نشریه کاربرد شیمی در محیط زیست
پیاپی 41 (زمستان 1398)

The growth of industry fulfills our necessity and promotes economic development. However, pollutants from such industries pollute water bodies which pose a high risk for living organisms. Thus, researchers have been urged to develop an efficient method to remove toxic heavy metal ions from water bodies. The adsorption method shows promising results for the removal of heavy metal ions and is easy to operate on a large scale, thus can be applied to practical applications. Numerous adsorbents were developed and reported, among them hydrogels, which attract great attention because of the reusability, ease of preparation, and handling. Hydrogels are macromolecular networks that swell, but do not dissolve, in water. The ability of hydrogels to absorb water arises from hydrophilic functional groups such as -NH2, -COOH, -OH, -CONH2, - CONH -, and -SO3H attached to the polymeric backbone, while their resistance to dissolution arises from crosslinks between network chains. Thus, this review provides various methods of hydrogel adsorbents preparation and summarizes recent progress in the use of hydrogel adsorbents for the removal of heavy metal ions. Further, the mechanism involved in the removal of heavy metal ions is briefly discussed. The most recent studies about the adsorption method for the treatment of heavy metal ions contaminated water are presented.

Methylene blue dye is the most common dye for dyeing cotton, wool and silk. Inhalation of this dye can cause respiratory distress and while direct exposure to it can also cause permanent eye damage, burning sensation in the exposed areas, Nausea and vomiting, excessive sweating and mental disorders. In this paper, silver nanoparticles was synthesized via a simple method. Various techniques such as FESEM, XRD, UV-Vis DRS were used to identify the morphology, structural composition and optical properties of synthesized silver nanoparticles. The results of UV-Vis DRS showed that the prepared silver nanoparticles effectively improved the efficiency of the visible light response in the process of photocatalytic degradation of methylene blue dye. The results of pseudo-first-order linear kinetics showed that the value of k increased with increasing of MB dye concentration from 0.0264 to 0.0614 min-1. In general, nano-silver synthesis showed a high potential in removing MB dye from aqueous solutions.

Polymers have been substituted for metal in many applications due to their good mechanical and chemical properties, but their flammability has limited their use, and many studies have been performed to improve the flame retardancy of polymers. Thermal pyrolysis of polymers leads to the formation of highly reactive radical species • O •, H and • OH [3]. The first two species are mainly converted to hydroxyl radicals (• OH). OH's participation in the exothermic reaction provides the heat needed to spread the flame. Inhibition (• OH) prevents the flame from advancing. Halogen flame retardants, which produce radical halogens, release phosphate inhibitors that release HPO, PO, or PO2, inhibiting OH. To reduce the flammability of polymers, either the polymer structure can be manipulated or the surface coating of the polymer textiles can be barrier-layered. The flame retardant halogen in the produced samples weakens the mechanical properties compared to the observed grade. In flame retardant, as the percentage of halogenated flame retardant compounds in the polymer increases, the polymer flame retardant increases in approximately the same proportion.

Water always contains solutes, suspended solids and soluble gases. Water plays an essential role in the transmission and spread of many important microbial, viral and parasitic diseases. Basically, no water can be consumed with confidence before examining its physicochemical parameters and microbial index. the main reason for investigating the issue of irreparable damage due to chemical impurities in drinking water has been more than allowed and ensuring public health.

In this work, we prepared co-hydrogel with two monomers of vinyl pyrolidone and vinyl sulfonic acid by free radical polymerization metod and azobisisobutyronitrile (AIBN) is a initiator ,and N,N-methylen ebisacryl amide is an crosslinker agent in 65ċ and 5 hours and 45 minutes.we synthesized co-hydrogel 1:1,1:0.5,1:0.25 mol ratio on feed composition. there for we obtain amphiphilic hydrogels. for invistigation of complexation behavior between two monomer (cationic and anionic monomer) we used uv spectroscopy. there for, we invistigation of swelling properties of synthesized co-hydrogels (amphiphilite hydrogels)in different PH 1,4,7,10,12 also we obtaine ratio amount of swelled hydrogel.

Chitosan is a natural cationic polysaccharide. Chitosan and its hybrid materials are used in various industrial sectors due to their wide range of physical and biochemical properties. Textile dyes and other industrial effluents are widely endangered plant growth and affect the food chain, these substances may also cause toxicity, mutagenicity and carcinogenicity. Therefore, attention towards chitosan and modified chitosan-based materials has been devoted in the previous few decades due to its biocompatibility, biodegradability, less-toxic, and eco-friendly nature. However, its attractive properties rely on its ability to form linkages with the sulfonic groups of anionic dyes by the electrostatic force of attraction and adsorption of dyes effluents and other heavy metals in various capacities. this review describes the improved properties and modifications of chitosan for dye adsorption from the textile industry, through crosslinking, graft copolymerization, and surfactant impregnation for the development of chitosan based hybrid. In addition, chitosan nanostructures that are being studied for the smart degradation of textile dyes and effluents have also been discussed. This review provides an insight into the chitosan-based adsorbents for the removal of various dyes and colored effluents.