Enhanced heavy metals removal and recovery by mesoporous adsorbent prepared from waste rubber tire

A novel carbon (RTAC) developed by physical activation from waste tire rubber, was used as adsorbent for assessing its removal capacity of lead and nickel ions from aqueous solutions. A well developed mesoporous structure in RTAC was conducive for its enhanced batch adsorption capacity of the studied metal ions removal in comparison to a microporous commercial carbon (CAC). Uptake trend of RTAC for Pb2+ > Ni2+ revealed the adsorbate properties of electronegativity and ionic radii to play a contributory role. Effect of various operating parameters along with equilibrium, kinetic and thermodynamic studies reveal the efficacy of the RTAC for lead and nickel removal. The adsorption equilibrium data obeyed the Langmuir model and the kinetic data were well described by the pseudo-second-order model. A physical electrostatic adsorbate–adsorbent interaction is revealed from pHPZC studies and from D–R model constants. The adsorption process is believed to proceed by an initial surface adsorption followed by intraparticle diffusion. Thermodynamic studies revealed the feasibility and endothermic nature of the system. Such promising results were confirmed by column experiments. Adequate desorption as well as reusability without significant loss of efficiency established the practicality of the developed system and demonstrated an important criterion of advanced adsorbent in RTAC for waste water treatment. Approximately 96% and 87% lead and nickel removal was achieved by RTAC from a simulated electroplating industry wastewater. The experimental results reveal the technical feasibility of RTAC, its easy synthesis, economic, eco-friendly and a promising advanced adsorbent in environmental pollution cleanup.

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► Novel RTAC developed by activation exhibits better and favorable mesopore volume.
► RTAC exhibited better adsorption capacity for lead and nickel removal from waters.
► The mechanism involved physical electrostatic adsorbate–adsorbent interaction.
► Desorption and reuse without loss of efficiency showed its practical utility.