Utilization of Zero Valent Iron (ZVI) Particles Produced from Steel Industry Waste for In-Situ Remediation of Ground Water Contaminated with Organo- Chlorine Pesticide Heptachlor

Treatment of ground water contaminated with halogenated pesticides is a challenging task. This paper focuses on preparation, characterization and treatment of heptachlor by iron particles synthesized from steel industry waste (S-ZVI). The BOF sludge, which is dumped in landfills, is an iron rich source and was used as the source material for S-ZVI synthesis. The vital step was reducing agent sodium borohydride optimization and a high dose of 3.5g/10mL of dose was required for production of S-ZVI. The average particle size for S-ZVI and after modifying using surfactant PAA (5%) was 1660 nm and 300 nm, respectively. Crystalline structure of S-ZVI and a diverse chemical composition was found with high contents of Na, Ca and Mg. Reduction of heptachlor was studied in batch reactors using S-ZVI, PAA modified S-ZVI, Tween 20 modified S-ZVI and pure ZVI. After 48h, the reduction efficiency of heptachlor, by various forms of ZVI, was found to be 87%, 89%, 75 % and 93% respectively. The observed dechlorination rate constant of Heptachlor by PAA modified S-ZVI was found to be the highest (1.959/hr) followed by Tween 20 modified S-ZVI (1.106 /hr), unmodified S-ZVI (0.526 /hr) and pure ZVI (0.09 /hr). The Surface Area Normalised Rate constant (kSA) were found to be 0.2884 L/hr/m2, 0.1074 L/hr/m2, 0.06606 L/hr/m2 , and 0.000486 L/hr/m2 for S-ZVI, PAA modified S-ZVI, Tween 20 modified S-ZVI, and pure ZVI respectively.