Browsing by Author "Pratibha Mandal"

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Anionic natural graft copolymer used in removal of hazardous dye water pollutants
(National Institute of Science Communication and Information Resources, 2020) Arti Srivastava; Pratibha Mandal; Rajesh Kumar
The carboxymethyl cellulose (CMC), guar gum, sodium alginate and chitosan etc. are natural polysaccharides. This paper presents the synthesis and characterization of natural polymer carboxymethyl cellulose (CMC) and synthetic monomer acrylic acid (AA) based graft copolymer (CMC–g–AA) and its applications in removal of Methylene blue dye from industrial effluents. CMC–g–AA has been synthesized using free radical initiator and characterized by FTIR, TGA, and SEM analysis. The AA concentration has been varied from 5.5 x 10-2 to 35.5 x 10-2 mol dm-3 to get maximum grafting of AA monomer onto CMC. The FTIR spectral analysis proves the successful grafting. The synthesized graft copolymer (CMC–g– AA) has been applied in adsorption of a water soluble monovalent cationic dye such as Methylene Blue. © 2020, National Institute of Science Communication and Information Resources. All rights reserved.
Solid state thermal degradation behaviour of graft copolymers of carboxymethyl cellulose with vinyl monomers
(Elsevier B.V., 2016) Arti Srivastava; Pratibha Mandal; Rajesh Kumar
The graft copolymer of sodium carboxymethyl cellulose (CMC) with acrylamide (ACM), dimethylacrylamide (DMA), N-vinyl pyrrolidone (NVP), 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) and vinyl caprolactum (VCL) were synthesized in nitrogen atmosphere by employing redox initiators. The integral procedural decomposition temperature (IPDT) of CMC and its graft copolymer with ACM, DMA, AMPS, NVP and VCL have been found to be 274 °C, 375 °C, 421 °C, 404 °C, 466 °C and 331 °C, respectively. The higher value of IPDT showed more thermal stability. Among all five graft copolymers, the graft copolymer of CMC with NVP is thermally more stable and VCL grafted copolymer was found least thermally stable. The higher char yield and final decomposition temperature (FDT) were obtained in the case of more thermally stable graft copolymer. All five graft copolymers have shown more than one Tmax, which suggests that degradations were multistep process. © 2016 Elsevier B.V.
Temperature-Tunable Adsorption of Methylene Blue by Poly(AAc-Co-AAm) Hydrogels: Swelling Behavior, Kinetics, and Isotherm Studies
(John Wiley and Sons Inc, 2025) Pratibha Mandal; Kawale Ashlesha Purushottam; Nishant Shekhar; Arti Srivastava; Sheetal Jaiswal; Manoj Kumar Bharty; Rajesh Rakesh Kumar
In this study, poly(acrylic acid-co-acrylamide) [poly(AAc-co-AAm)] hydrogels were synthesized via free radical polymerization using acrylic acid (AAc), acrylamide (AAm), and N, N′-methylenebisacrylamide (MBA) as a crosslinker. The synthesized hydrogels were characterized by FTIR, 1H-NMR, TGA, and SEM to confirm structural integrity, crosslinking, and thermal stability. Swelling behavior was evaluated at varying temperatures (30°C, 35°C, and 45°C) and pH (3.0–8.0). Maximum equilibrium swelling was observed for poly(AAc-co-AAm)3 due to higher hydrophilic group content, reaching saturation within 3 h. Swelling increased with both temperature and pH due to hydrogen bond disruption and ionic repulsion. TGA demonstrated a three-step decomposition, indicating stability up to ~180°C. Adsorption studies were performed by using methylene blue (100 mg/L) with 12 mg of hydrogel at pH 8.0. Optimal dye uptake occurred within 8 h. Adsorption increased with increase in dye concentration (20–100 mg/L), and the hydrogel showed enhanced adsorption at higher pH due to deprotonation of carboxylic groups. Kinetic analysis confirmed the pseudo-second-order model (R2 > 0.995) best described the process, indicating chemisorption. Freundlich isotherm (R2 = 0.998) best fit equilibrium data, suggesting multilayer adsorption on a heterogeneous surface. These findings validate the hydrogels as efficient, pH-sensitive, and thermo-responsive adsorbents for dye removal applications. © 2025 Wiley Periodicals LLC.