Removal of Co(II) from aqueous solution by using hydroxyapatite |
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Authors: | Yan Huang Liang Chen Hualin Wang |
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Institution: | (1) School of Chemical Engineering, Hefei University of Technology, Hefei, 230009, Anhui, People’s Republic of China; |
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Abstract: | Herein, hydroxyapatite (HAP) was prepared by aqueous precipitation technique and was characterized by using FT-IR and XRD
to determine its chemical functional groups and micro-structure. The removal of cobalt from aqueous solution to HAP was studied
by batch technique as a function of various environmental parameters such as contact time, pH, ionic strength, foreign ions,
fulvic acid (FA), and temperature under ambient conditions. The results indicated that the sorption of Co(II) on HAP was strongly
dependent on pH and ionic strength. The presence of FA enhanced the sorption of Co(II) on HAP at low pH, whereas reduced Co(II)
sorption on HAP at high pH. The Langmuir, Freundlich and D-R models were used to simulate the sorption isotherms at three
different temperatures of 303.15, 323.15 and 343.15 K. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature dependent sorption isotherms indicated that the sorption process of Co(II) on HAP was spontaneous
and endothermic. The sorption of Co(II) was dominated by outer-sphere surface complexation and ion exchange at low pH, whereas
inner-sphere surface complexation or surface precipitation was the main sorption mechanism at high pH values. The results
suggest that the HAP is a suitable material in the preconcentration and solidification of Co(II) from large volumes of aqueous
solutions. |
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