Development of Adsorption Media for Removal of Lead and Nitrate from Water

Abstract

The present work was aimed to develop some potential adsorption media for removal of lead (II) and nitrate from water. Polyacrylamide thorium (IV) phosphate and polycinnamamide thorium (IV) phosphate were synthesized for the removal of lead (II) and various samples of LDHs were synthesized for the removal of nitrate from water. The adsorption media were characterized by chemical analysis, specific surface area analysis (BET), XRD, FITR, TGA, DSC, SEM etc. Batch experiments, for the removal of lead (II) and nitrate using initial adsorbate concentration of 10 mg/L, 50 mg/L and 100 mg/L, were carried out by changing the variables like adsorbent dose, pH, temperature, initial adsorbate concentration and time. Desorption and regeneration studies were also carried out to know the reusability. The materials synthesized were excellent adsorption media. The removal of lead (with initial lead concentration of 100 mg/L) was 81.2% under normal condition of pH, at room temperature and with optimum polycinnamamide thorium (IV) phosphate dose, which was increased to 99.9% by increasing the pH of water. Similarly the removal efficiency of nitrate by Mg-Al-Cl LDH was 87.6% (with initial nitrate concentration of 10 mg/L) which can bring the nitrate level much below the permissible limit. Kinetic study revealed that removal of lead and nitrate followed first order kinetics. Intraparticle diffusion rate constant were calculated which was found to increase with increase in initial adsorbate concentration, indicate the probability of concentration diffusion. Thermodynamic parameters were calculated which indicates feasibility and spontaneity of the ongoing process. Column study and breakthrough analysis were also carried out to know the breakthrough time of different adsorbents. The breakthrough time for polyacrylamide thorium (IV) phosphate and polycinnamamide thorium (IV) phosphate were found to be 8 hours and 7 hours respectively, and for LDHs, it was found to be 10 hours.