Antimicrobial zinc oxide/polymer nanocomposites for the removal of toxic textile dye

This work aimed for the preparation of zinc oxide nanoparticles (ZnONPs) using hydroxyethyl cellulose (HEC) as a capping agent. The preparation of ZnONPs was first affirmed using UV–Vis spectra, illustrating the presence of an absorption peak at 364 nm. Meanwhile, the well distribution of ZnONPs was proved via transmission electron microscope (TEM). Then, ZnONPs were blended with a solution composed of HEC and sodium alginate (SA) to form an efficient hydrogel that crosslinked with calcium chloride (CaCl₂). FTIR, SEM–EDX, and swelling ratios were employed to confirm the successful preparation of ZnONPs@HEC-SA in a hydrogel form. This investigation was extended to explore the efficacy of HEC-SA hydrogel and ZnONPs@HEC-SA hydrogel in removing Crystal Violet (CV) dye from water. Various variables, such as varied pH levels, contact periods, and concentrations of ZnONPs, were used to assess the hydrogel's adsorption capabilities. ZnONPs@HEC-SA hydrogel was also tested for photocatalytic degradation efficiency when exposed to visible light. At greater ZnONPs@HEC-SA dosage and shorter irradiation periods, our findings showed that the ZnONPs@HEC-SA hydrogel completely degraded (100%) the CV dye after 105 min. The maximum adsorption capacity observed was 320 mg/g, indicating a large removal capacity of the hydrogel. Besides, the reusability of the hydrogel was confirmed by its capability to maintain influential adsorption effectiveness over five consecutive cycles. The adsorption capacity of the tested hydrogel increased exponentially as the pH of the CV dye solution decreased. The nature of ZnONPs@HEC-SA hydrogel was reaffirmed by adding SA to the mixture, as detected by a point zero charge (PZC) of 8.4. The ZnONPs@HEC-SA hydrogel displays a considerable potential for applications in wastewater treatment. Its dual functionality as a photocatalyst and adsorbent for CV dye reduction, integrated with its antimicrobial properties, makes it a versatile and effective solution for managing pollution in water sources owing to its durability and efficiency over multiple cycles, enhancing its appeal for practical use in wastewater treatment processes.