Peat water purification using nanohydroxyapatite synthesized from carbon negative precipitated calcium carbonate precursor

Abstract

Peatlands covers a vast area globally and used as drinking water source in some parts of Indonesia. Peat water, commonly found in swampy areas, stands out for its striking color intensity, acidic pH levels, and its high affinity for metal binding. Developing various peat water treatment techniques can help provide clean water for local communities. This study reported the preparation of hydroxyapatite (HAp) via hydrothermal method using Carbon Negative Precipitated Calcium Carbonate (PCC) as precursor, obtained from PT. Pertamina, a leading energy company of Indonesia, for treating peat water. HAps were synthesized from precursors that were calcined at 900 °C (HAp 900) and 1000 °C (HAp 1000). Its potential as an adsorbent for peat water purification was evaluated. X-ray diffraction (XRD) revealed good crystallinity in HAp 900 and HAp 1000, with values of 82.33 % and 86.90 %, respectively. These samples also displayed nano-sized crystals, measuring 14.2 ± 0.3 nm and 23.80 ± 0.2 nm. The Ca/P molar ratios were 1.6 for HAp 900 and 1.57 for HAp 1000, which was close to the the theoretical hydroxyapatite ratio of 1.67. FTIR analysis detected the presence of carbonate groups at 1450.42 cm−1 for HAp 900 and 1426 cm−1 for HAp 1000, indicating the formation of carbonated hydroxyapatite. Scanning electron microscopy (SEM) revealed agglomerations and irregularly shaped particles in both HAp samples. Optimal conditions for peat water purification experiment, determined through UV-Vis spectrophotometry, were pH 2, 1 h contact time, and 1 g adsorbent mass for both HAp 900 and HAp 1000.