Synthesis Of TCAS And Its Application In Lead Contaminated Soil Washing

This paper briefly reviews the synthesis and application research process of new type of supramolecular host compounds-thiacalixarenes, and described the current situation of lead contaminated soil and prothetic methods of heavy metal contaminated soil at home and abroad. Aimming at the actuality of serious lead contamination and the shortage of existing washing liquid, this paper uses supramolecular host compounds-thiacalix[4]arenetetra-sulfonate (for short TCAS) as new soil eluent, and studys the restoration effectiveness of lead contaminated soil and influencing factors.This paper uses two-step synthetical method to synthesize TCAS, TCAS and its intermediate products TCA are characterized by the means of IR spectrum, UV spectrum,1H-NMR and ESI-MS. And we uses Tessier five states sequence extraction method to investigate the species distribution of lead in the artificial contaminated solid, and the results show that lead in soil mainly exists in the form of exchangeable speciation(45.2%), carbonate combination speciation(18.6%) and iron manganese oxide combination speciation(18.6%), and biological toxicity is stronger. And this paper systematically research the elutional effect of TCAS to lead in soil with different conditions of pH value, liquid-solid ratio, elutional temperature and elutional time and so on. The results show that the eluting effect of lead would increase gradually with increase of initial pH value about TCAS solution, and would reach maximum when the pH is equal to11, then would reduce with the further increase of the pH value, this phenomenon mainly appertain the complexational mechanism of TCAS with metal and the molecular characteristics of themselves; Too large or too small liquid-solid ratio is not conductive to the elution of lead, and the best liquid-solid ratio is equal to10:1. The removal quantity of lead would reduce with the rise of elutional temperature, but the range marginally decrease. The eluting effect of lead would increase with the increase of TCAS concentration, the best removal efficiency would reach98%. The results of kinetics show that the desorption of lead orderly enter the rapid reaction stage, the slow reaction stage and the equilibrium stage with the extension of elutional time. The dynamic process using TCAS to elute lead corresponds Elovich model. The process desorbing lead from the soil is non-homogeneous diffusion process.