Abstract: In recent years, the widespread occurrence of alkyl and chlorinated organophosphate flame retardants (OPFR) pollution in various environmental media has attracted increasing attention. Tris(2-butoxy) ethyl phosphate (TBOEP), tripropyl phosphate (TPrP) and tris(1, 3-dichloroisopropyl) phosphate (TDCPP) are representative compounds of alkyl- and chlorinated- OPFRs, respectively. In this study, using discarded peanut shells as biochar precursor and KOH as a modifying agent, four types of modified peanut shell-derived biochars were prepared at different pyrolysis temperatures via a simple pyrolysis process. These biochars were subsequently applied for adsorption removal of the three selected OPFR pollutants. Characterization techniques including scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, Fourier-transform infrared spectroscopy (FT-IR), x-ray photoelectron spectroscopy (XPS), zero potential measurement, and water contact angle analysis reveal that the biochar pyrolyzed at 600 ℃ (PBC600) exhibited a high specific surface area (SSA), well-developed pore structure, and abundant surface functional groups such as —OH, —NH and —COOH. Under the experimental conditions of an initial OPFR concentration of 5 mg·L^-1 and pH 5, the addition of 10 mg of PBC600 resulted in removal efficiencies of 73%, 80% and 89% for TBOEP, TPrP and TDCPP, respectively, after 3-h of adsorption. Common coexisting ions in environmental water systems, including K⁺, Na⁺, Ca²⁺, Mg^2+, Al³⁺, Cl^- and SO₄^2-, exhibited negligible interference with the adsorption process. Comparative analysis of SEM-EDS and FTIR spectra before and after adsorption, combined with adsorption experiments, model fitting, and density functional theory (DFT) calculations, indicates that the adsorption of TDCPP by PBC600 followed a pseudo second-order kinetics model, suggesting a chemical adsorption. In contrast, TBOEP adsorption was better described by the pseudo first-order kinetics model, indicating a physisorption mechanism. The theoretical maximum adsorption capacity (Q_m) (110.62 mg·g^-1) calculated from the model was consistent with the experimentally observed value (108.2 mg·g^-1). The adsorption capacities of PBC600 for the three OPFRs followed the order: TDCPP > TPrP > TBOEP, which was attributed to differences in their molecular electrostatic potentials. The adsorption isotherms of all three OPFRs on PBC600 were better fitted by the Langmuir model; however, discrepancies between theoretical and experimental adsorption capacities suggested the occurrence of non-uniform multilayer adsorption. The primary adsorption mechanism involved pore-filling, hydrogen bonding, and hydrophobic interactions, with TDCPP also exhibiting weak electrostatic interactions. In real-world waters, the removal efficiency of OPFRs slightly decreased, and the adsorption capacity diminished after five regeneration cycles. These findings are expected to provide a theoretical basis for the development of eco-friendly adsorbent materials for the remediation of OPFR-contaminated environments.