Removal of Ni2+ ion from waste water by Geopolymeric Adsorbent derived from LD Slag

In the present study LD slag geopolymer (LDSGP) was synthesised from calcium oxide rich raw LD slag, a waste of steel making industries for the use as a potential low cost adsorbent for high removal of Ni2+ ions from aqueous solution. The geopolymerisation of LD slag was performed in a plastic mould where the colloid mixture of raw LD slag and alkaine activator (sodium hydroxide and sodium sillicate (1:1 w/w)) were cured for 3 days at room temperature. The LDSGP was characterized by using XRF technique, BET surface area, SEM & TEM images, XRD patterns, FTIR spctra and TGA. Batch experiments for the adsorption study of Ni2+ ions were conducted at different temperatures (298 K, 308 K, 318 K). The equlibrium data was successfully fitted the Langmuir isotherm and the maximum adsorption uptake of Ni2+, onto LDSGP, was found to be 85.29 mg/g and at 318 K. The adsorption rate data was fitted well to pseudo-second-order model indicating the process to be dominated by chemisorption. Thermodynamic analysis proved that the adsorption process was spontaneous in nature.