## 2 Source and Modification Methods of Biochar for Pesticide Remediation
### Biochar Production
The mechanisms of low-surface-area and high-temperature biochar for adsorbing acidic and nonpolar pesticides include the pore filling mechanism, the hydrophobic effect, the H-bond and \(\pi\)-bond, which are changed to \(\pi\)-\(\pi\) interaction, electrical interaction, physical adsorption, and chemical adsorption after the modification. The mechanisms of low-surface-area and low-temperature biochar for adsorbing nonpolar pesticides are the surface polarity mechanism, the pore-filling mechanism, the hydrophobic effect, and \(\pi\)-\(\pi\) interaction. After modification, the adsorption mechanisms are electrostatic interaction and physical adsorption (Tables 1 and 2). The removal of pesticides with biochar is mainly attributed to the adsorption of biochar. It indicates specific interactions such as the pore-filling mechanism and hydrophobic and \(\pi\)-\(\pi\) interaction between biochar and pesticide in the process of adsorption, which illustrates that the Freundlich isotherm model fits better for the adsorption process. Due to large SSA and sufficient surface pores, biochar possesses high adsorption capacity and can adsorb a large amount of pesticide in a short time. \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline  & \multicolumn{3}{c}{**Pyphysis**} & \multicolumn{3}{c}{**Specitic**} & \multicolumn{3}{c}{**Outal Powe**} & \multicolumn{3}{c}{**Maximum**} & \multicolumn{3}{c}{**Maximum**} & \multicolumn{3}{c}{**Adaorption**} & \multicolumn{3}{c}{**Adaorption**} & \multicolumn{3}{c}{**Adaorption**} & \multicolumn{3}{c}{**Adaorption**} & \multicolumn{3}{c}{**Adaorption**} & \multicolumn{3}{c}{**Adaorption**} \\ \cline{2-15}
**Material** & **Time-wave** & **pH** & **Method** & **Surface Area** & **Volume** & **Complexity** & **Rate** & **V** & **Transmission** & **Radvern** & **Transmission** & **Radvern** & **Transmission** & **Radvern** & **Transmission** & **Radvern** & **Transmission** & **Radvern** \\  & **\({}^{*}\)C** & & & & (m\({}^{*}\)g\({}^{-1}\)) & (m\({}^{*}\)g\({}^{-1}\)) & (m\({}^{*}\)g\({}^{-1}\)) & & & & & & & & & & \\ \hline \hline walnut & \multirow{2}{*}{70} & \multirow{2}{*}{7} & \multirow{2}{*}{116e/C3} & \multirow{2}{*}{232.77} & \multirow{2}{*}{0.29} & \multirow{2}{*}{126.72} & \multirow{2}{*}{95\%} & \multicolumn{3}{c}{**Ingredihort**} & \multicolumn{3}{c}{**Ingredihort**} & \multicolumn{3}{c}{**Ingredihort**} \\  & & & & & & & & & & & & & & \\ oil palm & & & & & & & & & & & & & & \\ empty fruit & & & & & & & & & & & & & & \\ brush & & & & & & & & & & & & & & \\ plans & &  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Raw Material**} & \multicolumn{2}{c}{**Pyupphesis**} & \multirow{2}{*}{**pH**} & \multirow{2}{*}{**Modification Method**} & \multicolumn{2}{c}{**Specific Surface**} & \multicolumn{2}{c}{**Out Power**} & \multicolumn{2}{c}{**Maximum  
Due to the diverse features of biochar, which vary significantly with different source materials and pyrolysis settings, it can serve as both a soil amendment and a corrective remedy for pesticide breakdown. Biochar works as a super sorbent by lowering pesticides' accessible concentrations, which results in an increase in soil microbial biomass and the potential to improve soil quality [69; 70].