Review of hospital plastic waste management strategies for Pakistan

Environmental Science and Pollution Research - Healthcare waste management is considered one of the biggest challenges that the world is going to face in the future. This threat is becoming reality...     

Titania-supported silver-based bimetallic nanoparticles as photocatalysts

Photocatalytic process has shown recently a great potential as an environmental friendly and clean remediation technology for organic pollutants in wastewater. This work described the synthesis of silver-based bimetallic nanoparticles using colloid chemistry and the subsequent immobilization onto titania to form composite photocatalytic materials (titania-supported Ag–Pt nanoparticles). The photocatalysts were characterized by X-ray diffraction, electron microscopy, and nitrogen physisorption. The catalytic activity of the photocatalysts was evaluated by photocatalytic degradation of phenol and 2-chlorophenol (2-CP) in synthetic wastewater solutions. The photocatalytic processes were conducted in a batch photoreactor containing appropriate solutions of phenol and 2-CP with UV irradiation of 450 W. UV-visible spectrophotometer was used for analyzing the concentration of phenol and 2-CP in solutions. Parameters affecting the photocatalytic process such as the solution pH, phenol and 2-CP concentrations, and catalyst concentration were investigated. The results obtained revealed that TiO₂-supported Ag/Pt nanoparticles showed a higher activity for UV-photocatalytic degradation of both phenol and 2-CP pollutants in the solution (as compared to the plain rutile TiO₂). The photodegradation processes were optimized by the 0.5-g/L catalyst with a pollutant concentration of 50 mg/L for all the samples. Complete degradation for both phenol and 2-CP was achieved after 120 min.     

Potential applications of immobilized bitter gourd (Momordica charantia) peroxidase in the removal of phenols from polluted water

The potential applications of immobilized bitter gourd peroxidase in the treatment of model wastewater contaminated with phenols have been investigated. The synthetic water was treated with soluble and immobilized enzyme preparations under various experimental conditions. Maximum removal of phenols was found in the buffers of pH values 5.0-6.0 and at 40 degrees C in the presence of 0.75 mM H(2)O(2). Fourteen different phenols were independently treated with soluble and immobilized bitter gourd peroxidase in the buffer of pH 5.6 at 37 degrees C. Chlorinated phenols and native phenol were significantly removed while other substituted phenols were marginally removed by the treatment. Phloroglucinol and pyrogallol were recalcitrant to the action of bitter gourd peroxidase. Immobilized bitter gourd peroxidase preparation was capable of removing remarkably high percentage of phenols from the phenolic mixtures. Significantly higher level of total organic carbon was removed from the model wastewater containing individual phenol or complex mixture of phenols by immobilized bitter gourd peroxidase as compared to the soluble enzyme. 2,4-dichlorophenol and a phenolic mixture were also treated in a stirred batch reactor with fixed quantity of enzyme for longer duration. The soluble bitter gourd peroxidase ceased to function after 3h while the immobilized enzyme was active even after 6h of incubation with phenolic solutions.     

Determining soil quality in urban agricultural regions by soil enzyme-based index

Urban agricultural soils are highly variable, and careful selection of sensitive indicators is needed for the assessment of soil quality. This study is proposed to develop an index based on soil enzyme activities for assessing the quality of urban agricultural soils. Top soils were collected from urban agricultural areas of Korea, and soil chemical properties, texture, microbial fatty acids, and enzyme activities were determined. The soils belonged to five textural classes with the highest frequency of sandy loam. There was no clear correlation between the soil chemical properties and soil microbial properties. Principal component analysis (PCA) and factor analysis were applied to microbial groups for identification of microbial community variation in soils. Two soil groups, namely group 1 (G1) and group 2 (G2), based on microbial community abundance were examined by PCA, and those were more prominent in factor analysis. The G1 soils showed higher microbial community abundance than G2 soils. The canonical discriminant analysis was applied to the enzyme activities of sandy loam soil to develop an index, and the index validation was confirmed using the unused soils and published data. The high-quality soils in published literature assigned the high valued index. Microbial fatty acids and soil enzyme activities can be suitable indicators for soil quality evaluation of urban agricultural soils.

     

Use of Maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) for phytomanagement of Cd-contaminated soils: a critical review

Maize (Zea mays L.) has been widely adopted for phytomanagement of cadmium (Cd)-contaminated soils due to its high biomass production and Cd accumulation capacity. This paper reviewed the toxic effects of Cd and its management by maize plants. Maize could tolerate a certain level of Cd in soil while higher Cd stress can decrease seed germination, mineral nutrition, photosynthesis and growth/yields. Toxicity response of maize to Cd varies with cultivar/varieties, growth medium and stress duration/extent. Exogenous application of organic and inorganic amendments has been used for enhancing Cd tolerance of maize. The selection of Cd-tolerant maize cultivar, crop rotation, soil type, and exogenous application of microbes is a representative agronomic practice to enhance Cd tolerance in maize. Proper selection of cultivar and agronomic practices combined with amendments might be successful for the remediation of Cd-contaminated soils with maize. However, there might be the risk of food chain contamination by maize grains obtained from the Cd-contaminated soils. Thus, maize cultivation could be an option for the management of low- and medium-grade Cd-contaminated soils if grain yield is required. On the other hand, maize can be grown on Cd-polluted soils only if biomass is required for energy production purposes. Long-term field trials are required, including risks and benefit analysis for various management strategies aiming Cd phytomanagement with maize.     

Role of economic growth and innovative technologies in the outlook of energy and environmental efficiency: a way forward for developing Asian economies

Environmental Science and Pollution Research - Energy consumption is widely regarded as the primary driver of economic development and environmental degradation. The current study examines how...     

Correction to: Determining soil quality in urban agricultural regions by soil enzyme-based index

Environmental Geochemistry and Health - Unfortunately, in the original publication of the article, Prof. Yang Sik Ok’s affiliation was incorrectly published. The author’s affiliation is...     

Assessment of radiological hazard of NORM in Margalla Hills limestone, Pakistan

Studies on naturally occurring radioactive material (NORM) in the limestone from the Margalla Hills have been carried out by measuring gamma activity and to access its radiological implications if any. For data acquisition, a High-Purity Germanium detector was employed. The activity concentrations of (226)Ra, (232)Th, and (40)K were found to be 14.32?±?0.24, 2.05?±?0.04, and 13.80?±?0.20 Bq kg(-1), respectively. These values are relatively lower as compared to that in the limestone of other countries and much lower than the values reported for the natural building stones. The average specific activities due to (226)Ra were found to be higher when compared with (40)K and (232)Th. Indices of radium equivalent activity (Ra(eq)), internal hazard (H(in)), indoor absorbed gamma dose rate (D(R,)), and corresponding annual effective dose (E(eff)) were also determined for the limestone-made rooms. All of these indices were found to be in the lower ranges. The Margalla Hills limestone does not pose any excessive radiological health hazard as a building material and in industrial uses for a common man.     

Kinetics of carbon mineralization of biochars compared with wheat straw in three soils

Application of biochars to soils may stabilize soil organic matter and sequester carbon (C). The objectives of our research were to study in vitro C mineralization kinetics of various biochars in comparison with wheat straw in three soils and to study their contribution to C stabilization. Three soils (Oxisol, Alfisol topsoil, and Alfisol subsoil) were incubated at 25°C with wheat straw, charcoal, hydrothermal carbonization coal (HTC), low-temperature conversion coal (LTC), and a control (natural organic matter). Carbon mineralization was analyzed by alkali absorption of CO released at regular intervals over 365 d. Soil samples taken after 5 and 365 d of incubation were analyzed for soluble organic C and inorganic N. Chemical characterization of biochars and straw for C and N bonds was performed with Fourier transformation spectroscopy and with the N fractionation method, respectively. The LTC treatment contained more N in the heterocyclic-bound N fraction as compared with the biochars and straw. Charcoal was highly carbonized when compared with the HTC and LTC. The results show higher C mineralization and a lower half-life of straw-C compared with biochars. Among biochars, HTC showed some C mineralization when compared with charcoal and LTC over 365 d. Carbon mineralization rates were different in the three soils. The half-life of charcoal-C was higher in the Oxisol than in the Alfisol topsoil and subsoil, possibly due to high Fe-oxides in the Oxisol. The LTC-C had a higher half-life, possibly due to N unavailability. We conclude that biochar stabilization can be influenced by soil type.     

Decolorization of direct dyes by salt fractionated turnip proteins enhanced in the presence of hydrogen peroxide and redox mediators

The present paper demonstrates the effect of salt fractionated turnip (Brassica rapa) proteins on the decolorization of direct dyes, used in textile industry, in the presence of various redox mediators. The rate and extent of decolorization of dyes was significantly enhanced by the presence of different types of redox mediators. Six out of 10 investigated compounds have shown their potential in enhancing the decolorization of direct dyes. The performance was evaluated at different concentrations of mediator and enzyme. The efficiency of each natural mediator depends on the type of dye treated. The decolorization of all tested direct dyes was maximum in the presence of 0.6mM redox mediator at pH 5.5 and 30 degrees C. Complex mixtures of dyes were also maximally decolorized in the presence of 0.6mM redox mediator (1-hydroxybenzotriazole/violuric acid). In order to examine the operational stability of the enzyme preparation, the enzyme was exploited for the decolorization of mixtures of dyes for different times in a stirred batch process. There was no further change in decolorization of an individual dye or their mixtures after 60 min; the enzyme caused more than 80% decolorization of all dyes in the presence of 1-hydroxybenzotriazole/violuric acid. However, there was no desirable increase in dye decolorization of the mixtures on overnight stay. Total organic carbon analysis of treated dyes or their mixtures showed that these results were quite comparable to the loss of color from solutions. However, the treatment of such polluted water in the presence of redox mediators caused the formation of insoluble precipitate, which could be removed by the process of centrifugation. The results suggested that catalyzed oxidative coupling reactions might be important for natural transformation pathways for dyes and indicate their potential use as an efficient means for removal of dyes color from waters and wastewaters.