Preparation and evaluation of layered double hydroxides (LDHs) for phosphate removal

Abstract: Nitrate-intercalated layered double hydroxides (LDHs) were prepared and assessed for phosphate removal from water. The sorption experiments for phosphate uptake were carried out as a function of LDHs’ dose, contact time, initial pH of solution and initial phosphate concentration. The results show that about 97–99% phosphate removal was achieved at dose 0.3 g/L for the 10 mg-P/L test solution by Ca-based LDHs. The adsorption data fitted well with Langmuir isotherm and the maximum sorption capacity can be up to 70.9 mg-P/g of adsorbent. All selected Ca-based LDHs were observed to have a strong buffering capacity, indicating the suitability of potential application under different pH systems. The results also demonstrated that the real effluent from a wastewater treatment plant with high P content (3.4–10.4 mg/L) can be treated by Ca–Al-60 LDH with more than 90% P removal.