Biosorption of chromium ion by biomass of silybum marianum

Heavy metals have been a major preoccupation for many years because of their toxicity towards aquatic life, human beings and the environment. [1]. A number of technologies such as adsorption, precipitation, solvent extraction, ion exchange have been developed for the removal of metal ions [2]. Adsorption is now recognized as an effective and economic method for heavy metal wastewater treatment. The adsorption process offers flexibility in design and operation and in many cases will produce high-quality treated effluent [3]. Biosorption of heavy metals from solutions is a new process that has been confirmed a promising process in the removal of heavy metal. The major advantages of biosorption are its high effectiveness in reducing the heavy metals and the use of inexpensive biosorbents [3]. In this project, Silybum marianum biomass (mass index) has been used for the removal of chromium as heavy metal. The effect of pH, amount of the adsorbent, ion concentration and the time of exposure are the parameters that have been evaluated.In this project the most appropriate pH reported for chromium was 4. The best time of exposure that has been achieved in this biomass is 60 minutes and it has been observed that after increasing the amount of absorbent to its optimum amount, 2 grams, the amount of absorption remained unchanged. As ion concentration, the percentange of ion removal has reduced while the amount of ion in the solution increased. Furthermore, Langmuir adsorption model was determined as the best adsorpotion isthorem for the element. Due to appropriate removal yield, low cost and non-production of harmful materials to the environment, this substance can be used for removing chromium from industrial waste