Polyelectrolytic aqueous guar gum for adsorptive separation of soluble Pb(II) from contaminated water

Abstract

The article introduces the concept of homophase adsorption of soluble Pb(II) from contaminated water using aqueous guar gum (GG). The process appears to be extremely handy since it avoids hectic sample preparation and adsorbent recovery stages. The results show that, addition of only 1000 ppm GG removes 56.72% of the contaminated Pb(II) within 150 min at 303 K. The best working pH has been found to be at 4.5. At this point GG molecules show greatest balance between negative zeta potential and high molecular size. Mechanistically, the adsorption follows Langmuir model since on formation of a monolayer, the positive Pb(II) prevent subsequent adsorption through strong electrostatic repulsion. The adsorption kinetics follows pseudo second order model. Both kinetics and thermodynamics of the process complies with the conventional hetero facial adsorption models despite huge procedural differences.

Keywords: Adsorption; Guar gum; Lead; Polyelectrolyte; Zeta potential.