In order to enhance phosphate removal from aqueous solution using iron-oxide-coated sand (IOCS) filter media, a new type of IOCS was prepared by improving coating process based on the previous study. The adsorbability of phosphate on IOCS, and the possibility of regeneration and reuse of phosphate adsorbed IOCS were investigated. Scanning electron microscopy(SEM) and X-ray diffraction spectroscopy(XRD) were used to observe the surface properties and morphology of the coated layer. Effects of pH, contact time and dose of IOCS on phosphate removal were studied in batch experiments. Three isotherm equations (Langmuir, Freundlich and Temkin) were used for data fitting. The results showed that the data obtained from isotherm experiments (at the temperature of 25°C) could be well described using the three isotherm equations, with the correlation coefficients R2 > 0.9200. The phosphate adsorption capacity of IOCS obtained from Langmuir fitting data was 0.2668 mg/g. Compared with the IOCS in other studies of the same kind, the IOCS in this study has higher adsorption capacity for phosphate. The results of adsorption thermodynamics of phosphate by IOCS indicate that the adsorption of phosphate on IOCS is spontaneous (ΔG° > 0) and endothermic (ΔH° > 0). The sequence of anions studied affecting the adsorption of phosphate on IOCS is HCO3- > SO42- > Cl-, but their effect was not obvious. Column experiments indicate that IOCS has a high phosphate removal rate, and saturated IOCS can be regenerated effectively by 0.1, mol/L NaOH solution. This study demonstrates that IOCS can be used as an alternative filter media for water and wastewater treatment without any side effect or treatment process alternation.
|Number of pages
|Tianjin Daxue Xuebao (Ziran Kexue yu Gongcheng Jishu Ban)/Journal of Tianjin University Science and Technology
|Published - 2010 Dec
- Iron-oxide-coated sand
- Phosphate removal