Polypyrrole/zeolite composite - A nanoadsorbent for reactive dyes removal from synthetic solution.

Synthetic dyes are among the common pollutants in the ecosystem. In the present study, polypyrrole/zeolite (PPy/Ze) nanocomposite was prepared and subsequently assessed for the removal of Reactive blue (RB) and Reactive red (RR) from synthetic solution. The polymeric PPy/Ze composite was synthesized by chemical oxidation of pyrrole in the presence of zeolite. Electron microscopic images (transmission and scanning) indicate that PPy/Ze nanocomposite was spherical in shape with an average size of 40-80 nm. The characteristic pyrrole and zeolite Fourier transform infrared spectrum peaks (1542 cm-1, 1463 cm-1, 1156 cm-1, 1054 cm-1, 879 cm-1 and 756 cm-1) in the nanocomposite confirmed zeolite integration with polypyrrole. Experimental variables such as PPy/Ze nanocomposite dose, initial RB and RR concentration, reaction temperature and pH were optimized. The PPy/Ze nanocomposite adsorbed 86.2% of RB and 88.3% of RR from synthetic solution at optimal conditions (pH 9, initial RR or RB concentration, 75 mg/l; PPy/Ze dose, 1.8 g/l; and temperature, 50 °C). Freundlich isotherm model and pseudo-second-order kinetics showed better fit for both RB and RR removal from synthetic solution. X-ray diffractogram confirmed the amorphous nature of PPy/Ze nanocomposite and that it was not altered even after dye adsorption. Adsorption-desorption studies showed that the composite has satisfactory adsorption potential for four cycles. The results show that the PPy/Ze nanocomposite could be used for the removal of dyes from wastewaters.

Significance of conducting polyaniline based composites for the removal of dyes and heavy metals from aqueous solution and wastewaters - A review.

Dyes and heavy metals pollution have become a major environmental concern worldwide. Various methods, such as advanced oxidation, biodegradation, precipitation, flocculation, ultra filtration, ion-exchange, electro-chemical degradation and coagulation, have been proposed for the removal of dyes and heavy metals from contaminated wastewater. Of these methods, adsorption and detoxification are considered as the most promising and economically viable. Polyaniline-based composites, a material prepared by combining polyaniline with one or more similar or disimilar materials, have been reported as good adsorbents to remove and detoxify different groups of pollutants due to their unique physical and chemical properties. In the last decade, several studies have reported the effective adsorption (∼95%) of dyes and heavy metals onto polyaniline based composites. Furthermore, some polyaniline -composites reduced the adsorbed heavy metals into less toxic state. This review compiles the application of different polyaniline composites for adsorption and/or detoxifcation of dyes and heavy metals and documents composite preparation methods, morphology and properties of the composites, and mechanism of dyes and heavy metals adsorption. Based on the avilabile literature, this review suggests that more studies are warranted to understand the influence of various conditions and experimental variables on dyes and heavy metals removal from wastewater and/or aqueous solution.

Rhodium(III) complexes derived from complexation of metal with azomethine linkage of chitosan biopolymer Schiff base ligand: Spectral, thermal, morphological and electrochemical studies.

Rhodium(III) complexes such as [Rh(Chi4Hy3mb)(H2O)2]Cl2, [Rh(Chi2Hymb)(H2O)2]Cl2, and [Rh(Chi2Hy3mb)(H2O)2]Cl2 were synthesized by metal chelation/complexation with chitosan Schiff base ligands. Stable Schiff base ligands were prepared by chemical modification of chitosan with aromatic aldehydes such as vanillin, salicylaldehyde and orthovanillin. These chitosan based Schiff base ligands were performed as bidentate ligands through azomethine nitrogen atom and methoxy/hydroxy oxygen atom. These bidentate ligands were favoured to the formation of stable coordination complex with metal ions. The series of Rhodium(III) complexes were characterized by Elemental analysis, FT-IR, UV-Vis spectroscopy, P-XRD and Thermo-gravimetric analysis (TGA). The electrochemical property of Rhodium(III) complexes were analyzed by cyclic voltametry.