Organically modified montmorillonite as an environmental adsorbent of pollutants: Formaldehyde from urea-formaldehyde resin and Acid Red 183 dye from the aqueous solution

In this research, a composite based on montmorillonite (K10) modified with HDTMABr was used. The characterization of the pure K10, NaMMT and OMMT was performed using XRD, FTIR-ATR, SEM, TG, DTG, and DTA. Ion exchange capacity (CEC) and specific surface area (SSA) were also determined. The sulfite method was used to determine free and liberated formaldehyde (FA) from synthesized urea-formaldehyde/montmorillonite (UF/MMT) composites. This research aims to demonstrate the bifunctionality of OMMT and that it can be used both for the capture of FA from the synthesized cross-linked UF resin and for the adsorption of the anionic dye Acid Red 183 (AR183) from aquatic medium. SEM analysis showed that there are changes in the morphology of the OMMT and the formation of a hollow network, which affects the absorption capacity of the clay. The calculated values of free and liberated FA in the UF/OMMT composites are drastically reduced and amount to 0.12% and 0.96%, respectively, compared to the composites with K10 (0.6% and 2.04%, respectively). Also, very promising results were obtained of the adsorption of AR183 dyes from the aquatic medium using OMMT. The results show that OMMT (0.5 g OMMT/50 cm3 aqueous dye solution, c=20 mgdm−3) managed to remove 85.95% of AR183 dye (pH dye=7). The adsorption mechanism of AR183 on OMMT follows the Freundlich isotherm and proceeds according to the pseudo-first-order kinetic model. Overall, the findings of this work indicate that the use of the obtained OMMT has great potential in removing pollutants from two totally different systems. [Display omitted] •Montmorillonite K10 was modified with Hexadecyltrimethylammonium bromide HDTMABr.•OMMT successfully reduced the content of FA from the cross-linked UF resin.•Hydrolytic stability decreases in the following order:UF/OMMT>UF/K10 >UF/NaMMT•OMMT managed to remove 85.95% of AR183 dye (pH = 7).•The bifunctionality of OMMT has been confirmed.