Removal of Cadmium from Aqueous Solution using Modifed Saffron Corm Tunics as Biocorbent

Recently, biosorption using agricultural waste materials has emerged as the most promisingand viable method, with advantages of high adsorption capacity and no detrimental effects onthe environment [۱, ۲]. Pretreatment with dilute sodium hydroxide solution has been the mostpopular method of improving surface properties and removing soluble organic components ofplant wastes applied for biosorption [۳]. Saffron (Crocus sativus L.) corm tunics is anagricultural waste, which has been studied for its potential application as a biosorbent.Surface modification was carried out in NaOH solution at ۷۰˚C for ۲ h. The results showedthat the adsorption process was highly dependent on the adsorbent dosage and Cd۲+ initialconcentration. A sample pH ۶.۰-۷.۰ was Favourable and, Kinetic data were fitted well to thepseudo- second-order model with R۲=۰.۹۹۷ and qmax=۲۵.۶۴ mg g-۱ at the initial concentration of ۵۰ mg L-۱. The Langmuir isotherm model was best applicable for obtaining theequilibrium parameters with R۲=۰.۹۹۹. KL=۰.۰۷۲ L mg-۱, and qmax= ۲۰.۱۱ mg g-۱. Thenegative values of ΔGº imply that the adsorqtion of Cd۲+ was a spontaneous and favourableprocess at temperatures below ۴۰ºC. The ΔHº is also negative, revealing the exothermicnature of the process. These results demonstrate that saffron corm tunics are effective,environmentally friendly, and low-cost biomaterial for Cd۲+ removal from aqueous solutions.