T. Vidhyadevi

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...

A study on the removal of heavy metals and anionic dyes from aqueous solution by amorphous polyamide resin containing chlorobenzalimine and thioamide as chelating groups

Poly(chlorobenzalimino thiourea amide) (PCBA) resin was synthesized by using the phosphorilation poly condensation method. PCBA was characterized by analytical techniques, and it was used for the adsorption of heavy metals (Ni2+ and Zn2+) and anionic dyes (methyl orange (MO) and acid orange (AO)). The variables which affect the adsorption efficiency, such as pH, adsorbate concentration, adsorbent dose and contact time were studied. The results show that the adsorption of Ni2+, Zn2+, MO and AO follows the pseudo-second order kinetic model. The maximum monolayer adsorption capacity of PCBA for Ni2+, Zn2+, MO and AO, calculated using Langmuir isotherm is 191.2, 247.1, 153.8, 149 mg/g, respectively. Surface area (21.1m2/g) and crystal size are 21.1m2/g and 0.35 nm, respectively. High efficiency of the polymeric resins may be due to their amorphous nature and the presence of strong binding sites in the polymer structure. Thermodynamic parameters such as change in standard free energy change, enthalpy and entropy ΔG0, ΔH0 and ΔS0 were evaluated, and the adsorption process was found to be feasible, exothermic and spontaneous. Desorption studies show that adsorption efficiency of PCBA was retained even after four cycles.

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.

Kinetic and equilibrium studies on the biosorption of textile dyes onto Plantago ovata seeds

The powdered seeds of Plantago ovata (PSPO) were utilized for the removal of Malachite Green (MG) and Rose Bengal (RB) dyes from aqueous media by batch adsorption. The Fourier transform infra red spectroscopy (FTIR) results showed that both the dyes were adsorbed between the cellulose matrices, and this has been verified from the intensifying and narrowing aromatic C-H bending vibration. The morphology of the dye laden adsorbent was studied by scanning electron microscopy (SEM), which showed that the dyes were adsorbed between the cellulose matrices of the adsorbent. The PSPO was found to be very effective for the removal of MG and RB at pH 7, and equilibrium was attained within 200 min. The kinetic study indicated that the rate limiting step for MG and RB adsorption may be chemisorption and intraparticle diffusion. Adsorption equilibrium data were fitted to Langmuir, Freundlich, Redlich-Peterson and Temkin adsorption isotherms. It is inferred from the equilibrium studies that the adsorption of MG follows the Freundlich isotherm and the adsorption of RB follows the Langmuir isotherm. The maximum monolayer adsorption capacity of the PSPO was found to be 86.23 mg/g for MG and 81.23 mg/g for RB, respectively.

Evaluation of equilibrium, kinetic, and thermodynamic parameters for adsorption of Cd2+ ion and methyl red dye onto amorphous poly(azomethinethioamide) resin

AbstractBatch adsorption studies were carried out for the removal of cadmium ion (Cd2+ ion) and methyl red (MR) from aqueous solutions using poly(azomethinethioamide) (PATA) resin which is having pendent chlorobenzylidine ring. PATA was characterized by FT-IR spectroscopy, NMR spectroscopy, transmission electron microscope (TEM), and scanning electron microscope (SEM) techniques. Parameters like pH, initial dye and metal ion concentration, adsorbent dose, and contact time have been studied. Maximum adsorption was observed at pH 6 for Cd2+ and at 7 for MR. Langmuir, Freundlich, Dubinin–Raduskevich (D–R), and Temkin adsorption models were applied to describe the equilibrium isotherms. The maximum monolayer adsorption capacities of Cd2+ ion and MR dye are found to be 100 and 90.9 mg/g, respectively. The adsorption of Cd2+ ion and MR follows second-order kinetics. The thermodynamics parameters such as ΔG°, ΔH°, and ΔS° were also evaluated. The adsorbed Cd2+ ion and MR were eluted by treatment with 0.2 N HCl s...

Adsorption kinetic, equilibrium and thermodynamic investigations of Zn(II) and Ni(II) ions removal by poly(azomethinethioamide) resin with pendent chlorobenzylidine ring

Abstract This paper reports the application of poly(azomethinethioamide) (PATA) resin having the pendent chlorobenzylidine ring for the removal of heavy metal ions such as Zn(II) and Ni(II) ions from the aqueous solutions by adsorption technology. Kinetic, equilibrium and thermodynamic models for Zn(II) and Ni(II) ions adsorption were applied by considering the effect of contact time, initial metal ion concentration and temperature data, respectively. The adsorption influencing parameters for the maximum removal of metal ions were optimized. Adsorption kinetic results followed the pseudo-second order kinetic model based on the correlation coefficient (R2) values and closed approach of experimental and calculated equilibrium adsorption capacity values. The removal mechanism of metal ions by PATA was explained with the Boyd kinetic model, Weber and Morris intraparticle diffusion model and Shrinking Core Model (SCM). Adsorption equilibrium results followed the Freundlich model based on the R2 values and error functions. The maximum monolayer adsorption capacity of PATA for Zn(II) and Ni(II) ions removal were found to be 105.4 mg/g and 97.3 mg/g, respectively. Thermodynamic study showed the adsorption process was feasible, spontaneous, and exothermic in nature.