Arsenate removal from aqueous solution by cellulose-carbonated hydroxyapatite nanocomposites.

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, CaCl(2), and NaH(2)PO(4). 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 (5 min - 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 12.72 mg/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 SiO(3)(2-), followed by PO(4)(3-) and NO(3)(-). The adsorption process appeared to be controlled by the chemical process.

Physicochemical characterization and adsorption behavior of Ca/Al chloride hydrotalcite-like compound towards removal of nitrate.

The objective of the present research was to synthesize, characterize and to investigate adsorption of nitrate from synthetic nitrate solution by Ca-Al-Cl HTlc. In the present study Ca-Al-Cl HTlc was synthesized by co-precipitation method and was characterized using SEM, XRD, FTIR and TGA-DSC. To assess the practical usefulness, a detailed removal study of nitrate was carried out. The removal of nitrate was 84.6% under neutral condition using 0.35 g of adsorbent in 100mL of nitrate solution having initial concentration of 10mg/L. Adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to linearly transformed Langmuir adsorption isotherm with R(2) (correlation coefficient)>0.99. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with Dubinin-Radushkevich isotherm.

Physicochemical characterization of hydroxyapatite and its application towards removal of nitrate from water.

A laboratory study was conducted to investigate the efficiency of hydroxyapatite (HAP) towards removal of nitrate from synthetic nitrate solution. In the present research HAP synthesized from egg-shell was characterized using SEM, XRD, FTIR and TGA-DSC. The removal of nitrate was 96% under neutral conditions, using 0.3 g of adsorbent in 100 mL of nitrate solution having an initial concentration of 100 mg/L. An adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to a linearly transformed Langmuir isotherm with correlation coefficient (R(2))>0.98. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with the Dubinin-Radushkevich isotherm. The process was rapid and equilibrium was established within the first 40 min.

Removal of lead (II) from aqueous environment by a fibrous ion exchanger: polycinnamamide thorium (IV) phosphate.

The objective of the present research was to synthesize, characterize and to investigate the removal efficiency of lead (II) ion from synthetic lead solution by a hybrid fibrous ion exchanger. In the present study polycinnamamide thorium (IV) phosphate was synthesized by co-precipitation method and was characterized using SEM, XRD, FTIR and TGA-DSC. To know the practical applicability, a detailed removal study of lead ion was carried out using the material. The removal of lead was 81.2% under optimum conditions. Adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to linearly transformed Langmuir isotherm with R(2) (correlation coefficient) >0.99. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with Dubinin-Radushkevich isotherm.

Nitrate sorption by thermally activated Mg/Al chloride hydrotalcite-like compound.

A laboratory study was conducted to investigate the ability of Mg-Al-Cl hydrotalcite-like compound for the removal of nitrate from synthetic nitrate solution. In the present study Mg-Al-Cl hydrotalcite was synthesized by co-precipitation method and was characterized using SEM, XRD, FTIR and TGA-DSC. To know the practical applicability, a detailed removal study of nitrate ion was carried out. The removal of nitrate was 87.6% under neutral condition, using 0.3g of adsorbent in 100mL of nitrate solution having initial concentration of 10mg/L. Adsorption kinetic study revealed that the adsorption process followed first-order kinetics. Adsorption data were fitted to linearly transformed Langmuir isotherm with R(2) (correlation coefficient)>0.99. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with Dubinin-Radushkevich isotherm. The percentage removal was found to decrease gradually with increase in pH and the optimum pH was found to be 6. The process was rapid and equilibrium was established within first 40 min.

Polyacrylamide thorium (IV) phosphate as an important lead selective fibrous ion exchanger: synthesis, characterization and removal study.

The objective of the present research was to synthesize, characterize and to investigate the removal efficiency of lead (II) ion from synthetic lead solution by a hybrid fibrous ion exchanger. In the present study polyacrylamide thorium (IV) phosphate was synthesized by co-precipitation method and was characterized using SEM, XRD, FTIR and TGA-DSC. To know the practical applicability, a detailed removal study of lead ion was carried out. The removal of lead was 52.9% under neutral condition, and using 0.4 g of adsorbent in 100 mL of lead solution having initial concentration of 100 mg/L. Adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to linearly transformed Langmuir isotherm with R(2) (correlation coefficient)>0.99. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with Dubinin-Radushkevich isotherm. The percentage removal was found to increase gradually with increase in pH and 99% removal was achieved at pH 10. The process was rapid and equilibrium was established within first 30 min.