Study On Characteristics Of Rice Husk-based Activated Carbon Absorbent For Phosphates Removal

Phosphorus is considered to be the key factor leading to water eutrophication. While with the wide application of phosphate chemicals, large amounts of phosphorus flow into the natural water bodies which stimulate the over growth of algae, and finally leaded to eutrophication. Among methods of phosphorus remo val, adsorption have been used widely for its large adsorption capacity, high efficiency and adapting to low phosphorus removal. A composite adsorbent(denoted as MgOPC) synthesized by loading MgO and Pullulan onto Rice Husk based activated carbon using sol- gelmethod, showed excellent ability of defluoridation, but it have not been studied for removing phosphorus. The present study has been mainly focused on characteristics of MgOPC adsorbent for phosphates removal.In the static adsorption experiments, effects of solid- liquid ratio, contact time, temperature, solution pH, initial phosphorus concentration, coexisting anions on phosphorus removal have been investigated. The results indicated that after 100 minutes of contact time phosphorus removal efficienc y reached 97.77% and the corresponding maximum adsorption capacity is 6.518mg/g when the dosage is 1.5g/L, pH equals 5.0, initial phosphorus concentration is 10mg/L at temperature of 25?;that the fluoride ions exhibited significant competing effect. Isotherm and kinetic models had been employed to fit the experimental data of phosphorus adsorption onto MgOPC, and the results showed that the Langmuir model described it well, the adsorption kinetics followed the pseudo-second-order and intra-particle model well. Through optimization of the experimental condition by response surface method, optimum process parameters are obtained, including solid- liquid ratio 1.0g/L, solution pH 5.0, initial phosphorus concentration 15mg/L, temperature 27.5? with a corresponding maximum adsorption capacity of 14.53mg/g.In the dynamic adsorption experiments,effects of bed quality,hydraulic loading rate, initial solution p H, temperature and initial phosphorus concentration on breakthrough curve have been studied and optimum column adsorption process parameters have been observed. Several mathematical models were employed to describe the experimental data, thereby these data established the foundation for the practical application of the adsorbent.