Stability of Functionally Modified Biochar: The Role of Surface Charges and Surface Homogeneity

Biochar modification has received significant research attention due to its attractive and fruitful rewards in improving biochar performances. However, the determinants of modified biochars’ stability ability aged biochars remove heavy metals have not been comprehensively evaluated. Therefore, three commonly used functional groups (5% 10% H2O2-modified (BCH5 BCH20); 25% 65% HNO3-modified (BCA25 BCA65); amino-modified (BCN), were prepared this study explore their Cd(II) removal performance was studied. The results showed that O/C ratio is sensitive enough predict biochars, which evaluate pristine (BC0); instead, -COOH content crucial for (r = −0.99, r −0.91, p < 0.05). BCA65 displayed highest less prone oxidation property, indicated high surface charges uniform determined functionally biochars. order > amino-modified. After oxidation, pores significantly reduced, Cd2+ adsorption mechanism changed from multilayer monolayer adsorption, led a reduction overall removal. maximum capacities reduced 18.15 mg·g−1 4.86 after particularly. In design preparation biochar, long-term structure function sustainable application environment should be considered while metal