Alumina, a support material, was loaded with chitosan to form a chitosan/alumina composite (CA) and was utilized for removing sulfonated azo-dye methyl orange (MO) from aqueous media in this study. The adsorbents were characterized by Fourier transform infrared (FTIR) spectra to confirm that chitosan was successfully immobilized on alumina, and some functional groups were successfully introduced into the surface of alumina after modification. The effects of pH, the amount of adsorbent, initial concentration, time, and temperature were studied in batch experiments. The experimental data were analyzed by Langmuir and Freundlich adsorption isotherms. Thermodynamic parameters such as ΔG o , ΔH o , and ΔS o have also been evaluated, and it has been found that the sorption process was spontaneous and exothermic in nature. Pseudofirst-order and pseudosecond-order kinetic models were used to fit the experimental data. Kinetic parameters, rate constants, equilibrium adsorption capacities, and related correlation coefficients for each kinetic model were calculated and discussed. It revealed that the adsorption of MO could be described by the pseudosecond-order equation, suggesting that the adsorption process is presumably chemisorption.
The removal of enrofloxacin, a fluoroquinolone antibiotic, from aqueous solution by adsorption onto bentonite was investigated in this study. The effects of initial concentrations, contact time and temperature on the adsorption of enrofloxacin were studied via batch experiments. The adsorption equilibrium was achieved within 60 min for all studied concentrations. The adsorption capacity increased with the increase of initial concentration within a concentration range. Higher temperatures were favourable for the adsorption. The change of Gibbs free energy (ΔG°), change of enthalpy (ΔH°) and change of entropy (ΔS°) were evaluated and the results indicate that the adsorption should be an endothermic and spontaneous process. The Langmuir isotherm model fitted to the experimental data better than the Freundlich model. The adsorption follows the pseudo-second order kinetic model.
The similarities and differences in the removal of two acid dyes tartrazine (TA) and indigo carmine (IC) from aqueous solutions by active carbon prepared from maize cob was investigated in the study. The effects of initial concentration, contact time, and temperature were discussed. The maize cob carbon (MCC) showed better adsorption performance for IC than TA. The adsorption equilibrium was reached within 80 min for IC and 270 min for TA with an initial concentration of 400 mg/L. The maximum adsorption capacity was 68.78 mg/g for TA and 118.48 mg/g for IC at 25 • C on the basis of Langmuir isotherm. The formation of hydrogen bonds was considered to be the predominant influence in enhancing the interaction between IC and MCC. The kinetic studies showed that the adsorption of both dyes onto MCC exactly followed the pseudo-second order kinetic model for all studied concentrations. Thermodynamic studies revealed that the adsorption was a spontaneous and physical adsorption process for both dyes.
A B S T R A C TActivated carbon (AC) prepared from peanut shell (PS) with microwave treatment was used to remove indigo carmine (IC) from aqueous solution in this study. PS and AC were examined by pore structural analysis, scanning electron microscopy, and elemental analysis. Effect of initial dye concentration, contact time, pH, and temperature on IC removal was investigated by batch experiments. The adsorption capacity increased with the increase of initial concentration, and decreased with increasing pH. Higher temperatures were favorable for the adsorption. The adsorption equilibrium could be reached within 90 min for all studied concentrations. The results showed that the Langmuir isotherm model had a good fit for the equilibrium data. Kinetic studies revealed that the adsorption followed the pseudo-second-order kinetic model. Thermodynamic studies indicated that the adsorption was a spontaneous, endothermic process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.