Photocatalytic inactivation of bacteria in water using suspended and immobilized silver-TiO2

Abstract

Incorporation of silver to titanium dioxide is of great interest for photocatalytic disinfection applications since in addition to the enhancement of the electron-hole separation and interfacial charge transfer and the increase in the visible light response, silver compounds present a strong bactericidal effect. Ag/TiO 2 materials used in suspension and immobilized in two different configurations (catalytic wall and fixed-bed reactors) have been prepared, characterized and tested using Escherichia coli as model microorganism. Although the incorporation of silver to powdered Degussa P25 TiO 2 increases the activity, the thermal treatment required for the stabilization of the supported metal particles reduces the global efficiency. The comparison with experiments of dye photodegradation indicates that the activity of Ag/TiO 2 is mainly due to the bactericidal role of silver and not to the enhancement of the photocatalytic mechanism. The best tested system has been proved to be the Ag/TiO 2 catalytic wall reactor with a 0.6 wt% of Ag loading, showing a high activity both in relative (per gram of TiO 2 ) and absolute terms, an optimal use of the radiation source, and a good stability of the film with negligible silver lixiviation, allowing the continuous treatment of water.

Enhancement of Air Filter with TiO2 Photocatalysis for Mycobacterium Tuberculosis Removal

“…10). In addition to more silver loading than iron loading on the filters as shown in Table 1, silver can destroy lipopolysaccharide molecules in cell membranes and even destroy the DNA of microorganisms (van Grieken et al, 2009). …”

Comparative study on the photoelectrocatalytic inactivation of Escherichia coli K-12 and its mutant Escherichia coli BW25113 using TiO2 nanotubes as a photoanode

“…This limitation can be surpassed by synthesizing new form of efficient photocatalysts or immobilizing TiO 2 catalysts onto conductors that enables the application of electrochemical techniques. Moreover, a photoeletrocatalytic (PEC) system with an external potential bias can provide a superior solution by suppressing the charge recombination [17][18][19][20][21][22][23][24]. Furthermore, compared to the powder forms of TiO 2 , TiO 2 nanotubes can transfer electron more effectively due to their special cannular structure [22,[25][26][27], and subsequently the bactericidal efficiencies in a PEC system can be remarkably enhanced [17,22,23,27].…”

Additional Effects of Silver Nanoparticles on Bactericidal Efficiency Depend on Calcination Temperature and Dip-Coating Speed

“…The deposition of metal elements into the TiO 2 matrix has been used to increase the efficiency of photocatalytic disinfection (12,37), resulting in an increase in the hole concentration and a decrease in band gap energy, which extends the range of the photoactive response to the visible light spectrum (36). Silver doping enhances electron hole separation in TiO 2 , the visible light excitation of TiO 2 , and by extension enhancement of the photocatalytic inactivation of microorganisms (30).…”