PPy-Related Composites in Water Purification

PPy is one of the most extensively studied condudive polymers due to the unique properties of pyrrole monomers, such as easy oxidization, water solubility, commercial availability, environmental stabiHty, good redox property, and high electrical conductivity [59]. Ihe first examples of PPy were reported in 1963 as a highly conductive material by Weiss and coworkers [60]. 

Other PPy/inorganic composites involved the removal of humic acid by PPy/glass beads composite, [65] adsorption of polyoxometalate SiMOj O g by PPy/In Oj composite, [66] the Cr(Vl) concentration by PPy/mont-morillonite clay composite, [67] and the PPy/Al O composite for Cd(II) removal.  

Compared with the limited PPy/inorganic composites, a variety of organic materials were combined with PPy, which included sawdust, polysaccharides, carbon-related nanomaterials, rice husk ash, etc. This can be attributed to the natural compatibility and the easy covalent bonding with PPy. PPy/sawdust composites were synthesized by in situ FeCl oxidation and had applied to remove Cr(VI), [13] Zn(Il), [14] phosphate, [12] nitrate. 

Cellulose acetate membrane [69] and cellulose fiber [70] were coated on PPy to remove gold iodide and Cr(VI), respectively. Ionic exchange was ascribe for the gold iodide removal and the reduction of Cr(VI) to Cr(III), followed by adsorption. A covalently immobilized heparin-PPy/ poly(ethylene glycol) methacrylate composite was also fabricated for biological applications to reduce the protein and thrombus formation [71]. 

The PPy/reduced GO composite was also investigated to remove Hg(II), [75] Pb(II), [76] and Cr(VI) [77]. The chemical oxidation polymerized PPy/reduced GO composites showed a higher selective Hg(II) removal 

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