Pesticides and organic waste constitute a group of environmental pollutants that are widely distributed in our environment due to various human activities. Adsorptive removal and photocatalytic ...degradation of these pollutants from water have emerged as energy and cost-effective technologies. However, advanced oxidation technologies are gaining attention as an effective method for wastewater treatment capable of degrading a diverse spectrum of organic contaminants. Photocatalysis is a promising advanced oxidation technology to alleviate water pollution problems. Titanium dioxide (TiO
2
) is the most popular photocatalyst due to its low cost, nontoxicity, high oxidizing abilities, and easy immobilization on various surfaces. The current review aims to highlight recent advancements in photocatalytic degradation of pesticides and major organic pollutants using TiO
2
-based photocatalysts. Indeed, most of the methods, which employed potent catalysts, showed and exhibited successful degradation of the pesticides under various conditions. We believe this topic of research is extremely vital and will continue to grow in recent years, reaching ultimate desirable results and find more applications in different fields of study.
Zeolite frameworks provide an excellent host for metal ions like silver, gold, and copper. The modified zeolites were characterized using various spectroscopic techniques, including low-temperature ...solid-state luminescence, Raman and FT-EXAFS, SEM–EDS, X-Ray fluorescence, along with theoretical calculations. Analyses indicate the formation of metal ion oligomers for the studied silver- and gold-incorporated zeolite catalysts. The oligomer-incorporated zeolites were found to provide strong photocatalytic behavior towards pesticides and chlorinated organic pollutants. Various catalytic parameters like the metal composition, pore diameter, structure, surface area as well as proposed kinetic mechanisms for the photocatalytic reactions are presented in this mini review.
Larvae of black soldier flies, Hermetia illucens, are increasingly used for biological conversion of animal and plant wastes into ingredients of animal feeds on an industrial scale. The presence of ...pathogenic microorganisms in harvested larvae may be a serious problem for wide-scale adoption of this technology. Fortunately, black soldier fly larvae may have some antimicrobial properties. Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium associated with various environments that can be pathogenic to humans and farmed animals. We tested whether black soldier fly larvae suppress MRSA on potato substrate. Autoclaved potatoes containing black soldier fly larvae (P+BSFL), potatoes inoculated with MRSA and containing black soldier fly larvae (P+MRSA+BSFL), and potatoes inoculated with MRSA (P+MRSA) were incubated in glass jars. Substrate samples were taken after 3 and 7 days of incubation and plated on Trypticase soy agar (TSA) and Staphylococcus medium 110 agar (SA) to quantify total bacteria and MRSA, respectively. DNA was extracted from potato substrates on both days and sequenced to assess bacterial and fungal diversity using 515F/806R and internal transcribed spacer (ITS) 1/2 primers, respectively, and QIIME 2.0 software. Both total bacterial and MRSA-specific CFU were reduced in the presence of black soldier fly larvae, with a larger reduction for the latter. Twenty-five bacterial genera and 3 fungal genera were detected. Twenty bacterial genera were shared among the treatments and the days, but their relative abundances often varied. Among the most abundant genera, only
and
were universally present. Our findings confirm antimicrobial properties of black soldier fly larvae.
Larvae of black soldier flies, Hermetia illucens, may be used to provide an environmentally sustainable and economically viable method for biological conversion of animal and plant wastes into ingredients of animal feeds on an industrial scale. However, contamination of harvested larvae by pathogenic microorganisms inhabiting decaying substrates may be a serious problem for wide-scale adoption of this technology. Fortunately, black soldier fly larvae may have some antimicrobial properties, including suppression of several common pathogens. Our study showed that such a suppression applies to methicillin-resistant Staphylococcus aureus, which is a ubiquitous bacterium pathogenic to animals (including humans).
Chemical waste constitutes a group of environmental pollutants including pesticides, heavy metals, hormones, pharmaceuticals, and healthcare products that are widely distributed in our environment ...due to their wide use in various human activities. The presence of these compounds within local communities and ecosystems has drawn significant interest in improving the detection and bioremediation efforts of these compounds. Since these pollutants are highly mobile and stable under ambient conditions, there is a need to detect such pollutants in water and soil samples as an initial step that helps to eliminate their effect through adsorption or photocatalytic degradation processes. This review aims to highlight the origin of these pollutants and recent advancements in available analytical tools to detect such pollutants in environmental samples with a focus on pesticides, hormones, and pharmaceutical products. The environmental ecosystems of focus in this review involve soil, groundwater, and freshwater ecosystems. Various extraction and other pretreatment processes were also highlighted with a major focus on methods reported to decontaminate and help the environment through photocatalytic degradation of these pollutants under various conditions.
Graphical abstract
is a common and ubiquitous bacterium that can cause foodborne illnesses in humans and other animals. Common methods of contact between foodborne pathogens and their victims include exposure through ...contaminated food or food containment products. Using larvae of black soldier flies,
, for biological conversion of wastes into components of animal feeds is a rapidly growing technology. However, contamination of larval biomass with pathogenic microorganisms may challenge its use on an industrial scale. We conducted laboratory experiments to test the effects of the black soldier fly larvae developing on simulated potato waste substrate on
abundance. We observed a general increase in the number of colony-forming units and concentration of
- gene when the larvae were present in the substrate, although the effect was modulated by larval densities and time since inoculation. It is possible that starch breakdown by black soldier fly larvae may provide a beneficial environment for
. Our results differ from the suppression in the presence by black soldier fly larvae reported for several other bacterial species and highlight the importance of taking proper food safety measures when using this technology.
Phosphonium iodobismuthates(III) (MePh
3
P)
3
Bi
3
I
12
(
1
) and (Ph
4
P)
3
Bi
3
I
12
(
2
) were prepared, and X-ray crystal structures were determined for both complexes. Photophysical behavior ...of both complexes was determined via diffuse reflectance spectroscopy and photoluminescence measurements. Photoluminescence results for complex
2
revealed room temperature emission, which has been rarely reported by bismuth compounds. Low-temperature luminescence scans further indicated a dramatic change in emission properties between the MePh
3
P
+
and Ph
4
P
+
complexes. Photodegradation studies using both ultraviolet and visible light were carried out to determine the light-absorbing capabilities of both complexes. Visible light-promoted degradation studies in the presence of catalytic amounts of
1
and
2
showed significant degradation of aqueous methylene blue and carbaryl solutions over a period of 1 h. The reported photoirradiation studies indicated the phosphonium iodobismuthate salts promote visible light harvesting and facilitate catalytic dye photosensitization. This sensitization allows for the degradation of organic pollutants in the presence of visible light and suggests coupling with fluorescence dyes is viable in photovoltaic applications.
Optimizing materials and associated structures for detecting various environmental gas pollutant concentrations has been a major challenge in environmental sensing technology. Semiconducting metal ...oxides (SMOs) fabricated at the nanoscale are a class of sensor technology in which metallic species are functionalized with various dopants to modify their chemiresistivity and crystalline scaffolding properties. Studies focused on recent advances of gas sensors utilizing metal oxide nanostructures with a special emphasis on the structure-surface property relationships of some typical n-type and p-type SMOs for efficient gas detection are presented. Strategies to enhance the gas sensor performances are also discussed. These oxide material sensors have several advantages such as ease of handling, portability, and doped-based SMO sensing detection ability of environmental gas pollutants at low temperatures. SMO sensors have displayed excellent sensitivity, selectivity, and robustness. In addition, the hybrid SMO sensors showed exceptional selectivity to some CWAs when irradiated with visible light while also displaying high reversibility and humidity independence. Results showed that TiO
surfaces can sense 50 ppm SO
in the presence of UV light and under operating temperatures of 298-473 K. Hybrid SMO displayed excellent gas sensing response. For example, a CuO-ZnO nanoparticle network of a 4:1 vol.% CuO/ZnO ratio exhibited responses three times greater than pure CuO sensors and six times greater than pure ZnO sensors toward H
S. This review provides a critical discussion of modified gas pollutant sensing capabilities of metal oxide nanoparticles under ambient conditions, focusing on reported results during the past two decades on gas pollutants sensing.
Bacillus cereus is a common and ubiquitous bacterium that can cause foodborne illnesses in humans and other animals. Common methods of contact between foodborne pathogens and their victims include ...exposure through contaminated food or food containment products. Using larvae of black soldier flies, Hermetia illucens, for biological conversion of wastes into components of animal feeds is a rapidly growing technology. However, contamination of larval biomass with pathogenic microorganisms may challenge its use on an industrial scale. We conducted laboratory experiments to test the effects of the black soldier fly larvae developing on simulated potato waste substrate on B. cereus abundance. We observed a general increase in the number of colony-forming units and concentration of hblD - gene when the larvae were present in the substrate, although the effect was modulated by larval densities and time since inoculation. It is possible that starch breakdown by black soldier fly larvae may provide a beneficial environment for B. cereus. Our results differ from the suppression in the presence by black soldier fly larvae reported for several other bacterial species and highlight the importance of taking proper food safety measures when using this technology.
The focus of this thesis is to investigate the structural modification and characterization potential of common photocatalysts that have various uses for environmental remediation purposes. Pollution ...involving organic chemicals is one of the most common scenarios found in communities throughout the country. Efforts to rid contaminated drinking water supplies of these chemicals include physical and chemical filters, which have limited ability and efficacy. This lack of efficient filtration services has led to an increased demand for more effective treatment methods. Chemical species that react in the presence of light are known as photocatalysts and have been used in previous studies involving chemical reduction of pollutant species. Photocatalytic semiconductors have been investigated for their photochemical responses and ability to mineralize organic pollutants into unreactive species such as carbon dioxide. These photochemical responses have shown favorable in water treatment applications that utilize high energy irradiation sources. Previous studies have indicated complexes that contain bismuth were more efficient at photochemical reduction of organic pollutants as opposed to titanium centered species.In this study, well known photocatalytic complexes were modified through the addition of d-block metallic species. Complexes comprised of primarily Bi(III) centers where synthesized due to their ubiquitous presence in enviornmental remediation efforts. Concerns over the long-term environmental presence of these catalysts led to the development of complexes such as the ones listed in this study that remain environmentally benign. Mechanistic investigations of catalysis pathways revealed the distribution of electrons was facilitated through single electron transfer (SET) mechanisms. Oxidation-reduction reactions involving molecules of the surrounding medium generated free radical species that facilitated the hydrolyzation of the target pollutants. Novel findings in this study include the “electron trap” effect of photophysically active d-block elements in the presence of a known catalyst. The modified compounds of TiO2 and BiOCl have demonstrated remarkable efficacy and durability in photocatalytic applications yet continue to encounter serious drawbacks in continual wastewater treatment efforts.Several investigations were conducted throughout this study that determined the effectiveness of novel compounds in photocatalytic applications. To measure how these complexes react in the presence of various excitation sources, photoluminescence studies were performed to determine energetic pathways. Photodegradation experiments were conducted in aqueous solutions using both visible and ultraviolet irradiation sources. X-ray diffraction measurements on single crystal and powder samples were performed to corroborate the photophysical observations and physical structure. Transmission electron microscopy was used to measure photocatalyst size and morphology. Several visible light experiments were conducted throughout this study and only one compound, a halogenobismuth species, produced sufficient degradation results. The primary motivation for these studies were industrial drawbacks that led to the synthesis and design of photophysically active complexes which permitted solar utilization of ultraviolet and visible light. The addition of d10 metallic ions permitted increased proliferation of charge transfer mechanisms and formation of reactive radical species, which are the primary contenders in degradation through photocatalysis. These increased charge transfer mechanisms equate to sustain photodegradation and mineralization of organic species present. Our findings throughout this study enhance the experimental and mechanistic understandings of these metallic photocatalytic species in the use of environmental and wastewater treatment efforts.
