Reusable Macroporous Hydroxyethyl Cellulose/Polyethylene Glycol Cryogel Loaded with Activated Carbon and Strontium Oxide for Effective Disinfection of Waterborne Pathogens

Waterborne pathogens and bacterial communities that can form biofilms still persist, and microbial contamination of water remains an important public health problem. A multifunctional hydroxyethyl cellulose/polyethylene glycol cryogel incorporated with strontium oxide and activated carbon (HEC/PEG–SrO/AC) was developed for the efficient disinfection of water. Structural characterization verified the interconnection of the macroporous network and the successful incorporation of SrO and AC in the polymer matrix. The composite showed a wide antibacterial spectrum against Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis , and Bacillus cereus with inhibition zones of 34.0, 31.1, 21.3, and 18.7 mm, respectively, compared to pristine HEC/PEG cryogel. A strong dose-dependent bacterial inactivation was noticed with about 6 log₁₀ reductions for all tested pathogens. Mechanistic studies showed significant membrane damage, evidenced by time-dependent leakage of cytoplasmic proteins. Further, the cryogel effectively inhibited biofilm formation and almost completely removed the mature biofilms after 14 days. The bioluminescence test with Aliivibrio fischeri for measuring acute toxicity showed low toxicity (< 8% inhibition). The as prepared cryogel matrix showed a remarkable reduction of heterotrophic bacteria, coliforms, and Salmonella spp., in domestic wastewater within 30 min. This suggests its potential as a biocompatible and efficient water disinfection material. The results show that the HEC/PEG–SrO/AC cryogel can be considered a reusable multifunctional material for wastewater disinfection.