L. Ravikumar

Novel Polymeric Adsorbents Bearing Amide, Pyridyl, Azomethine and Thiourea Binding Sites for the Removal of Cu(II) and Pb(II) Ions from Aqueous Solution

Novel polyamides bearing pyridyl and azomethine groups as pendant pyridylformylimino groups along with thioamide moieties in the polymer backbone were synthesized using 4-pyridylformylimino-N-(phenyl,2′,5′-dicarboxylic acid) with 4,4′-(bisthiourea)benzidine and 4,4′- diaminodiphenyl methane through one pot phosphorylation polymerization technique. The optimization of experimental conditions and parameters including pH, adsorbent dosage, contact time, and initial metal ion concentration for the removal of heavy metal has also been investigated. Kinetic studies showed that the pseudo second order rate equation fits well with experimental values. The FT-IR spectrum indicated that the pyridine, amide, amide carbonyl, and azomethine groups were the major binding sites with metal ions. The maximum adsorption capacities of the resin for Cu(II) and Pb(II) evaluated from Langmuir models were 389.9 and 403.1 mg/g, respectively. Desorption studies revealed that Cu(II) and Pb(II) can be easily removed by treating metal ion adsorbed resins with 0.1 M H2SO4 or 0.1 M HCl. The adsorption-desorption process was a reversible process, which indicates that the polyamides are promising adsorbents for heavy metal removal from aqueous medium.

Equilibrium and kinetic studies on the adsorption of Ni(II) ion from an aqueous solution using activated carbon prepared from Theobroma cacao (cocoa) shell

AbstractThe adsorption of Ni(II) ion from an aqueous solution was successfully carried out using activated carbon prepared from Theobroma cacao (cocoa) shell, an agricultural solid waste biomass. The activated carbon prepared at ambient temperature (TCAC1) and the one prepared at 350 °C (TCAC2) were characterised by the FT-IR, BET, SEM, EDAX and Particle size analysis methods. The effects of the pH, dosage, initial metal ion concentration and agitation time were studied. The maximum adsorption was observed at pH 6 and the adsorption equilibrium was attained within 60 min. Adsorption isotherm data have been analysed, and the data fitted well in the order Langmuir > Redlich–Peterson > Temkin > Freundlich isotherm models. The maximum adsorption capacities of TCAC1 and TCAC2 for Ni(II) ions were calculated from the Langmuir isotherm as 97.59 and 158.8 mg/g, respectively. The kinetics of Ni(II) ion adsorption has been described, using five kinetic models viz, the pseudo-first order, pseudo-second order, Elovic...

Synthesis and Characterization of Epoxy-Containing Schiff-Base and Phenylthiourea Groups for Improved Thermal Conductivity

Three new diglycidyl monomers bearing phenylthiourea and azomethine groups were synthesized using 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, and 4,4′-diaminodiphenyl sulphone as starting materials. The monomers were characterized through IR and 1H-NMR spectroscopic analysis. The monomers were blended with epoxy based trickle impregnation resin (Dobeckot 605) and cured. The cured resins were subjected to TGA and DSC analysis. Presence of 3% by weight of the diglycidyl monomers bearing thiourea and azomethine groups in the cured blends did not alter the thermal stability but increased the thermal conductivity. The thermal conductivity of the cured blends were approximately 1.9 times higher than that of epoxy-based trickle impregnation resin and comparable with the epoxy-based resin filled with 20% inorganic fillers.

Adsorption of Congo Red Dye over Pendent Chlorobenzylidine Rings Present on Polythioamide Resin: Kinetic and Equilibrium Studies

The removal of Congo Red (CR) from an aqueous solution, using aromatic polythioamide resin (PTA) was studied. The effective pH and equilibrium time for the maximum adsorption of the CR on the PTA is found to be 7 and 45 min, respectively. Among the three kinetic models studied, the pseudo-second order kinetic model describes adsorption of the CR on the PTA efficiently. The maximum adsorption capacity of PTA for CR calculated from the Langmuir isotherm is 452.1 mg/g. The surface morphology of the PTA and dye adsorbed PTA were determined using scanning electron microscopy. The adsorption efficiency of the PTA was retained even after four cycles.