Organic and inorganic flocculants are used in treatment of water and industrial effluents. Polymeric flocculants, synthetic as well as natural, because of their natural inertness to PH changes, low dosage, and easy handling, have become very popular in industrial effluent treatment. It has been established in the authors' laboratory that by grafting polyacrylamide branches on rigid backbone of polysaccharides, the dangling grafted chains have easy approachability to contaminants in effluents. Thus grafted polysaccharides are very efficient, shear stable and biodegradable flocculants. They also exhibit turbulent drag reducing characteristics. Among grafted guar gum, xanthan gum, carboxymethyl cellulose, and starch, grafted starch performs the best. Starch consists of amylose (a low molecular weight linear polymer) and amylopectin (a high molecular weight, branched polymer). The grafted amylopectin is found to be the best flocculant for various kinds of industrial effluents, providing credibility to the above‐cited model. In the present paper, the details about grafted polysaccharides as turbulent drag reducers and flocculants are given, along with their applications.
ABSTRACT:The synthesis of sodium alginate-g-polyacrylamide was carried out by a ceric-ion-induced solution polymerization technique. Six grades of graft copolymers were synthesized by the variation of catalyst and monomer concentrations. These graft copolymers were characterized by intrinsic viscosity measurements, 13 C-NMR spectroscopy, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction. From the characterizations, it could be concluded that there was a substantial amount of grafting with a minimum formation of homopolymer.
Background: The present paper describes a less time-consuming and eco-friendly method for the synthesis of silver nanoparticles (AgNPs) using an aqueous solution of silver nitrate and Amaranthus gangeticus Linn (Chinese spinach) leaf extract. The synthesized AgNPs which are to be used as an antimicrobial and Congo red dye is to be used as a toxic-degrading agent. Methods: AgNP was prepared by the reduction of silver nitrate solution by the leaf extract of Amarranthus Gangeticus Linn leaf extract in aqueous medium on heating for about 15 mins at 80°C in presence of one drop 0.05 (M) NaOH. Results: The size of the synthesized silver nanoparticles (AgNPs) using Amaranthus gangeticus Linn leaf extract and aqueous solution of silver nitrate (10 −3 M) are formed at their stable condition within the range of 11-15 nm. AgNPs are obtained by this process within a couple of minutes of reaction without using reducing and stabilizing agents or harsh conditions. High-resolution transmission electron microscope (HR-TEM), selected area electron diffraction (SAED), ultraviolet-visible (UV-VIS) spectroscopy, and Fourier transform infrared spectroscopy (FTIR) are used to characterize the prepared AgNPs which show that the nanoparticles are globular in shape and polycrystalline. The synthesized silver nanoparticles showed inhibitory activity towards Gram positive, Gram negative bacteria and fungus and also showed good Congo red dye-degrading agents.
Conclusions:The overall outcome of this study suggests that green synthesis AgNPs hold promise as a potent antibacterial and antifungal agent. The particles obtained were also found to degrade toxic Congo red dye.
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