Novel adsorbent of removal phosphate from TFT LCD wastewater

In this study, a waste iron oxide material (BT-1), which is a by-product of the fluidized-bed Fenton reaction (FBR-Fenton), was thermally treated between 200 and 900°C and was used as an efficient adsorbent for the removal of phosphate in an aqueous system. The wastewater was discharged from a real TFT-LCD plant in Taiwan and diluted to 10.51mM phosphate before experiments. The XRD and SEM analyses indicated that BT-1 was mainly composed of the poorly crystallized goethite (α-FeOOH). After adsorption, the phosphate surface was occupied on BT-1 using EDS and FTIR analysis. The adsorption isotherms are consistent with Temkin, Langmuir, and Freundlich models and indicated the BT-1 was a suitable adsorbent for the removal of phosphate. The maximum adsorption capacity of BT-1 was 2.32mmol-P/g (72mg-P/g). The coexisting anions affected the phosphate adsorption capacity of BT-1 at pH 2.11±0.2 in this order: SO₄^2->NO₃^->Cl^->F^-. The coexisting anions F^- and Cl^- did not influent the adsorption capacity significantly, but SO₄^2- and NO₃^- affected the phosphate adsorption capacity of BT-1. Finally, there are almost 48% phosphate desorption form the adsorbed BT-1 in the NaOH alkaline solution.