Designing Co3O4/silica catalysts and intensified ultrafiltration membrane-catalysis process for wastewater treatment

An integrated cobalt oxide catalyst supported on silica (Co3O4/SiO2) packed in the lumen of tubular alumina (Al2O3) membrane was designed to realize a Fenton-like oxidation coupling with ultrafiltration water treatment technology to remove persistent and hazardous pollutants. We employed a selection of SiO2 support materials with a range micro/mesostructures to immobilize the Co3O4 catalyst. These were evaluated and screened to achieve the highest pollutant decolorization rate and maximum decolorization efficiency. Then, an integrated catalyst-membrane was developed as proof-of-concept for advanced water treatment. Batch degradation results showed acid orange 7 dye (AO7) was effectively removed using Co3O4 deposited on MCM-41 silica, with 97% decolorization efficiency achieved in 15 mins owing to the large surface area and high porosity of the MCM-41 support. In contrast, humic acid (HA) was relatively difficult to degrade using this catalyst, and was however found to inhibit AO7 degradation. The integrated catalyst-membrane successfully removed both AO7 and HA with only a 10% water flux reduction from 25.0 to 22.5 kg m(-2) h(-1) bar(-1) with excellent co-pollutant removal rate of 99% over 40 h. Furthermore, the integrated catalyst-membrane also removed a range of organic pollutants (neutral red, tetracycline hydrochloride, oxytetracycline) achieving > 90% rejection and 30 kg m(-2) h(-1) bar(-1). These results show that the integrated catalyst-membrane can effectively purify a binary pollutant mixture containing both hazardous dye and natural organic matter and other pharmaceutical chemicals whilst producing process water for recycling and reuse.

Automated summary

An integrated Co3O4/SiO2 catalyst supported on silica and packed in an alumina membrane was developed for Fenton-like oxidation coupling with ultrafiltration water treatment, successfully removing various persistent and hazardous pollutants. The catalyst showed high efficiency in decolorizing dyes and degrading organic pollutants, with minimal water flux reduction, demonstrating its potential for advanced water purification applications.