The application of water bamboo (Zizania latifolia) husk-derived biochar for copper-contaminated irrigation water treatment and soil amendment

In Taiwan, farmlands are polluted with metals mainly caused by irrigation water and sediments in irrigation channels. Copper (Cu) presents a major challenge in Taiwan's agricultural lands. This study investigates the potential of utilizing water bamboo (Zizania latifolia) husk-derived biochar (WBC) for the treatment of copper-contaminated irrigation water and soil amendment. The BET-SSA for WBC that is produced at 600 °C is 192 m² g⁻¹ and the pore volume is 0.174 cc g⁻¹. The FTIR spectrum of WBC exhibits several functional groups, such as phosphate, carboxylate (–COO), or aromatic (CC) that can contribute to biochar alkalinity. The point of zero charge (pH_PZC) of WBC is determined to be 2.7. The optimum adsorption of copper by WBC occurs at pH 5. Copper adsorption by WBC fits well with pseudo-second-order kinetics and the Langmuir isotherm, which demonstrates that chemisorption and monolayer adsorption are the dominant mechanisms for copper removal. The maximum Cu²⁺ adsorption capacity of WBC is 144.9 mg g⁻¹, which is much higher than those of many existing reports. The addition of 1 to 5% (wt/wt) WBC neutralizes acidic soil pH effectively, making it suitable for water bamboo cultivation.