title: A study on the adsorption of methylene blue onto gum ghatti/TiO2 nanoparticles-based hydrogel nanocomposite.
abstract: The objective of this work was to study the isotherm and kinetic models for the adsorption of methylene blue (MB) onto a TiO2 nanoparticle (TiO2NP)-containing hydrogel nanocomposite (HNC) of polyacrylamide-grafted gum ghatti (PAAm-g-Gg). The grafting of PAAm onto Gg was conducted using N,N'-methylene-bis-acrylamide (MBA) as a crosslinker, and different weight percentages of TiO2NPs were incorporated into the hydrogel matrix during the grafting reaction. The graft co-polymerization and the formation of the HNC were confirmed using FTIR, XRD, BET, SEM, TEM and EDS analyses. The adsorption of MB was studied in batch mode and it was found to be highly dependent on solution pH, ionic strength temperature and adsorbent loading. The MB-adsorption process followed the pseudo-second-order rate model and Langmuir adsorption isotherm with a maximum adsorption capacity of 1305.5mgg(-1). Thermodynamic studies revealed that the adsorption of MB onto the HNC surface was spontaneous, endothermic and through a process of physisorption. The results also showed that the HNC was much more effective for the adsorption of cationic dyes than anionic dyes, and it retained its original adsorption capacity for five successive cycles of adsorption-desorption. In conclusion, the hydrogel nanocomposite showed huge potential for remediating industrial wastewater polluted by toxic cationic dyes.
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Doornfontein 2028, Johannesburg, South Africa; DST-CSIR National Centre for Nanostructured Materials, Council for Scientific and Industrial Research, Pretoria 0001, South Africa. Electronic address: mittal.hemant5@gmail.com.
authors.forename: Hemant
authors.initials: H
authors.lastname: Mittal
authors.affiliation: Department of Applied Chemistry, University of Johannesburg, Doornfontein 2028, Johannesburg, South Africa; DST-CSIR National Centre for Nanostructured Materials, Council for Scientific and Industrial Research, Pretoria 0001, South Africa. Electronic address: rsuprakas@csir.co.za.
authors.forename: Suprakas Sinha
authors.initials: SS
authors.lastname: Ray
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D000180:Acrylic Resins / Q000737:chemistry; D000327:Adsorption; D004396:Coloring Agents / Q000302:isolation & purification*; D003432:Cross-Linking Reagents / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008751:Methylene Blue / Q000302:isolation & purification*; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D009994:Osmolar Concentration; D053149:Plant Gums / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*; D000099166:Polyacrylamides
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D004396:Coloring Agents; D003432:Cross-Linking Reagents; D008751:Methylene Blue; D053149:Plant Gums; D014025:Titanium; D062065:Wastewater; D014874:Water Pollutants, Chemical; D000099166:Polyacrylamides; C009495:titanium dioxide; C021221:N,N'-methylenebisacrylamide; C015253:gum ghatti
keywords: Adsorption kinetics and isotherms; Methylene blue; Polyacrylamide-grafted gum ghatti hydrogel nanocomposite