The Effect Assessment Of Nano-Particle Hydroxyapatite Walnut Shell And Peanut Hull Remediation On CD And PB Contaminated Soil

In this article, the forms of cadmium and lead have been analyzed with improved five-step Tessier extraction method by adding different proportions of nano-hydroxyapatite, walnut shell and peanut hull and taking artificial soil pollution means.Main conclusion of the study were as follows:1. The soil of Qingdao urban nearby Shangwangbucun was polluted by cadmium and lead,and the pollution situation was severe. When 5g of n-HAP was added into 100g of soil sample, the effect of remediation was best, and the removal rate of n-HAP to the available state of cadmium of that was 49%; The inactivation of n-HAP on active forms of Lead was relatively effective, the decreased rate reached the level of 90% and the longer balance the better result.2. The mechanism of n-HAP repairing lead was different from cadmium.The mechanism of repairing cadmium mainly based on the coordination of the surface, ion exchange and generation of imcrystal material,however lead based on dissolve and precipitation. n-HAP had a better remediation effect on lead contaminated soil than the cadmium.3. Walnut shell and peanut hull had a certain repairing effect on cadmium and lead, in the simulation the decreased range of effective state of Cd was 10%,while he decreased range of effective state of Pb was 20%. For the same pollution level, different proportion of walnut shell and peanut hull had different effects in repairing, at the given dosage range, the best ratio was 5%.4. The mechanisms of walnut shell and peanut hull repairing lead and cadmium were same. With the increasing of the concentration of lead, the effect remediation on Cd was worse,but when the increasing of the concentration of cadmium, there was only a little influence on Pb,because lead's adsorption ability of competition was stronger.5. Walnut shell and peanut hull were applicable to the light soil contaminated by Pb,so we can consider that when in farming stirs walnut shell and peanut hull in soil with fertilizers. But duing to the limited adsorption capacity, walnut shell and peanut hull were not applicable to serious soil contaminated by cadmium and lead.