The efficiency of pugu kaolin clay in the removal of selected heavy metals from water

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University of Dar es Salaam,
The present work examined the suitability of Pugu Kaolin Clay (PKC) in removing Cr3+ and Pb2+ions from water. The characterization of PK clay was performed by X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and nitrogen physisorption techniques. The XRD results revealed the presence of kaolinite, illite and quartz in the studied PK samples. XRF results showed that the chemical composition of Pugu kaolin clay was dominated by SiO2 and Al2O3whereas other oxides such as K2O, Na2O, CaO,MgO, Fe2O3 and TiO2were observed to be present in trace amounts. ATR FTIR studies showed bands at 3618-3684 cm–1for OH stretching vibration, 640-1113 cm–1for Si-O stretching vibration and 457-526 cm–1 for Si-O-Si bending vibration mode. The nitrogen physisorption results revealed that PK clay was mesoporous material with pore diameter, pore volume and surface area of 4.616 nm, 0.509cm3/g and 123.423 m2/g, respectively. The influence of some experimental parameters such as particle size, adsorbent dose, contact time, initial metal ion concentration and pH were investigated. The result showed that the percentage adsorption of both heavy metal ions increase with increasing particle size, adsorbent dose, contact time and pH. An equilibrium time of 30 min was required for adsorption of Cr3+ and Pb2+ ions onto PK clay. The optimum conditions for batch adsorption were particle size 125 µm, adsorbent dose 1 g, contact time 30 min and initial concentration 5 mg/L for both Cr3+ and Pb2+ ions while solution pH were 4 and 6 for Cr3+ and Pb2+ ions, respectively. The Langmuir correlation coefficients (R2) were 0.999 and 0.992 for Cr3+ and Pb2+ions, respectively, while the Freundlich correlation coefficients (R2) were 0.984 and 0.932for Cr3+ and Pb2+ions, respectively. The results for equilibrium data tested by Langmuir and Freundlich isotherm equations showed that adsorption data were best described by both Langmuir and Freundlich isotherm with R2 close to unity. However, Langmuir isotherm had a better fitting model than Freundlich isotherm due to higher value of correlation coefficient, thus indicating the applicability of monolayer coverage of both heavy metals on the surface of PK clay.
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF TD753.5.A44)
Heavy metals removal, Sewage, Purification, Adsorption, Kaolin clay
Ali, H J (2017) , The efficiency of pugu kaolin clay in the removal of selected heavy metals from water,Master dissertation, University of Dar es Salaam. Dar es Salaam