• Varandani Sonia
• Dr. Prabhu Pradnya

The present study was initiated after the water catastrophe in Flint Michigan, USA (2014), when lead, a toxic metal seeped into drinking water and caused a massive health crisis and a state of emergency. The adsorption and treatment of lead in aqueous system was investigated using fly ash-based zeolite A sodalite (FAZAS). Fly ash, the starting material of FAZAS is inexpensive, abundant and currently underutilized. The fusion treatment of acidified fly ash with sodium hydroxide at 600oC followed by hydrothermal treatment in presence of sodium aluminate results in formation of FAZAS. The FAZAS was characterized by XRD, SEM, FTIR spectroscopy and point of zero charge measurement. Modification of raw fly ash into FAZAS altered the ratio of Si: Al, increase the surface area and increase its utility as adsorbent. The adsorption capacity and estimation of efficiency of synthesized FAZAS for the removal of Pb was carried out in batch equilibrium wherein the influence of contact time, pH, and initial concentration of lead and FAZAS dosage on the adsorption process was investigated. It was found that the adsorption capacity of FAZAS increases with increase in concentration of Pb loaded on it. Removal efficiency was 99.88% at low concentration (20ppm) of lead solution and low dose (0.4g/dm3) of the adsorbent. The moderate acidic condition (pH 3.0 to 5.00) had significant impact on adsorption capacity. The equilibrium data analyzed by two classical isotherm models, Langmuir and Freundlich, showed that the data agreed with both these isotherms. The maximum monolayer capacity of sodalite zeolite was found to about 100 mg per gram. The pseudo second order kinetic models helped to determine adsorption rate constants. Thermodynamic studies indicate that the adsorption process was spontaneous and adsorption was exothermic in nature. In the present studies, high temperature combustion at 823.15K for 3 hours has been used for regeneration of used FAZAS. The work concludes that sodalite could be effectively employed as an effective low-cost adsorbent for the removal of lead from aqueous solutions and the spent FAZAS can be recycled and reused for 5 cycles with decreasing efficiencies

Fly ash, Zeolite, Adsorption Efficiency, Adsorption isotherms, Regeneration

"Evaluation of fly-ash based zeolite as an adsorbent for removal of lead in aqueous systems", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 4, page no.628-642, April-2019, Available :http://www.jetir.org/papers/JETIR1904P97.pdf

"Evaluation of fly-ash based zeolite as an adsorbent for removal of lead in aqueous systems", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 4, page no. pp628-642, April-2019, Available at : http://www.jetir.org/papers/JETIR1904P97.pdf