Comparison The Ability Of Nano-Clays And Clays Extracted From Different Soils In Retention of Some Heavy Metals

nano-clays and clays are the most important components constructing soil ecosystems. Which The soil physical and chemical properties depend on their types and amounts. Therefore, they have a key role in soil quality. Most clays particles have nano size at least in one dimention. This characteristic of clay enriches some soil capabilities such as the heavy metals retention processes in soil. Clays separated from volcanic ash like Andisol, in clay size particles there are different structures of nano particles such as alominosilicats with nanoball and nanotube constriction. These particles play an important role in the physical and chemical properties of volcanic soils, stored organic matter, phosphorus stabilization, heavy metals retention, water and biogeochemical processes. Release of heavy metal onto the water and soil as a result of agricultural and industrial activities may pose a serious threat to the environment. In this study, the adsorption of Pb2, Cd2 has been studied in order to compare the ability of Nano-Clays And Clays separated from Different Soils in Retention of Some Heavy Metals.
Twelve samples taken from 5 pedons with different clay mineralogy in three regions around the city of Karaj were measured. After the removing organic material, the soluble salts, carbonates and iron oxides from the soils, pure clays were treated by x-ray diffractive device and diffractions were interpreted. clays and nano-clays were purified and measured retention of cadmium and lead in solutions with different concentrations, 0, 1.6, 8.3, 16.6 and 33.3 ppm, at constant pH. The aim of this research is to evaluation of the effect of soil components particularly clay and nano Clay on the absorption of heavy metal at constant pH. Therefore, we studied absorption amount of lead and cadmium by the clay and natural nanoclay soils after removing cement and seprating using standard methods, at pH 6.
The soils were classified in two groups of Aridisol and Andisol. The current study showed that the bulk of soil mineralogy consist of combination of ilitic, cloritic, smectite and hydroxy inter layer minerals. Also the results showed that the heavy metals retention of soils depend on the different types of element. In all Andic and non-Andic samples, the retention capability showed significant enrichment with increasing heavy metals concentrations. But the trends of retention in nano-clays showed a steeper slope in comparison with clays.
Cadmium absorption of the samples(nano-clays and clays) stopped at 8/3 mg/lit, but lead absorotion. But lead absorption at studied cincentration was increased by increasing trend. The results indicated that in the most samples derived from non-Andic soils their absorption trend was as (Pb> Cd) and in the Andic soils it was (Pb> Cd).