Organosilicon Sorbents for Some Toxic Metals

Abstract

A large number of sorption materials differing in both nature and structure have been proposed for the removal of toxic metal ions from process and natural waters [1‐3]. Due to various limitations (complex production technology, low chemical and mechanical stability, low efficiency, and incompatibility of the concentrated product thus obtained with the subsequent method of analysis), only few of them can be used in practice. The increase in man-caused impact on the environment strongly calls for the design of efficient methods for neutralization of industrial waste water and, what is equally important, highly sensitive and fast methods for determination of toxic metals in natural waters. In this study, we demonstrate that two organosilicon polymers, poly[ N -(3-silsesquioxanylpropyl)thioacetamide] O 1.5 Si ( CH 2 ) 3 NHC (= S ) CH 3 ( I ) and poly[ N -(3-silsesquioxanylpropyl)- N '-acetylthiocarbamide] O 1.5 Si ( CH 2 ) 3 NHC (= S ) NHC (= O ) CH 3 ( II ), can be used as effective sorbents for Hg(II), Cd(II), and Bi(III) ions. Polymers I and II are carbofunctional polyorganylsilsesquioxanes; they possess higher chemical and thermal stability and higher mechanical strength than their organic analogs [4‐6]. The production process for these materials is very simple; it is based on hydrolytic polycondensation of the corresponding γ -carbofunctionally substituted triethoxypropylsilanes [7, 8]. These polymers are yellow or pale brown powders having a developed surface ( S sp = 450‐ 600 m 2 /g) and high porosity ( = 1.8‐2.1 cm 3 /g). The sorption capacity of polymers I and II was stud