Study On Preparation Of DTCL Chelating Agent And Its Application To The Treatment Of Fly Ash

With economic development and improvement of people’s living standard, the amount of solid waste (SW) also increased dramatically. SW incineration treatment has become the most important process in solid waste management. Fly ash, which derived from incineration of solid waste as debris, has been defined as a kind of hazardous waste (HW18) because it enriches in varieties of heavy metals. The research on fly ash treatment technologies become an important topics of solid waste management. For this reason, it has been studied in this paper that the preparation of DTCL chelating agent and its application to the treatment of fly ash.Based on the physical and chemical properties of fly ash from the SW incineration plant in Fujian, it has been studied in this paper that the DTCL chelating agent preparated using Mannich modified natural and polymer lignin, then react with CS2under alkaline conditions and get DTCL chelator; that the characteristics of DTCL chelating agent has been identified using infrared spectrum and SEM analyze structure, and that the effectives of the DTCL chelating agent application to the treatment of stabilization/solidification of the fly ash has been discussed. The research results in this paper show that:(1) Fly ash particles which main mineral phase is CaCO3、SiO2and so all like dense and porous, most of heavy metals’occurrences in fly ash are in residual state, the fly ash produced by Fujian incineration plant is hazardous waste in that Pb、Cr、Ni and Zn exceed Idedification standard for hazardous wastes-Idendification for extraction toxicity;(2)Use of uniform design to optimize the condition of synthesis of DTCL, show that the best condition is lignin-amine and CS2molar ratio of3.4, temperature of45℃, time of16h; it is proved that DTCL chelating agent has DTC group because it finds that it has infrared characteristic absorption peak of carbon-nitrogen bond and carbon-sulfur bond in 1513-1330cm-1and1093-758cm-1;(3) Fly ash leaching rate of heavy metal fall markedly compared with fly ash when they were stabilization by DTCL chelating agent, leaching ratio of Pb、Cr、Ni and Zn drop from68.33%、15.63%、17.56%and45.26%to2.14%、0.868%、1.45%and3.22%; the main factors of effect of stabilization are dosage of DTCL and pH of leaching agent beside heavy metals it selves. The experimental results of solidification show that:adding0.4%DTCL chelator can make solided of leaching concentration of heavy metals to meet the "Standard for pollution control on the security landfill site for hazardous wastes",(GB18598-2001). It is entirely feasible that DTCL chelator apply to pullution control fly ash.