Study On Silver-loaded And Copper-type Diatomite-based Composite Antibacterial Ceramics For Water Treatment

Ceramic filters for point-of-use water treatment are widely used in the world.At present,both silver nanoparticles and salts are added to ceramic filters to enhance its disinfectant properties.However,it may cause biotoxity due to the significant release of silver into the filter disk effluent.In this study,we report an easy and effective method for the preparation of ceramic filters which have minimum release of ions and high antibacterial activity.Diatomite-red porcelain porous ceramics were prepared by means of dry pressing process at different sintering temperature(range from 1000? to 1100?).The porosity and filtering performance of the materials were tested.Results show that the porosity of materials decrease from 72% to 58% and the pore sizes is less than 10?m.The amorphous silica of diatomite were transformed into quartz or cristobalite under high temperature.The best sintering temperature range from 1000? to 1100? were selected.The prepared ceramics exhibit a high filtration rate and purification ability of water bodies.The ceramics can remove 99.99% of Escherichia coli through the filter performance.With silver nitrate as antibacterial agent source,silver nanoparticle-diatomite antibacterial ceramic composites were firstly prepared by a pre-vacuum dipping method and a dry pressing process,and then sintered.The median pore diameter of prepared silver nanoparticle-diatomite antibacterial ceramic composites are 2.1?m.The deposition of silver did not change the phase composition and crystal structure of diatomite.The silver in the ceramic exist in the form of Ag2 O and metallic Ag with a particle size less than 100 nm.The silver nanoparticles combine strongly with the ceramic matrix and trace amount of silver can be released continuously and stably in water.The prepared composite exhibits a high inhibiting effect and antibactericidal ability against Escherichia coli,Staphylococcus aureus and Penicillium.The ceramic composites can remove 100% of the applied bacteria by the filter performance combined with the antibacterial activity of silver nanoparticles.With copper nitrate as antibacterial agent source,copper oxide nanoparticle-diatomite antibacterial ceramic composites were prepared.The particle size of copper oxide nanoparticles range from 5nm to 50 nm.The copper oxide nanoparticles exhibit a high antibacterial activity with a low release rate from the ceramic.This paper suggests that the silver nanoparticle-diatomite antibacterial ceramic composites and the copper oxide nanoparticle-diatomite antibacterial ceramic composites are promising candidate materials for point-of-use water treatment.