دانلود رایگان مقاله انگلیسی حذف فلزات سنگین از فاضلاب با استفاده از جاذب های کشاورزی اصلاح شده - الزویر 2017

Abstract

Agricultural waste has been investigated as an efficient adsorbent for heavy metal removal because of their low cost. The functional groups present in agricultural wastes such as carbonyl, phenolic, acetamido, alcoholic, amido, amino and sulphydryl group etc. have an affinity for heavy metal ions to form metal complexes or chelates. The removal of heavy metal ions from wastewater using agricultural waste is based upon metal biosorption. The mechanism of biosorption includes chemisorption, complexation, adsorption on the surface, diffusion through pores and ion exchange etc. These heavy metal ions cause life-threatening problems for the humans and aquatic ecosystem. Certain modifications in these adsorbents enhance the adsorption capacity of these adsorbents. Some chemicals such as mineral and organic acids, bases, oxidising agent are used for modification of adsorbents. The purpose of this article is to compare removal efficiency of different adsorbents.

Conclusions

Different type of adsorbents has been used for removal of heavy metal from wastewater. In this respect, agricultural wastes are economical for removal of heavy metal because of their low cost, easy availability, renewability and high affinity for heavy metals. Different types of adsorbents have been tried for chromium removal in the laboratory. Thus in our work, it was observed that percent removal capacity is higher for activated carbon and chemically modified wheat bran. After modification removal capacity of wheat bran reaches nearly up to activated carbon. The heavy metal removal by using agricultural wastes requires further investigation in the direction of modelling, adsorbent regeneration and metal ion recovery.