Hydrolysis of poly(acrylamide)–starch graft copolymer

Anionically functionalized guar gum embedded with silica nanoparticles: An efficient nanocomposite adsorbent for rapid adsorptive removal of toxic cationic dyes and metal ions

In the present work, a novel biodegradable nanocomposite has been developed (h-GG/SiO₂) based on anionically modified guar gum and in-situ deposited SiO₂ NPs through sol-gel technique. Here the anionically modified guar gum stimulates the silica polymerization process and hence acts as a unique template for the development of spherical SiO₂ NPs. Batch adsorption studies indicate that h-GG/SiO₂ nanocomposite shows remarkable adsorption capacity for cationic dyes/metal ions (Q_max: 781.25mgg^-1for malachite green (MG), 281.69mgg^-1 for safranin (SF); 645.16mgg^-1 for Pb²⁺, 709.21mgg^-1 for Cd²⁺) as well as it efficiently and selectively removes cationic MG from mixture of dye solutions. Finally the worthy regenerative efficacy of h-GG/SiO₂ facilitates the adsorbent to be economically promising for practical application in the field of wastewater management.

Enhanced removal of methylene blue and methyl violet dyes from aqueous solution using a nanocomposite of hydrolyzed polyacrylamide grafted xanthan gum and incorporated nanosilica

The synthesis and characterization of a novel nanocomposite is reported that was developed as an efficient adsorbent for the removal of toxic methylene blue (MB) and methyl violet (MV) from aqueous solution. The nanocomposite comprises hydrolyzed polyacrylamide grafted onto xanthan gum as well as incorporated nanosilica. The synthesis exploits the saponification of the grafted polyacrylamide and the in situ formation of nanoscale SiO2 by a sol-gel reaction, in which the biopolymer matrix promotes the silica polymerization and therefore acts as a novel template for nanosilica formation. The detailed investigation of the kinetics and the adsorption isotherms of MB and MV from aqueous solution showed that the dyes adsorb rapidly, in accordance with a pseudo-second-order kinetics and a Langmuir adsorption isotherm. The entropy driven process was furthermore found to strongly depend on the point of zero charge (pzc) of the adsorbent. The remarkably high adsorption capacity of dyes on the nanocomposites (efficiency of MB removal, 99.4%; maximum specific removal Qmax, 497.5 mg g(-1); and efficiency of MV removal, 99.1%; Qmax, 378.8 mg g(-1)) is rationalized on the basis of H-bonding interactions as well as dipole-dipole and electrostatic interactions between anionic adsorbent and cationic dye molecules. Because of the excellent regeneration capacity the nanocomposites are considered interesting materials for the uptake of, for instance, toxic dyes from wastewater.

High performance polymeric flocculant based on hydrolyzed polyacrylamide grafted tamarind kernel polysaccharide (Hyd. TKP-g-PAM)

A high performance anionic flocculant was synthesized by partial alkaline hydrolysis of polyacrylamide grafted tamarind kernel polysaccharide. Various macromolecular characterizations were employed to confirm that partial alkaline hydrolysis of grafted polyacrylamide chains does take place. The flocculation characteristics of the hydrolyzed and unhydrolyzed grafted products were carried out in kaolin suspension and municipal sewage wastewater and it has been found that hydrolyzed product outperforms the unhydrolyzed grafted TKP.

Chemically modified polyacrylamide-g-guar gum-based crosslinked anionic microgels as pH-sensitive drug delivery systems: preparation and characterization

New spherically shaped cross-linked hydrogels of polyacrylamide-grafted guar gum were prepared by the emulsification method. These were selectively derivatized by saponification of the -CONH2 group to the -COOH group. The derived microgels were characterized by FTIR and elemental analyses. The derivatized microgels were responsive to pH and ionic strength of the external medium. The swelling of microgels increased when the pH of the medium changed from acidic to alkaline. Transport parameters, viz., solvent front velocity and diffusion coefficients were calculated from a measurement of the dimensional response of the microgels under variable pH conditions. The variation in pH changed the transport mechanism from Case II (in 0.1 N HCl) to non-Fickian (in pH 7.4 buffer), and these processes are relaxation-controlled. Ionic strength exerted a profound influence on the swelling of the microgels. Swelling was reversible and pulsatile with the changing environmental conditions. The pH-sensitive microgels were loaded with diltiazem hydrochloride and nifedipine (both antihypertensive drugs) and their release studies were performed in both the simulated gastric and intestinal pH conditions. The release was relatively quicker in pH 7.4 buffer than observed in 0.1 N HCl; the release followed non-Fickian transport in almost all the cases.