Preliminary evidence for enhanced adsorption of cadmium(II) ions using nano-magnetite aligned in silica gel matrix

The effect of aligning nano-magnetite particles in silica gel matrix to the adsorption was studied. Nanomagnetite particles were first synthesised and then aligned in a silica gel matrix to form nanocomposite. As such, it prevents the agglomeration of nanoparticles while providing porous path for the adsorbate to adhere on the adsorption sites. By aligning the nanoparticles in gel matrix, mutual cancellations of local magnetic fields among nanoparticles can be minimised. It is hypothesised that aligning the nano-magnetite particles in gel matrix can enhance its adsorption performance. Adsorption of Cd2+ ions were carried out using both nonaligned and aligned nanocomposite. Two adsorbent dosage was used, i.e., 0.1 g and 1 g in 50 mL of 100 ppm Cd2+ solution. Enhanced adsorption capacity was observed in aligned nanocomposite under both of these dosages. For the low dosage adsorption, the equilibrium adsorption capacity (Qe) obtained from pseudosecond order model is 978.8 mg/g, which is 68 % higher than the non-Aligned nanocomposite. Whereas for high dosage adsorption, Qe does not show significant difference in both the aligned and non-Aligned nanocomposites. It is evident that aligning nano-magnetite particles in gel matrix enhanced adsorption performance of nanocomposite. However, the advantage of such nanocomposite diminished with high adsorbent dosage due to near-field interactions of adsorbent. Proper adsorption scheme should be carefully designed to utilise the full potential of such nanocomposite.