Recycling polymeric waste from electronic and automotive sectors into value added products

The environmentally sustainable disposal and recycling of ever increasing volumes of electronic waste has become a global waste management issue. The addition of up to 25% polymeric waste PCBs (printed circuit boards) as fillers in polypropylene (PP) composites was partially successful: while the tensile modulus, flexural strength and flexural modulus of composites were enhanced, the tensile and impact strengths were found to decrease. As a lowering of impact strength can significantly limit the application of PP based composites, it is necessary to incorporate impact modifying polymers such as rubbery particles in the mix. We report on a novel investigation on the simultaneous utilization of electronic and automotive rubber waste as fillers in PP composites. These composites were prepared by using 25 wt.% polymeric PCB powder, up to 9% of ethylene propylene rubber (EPR), and PP: balance. The influence of EPR on the structural, thermal, mechanical and rheological properties of PP/PCB/ EPR composites was investigated. While the addition of EPR caused the nucleation of the β crystalline phase of PP, the onset temperature for thermal degradation was found to decrease by 8%. The tensile modulus and strength decreased by 16% and 19%, respectively; and the elongation at break increased by ~71%. The impact strength showed a maximum increase of ~18% at 7 wt.%–9 wt.% EPR content. Various rheological properties were found to be well within the range of processing limits. This novel eco-friendly approach could help utilize significant amounts of polymeric electronic and automotive waste for fabricating valuable polymer composites.

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Removal of hexavalent chromium upon interaction with biochar under acidic conditions: mechanistic insights and application

Environmental Science and Pollution Research - Chromium pollution of soil and water is a serious environmental concern due to potential carcinogenicity of hexavalent chromium [Cr(VI)] when...     

Black carbon aerosols in urban air in South Asia

We report data from a yearlong (2006–2007) study of black carbon concentrations ([BC]) measured at 5-min intervals with an Aethalometer in Karachi, Pakistan. Daily mean [BC] varied from about 1 to 15 μg m^?3. However, short-term spikes exceeding 40 μg m^?3 were common, occurring primarily during the morning and evening rush-hour periods. The [BC] values were highest during November through February, ～10 μg m^?3, and lowest during June through September, ～2 μg m^?3. Diurnal, seasonal, and day-of-the-week trends are discussed. It is demonstrated that these trends are strongly affected by meteorological patterns. A simple expression is applied to the concentration profiles to separate the effects of meteorological conditions and elucidate the underlying emissions patterns. Daily emissions varied from 14,000 to 22,000 kg of BC per day. When integrated over the year emissions for Karachi Proper were estimated at 6.7 kilometric tons per year and emissions for greater Karachi were 17.5 kilometric tons per year. Folding in the populations of each area yields BC emissions of 0.74 and 1.1 kg per person per year, respectively. Applying the model to previously collected data at Lahore, Pakistan yields emissions during November–January that are around a factor of two higher than those in Karachi, but because the BC measurements in Lahore covered only three months, no estimates of annual emissions were attempted. Given the large populations of these cities the local health impact from PM alone is expected to be severe but because of the high [BC] emissions the impact on the global climate may be equally significant.     

Gender-based comparative toxicity of di-ethyl phthalate in Wistar rats

In recent years, the exposure of humans to phthalate esters through environmental contamination has increased. One among them is di-ethyl phthalate (DEP), which is used as a plastisizer for cellulose ester plastic films and sheets, solid rocket propellants, molded and extruded articles, as a component in insecticide sprays and various other substances, as well as in industrial applications. Release into the environment occurs primarily as a result of production and manufacturing of DEP and during the use and disposal of products containing DEP. Therefore, a study was undertaken to evaluate gender-specific toxicity of DEP in Wistar rats. Rats of both sexes, weighing 125–130?g, were administered 50?ppm (w/v) DEP in water ad libitum for a period of 180 days and were given normal diet. Control animals received normal diet and water ad libitum. During the treatment, rats were weighed every week and water consumption per day was measured. After the completion of treatment, liver weight?:?body weight^?1 ratio, liver weight, body weight^?1, liver and serum enzymes, and other biochemical parameters of liver and serum were assessed. It was observed that there was no significant change in body weight^?1, liver weight, liver weight?: body weight^?1 ratio, and water consumption in both sexes. There were significant increases in liver acid phosphatase (ACP) activity and kidney glutathione levels, and nonsignificant changes in liver alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), succinate dehydrogenase (SDH), and lactate dehydrogenase (LDH) activities in DEP-treated male rats, whereas in DEP-treated female rats the liver showed significant decrease in ALP and SDH and nonsignificant changes in AST, ALT, and LDH activities. Serum ACP and LDH levels in DEP-treated male rats were significantly decreased, and in the case of DEP-treated female rats, only serum LDH levels were significantly decreased. There was no significant change in serum ALP, AST, and SDH levels in DEP-treated male and female rats as compared to control rats. Histology of the livers of both male and female rats showed loss of hepatic architecture, degenerative changes in hepatocytes, and vacuolation in hepatocytes in both the centrilobular and periportal areas. It can be concluded from this study that prolonged exposure to DEP at 50?ppm levels can be harmful to animals and humans. This is evident from the present study as certain significant changes in enzyme activities in the liver, serum, and histological alterations in liver were observed.     

Determination of cadmium in water and herbal medicine by Penicillium chrysogenum immobilized on silica gel for flame atomic absorption spectroscopy

Penicillium chrysogenum was immobilized on silica to develop a simple and cost effective method for solid phase extraction of Cd(II) and determination using flame atomic absorption spectrometry (FAAS). The sorbent was characterized by Fourier transform infrared spectroscopy and packed into a column. The conditions for quantitative sorption and desorption of Cd(II) were optimized. The preconcentration factor was 100 while detection limit was 0.61 µg L^?1 with a relative standard deviation of 1.0%. The method was applied for determination of Cd in herbal medicine and tap water.     

Variations in physico-chemical and microbiological characteristics of water during breeding of Cyprinus carpio in a closed hatchery system

Physico-chemical and microbial characteristics of culture water were examined during the induced breeding of Cyprinus carpio in a controlled environmental system. Water temperature, dissolved oxygen, nitrate, phosphate, pH, ammonia nitrogen, total bacterial count, hardness, salinity, carbonate and bicarbonate were estimated before and after spawning and hatching. Average alteration in water pH before and after spawning was 7.91-7.57 and 7.86-7.58 respectively. Total hardness, carbonate and bicarbonate showed insignificant variations. Nitrate, ammonia nitrogen and phosphate contents significantly increased after spawning and hatching p < 0.05. The average increase in nitrate was from 2.94 to 8.62 microg l(-1) after spawning and 3.10 to 8.49 microgl(-1) after hatching. Ammonia nitrogen contents were sharply increased from an average of 0.011 to 1.87 mg l(-1) after spawning and 0.013 to 0.56 mg l(-1) after hatching. The average phosphates increased from 2.59 to 4.15 microg l(-1) after spawning and 2.61 to 4.03 microg l(-1) after hatching. Dissolved oxygen was sharply depleted even after a continuous aeration. Temperature played a vital role during breeding. No successful breeding was observed at a temperature of 17 degrees C or below and 31 degrees C or above. There is a significant association between temperature, spawning and hatching (p < 0.05). By optimizing temperature, the breeding success of this carp was achieved with a statistical significance of p < 0.05. Total bacterial count was significantly increased after spawning and hatching. It was related to the amount of discharge and may cause mass mortality of fish embryo and spawn in a closed hatchery system.     

Acidic bioleaching of heavy metals from sewage sludge

The overall objective of this study was to evaluate the use of controlled bio-acidification prior to land application as a decontamination process to remove heavy metals from sludge. The sulfur-oxidizing bacteria were naturally available in the sludge samples and were activated by providing sulfur and aeration at 28°C–30°C. Activation resulted in bio-acidification to pH 2 within 5–11 days. Successive inoculation of fresh sludges with 5% acidified samples reduced the acidification time to 2–3 days in most samples. Bio-acidification resulted in dissolving significant quantities of heavy metals from all sludge types tested. The maximum solubilization results were: 86%–97% for Ni; 48%–98% for Pb; 26%–71% for Cr; 18%–91% for Zn; 16%–90% for Cu; 7%–60% for Cd. Limited metal solubilization results were observed in the various control samples that accompanied the bio-acidified samples. The leaching results in the control samples were limited to 2%–19% for Ni, 0%–7% for Pb, 0%–5% for Cr, 0.3%–4% for Zn, 0.2%–4% for Cu and 0%–3% for Cd. The results confirmed that Ni and Pb were the easiest metals to dissolve from the various sludge types. On the other hand, the lowest solubilization results were observed for Cu and Cd, and moderate solubilization results were achieved for Cr. The bio-acidification process resulted in moderate gains in terms of improving the suitability of tested sludges for land application. Received: April 19, 1999 / Accepted: November 4, 1999     

A linear and nonlinear approach for interpretation of groundwater quality based on water quality index

In this study using linear and nonlinear approach, aggregate indices for various water quality parameters were analyzed. Using a linear and nonlinear interpolating surface, various water quality variables at grid points were investigated that is essential for mapping. The values help in constituting a key approach for determining the water quality index (WQI), which converts pollutant concentration data into subindex values and then combines them into a single score. One of the biggest advantages of WQI is its summary and intuitive communication capability which will be extremely helpful for demarcating safe aquifer zones of groundwater and in the selection of suitable method for remedial. The present study also describes pollution potential in ground water of Madhya Pradesh, India. The aggregate indices suggest intermediate to high pollution susceptibility in some region of Madhya Pradesh that may increase further if not managed. The overall interpretation of the study will be helpful in formulating suitable approach for water quality interpretation and sustainable planning of groundwater resources.     

Appraisal of salinity and fluoride in a semi-arid region of India using statistical and multivariate techniques

Various physico-chemical parameters, including fluoride (F⁻), were analyzed to understand the hydro-geochemistry of an aquifer in a semi-arid region of India. Furthermore, the quality of the shallow and deep aquifer (using tube well and hand pumps) was also investigated for their best ecological use including drinking, domestic, agricultural and other activities. Different multivariate techniques were applied to understand the groundwater chemistry of the aquifer. Findings of the correlation matrix were strengthened by the factor analysis, and this shows that salinity is mainly caused by magnesium salts as compared to calcium salts in the aquifer. The problem of salinization seems mainly compounded by the contamination of the shallow aquifers by the recharging water. High factor loading of total alkalinity and bicarbonates indicates that total alkalinity was mainly due to carbonates and bicarbonates of sodium. The concentration of F⁻ was found more in the deep aquifer than the shallow aquifer. Further, only a few groundwater samples lie below the permissible limit of F⁻, and this indicates a risk of dental caries in the populace of the study area. The present study indicates that regular monitoring of groundwater is an important step to avoid human health risks and to assess its quality for various ecological purposes.     

Nano-inspired systems in food technology and packaging

Creation of food-based nanomaterials for food processing and packaging applications is actually gaining in importance. Indeed, the design of a suitable food carrier system controls the encapsulation efficiency, the product stability and release of bioactives such as micronutrients, antimicrobial compounds and antioxidants. The smaller size of nanomaterials provides higher thermodynamic and kinetic stability. Whereas the higher surface area enhances compound solubility. Nanoemulsions both encapsulate bioactive compounds effectively and address the food safety concerns of the fresh produce associated with foodborne pathogens. Nanoliposomes encapsulate bioactive whey peptides and fat-soluble vitamins with improved functionalities. Encapsulated bioactive molecules are released by diffusion into the surrounding environment after degradation of the surrounding polymeric matrix.