Sustainable conversion of COsub.2 to fuels using solar energy is highly attractive for fuel production. This work focuses on the synthesis of porous graphitic carbon nitride nanobelt catalyst ...(PN-g-Csub.3Nsub.4) and its capability of photocatalytic COsub.2 reduction. The surface area increased from 6.5 msup.2·gsup.−1 (graphitic carbon nitride, g-Csub.3Nsub.4) to 32.94 msup.2·gsup.−1 (PN-g-Csub.3Nsub.4). C≡N groups and vacant Nsub.2C were introduced on the surface. PN-g-Csub.3Nsub.4 possessed higher absorbability of visible light and excellent photocatalytic activity, which was 5.7 and 6.3 times of g-Csub.3Nsub.4 under visible light and simulated sunlight illumination, respectively. The enhanced photocatalytic activity may be owing to the porous nanobelt structure, enhanced absorbability of visible light, and surface vacant N-sites. It is expected that PN-g-Csub.3Nsub.4 would be a promising candidate for COsub.2 photocatalytic conversion.
NiTiOsub.3-BiOBr heterostructured photocatalysts were constructed via precipitation, calcination and hydrothermal treatments. Various characterizations demonstrated that BiOBr nanosheets were ...decorated on NiTiOsub.3 nanoparticals, forming porous rod-like heterojunctions. Compared with independent NiTiOsub.3 and BiOBr, the composites with optimal BiOBr content presented highly improved visible-light photocatalytic efficiency. The degradation rates of Rhodamine B (RhB) and tetracycline (TC) reached 96.6% in 1.5 h (100% in 2 h) and 73.5% in 3 h, which are 6.61 and 1.53 times those of NiTiOsub.3, respectively. The result is an improved photocatalytic behavior from the formation of heterojunctions with a large interface area, which significantly promoted the separation of photogenerated carriers and strengthened the visible-light absorption. Based on the free radical capture experiments and band position analysis, the photodegradation mechanism of type-II heterojunction was deduced. This study provides a new way to fabricate highly efficient NiTiOsub.3-based photocatalysts for degrading certain organics.
Water pollution is one of the major threats to public health in Pakistan. Drinking water quality is poorly managed and monitored. Pakistan ranks at number 80 among 122 nations regarding drinking ...water quality. Drinking water sources, both surface and groundwater are contaminated with coliforms, toxic metals and pesticides throughout the country. Various drinking water quality parameters set by WHO are frequently violated. Human activities like improper disposal of municipal and industrial effluents and indiscriminate applications of agrochemicals in agriculture are the main factors contributing to the deterioration of water quality. Microbial and chemical pollutants are the main factors responsible exclusively or in combination for various public health problems. This review discusses a detailed layout of drinking water quality in Pakistan with special emphasis on major pollutants, sources of pollution and the consequent health problems. The data presented in this review are extracted from various studies published in national and international journals. Also reports released by the government and non-governmental organizations are included.
Emerging organic contaminants (EOCs) detected in groundwater may have adverse effects on human health and aquatic ecosystems. This paper reviews the existing occurrence data in groundwater for a ...range of EOCs including pharmaceutical, personal care, ‘life-style’ and selected industrial compounds. The main sources and pathways for organic EOCs in groundwater are reviewed, with occurrence data for EOCs in groundwater included from both targeted studies and broad reconnaissance surveys. Nanogram-microgram per litre concentrations are present in groundwater for a large range of EOCs as well as metabolites and transformation products and under certain conditions may pose a threat to freshwater bodies for decades due to relatively long groundwater residence times. In the coming decades, more of these EOCs are likely to have drinking water standards, environmental quality standards and/or groundwater threshold values defined, and therefore a better understanding of the spatial and temporal variation remains a priority.
► First review to focus on EOCs in groundwater. ► A large range (n>180) of EOCs are detected in groundwater. ► Significant concentrations (102–104ng/L) for a range of EOCs, including endocrine disruptors. ► Groundwater EOC occurrence is poorly characterised compared to other freshwater resources.
A large range of emerging organic contaminants are now being detected in groundwater as a result of recent and historical anthropogenic activities.
PAN-COOH fibers were prepared with PAN fibers and used as templates, carbon source and nitrogen source for the first time to prepare carbon- and nitrogen-doped TiO.sub.2/carbon (C, N-TiO.sub.2) ...composite fibers. The C, N-TiO.sub.2 composite fibers were characterized by TEM, SEM, XPS, XRD, IR, Raman and UV-Vis spectrum. The composite fibers exhibited strong photocatalytic activity in photodegradation of Rh B solution under UV-Vis light. Doping C and N into TiO.sub.2 materials could reduce the band gap width of TiO.sub.2 and expand the light absorption range. The carbon fiber inside the composite fiber promoted the transfer of photoelectrons and inhibited the combination of photogenerated electrons and holes. The large specific surface area of C, N-TiO.sub.2 composite fibers was also conducive to the photocatalytic activity. The macroscale C, N-TiO.sub.2 composite fibers were easy for recycling. Therefore, the C, N-TiO.sub.2 composite fibers had the potential for dealing with organic pollutants in water.
Marine debris, especially plastic debris, is widely recognized as a global environmental problem. There has been substantial research on the impacts of plastic marine debris, such as entanglement and ...ingestion. These impacts are largely due to the physical presence of plastic debris. In recent years there has been an increasing focus on the impacts of toxic chemicals as they relate to plastic debris. Some plastic debris acts as a source of toxic chemicals: substances that were added to the plastic during manufacturing leach from plastic debris. Plastic debris also acts as a sink for toxic chemicals. Plastic sorbs persistent, bioaccumulative, and toxic substances (PBTs), such as polychlorinated biphenyls (PCBs) and dioxins, from the water or sediment. These PBTs may desorb when the plastic is ingested by any of a variety of marine species. This broad look at the current research suggests that while there is significant uncertainty and complexity in the kinetics and thermodynamics of the interaction, plastic debris appears to act as a vector transferring PBTs from the water to the food web, increasing risk throughout the marine food web, including humans. Because of the extremely long lifetime of plastic and PBTs in the ocean, prevention strategies are vital to minimizing these risks.
Microplastic pollution of marine environment is receiving increased publicity over the last few years. The present survey is, according to our knowledge, the survey with the largest sample size ...analyzed, to date. In total, 1337 specimens of fish were examined for the presence of plastic microlitter representing 28 species and 14 families. In addition, samples of seawater and sediment were also analyzed for the quantification of microplastic in the same region. Samples of water/sediment were collected from 18 locations along the Mediterranean coast of Turkey. 94% of all collected plastic microlitter from the sea was in the size range between 0.1 and 2.5 mm, while the occurrence of other sizes was rare. The quantity of microplastic particles in surface water samples ranged from 16 339 to 520 213 per km2. Fish were collected from 10 locations from which 8 were either shared with or situated in the proximity of water/sediment sampling locations. A total of 1822 microplastic particles were extracted from stomach and intestines of fish. Majority of ingested particles were represented by fibers (70%) and hard plastic (20.8%), while the share of other groups: nylon (2.7%), rubber (0.8%) and miscellaneous plastic (5.5%) were low. The blue color of plastic was the most dominant color. 34% of all examined fish had microplastic in the stomach. On average, fish which had microplastic contained 1.80 particles per stomach. 41% of all fish had microplastic in the intestines with an average of 1.81 particles per fish. 771 specimens contained microplastic in either stomach and/or intestines representing 58% of the total sample with an average of 2.36 particles per fish. Microplastic was found in all species/families that had sample size of at least 2 individuals. The number of particles present in either stomach or intestines ranged between 1 and 35. Ingested microplastic had an average diameter ±SD of 656 ± 803 μm, however particles as small as 9 μm were detected. The trophic level of fish species had no influence whatsoever on the amount of ingested microplastic. Pelagic fish ingested more microplastic than demersal species. In general, fish that ingested higher number of microplastic particles originated from the sites that also had a higher particle count in the seawater and sediment.
Display omitted
•58% of the fish ingested microplastic with an average of 2.36 particles per fish.•Microplastic was found in all species that had sample size of at least 2 individuals.•Ingested microparticles had an average diameter of 656 ± 803 μm.•Trophic level had no influence whatsoever on the amount of ingested microplastic.•Pelagic fish ingested more microplastic than demersal species.
58% of all the fish ingested microplastic with an average of 2.36 particles per fish and mean diameter ±SD of 656 ± 803 μm. Ingested particles were mainly fibers and hard plastic. Trophic level had no influence on the amount of ingested microplastic.
Tetracycline antibiotics (TCs) are widely used all over the world in recent decades. TCs are a family used as broadspectrum antibiotics and animal veterinary drugs. Among the TCs, tetracycline (TC) ...is the most use. Due to the rapid development of antibiotics industry, the dosage standards of TC are not yet clearly defined in most countries and regions. TC is hard to degrade in living organisms and can even be converted to more toxic substances. The overuse and wanton discharge of TC, also caused serious pollution of groundwater. This article attempts to summarize the latest knowledge on the nature, sources, pollution status, the impact on water environment toxicity of TC respectively. Meanwhile, there are many technologies to remove TC. This paper mainly included 12 kinds of degradation methods, including photodegradation, microbial removal, adsorption, electrochemical and sludge digestion. This review will provide a reference for the study of the basic properties and removal methods of TC.
PDF
