Preparation of sulfonic acid-based functionalized biochar (PPBC) by modifying discarded pomelo peels through low-temperature sulfonation method and its application in adsorbing iron ions from high-concentration sulfuric acid solutions was investigated. The effects of adsorption time, temperature, stirring speed, initial mass concentration of iron ions and acidity on the adsorption performance of PPBC were examined, and the adsorption and separation mechanism as well as the recycling and regeneration performance were discussed. The results show that under the optimized conditions of sulfuric acid concentration of 0.1 mol/L, temperature of 55 ℃, stirring speed of 200 r/min, initial mass concentration of iron of 1 000 mg/L, and adsorption time of 120 min, the adsorption rate of PPBC for iron ions reaches 98.2%, and the adsorption capacity is 98.2 mg/g. When the initial mass concentration of iron ions is 5 000 mg/L, the adsorption capacity of PPBC for iron ions reaches a maximum of 324.6 mg/g. The adsorption behavior conforms to the Langmuir isothermal adsorption model and the pseudo-second-order kinetic model, and belongs to monolayer chemical adsorption. After five adsorption-desorption cycles, the regeneration rate of PPBC remains at 87.8%. PPBC has excellent structural stability and reusability, which can provide technical references for the treatment of high-acid and high-iron wastewater and the high-value utilization of agricultural waste.

sulfonated pomelo peel  /  low-temperature sulfonation method  /  modification  /  biochar  /  adsorbent  /  sulfuric acid solution  /  adsorption  /  iron