A comprehensive study on the removal of Cd(II) from aqueous solution on a novel pentetic acid-clinoptilolite nanoparticles adsorbent: Experimental design, kinetic and thermodynamic aspects

摘要

Synergistic effects of ion exchange and complexation in Cd(II) removal was studied by the modification of nanoparticles of clinoptilolite zeolite (NCP) by pentetic acid (diethylenetriaminepentaacetic acid: DTPA) as a family of EDTA. XRD, FT-IR, BET, TG-DTG, and SEM-EDX were used for the characterization of the NCP and NCP-DTPA. The interactions of solution pH, NCP-DTPA dosage, concentration of cadmium solution and contact time were studied by Response Surface Methodology (RSM). The pH- adsorbent dosage and pH-C-cd interactions had the most important roles in the Cd(II) removal. Both Langmuir and Freundlich isotherms can model the removal results. The q(m) and K-L were about 138.9 (mg g(-1)) and 0.0007 (L mg(-1)) for the Langmuir isotherm. The values of 1.8 and 1.06 were obtained for n and K-F as Freundlich constants, respectively. The results can be well modeled by the pseudo-second-order kinetics model (r(2) = 0.9986) for describing the kinetics of the process. The best run included the adsorbent dose: 0.2 g L-1, pH: 5.9, C-cd: 985 mg L-1 and 205 min contacting time.