Hydrogel Films as Chlorine Reservoirs: Uptake, Release, and Biological Studies

Hydrogels present a sustainable alternative to conventional disinfection methods for mitigating pathogenic water contamination, which is a serious global health concern. Herein, natural flax hydrogel films were developed for chlorine uptake and subsequent bacterial detoxification studies. The films could effectively adsorb active chlorine from bleaching powder, with an adsorption capacity exceeding 25 mg/g and good recyclability up to 3 cycles, and post-chlorine uptake characterization revealed physisorption as the primary interaction mechanism. The hydrogel exhibited sustained chlorine release and acute biocidal activity against two representative Gram-positive (<i>S. aureus</i> and <i>B. subtilis</i>) and Gram-negative bacteria (<i>E. coli</i> and <i>P. aeruginosa</i>), achieving over 50% bacterial growth reduction within 6 h. For practical validation, the films were tested with real water samples and assessed for water decontamination. Their antibiofouling potential was also explored in flower preservation, maintaining flower freshness for up to 12 days, and as an antimicrobial fabric coating agent. The findings elucidate their multifunctional versatility in chlorine uptake, sustained release, and disinfection, with practical utility in environmental and biomedical sectors.