جستجوی مقالات مرتبط با کلیدواژه « حذف مواد رنگزا » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

The adsorption process is an effective method that is widely applied to remove dyes from wastewater due to its simplicity, availability, ease of process and reasonable price. Nano adsorbents with unique properties such as larger surface area, surface interactions and improved reactivity are providing new opportunities for removal of pollutants using an efficient and cost-effective method compared to other methods. In the meanwhile, a group of alumina nanocomposites have been considered as adsorbents owing to their high surface area, good mechanical properties and great resistance to thermal degradation. Nanocomposites consist of at least two phases that are dispersed into each other to form a three-dimensional network.  Nanocomposites display different properties of bulk material. In this study, the adsorption capacity of alumina-based composite Nano adsorbents, including alumina-carbon nanotubes, activated carbon, metal oxides, polymer and chitosan has been investigated. In the following, the removal of dyes and organic compounds by alumina-based composite Nano adsorbents and adsorption influencing factors has been reviewed. The effect of various factors on the adsorption capacity of alumina-based composite Nano adsorbents and the adsorption mechanism show that all alumina-based composite Nano adsorbents exhibit excellent adsorption capacity for dye removal.  Reviews indicate that Alumina/ Carbon nanotube (CNT) composite is used as an adsorbent to remove dyes. Alumina can affect compressive strength, hydrophilicity, porosity and CNT adsorption capacity. Alumina/CNT composite can multiply the adsorption capacity. Alumina / activated carbon composite can increase the adsorption owing to occurring adsorption process physically and chemically. Activated carbon possespore that can adsorb and alumina has functional groups in order to react with the dye.Chitosan contains functional groups -OH and amino -NH2 that can bind to the dye. Still, chitosan has a strong tendency to agglomerate and form a gel, so many of its functional groups lose the ability to react with the dye. Alumina/chitosan composite improves binding sites and mechanical stability.

Annually, insoluble biodegradable dyes in textile, leather, paper and food industries, photovoltaic cells are evacuated to natural water flows. The highly ordered TiO2 nanotube arrays made with titanium anodizing, due to its large surface area, strong oxidizing ability and excellent charge transfer performance, have been widely used as photocatalyst for decomposition of dyes in recent years. Nevertheless, the disadvantages of TiO2 are the vast energy gap (3.0-3.2 eV) and the high recombination of electron-hole derived from light that limits the use of TiO2 nanotubes in the use of visible light to decompose organic pollutants. For this purpose, in recent years, many attempts have been made to modify TiO2 nanotubes to increase light absorption to visible light, limit the band gap, increase surface area, and prevent the recombination of charge carriers. To overcome these limitations and increase photocatalytic activity of nanotubes, various methods have been investigated: decoration with noble metal particles, doping with metal elements, modification with semiconductor and doping with non-metallic elements.

The chitosan emulsion containing nano-particles has been prepared in a suspension form by adding drop-wise sodium polyphosphate (SPP) solution into a chitosan solution (CS). The results showed that the adsorption of C. I. Reactive Blue 19 (RB19) on chitosan emulsion was affected by contact time، initial dye concentration، pH، and temperature. For an initial dye concentration of 160ppm and 25°C in the optimum conditions (pH=4، [CS] / [SPP] =2. 85)، the chitosan nano-emulsion has much higher dye adsorption capacity. The RB19 removal in optimum condition was 60% and 100% for conventional chitosanand chitosan nano-emulsion respectively.