Removal of heavy metals cadmium (Cd) and copper (Cu) from waste water solution using Bauhinia variegata l. (Kachnar) leaves biomass
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Date
2020-12
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Industrialization and urbanization has caused various threats to environment and heavy metal pollution is one of them. In recent times Cd and Cu pollution has drawn great attention towards itself due to their availability and toxicity in water. The aim of present study is to determine bioadsorption capacity of leaves of Bauhinia variegata collected from plains of Uttarakhand. Today many industries face the problem of removal of heavy metals. Plant leaves waste can be used abundantly as adsorbent for the removal of heavy metals from aqueous solution. Leaves contain chlorophyll, anthocyanin, tannin and other compounds which are responsible for the metal biosorption. The leaves of Bauhinia variegata contains alkaloids, flavonoids, sugars, steroids and saponins which act as binding sites for the metal adsorption. The bioadsorbent prepared from the leaves were used for removal of Cd(II) and Cu(II) metal ions from waste water. AAS results showed that the best adsorption for Cd(II) took place under acidic condition at temperature 40+2oC with contact time of 120 min while the best adsorption for Cu was recorded at acidic pH under hot temperature with contact time of 90 min. The maximum removal of Cd (II) and Cu (II) at 25±2ºC and 40±2ºC temperature by Bauhinia variegata leaves was 82% and 86.6%, 38.6% and 76.3% respectively. Cd(II) ion have more affinity towards leaves of Bauhinia variegata than Cu(II) ions. Langmuir, Freundlich and Temkin adsorption isotherm models were used to explain adsorption phenomenon of Cd (II) and Cu (II). The powder was regenerated and found to exhibit binding capacity upto four cycles as indicated by AAS. Adsorption kinetics data were modeled using the first order, pseudofirst order, second order, pseudo-second order and Elovich equations models. The results indicate that the pseudo second-order model best describes adsorption kinetic data. The FT-IR analysis revealed that hydroxyl, amines, nitrile, ester and nitro are the main functional groups involved in biosorption of metals. Thus, it can be concluded that dried powder of Bauhinia variegata leaves which is waste can be used as an effective bioadsorbent to remove metals Cd(II) and Cu(II) and therefore can be used in the treatment of waste water for removal of heavy metals.