Investigating the Effect of Various Surface and Chemical Modification Approaches on Corn Residue and Common Reed Derived-biochar Traits

In recent years, modified biochar application has been receiving attention in removal of organic and inorganic contaminants, soil amelioration and production of biochar based slow release fertilizers. The aim of this study was to investigate the effect of various modification approaches on physical and chemical traits of corn residue and common reed derived-biochar. For this purpose, chemical modification methods (using iron- magnesium- and calcium- chloride) and surface modification (using sulfuric- and hydrochloric- acid, potassium- and sodium- hydroxide) were used to modify common reed and corn residues derived biochars in a completely randomized design. Then, the characteristics of modified biochars including yield, approximate analysis, pH, electrical conductivity (EC), cation exchange capacity (CEC), anionic exchange capacity (AEC) and specific surface area (SSA) were measured. The results showed that the highest specific surface area, cation exchange capacity and anion exchange capacity were observed in iron modified common reed biochar (217.94 m2 g-1, 111.43 cmolc kg-1 and 22.13 cmolc kg-1, respectively) and magnesium corn residue biochar (respectively, 210.83 m2 g-1, 137.40 cmolc kg-1 and 16.93 cmolc kg-1, respectively). Carbon content and C/N ratio decreased in the samples treated with acid, base and metal salts compared to the initial samples. Oxygen content, O/C and H/C ratios showed a decrease in in all treatments after chemical and surface modification. While the content of hydrogen and nitrogen in the acids and metal salts modified biochars were increased and decreased in the base modified treatments. In general, using various modification methods can play a very important role in optimizing biochar properties, according to the aim of its application in soil.