Pre-treatment and conditioning of chabazites followed by functionalization for making suitable additives used in antimicrobial ultra-fine powder coated surfaces

Abstract

Modified natural chabazites functionalized with silver–copper were used as an additive to develop antimicrobial powder coated surfaces. Two chabazites (named as LBC and LBN) were modified to enhance the ion-exchange properties by conditioning with sodium salt. The cation-exchange capacity (CEC) of those zeolites was improved from 3.31 meq. g⁻¹ and 3.46 meq. g⁻¹ to 3.77 meq. g⁻¹ and 4.09 meq. g⁻¹ respectively and they were used to produce silver–copper modified zeolites. In order to achieve durable and efficient antimicrobial additives, different combinations of these ions were used by varying the reaction time. These additives were used with a polyester resin system to produce ultrafine powder coated surfaces. Silver was utilized as an antimicrobial agent, whereas copper was used to prevent the reduction of silver during the coating process. All materials including the raw, modified and functionalized zeolites were characterized using XRD and TGA to observe the effect of treatment. ICP-OES was used for elemental analysis at every experimental stage. Color analysis proved that copper prevents silver from being reduced and maintains the color of the coated surface, which is comparable to the control surface. These coated surfaces have shown homogeneous antibacterial properties with excellent durability against E. coli for extended periods. Cell toxicity was evident from the LDH analysis of the fresh and used antimicrobial surfaces.