Synthesis, Characterization, and Photocatalytic Activity of N-Doped TiO2/Zeolite-NaY for Methylene Blue Removal

Dye is an important compound in textile industry. The famous dye for coloring of textile is methylene blue. Methylene blue degradation has been difficult when carried out naturally by microorganisms. The advanced oxidative process is a promising method to degrade methylene blue using semiconductor material TiO2 and its modification. The modification catalyst of TiO2 such as TiO2-N, TiO2/zeolite-NaY and TiO2-N/zeolite-NaY. These materials were synthesized by mixing TiO2 and urea, then followed by impregnation of the mixture to zeolite-NaY as support material. The materials have been synthesized then characterized by XRD, and FTIR. Degradation of methylene blue on the synthesized materials was tested under UV light for 5, 20, 30, 40, and 50 minutes. The results showed that the diffractogram of TiO-N/zeolite-NaY and TiO2/zeolite-Y has a similar spesific peak with TiO2 and zeolite-NaY. It indicates that the impregnation process was sucessfully. TiO2/zeolite-NaY and TiO2-N/zeolite-NaY also showed the excellent activity for degrading methylene blue, which reached up to 99% for 3 hours of reaction.

Photocatalytic Activity and Kinetic Study of Methylene Blue Degradation using N-Doped TiO2 with Zeolite-NaY

<p class="E-JOURNALAbstractBodyEnglish">Methylene blue is the most widely used dye in the industry and it is difficult to be degraded by the microorganism. This research aims to investigate the photocatalytic activity and effects of contact time on the photocatalytic degradation rate of methylene blue by TiO₂/Zeolite-NaY and TiO₂-N/Zeolite-NaY material based on the kinetic study. The Advanced Oxidative Process (AOP) method was used to degrade methylene blue. Furthermore, the AOP is a degradation process that uses semiconductor material such as TiO₂ or modification catalyst of TiO₂to be TiO₂/Zeolite-NaY and TiO₂-N/Zeolite-NaY. The degradation of methylene blue with catalyst TiO₂/Zeolite-NaY and TiO₂-N/Zeolite-NaY were tested under UV light for 5, 20, 30, 40, and 50 minutes. The result showed that TiO₂/Zeolite-NaY and TiO₂-N/Zeolite-NaY had an excellent activity for degrading the dye, which reached up to 99% after 20 and 30 minutes reaction, respectively. Also, a kinetic study of methylene blue degradation on TiO₂/Zeolite-NaY and TiO₂-N/Zeolite-NaY showed the kinetic models were according to pseudo-second-order.</p>

Survival and Inactivation by Advanced Oxidative Process of Foodborne Viruses in Model Low-Moisture Foods

Enteric viruses, such as human norovirus (NoV) and hepatitis A virus (HAV), are the major causes of foodborne illnesses worldwide. These viruses have low infectious dose, and may remain infectious for weeks in the environment and food. Limited information is available regarding viral survival and transmission in low-moisture foods (LMF). LMFs are generally considered as ready-to-eat products, which undergo no or minimal pathogen reduction steps. However, numerous foodborne viral outbreaks associated with LMFs have been reported in recent years. The objective of this study was to examine the survival of foodborne viruses in LMFs during 4-week storage at ambient temperature and to evaluate the efficacy of advanced oxidative process (AOP) treatment in the inactivation of these viruses. For this purpose, select LMFs such as pistachios, chocolate, and cereal were inoculated with HAV and the norovirus surrogates, murine norovirus (MNV) and feline calicivirus (FCV), then viral survival on these food matrices was measured over a four-week incubation at ambient temperature, by both plaque assay and droplet-digital RT-PCR (ddRT-PCR) using the modified ISO-15216 method as well as the magnetic bead assay for viral recovery. We observed an approximately 0.5 log reduction in viral genome copies, and 1 log reduction in viral infectivity for all three tested viruses following storage of select inoculated LMFs for 4 weeks. Therefore, the present study shows that the examined foodborne viruses can persist for a long time in LMFs. Next, we examined the inactivation efficacy of AOP treatment, which combines UV-C, ozone, and hydrogen peroxide vapor, and observed that while approximately 100% (4 log) inactivation can be achieved for FCV, and MNV in chocolate, the inactivation efficiency diminishes to approximately 90% (1 log) in pistachios and 70% (< 1 log) in cereal. AOP treatment could therefore be a good candidate for risk reduction of foodborne viruses from certain LMFs depending on the food matrix and surface of treatment.

Degradation of boscalid, pyraclostrobin, fenbuconazole, and glyphosate residues by an advanced oxidative process utilizing ultraviolet light and hydrogen peroxide

Recently an advanced oxidative process (AOP) combining H2O2 and UV-C light was observed to be effective at controlling Listeria monocytogens (Murray et al., 2018) and Escherichia coli O157:H7 and degrading chlorpyrifos residues on the surface of apples (Ho et al., 2020). Little is known about the application of AOP for the degradation of other pesticide residues. This study examined degradation of boscalid, pyraclostrobin, fenbuconazole and glyphosate by 3% (w/v) H2O2, UV-C (254 nm) irradiation and their combination on apple skin and glass. The extent of degradation was not significantly different between the AOP and optimal individual treatment. However, treatment susceptibility was different with glyphosate most effectively degraded by H2O2 exposure (up to 98% on apple, 3% (w/v) H2O2 at 30□C for 15 min) while boscalid, pyraclostrobin and fenbuconazole were more effectively degraded by UV-C (up to 88%, 100% and 70% degradation after ~11,000 mJ/cm2). Suggestions for possible causes of degradation are proposed.

Survival and Inactivation by Advanced Oxidative Process of Foodborne Viruses in Model Low-Moisture Foods

Enteric viruses, such as human norovirus (NoV) and hepatitis A virus (HAV), are the major causes of foodborne illnesses worldwide. These viruses are shed in high numbers, have low infectious dose, and may remain infectious for weeks in the environment and food. While numerous viral survival studies have been conducted in fresh fruits and produce, limited information is available regarding viral survival and transmission in low moisture foods (LMF). LMFs are generally considered as ready-to-eat products, which undergo no or minimal pathogen reduction steps. However, numerous foodborne outbreaks associated with LMFs have been reported in recent years. The objective of this study was to examine the survival of foodborne viruses in LMFs during long-term storage at ambient temperature and to evaluate the efficacy of advanced oxidative process (AOP) treatment in the inactivation of these viruses. For this purpose, select LMFs such as pistachios, chocolate, and cereal were inoculated with HAV and the norovirus surrogates, murine norovirus (MNV) and feline calicivirus (FCV), then viral survival on these food matrices was measured over a four-week incubation at ambient temperature, by both plaque assay and droplet-digital RT-PCR (ddRT-PCR). We observed an approximately 0.5 log reduction in viral genome copies, and 1 log reduction in viral infectivity for all three tested viruses following storage of select inoculated LMFs for 4 weeks. Therefore, the present study shows that foodborne viruses can persist for long-time in LMFs. Next, we examined the inactivation efficacy of AOP treatment, which combines UV-C, ozone, and hydrogen peroxide vapor, and observed that while approximately 100% inactivation can be achieved for FCV, MNV, and HAV in chocolate, the inactivation efficiency diminishes to approximately 90% in pistachios and 70% in cereal. AOP treatment could therefore be a good candidate for the elimination of foodborne viruses from certain LMFs depending on the food matrix and surface of treatment.ImportanceLow moisture foods have been increasingly recognized as important vehicles of foodborne pathogens. In the present study, we demonstrated that foodborne viruses remain infectious during long-term storage on select low moisture foods. In addition, we evaluated the efficacy of an advanced oxidative process in the inactivation of foodborne viruses in low moisture foods. This research will help increase the safety of low moisture foods and reduce the number of foodborne illnesses due to contaminated products.