Phoshporic acid actived biochar for efficient removal of paclobutrazol and alleviating its phytotoxicity to mung bean

[Display omitted] •A novel biochar was prepared by low temperature phosphoric acid activation pyrolysis.•Biochar has large specific surface area and abundant oxygen-containing functional groups.•The obtained biochar has excellent performance in the removal of paclobutrazol from water.•Biochar is rich in N and P nutrients and can promote the growth of mung bean seedlings.•The addition of biochar can reduce the bioavailability and phytotoxicity of paclobutrazol in soil. Using biochar to absorb organic pollutants in water and soil is a simple and efficient method. However, most biochar is typically prepared at high temperatures (>500 ℃), resulting in low yield and high production costs and hence limiting its practical applications. This study aimed to prepare biochar (P-BC) through low-temperature (280 ℃) phosphoric acid assisted pyrolysis of cotton stalks. P-BC possessed a large specific surface area (389.96 m2·g−1) and contained abundant oxygen functional groups as well as phosphorous and nitrogen nutrient elements. This study applied P-BC to remove paclobutrazol (PBZ) from water and remediate PBZ-polluted soil. The water adsorption capacity of P-BC was 192.89 mg·g−1. The adsorption mechanisms of P-BC included pore filling, hydrogen bonding, weak electrostatic effects, and π-π interactions. Adding 1 % P-BC to soil contaminated with 10 mg·kg−1 PBZ could alleviate PBZ induced phytotoxicity in mung bean seedlings, ensuring the normal growth of roots and plants.