Adsorptive removal of Pb²⁺ form aqueous solution by macrocyclic calix[4]naphthalene: kinetic, thermodynamic, and isotherm analysis

Ahmad, Rais; Kumar, Rajeev; Laskar, Mohammad Asaduddin

Adsorptive removal of Pb²⁺ form aqueous solution by macrocyclic calix[4]naphthalene: kinetic, thermodynamic, and isotherm analysis

2013

Ahmad, Rais | Kumar, Rajeev | Laskar, Mohammad Asaduddin

BACKGROUND: The adsorption characteristics of Pb²⁺ ions from aqueous solutions onto calix[4]naphthalene have been investigated. METHOD: Calix[4]naphthalene was prepared by the condensation of 1-naphthol and formaldehyde (1:2) in presence of hydrochloric acid at 80°C. The effect of various operation parameters, such as solution pH, initial metal ion concentration, contact time, and temperature, on the adsorption capacity of calix[4]naphthalene for Pb²⁺ have been investigated. RESULT: Experimental results showed that the adsorption of Pb²⁺ ions increased with the increase in solution pH and temperature. Langmuir and Freundlich isotherms models were used to describe the adsorption behavior of Pb²⁺ by calix[4]naphthalene. Equilibrium data fitted well with the Langmuir isotherm model and the maximum adsorption capacity of calix[4]naphthalene for Pb²⁺ at 30°C was found to be 29.15 mg g⁻¹. Kinetic studies indicated that the adsorption followed pseudo-second order model and the thermodynamic studies revealed that the adsorption process was spontaneous and endothermic in nature. The obtained results demonstrated that calix[4]naphthalene can be used as an effective adsorbent for Pb²⁺ ions removal from water.

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