首页|Adsorption of dental clinic pollutants using bone char: Adsorbent preparation,assessment and mechanism analysis
Adsorption of dental clinic pollutants using bone char: Adsorbent preparation,assessment and mechanism analysis
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NSTL
The assessment of bone char for the adsorption of toxic dental clinic pollutants is reported.Different conditions for bone char preparation via pyrolysis and its adsorption properties were evaluated using fluoride,mercury and arsenic as the target pollutants.The best pyrolysis conditions to improve the adsorption properties of this adsorbent for the removal of these dental clinical pollutants were identified.The best bone char was employed to quantify the experimental isotherms of the adsorption of mercury,fluoride and arsenic at pH 6 and 20-40 ℃.Results showed that the dehydroxylation of hydro-xyapatite contained in the bone char affected its adsorption properties for the removal of these pollutants and not only its defluoridation properties as has been already reported in the literature.It was concluded that the degree of hydroxy apatite dehydroxylation affected the ligand exchange involved in the adsorption mechanism of bone char for the removal of these adsorbates.Theoretical calculations with statistical physics and artificial neural networks indicated that fluoride and mercury adsorption on bone char was an endothermic multi-molecular process,while the arsenic adsorption was also endothermic but implying mono-adsorbate interactions.Bone char showed the best maximum adsorption capacities for fluoride(_(0.4)-1.58 mmol/g)followed by mercury(0.14-_(0.2)3 mmol/g)and arsenic(0.06-0.14 mmol/g),respectively.Calculated adsorption enthalpies for these pollutants ranged from 25.4 to 39.4 kj/mol.A detailed description of the adsorption mechanism and possible interactions involved in the removal of these dental clinic pollutants with bone char were also provided.This study contributes with theoretical and experimental results to support the development of an in situ solution for facing the water pollution problem caused by the dental clinics,which is an unregulated health care sector in terms of local and international legislations for water quality protection.
NSTL
