Abstract
Apatite ore from Lao Cai (Vietnam) has large reserves and low prices. Its main component is fluorapatite. The purification and modification of apatite ore can produce a material that can be used as an absorbent for heavy metals with high efficiency. The molecular structure, phase component, specific surface area, element component, and morphology of modified apatite ore from Lao Cai province, Vietnam, were characterized by IR, XRD, BET, EDX, and SEM methods. The IR and XRD results show that the modified process transformed apatite ore from fluorapatite to nanohydroxyapatite. The specific surface area of modified apatite ore (100.79 m2/g) is much higher than the original ore (3.97 m2/g). The modified apatite ore was used to adsorb Cd2+ and Cu2+ ions in water. The effect of adsorbent mass, pH, contact time, and initial concentration of Cd2+ and Cu2+ on the adsorption efficiency and capacity was investigated. Besides, the isotherm adsorption model was determined using Freundlich and Langmuir theories.
Highlights
Nowadays, water pollution caused by heavy metal is a serious problem for human health and the environment
Characterization of Original and Modified Apatite Ore. e infrared spectra and the SEM and TEM images of apatite ore and modified apatite ore are presented in Figures 1 and 2, respectively. e spectra show that characteristic bands of PO43− at 1097, 1046, 600, and 564 cm−1 correspond to the asymmetric stretching vibration of the P-O bond and the asymmetric bending vibration of O-P-O, respectively [32]
From SEM images, it can be seen that the particles of apatite ore do not have a uniform particle size. e size of large particles can be up to 15–20 μm. e smallest particles are about 200 nm
Summary
Water pollution caused by heavy metal is a serious problem for human health and the environment. Heavy metal poisoning will lead to many fatal diseases such as pulmonary edema, kidney failure, cancer. E content of heavy metal ions in drinking water is very low, maximum content of Pb: 0.05 mg/L; Hg: 0.006 mg/L; As: 0.01 mg/L; Cd: 0.003 mg/L; Cr: 0.05 mg/L; Mn: 0.1 mg/L; Cu: 2 mg/L following WHO standard [4]. Heavy metal ions can be removed by many methods using different materials such as activated carbon, zeolite, clay, silica, polymer, and apatite [3, 5,6,7]. Apatite includes hydroxyapatite (Ca5(PO4)3(OH), fluorapatite Ca5(PO4)3F, and chlorapatite Ca5(PO4)3Cl. Hydroxyapatite powder can remove some pollution ions and substances in water such as
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