Carboxymethyl cellulose (CMC), microcrystalline cellulose (MCC), and xylan are cross-linked with β-cyclodextrin (βCD) using ethylene glycol diglycidyl ether cross-linker to produce hydrogels, namely, βCD-CMC, βCD-MCC, and βCD-xylan, in alkaline medium at 1:1 mole ratio. Additionally pure βCD gel is also prepared in alkaline medium. The synthesized hydrogels are characterized by Fourier transform infrared spectroscopy, and the swelling ratio, gel fraction, and the morphologies are observed by a microscope. The hydrogels are used to adsorb cadmium (Cd­(II)) and nickel (Ni­(II)) ions from aqueous solution. The adsorption studies are carried out by varying adsorbent dosage from 80 to 500 mg, concentration from 5 to 500 mg L–1, pH from 2 to 8, and temperature from 25 to 55 °C. The equilibrium adsorption data closely follow the Langmuir model, suggesting the monolayer adsorption of metal ions by the hydrogels. The adsorption kinetics are found to closely follow the pseudo-second-order model.

No abstract

A new type of supported liquid membrane setup has been developed in this work. The setup consist of an in situ electrodeposition unit in strip phase which helps “stripped” nickel and zinc from synthetic wastewater get electrodeposited on the cathode surface. This type of separation technique not only helps to separate toxic heavy metals from wastewater but also yields an useful end product in the form of electroplated material. Two types of carrier, i.e., trioctyl amine and di-(2-ethylhexyl)­phosphoric acid, have been used in the organic phase to separate zinc and nickel. The separation has been done individually as well as in a condition of binary pollutant in the feed phase. Various physicochemical parameters have been optimized to maximize the transport and deposition of metals on the cathode surface. Face-centered central composite designs in response to surface methodology have been performed on varied ratios of binary pollutant and their carriers in order to obtain optimum performance of the separation unit.

Treatment of wastewater containing hexavalent chromium is the issue in this research. Supported liquid membrane with in situ electrochemical reaction in stripping section helps to reduce hexavalent chromium to trivalent chromium by forming chromium-iron complex. Iron plate acts as anode in stripping section. The chromium-iron complex is an useful value added product that can be used for various purposes such as catalyst in water-gas shift reaction. Aliquat 336 has been used as carrier for transport of hexavalent chromium. Various physicochemical parameters have been optimised to detect the condition of maximum transport and precipitation of chromium-iron complex in stripping phase. The important physico-chemical parameters such as strip phase concentration, strip phase pH and concentration of carrier (% v/v) in Liquid Membrane have been selected through response surface methodology to obtain optimum performance for %precipitation of chromium.

No abstract