This technology features a functional ceramic filter and its manufacturing method. It involves coating the surface of an alumina-based ceramic filter with nano-sized pores with a highly reactive composite layer consisting of metal oxides and layered double hydroxides (LDH). This allows for the simultaneous adsorption and subsequent desorption and reuse of both cationic and anionic heavy metals.
Membrane separation technologies like ceramic filters are durable and generate minimal sludge with little chemical usage. However, they often suffer from low treatment efficiency in high-concentration heavy metal wastewater due to limited surface reactivity and a reliance on physical filtration. Frequent filter replacement is required to maintain performance, and simple metal oxide coatings often face issues with metal leaching or coating delamination.
This technology involves immersing a filter in a first metal solution (magnesium, calcium, iron, etc.), followed by spraying and drying a layered double hydroxide precursor suspension—prepared by mixing first and second metals in a 2:1 to 5:1 molar ratio—and calcining it in a nitrogen atmosphere at 500–700°C. This process creates secondary pores of 13–18 nm, increasing the specific surface area and enhancing the adsorption/desorption efficiency of anionic heavy metals through interlayer anion exchange. Applicable to heavy metal wastewater treatment in plating, smelting, and semiconductor processes, as well as mine drainage, groundwater purification, and industrial wastewater treatment, this method extends filter life and allows for repeated use through desorption.
This invention was developed with support from the Ministry of Environment for the development of high-performance ceramic microfilter application technology for the removal of hazardous heavy metals.
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