Copper Adsorption Using Hydroxyapatite Derived from Bovine Bone

Abstract

Mining and smelting effluent have resulted in heavy metal-contaminated groundwater. Copper-polluted groundwater poses a severe threat to human health and the ecological environment. Permeable reactive barrier (PRB) has been rapidly developed as the in situ remediation technology to control toxic copper migration. Low cost, seepage stability, and great longevity are considered within PRB reactive media. In this paper, hydroxyapatite derived from bovine bone was proven to be a suitable adsorbent owing to cost-effectiveness, great adsorption capacity, and longevity. Batch experiments were carried out to determine the copper adsorption behavior as a function of copper concentration and contact time. Adsorption isotherm was represented by the Langmuir isotherm model, and the adsorption capacity of 25.7 mg/g was superior to most of the adsorbents. A kinetic study was accurately fitted by the pseudo-second-order kinetic model interpreted as a chemical reaction. In addition, the column study confirmed hydroxyapatite has excellent hydraulic performance with no clogging phenomenon happened. At C/C0 = 0.5, the number of pore volume (PV) reached 450. The batch and column experiments also revealed that the overall adsorption process followed up the monolayer chemisorption. Furthermore, systematic analyses demonstrated that surface adsorption was responsible for the copper removal by hydroxyapatite based on experimental analysis and density functional theory (DFT) calculations. This work provides an alternative strategy as filling material for in situ remediation of copper-contaminated groundwater and enriches relevant theoretical references.