The removal of nickel and lead ions from aqueous solutions using green synthesized silica microparticles

Abstract

Silica microparticles were synthesized from sugarcane bagasse via a green synthetic technique. The prepared silica microparticles were used to remove lead and nickel ions from their separate solutions. Microscopic analysis shows that the synthesized silica particles are spherical with good monodispersed properties. The average particle diameter of the silica microparticles is estimated to be about 432 nm. Batch adsorption experiment was employed to examine the influence of adsorbent dosage, contact time, heavy metal ion concentration and pH on the adsorption efficiency of the synthesized silica microparticles in removing the studied lead (Pb2+) and nickel (Ni2+) ions from their respective solutions. An increase in adsorbent dosage, heavy metal ion concentration, contact time and pH led to an increase in the percentage removal of Pb2+ and Ni2+ metal ions from their individual solutions. The adsorption process of Pb2+ ion onto the synthesized silica microparticles followed the Langmuir adsorption isotherm (R2 = 0.961), while, the nickel ion (Ni2+) followed the Freundlich isotherm (R2 = 0.869). The adsorption process of the studied heavy metals (Pb2+ and Ni2+) in their separate solutions favours pseudo-second-order reaction model (R2, 0.978 and 0.999) over the pseudo-first-order reaction model.