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Arsenate removal from aqueous solution by cellulose-carbonated hydroxyapatite nanocomposites

Author:
Islam, Mahamudur, Mishra, Prakash Chandra, Patel, Rajkishore
Source:
Journal of hazardous materials 2011 v.189 no.3 pp. 755-763
ISSN:
0304-3894
Subject:
adsorption, anions, aqueous solutions, arsenic, calcium chloride, cellulose, hydroxyapatite, microwave treatment, models, nanocomposites, nanomaterials, nitrates, pH, silicates, sorption isotherms, temperature, thermodynamics
Abstract:
Microwave-assisted synthesis of the cellulose-carbonated hydroxyapatite nanocomposites (CCHA) with CHA nanostructures dispersed in the cellulose matrix was carried out by using cellulose solution, CaCl₂, and NaH₂PO₄. The cellulose solution was previously prepared by the dissolution of microcrystalline cellulose in NaOH–urea aqueous solution. Study was carried out to evaluate the feasibility of synthetic CCHA for As(V) removal from aqueous solution. Batch experiments were performed to investigate effects of various experimental parameters such as contact time (5min – 8h), initial As(V) concentration (1–50mg/L), temperature (25, 35 and 45°C), pH (2–10) and the presence of competing anions on As(V) adsorption on the synthetic CCHA. Kinetic data reveal that the uptake rate of As(V) was rapid at the beginning and equilibrium was achieved within 1h. The adsorption process was well described by pseudo-first-order kinetics model. The adsorption data better fitted Langmuir isotherm. The maximum adsorption capacity calculated from Langmuir isotherm model was up to 12.72mg/g. Thermodynamic study indicates an endothermic nature of adsorption and a spontaneous and favorable process. The optimum pH for As(V) removal was broad, ranging from 4 to 8. The As(V) adsorption was impeded by the presence of SiO₃ ²⁻, followed by PO₄ ³⁻ and NO₃ ⁻. The adsorption process appeared to be controlled by the chemical process.
Agid:
1013406