrochemical modification (CEM) method, using a graphite electrode-based electric field and MgCl2 as electrolyte, was newly developed to prepare porosity-enhanced biochar containing periclase (MgO) nanocomposites (PE-MgO/biochar). During the CEM method, the dried marine macroalgae was immersed in the MgCl2 solution, and a voltage of 20V was then applied for 10min prior to pyrolysis. Morphological and chemical analyses results showed that nano-sized MgO particles with a highly crystalline structure were dispersed and enriched on the surface of the PE-MgO/biochar, which enabled higher phosphate adsorption capability. In an adsorption equilibrium test, among various biochars, PE-MgO/biochar exhibited the highest phosphate adsorption capacity from aqueous solution with a Langmuir-Freundlich maximum adsorption capacity as high as 620mg-Pg(-1). It can be concluded that the newly introduced CEM method is a potent additional technique to effectively prepare modified-biochar in terms of a simple and time-saving modification method.