REMOVAL OF NICKEL (II) FROM AQUEOUS SOLUTION BY ADSORPTION ONTO SPHERICAL CARBONACEOUS SORBENT DERIVED FROM LITSEA GLUTINOSA SEEDS

In this study, a spherical carbonaceous adsorbent derived from Litsea glutinosa seeds was used for removing nickel ions from aqueous solution. In order to determine the equilibrium adsorption of nickel(II) ions onto the obtained adsorbent, the studied adsorption process was carried out for various time intervals from 15 to 600 min, with an adsorbent dosage of 8 g/l and an initial metal concentration of 20 mg/l, at temperature of 25 degrees C and pH 4. The concentration of nickel(II) ions was determined photometrically using dimethylglyoxime at a wavelength of 470 nm. The results obtained from evaluating the adsorption capacity of the spherical carbonaceous sorbent indicated that the adsorption rate reached maximum within 120 min of contact time. Based on the investigation of the kinetic and isothermal characteristics, it was found that the adsorption of nickel(II) ions was adequately described by the Langmuir isotherm and this process was characterized by pseudo-second order kinetics. This finding demonstrated the chemical interactions between active oxygenated groups on the sorbent surface and adsorbate molecules. The experiments also showed that the maximum adsorption capacity of the spherical carbonaceous sorbent for nickel (II) ions was 7.2 mg/g. Comparison of this resulting value of the studied adsorbent with that of the others based on plant raw materials and waste allows us to conclude that the carbonaceous sorbent derived from Litsea glutinosa seeds can be recommended for water purification from nickel(II) ions. In addition, the study of thermodynamics in the temperature range from 298 to 318 K revealed that nickel(II) adsorption by the spherical carbonaceous adsorbent is a spontaneous endothermic process.