Preparation of Modified Pomelo Peel Biochars and Its Phosphate Removal Performance in Aqueous Solution

To deal with the phosphate pollution in surface water, CNZVI-PB was prepared with pomelo peel biochars (PB) modified by nano zero- valent iron (NZVI) and cetyl trimethyl ammonium bromide (CTMAB). Physical and chemical properties of the new complex adsorbent material (CNZVI-PB) were analyzed with scanning electron microscope (SEM), specific surface area analyzer (BET), and X-ray diffraction analyzer (XRD). Meanwhile the effects of CNZVI-PB on phosphate adsorption were carried out in terms of pH, dosage of the adsorbent, shaking time, initial concentration, and temperature. Results showed that CNZVI-PB was effective for phosphate removal from aqueous solution. The adsorption effect of phosphate on CNZVI-PB relied on pH, and the optimal pH among 3.0-7.0. Moreover, it was an endothermic process, and the pseudo-second-order kinetic model fitted the phosphate kinetic experimental data well. The equilibrium isotherm data of phosphate adsorption onto the CNZVIPB could be described by the Langmuir isotherm model, and the maximum phosphate adsorption capacities were 8.47-9.62 mg/g at 20-40 ℃. The adsorption mechanism of phosphate on the CNZVI-PB mainly included the electrostatic attraction and ligand exchange interaction.