Using chitosan-TiO₂ composites to recycle copper ions from water for antimicrobial application

Heavy metal pollution of soil, usually caused by wastewater, has drawn extensive attention recently. The resolution of heavy metal contamination in wastewater is a major environmental issue.Today, people spend most of their time in an indoor environment, and indoor microbial contamination has become a primary concern. In this study, we focus on the adsorption of copper in wastewater by chitosan absorbent, and the antibacterial activity of chitosan composites after absorbing copper. Comparing the different absorbent efficiency and antibacterial activity between the chitosan (CS) and chitosan-TiO2 (CST) composites. The CS and CST composites are characterized by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), nitrogen adsorption/desorption isotherm at 77K, Fourier Transform Infrared Spectrometer (FT-IR), Thermogravimetric Analysis (TGA). The adsorption ability was tested by the spectrophotometry-Bis(cyclohexanone)oxaldihydrazone (BCO) method in the lab with series of copper nitrate solution of different concentration. The antimicrobial activity was evaluated by the zone of inhibition (ZOI) assay against E. coli (Gram-negative) and S. epidermidis (Gram-positive). The result shows the shape, surface, size and elements of material, and the study confirmed the effect of adsorption Cu²⁺ and inhibiting E.coli. The best Qt was the condition CS with 3% glutaraldehyde and exchange with ammonia solution with 300 ppm initial concentration, which of the Qt is 30.73 mg/g. All of the samples had an antimicrobial capability, respectively, the antimicrobial efficacy were affected by the copper ion more than the TiO2 and glutaraldehyde. From the result of the experiments, we found that the composites showed good removal efficiency on copper ions, indicating that the CS/CST composites after absorption demonstrated excellent antimicrobial activity, and could solve the copper ion in wastewater pollution and improve the air quality by killing microbes.