Preparation, Characterisation And Application Of Activated Carbon From Terminalia Avicennioides Pods For The Removal Of Selected Heavy Metals From An Electroplating.

Abstract

In this study, activated carbons were produced from Terminalia avicennioides pods by chemical activation using 50% ortho-phosphoric acid and 1M NaOH labelled as Acid treated T. avicennioides activated carbon ATAC/H3PO4 and Base treated T. avicennioides activated carbon BTAC/NaOH, respectively. Physicochemical properties such as pH, bulk density, moisture content, ash content, volatile matter and fixed carbon were determined. The analysis results show optimum removal efficiency of the selected metals mostly observed at the pH 7, 1hr: 30mins, 0.9 g, and at a temperature of 45oC. The optimum percentage removal on varying the pH (3, 5, 7, 9) were 83%, 80%, 95%, and 35% with ATAC/H3PO4 and 80%, 80%, 93%, 70% with BTAC/NaOH for Fe, Ni, Zn and Cd respectively. On varying the contact time (30 mins, 60 mins, 90 mins, 120 mins), optimum percentage removal were 87.2%, 83.6%, 78%, 57.7% with ATAC/H3PO4 and 85.7%, 79%, 79%, 59.6% with BTAC/NaOH for Fe, Ni, Zn and Cd respectively. For dosage, 91.8%, 91.0%, 79.0%, 50.8% optimum were obtained with ATAC/H3PO4 and 90.7%, 79.2%, 90.9%, 68.8% with BTAC/NaOH for Fe, Ni, Zn, and Cd respectively. The temperature shows an optimum removal of 87%, 80%, 91%, 48% using ATAC/H3PO4 and 71%, 76%, 76%, 42% with BTAC/NaOH for Fe, Ni, Zn, and Cd ions, respectively. Generally, the results revealed that ATAC/H3PO4 activated carbon works better due to its higher surface of 380.076 m2 /g than BTAC/NaOH activated carbon with a value of 339.852 m2 /g. Cracks showed by Higher Resolution Scanning Electron Microscope further confirmed a better porosity of the ATAC/H3PO4 activated carbon. The kinetic plot of the linear form of pseudo-first and second-order for Ni, Cd, Zn and Fe ions adsorption indicated a better correlation between the experimental kinetic data and pseudo second-order model, which was the best-fit model.