Cadmium Removal by using Pumice Modified with Iron Nanoparticles from Aqueous Solutions

Abstract

In this study, the removal of cadmium by using pumice coated with iron nanoparticles (INPs) from synthetic wastewater was investigated. The effects of parameters influencing adsorption: contact time (10-20 min), pH (3-9), initial cadmium concentration (25-125 mg l ) were studied. The pumice stone used in this research was, first, crashed and then sieved with 20 mesh standard sieves (0.85 mm); finally, it was coated with INPs. An atomic absorption spectrophotometer was used to measure cadmium contents and isotherm models and adsorption kinetics were studied. The results showed the adsorption process of cadmium reached equilibrium at contact time of 80 min. With increasing pH solution, the efficiency enhanced which peaked at pH 7-8. Cadmium concentration increase resulted in a decrease in efficiency, whereas adsorbent dose increase improved it. Equilibrium data of adsorption followed isotherms models: Langmuir and Freundlich. The highest removal efficiency and adsorption capacity were, respectively, 83% and 17.27 mg g -1 . Furthermore, absorption kinetics is better described by the pseudo second-order model. According to the results obtained, pumice coated with INPs is an effective adsorbent and can be introduced as a suitable option in practical applications.

Adsorptive Removal of Methylene Blue in Aqueous Solutions Through Raw and Modified Cantaloupe Peel Wastes: Kinetic and Isotherm Study

“…pH PZC was determined by plotting the initial pH values against the final pH (16). The amounts of MB removal (%) by means of raw and modified cantaloupe peel and the adsorption capacity of the adsorbent wase estimated, respectively, using the following equations (17,18):…”

“…The second-order rate constants were applied to estimate the initial sorption rate (equation 17): h = k 2 q e 2 (17) If the second-order kinetics is applicable, then the plot of t/qt versus t can present a linear relationship. Values of k 2 and equilibrium adsorption capacity qe were estimated from the intercept and slope of the plots of t/qt versus t. The linear plots of t/qt versus t indicate good agreement between experimental and estimated qe values at different initial MB and adsorbent contents (Tables 3 and 4).…”