Influence of hydrodynamic size and zeta potential of a novel polyelectrolyte poly(acrylic acid) grafted guar gum for adsorption of Pb(II) from acidic waste water

• Poly(acrylic acid) grafted guar gum acts as noble polyanion.
• It is used for adsorption of Pb(II) from acidic waste water.
• Efficiency reaches 95.32% with 350 ppm feed Pb(II) concentration.
• Adsorption occurs through strong electrostatic interaction.
• The process follows pseudo-second order kinetics.

This article describes the influence of zeta potential and hydrodynamic size of a polyanion, poly (acrylic acid) grafted guar gum (GG-g-PAA) for adsorption of Pb(II). The copolymers were synthesized through surfactant mediated free radical polymerization technique. Aqueous dispersion of the copolymers were directly added to the contaminated water and the parameters such as copolymer grade, pH, adsorbent–adsorbate concentrations, adsorption time and temperature were varied to maximize the adsorption efficiency. The copolymer synthesized with 1:10, GG:AA mole composition and 0.5 wt% initiator content produced maximum adsorption (89.62%) at a pH of 4.5, which was further raised to 95.32% on manipulation. Regression analysis showed the polyanion chemically interacted with Pb(II) and formed a monolayer (Langmuir adsorption) while Chi-square (χ2) test indicated possibility of multilayer formation (both Langmuir and Freundlich isotherm models as well). The process followed pseudo second order kinetics alike all adsorption processes.

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