The removal of cationic dyes from industrial wastewaters is critical prior to their discharge into the environment. Iron based humic acid coated magnetic nanoparticles (HA-MNP) were evaluated for the potential remediation of polluted wastewaters using 2-[4-(Dimethylamino)styryl]-1-methylpyridinium iodide (2-ASP) as a model to cationic styryl pyridinium dyes. HA-MNPs were prepared by co-precipitation from a mixture of ferrous chloride tetrahydrate (FeCl2.4H2O) and ferric chloride hexahydrate (FeCl.6H2O). The HA-MNPs were characterized by FTIR, SEM and BET. The adsorption of 2-ASP, measured by fluorescence, demonstrates HA-MNPs are efficient for the removal of 2-ASP with a maximum adsorption capacity of 8 mg/g. Detailed kinetic studies showed the adsorption process is most accurately modeled by a pseudo 2nd order process. The adsorption also follows Langmuir type adsorption and is relatively fast with ~ 70 % of the adsorption complete within 30 min. The overall removal increases from 40 % at pH = 3 to 66 % at pH = 7.5. The observed increase with increasing pH can be assigned to an enhanced electrostatic attraction between the positively charged 2-ASP and the increase in the negative charge on the HA-MNP surface as a function of increasing solution pH. The increase in adsorption of a function of solution pH is not linear and may be related to specific pKa values of different functional groups present at the surface, for example carboxylates and phenols. The measurement of the temperature effects on the adsorption yields ΔG° = -2.48 (kJ mol−1) at 318.15 °K indicating a spontaneous adsorption process. The positive value of ΔH°=7.696 (kJ mol−1) shows the endothermic nature of the HA-MNP−2-ASP system. The sorption study of model dye, 2-ASP indicate that HA-MNP has potential as a powerful sorbent for the removal of cationic dyes.

Environmentally friendly humic acid coated magnetic iron nanoparticles for removal of model styryl pyridinium type cationic dyes

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.