Facile Synthesis And Characterization Of Beta-Cd(Oh)(2) Nanostructures For Adsorptive Removal Of Cr(Vi) Ions From Wastewater: A Statistical Approach For Multivariate Sorption Optimization

In the present study, nanostructured beta-Cd(OH)(2) adsorbent was synthesized, characterized by Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy analysis, and applied for Cr(VI) ions capturing (adsorption) from environmental aqueous samples. The central composite design of 18 adsorption experiments was employed for multivariate sorption optimization. Maximum adsorption (%) of Cr(VI) ions was calculated and found to be 98.5% with relative standard deviation (RSD) = 3.5 at optimum concentration 15 mg L-1, pH 4.0, adsorbent dosage 50 mg, shaking time 20 min and shaking speed 120 rpm at 25 degrees C. Langmuir, Freundlich and Dubinin-Radushkevich isotherms fitted well to adsorption data with correlation coefficient (R-2) of 0.993, 0.982 and 0.994, respectively. Mono-layered (Q(m)) and multi-layered (K-f) capacities of beta-Cd(OH)(2) adsorbent for Cr( VI) ions retention were calculated and found to be 202.02 +/- 2.0 and 4.95 +/- 2.5 mg g(-1), respectively. Sorption energy was calculated and found to be 8.45 +/- 2.0 kJ mol(-1), indicated chemisorption or ion exchange mechanism for Cr(VI) ions adsorption onto beta-Cd(OH)(2) adsorbent.