## 3 The Effect of Biochar on the Environmental Fate of Pesticides  
### The Effect of Biochar on Sorption of Pesticides  
According to [PERSON] and [PERSON] (2018) [76], adsorption onto inexpensive materials is a viable and promising strategy for removing both organic and inorganic pollutants [77]. Chemical sorption is less expensive, more efficient, and faster than biological methods. Adsorption occurs initially when pesticides encounter soil and is one of the most important processes for pesticide removal from soil. It has been shown to be a cost-effective and efficient pesticide removal technology [78]. Pesticide sorption and desorption in soil is the basis for understanding pesticide environmental behavior and biotoxicity [79]. Pesticide bioaccessibility and bioavailability in soil are inextricably tied to desorption processes, since the component must be released back into the soil solution to perform its intended impact [80]. Biochar can enhance pesticide sorption and lower the concentration of free pesticides in soil, which not only minimizes pesticide biotoxicity but also prevents pesticides from mitigating possible environmental dangers linked with harmful compounds and their metabolites [35; 81; 82]. Porosity, surface area, surface charge, pH, functional groups, carbon content, aromatic structure, and mineralogy all contribute to biochar's sorption ability [83; 84]. Biochar's high organic carbon content and large surface area provide an abundance of pesticide sorption sites via hydrophobic partitioning and pore-filling [85]. The variances in biochar's sorption capacity are frequently due to changes in their properties, which vary according to the biomass source and manufacturing process used. After a long time, the efficiency of biochar's sorption capacity is likely to be reliant on the initial rate of biochar application to the soil. However, aging in biochar-amended soils likely reduces biochar's adsorption capability by altering its physicochemical characteristics [86]. Further investigation is needed to get insight into the fundamental mechanisms to clarify the specific pesticide characteristics that determine each behavior [87]. Biochar has an ability as a soil supplement to minimize pesticide contamination by boosting sorption and decreasing mobility [88]. Adsorption of pesticides by biochar impacts the processes of mobility and conversion, as well as pesticide absorption and usage in plants.  
Several interactions between biochar and pesticides are depicted in Figure 3, including hydrophobic adsorption H-bonding, electrostatic, \(\pi\)-\(\pi\) electron donor-acceptor interactions, and cation-\(\pi\) bonding. Pesticides are removed from the environment by a variety of methods, including physical adsorption, complex formation, precipitation, ion exchange, and electrostatic interactions [89]. Through particular interactions and their strong aromaticity, surface functional groups and negative surface charge might enhance pesticide adsorption. The interaction between adsorbents and adsorbates is described using several adsorption isotherm models. The Langmuir and Freundlich isotherm models are the most often utilized in the adsorption system, demonstrating the presence of both physisorption and chemisorption [90]. On the basis of ideal monolayer adsorption, the Langmuir isotherm model was constructed, and the Freundlich isotherm model was used to calculate non-ideal adsorption on heterogeneous surfaces and multilayer adsorption. Pseudo-second-order kinetics is a third model that is also applicable to adsorption. However, it can serve as a theoretical foundation for the optimal use of biochar as a sorbent in environmental applications [91]. Adsorption is the simplest, most effective, and most widely used technology for most remediation attempts, and biochar is the most used adsorbent due to its wide applicability for pesticide removal [92].