Comparison of 1,2,3-Trichloropropane reduction and oxidation by nanoscale zero-valent iron, zinc and activated persulfate

Trichloropropane (TCP) is a chlorinated solvent which derives from chemical manufacturing as a precursor, and it is also an important constituent of solvent formulations in cleaning/degreasing operations. The control and remediation of TCP in polluted sites is a challenge for many conventional remediation techniques due to its refractory behaviour. This challenge in mind, some nano-materials and oxidants were tested to evaluate their effectiveness as in TCP degradation in a laboratory setting. Experimental results indicate that the use of nanoscale zero-valent iron prepared by green tea (GT) as a reductant has negligible degradation effect on TCP under normal temperature and pressure conditions. However, zinc powders of similar size but higher surface reactivity, demonstrated stronger dechlorination capacity in the breakdown of TCP, as almost all of TCP was degraded by carboxymethocel (CMC) stabilized nanoscale zinc within 24 h. Activated persulfate by citric acid (CA) and chelated Fe (Ⅱ) was also used for TCP treatment with a TCP removal efficiency rate of nearly 50% within a 24 h reaction period, and a molar ratio of S₂O₈^2-, Fe²⁺ and CA is 20:5:1. Both the reduction and oxidation reactions are in accordance with the pseudo-first order kinetic equation. These results are promising for future use of TCP for the remediation of polluted sites.