Cd (II) Removal from Aqueous Solutions by Adsorption on Henna and Henna with Chitosan Microparticles Using Response Surface Methodology

In this research, the capabilities of Henna and Henna with chitosan microparticles adsorbents were studied in order to remove the ion Cd (II). Response Surface Method (RSM) and Central Composite Design (CCD) were used to minimize the number of experiments (۲۱ runs) for Henna and (۲۶ runs) for the Henna with chitosan microparticles. The parameters were pH (۲-۹), initial solution concentration [۱۰-۱۰۰ mg/L (ppm)], adsorbent dosage (۰.۱-۱ g) and process time (۲۰-۱۵۰ min). It was concluded that Cd (II) removal increased from ۱۳.۷۸% to ۷۰.۰۶% with increasing the pH from ۲ to ۹ (maximum adsorption was at pH ۹) for Henna and ۸۲.۸۱% to ۹۷.۶۰% for the Henna with chitosan microparticles. The Cd (II) removal was decreased from ۷۸.۷۳% to ۴۰.۴۴% for Henna and ۹۶.۴۷% to ۹۰.۳۷% for the Henna with chitosan microparticles with increasing the initial solution concentration (from ۱۰ to ۱۰۰ ppm). Furthermore, the Cd (II) removal was increased from ۳۷.۵% to ۶۴.۵۹% for Henna and from ۸۶.۷۴% to ۹۷.۷۶ % for the Henna with chitosan microparticles with the adsorbent dosage increment (from ۰.۱ to ۱ g). The error for the optimum point between the statistical data and experimental ones were at ۱.۵۳% for Henna and at ۱.۶۱% for the Henna with chitosan microparticles. The Langmuir and Freundlich isotherm models were applied as the adsorption mechanism. Two correlations (with R۲=۰.۹۷۵۰ for Henna and R۲=۰.۸۵۳۸ for the Henna with chitosan microparticles) between the Langmuir model and experimental data were investigated‍ although Freundlich model showed the better agreements between the theoretical data and experimental ones (R۲=۰.۹۹۴۹ for Henna and R۲=۰.۹۹۵۵ for the Henna with chitosan microparticles). It also showed that the Henna with chitosan microparticles is a fantastic adsorbent for Cd (II) removal.

کلیدواژه ها:

Adsorption ، Biomass ، Chitosan ، heavy metals ، Wastewater