Silver nanoparticle-doped zirconia capillaries for enhanced bacterial filtration

Membrane clogging and biofilm formation are the most serious problems during water filtration. Silver nanoparticle (Agnano) coatings on filtration membranes can prevent bacterial adhesion and the initiation of biofilm formation. In this study, Agnano are immobilized via direct reduction on porous zirconia capillary membranes to generate a nanocomposite material combining the advantages of ceramics being chemically, thermally and mechanically stable with nanosilver, an efficient broadband bactericide for water decontamination. The filtration of bacterial suspensions of the fecal contaminant Escherichia coli reveals highly efficient bacterial retention capacities of the capillaries of 8 log reduction values, fulfilling the requirements on safe drinking water according to the U.S. Environmental Protection Agency. Maximum bacterial loading capacities of the capillary membranes are determined to be 3 × 109 bacterial cells/750 mm2 capillary surface until back flushing is recommendable. The immobilized Agnano remain accessible and exhibit strong bactericidal properties by killing retained bacteria up to maximum bacterial loads of 6 × 108 bacterial cells/750 mm2 capillary surface and the regenerated membranes regain filtration efficiencies of 95–100%. Silver release is moderate as only 0.8% of the initial silver loading is leached during a three-day filtration experiment leading to average silver contaminant levels of 100 μg/L

Exile Vol. V No. 2

EDITORIAL 4-6 Jamais (poem) by Iris Carroll 6 The Minister\u27s Narcissus by Julia Santucci 7-18 DRAWING by Anne Irgens 12 Solitude (poem) by Christine Condit 18 Island Lady\u27s Bill-Green Sky (poem) by Robert Wehling 19 Looking for Enchantment (poem) by Dennis Trudell 19 Silence (woodcut) by Carol Wilson 20 Saturday Night (story) by Ed Grimm 21-25 On Unemployment (poem) by William Bennett 25 Atlas (poem) by Bob Canary 26 A Psychology of Confrontation (essay) by Barbara Haupt 27-35 Urban (woodcut) by Carol Wilson 36 The Way They Make Guys (story) by Dennis Trudell 37-38 This story [ The Minister\u27s Narcissus ] by Julia Santucci has been awarded the semi-annual EXILE-Denison Bookstore creative writing prize. (pg 18

Effective Bacterial Inactivation and Removal of Copper by Porous Ceramics with High Surface Area

In this study, we present porous ceramics combining the antibacterial effect of copper with an integrated copper removal adsorbent. After preparing and characterizing the antibacterial copper-doped microbeads and monoliths (CuBs and CuMs), their antibacterial efficiency is probed against different nonpathogenic and pathogenic bacteria (<i>Bacillus subtilis</i>,<i> Escherichia coli</i>,<i> Staphylococcus aureus</i>, and <i>Pseudomonas aeruginosa</i>). An antibacterial efficiency of 100% is reached within 15 min to 3 h for all tested strains under static conditions. Dynamic tests with <i>B. subtilis</i> and <i>E. coli</i> showed high antibacterial efficiency up to 99.93% even at continuous flux. To avoid any adverse effects on the environment, continuous removal of released copper-ions is accomplished with porous, high surface area monolithic adsorbents (MAds). MAds are prepared similarly to the CuMs but without adding copper during the manufacturing process. MAds reduce the amount of copper released from the CuMs ≥ 99% during the first 15 min, ≥90% up to 2 h, and after 22 h of continuous filtration up to 56% of the released copper is removed