A Study On The Competitive Removal Of Pb(II) In The Presence Of Ni(II) Using Thiolated Rice Husk Through Equilibrium, Kinetic And Thermodynamic Modelling

Abstract

In the quest for finding effective adsorbents for metals, the present study is focused on the removal of Pb(II) ions from aqueous solution using thiolated rice husk by batch and column studies. The presence of metals as a single component in waste waters is highly unlikely, the effect of Ni(II) on the removal of Pb(II) from mixtures of Pb(II)+Ni(II) ions has been investigated. Thioglycolic acid has been used for thiolation of rice husk. The adsorbent has been characterized using proximate and FTIR analyses. Maximum adsorption obtained by batch studies is 93% at pH 5, metal ion concentration 300mg/L in 150mins for 212 micron size at 298K. Isotherm analyses show that both Langmuir and Freundlich isotherm models are best obeyed. The process is endothermic and spontaneous in nature and follows pseudo first order kinetics and intraparticle diffusion also occurs but is not the rate determining step. Application of Langmuir competitive model for the binary sorption system shows that adsorption of Pb(II) has been supressed by presence of Ni(II) ions. Breakthrough curve analyses of data from sequential bed as well as vertical bed columns at varying inlet concentrations and flow rates suggest that the adsorbent is effective and can find industrial applicability.