Search

In the present research, a biopolymer Chitosan (C) grafted with ethylenediamine (EDA) and methyl acrylate (MA) were compared for the adsorption of Congo red dye from aqueous phase. The grafted chitosan product was characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and point of zero charge to study the change in mechanical and thermal properties. The effects of process variables like adsorbent loading, initial dye concentration, initial solution pH, contact time and temperature on adsorption phenomena were investigated. The equilibrium isotherm data was analyzed using Langmuir and Freundlich isotherm models, and the adsorption followed the Langmuir isotherm model (R2 = 0.992 and 0.991 for EDAC and MAC, respectively). The maximum adsorption capacity of EDAC and MAC for Congo red uptake calculated from Langmuir isotherm model was 1607 mg/g and 1143 mg/g, respectively. The adsorption kinetics was studied using pseudo 1st and 2nd order models. Pseudo second order rate model provided the best fit for both grafted adsorbents with R2 ≥0.99. The values of Gibbs free energy (−9.628 and −8.878 kJ/mol), enthalpy (44.9 and 42.2 kJ/mol) and entropy (0.18 and 0.17 J/mol·K) revealed spontaneous and endothermic adsorption of Congo red onto EDAC and MAC surface. The pollutant adsorption test indicated that chitosan grafting with ethylenediamine is superior to Methyl acrylate grafting agent. Unlabelled Image • Successful grafting of chitosan with ethylene diamine and methyl acrylate • Adsorption mechanism follows Langmuir isotherm and pseudo 2nd order kinetics model. • Maximum uptake was 1607 and 1143 mg/g for EDA and MA grafted chitosan, respectively. [ABSTRACT FROM AUTHOR]

In this work, a novel approach is used to synthesize an iron oxide doped carbon nanotube (CNT) membrane, with the goal of fully utilizing the unique properties of CNTs. No binder is used for the synthesis of the membrane; instead, iron oxide particles serve as a binding agent for holding the CNTs together after sintering at high temperature. The produced membrane exhibited a high water flux and strong fouling resistance. In the first step, CNTs were impregnated with various loadings of iron oxide (1, 10, 20, 30 and 50%) via wet chemistry techniques. Impregnated CNTs were then compacted at 200 MPa and sintered at 1350 °C for 5 h to form a compact disc. The membranes were analysed by measuring their porosity, contact angle, diametrical compression test and water flux. The flux of pure water was observed to increase with an increase in iron oxide content. The permeate flux and rejection rate of sodium alginate (SA) were determined to predict the antifouling behaviour of the membrane. A maximum removal of 90 and 88% of SA was achieved for membranes with a 10 and 1% iron oxide content, respectively, after 3 h. A minor decline in the permeate flux was observed for all membranes after 4 h of operation. [ABSTRACT FROM AUTHOR]