[Show abstract][Hide abstract] ABSTRACT: The aim of this research was to generate titania-embedded polythene (PE) material that is photo catalytically degradable and could also serve as a photocatalysis vehicle. Titania Nanoparticles (TNPs) prepared from General Purpose TiO 2 powder, by hydrothermal method and characterized by SEM, XRD and EDX, were used to prepare pure and titania embedded (0e20%) PE composite films. Photocatalytic degradation, separately under UV and visible light, of these films was monitored for a period of 90 days. PE film weight loss, due to degradation, under UV and visible light, was found to be 60% and 33% respectively. The film deterioration was confirmed by FTIR and SEM analysis. On the other hand, the potential of the degraded titania-PE material, to photo catalytically degrade a model pollutant, Dri-marene Brilliant Red (DBR) dye, was examined. For this purpose, PE films having suffered around 50% weight loss were allowed to interact with DBR dye, in a batch mode, under UV and visible light. Compared to the fresh titania-embedded films, the degraded material showed a considerable activity as regards discoloration of the dye, following zero order kinetics. The novel photocatalyst (degraded titania embedded PE films) was recovered and reused for four cycles with minor loss of activity.
[Show abstract][Hide abstract] ABSTRACT: The study describes optimization of the laser-induced breakdown spectroscopy (LIBS) experimental parameters for the determination of heavy metals in ambient air particulate matter. The optimization was performed using solidified metal standards on filter discs. The optimized values of LIBS parameters were 4.5 μs (delay time), 89.5 mJ (laser pulse energy), and 70 mm (lens to sample surface distance). At these optimized values LIBS demonstrated strong spectrum lines for each metal keeping the background noise at minimum level.The new method of preparing metal standards on filter discs exhibited calibration curves with good linearity over the concentration range 50–500 ppm with correlation coefficients, R
2 in the range of 0.992–0.998. The limit of detection for the three metals was in the range of 29–48 ppm. The developed method was tested on real ambient air samples for determination of cadmium, zinc, and lead. The concentration of various metals determined by the developed LIBS method was verified against a conventional analytical technique, flame atomic absorption spectroscopy.
ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 07/2013; 38(7). DOI:10.1007/s13369-013-0548-7 · 0.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This paper illustrates systematic development of a convenient analytical method for the determination of chromium and cadmium in tannery wastewater using laser-induced breakdown spectroscopy (LIBS). A new approach was developed by which liquid was converted into solid phase sample surface using absorption paper for subsequent LIBS analysis. The optimized values of LIBS parameters were 146.7 mJ for chromium and 89.5 mJ for cadmium (laser pulse energy), 4.5 μs (delay time), 70 mm (lens to sample surface distance), and 7 mm (light collection system to sample surface distance). Optimized values of LIBS parameters demonstrated strong spectrum lines for each metal keeping the background noise at minimum level. The new method of preparing metal standards on absorption papers exhibited calibration curves with good linearity with correlation coefficients, R(2) in the range of 0.992 to 0.998. The developed method was tested on real tannery wastewater samples for determination of chromium and cadmium.
[Show abstract][Hide abstract] ABSTRACT: Due to large growth in leather and textile industries to cater for the needs of a growing world population, contamination of soil and water resources by chromium has become a great threat for humans and animals. In this work, Laser Induced Breakdown Spectroscopy (LIBS) was applied to monitor the remediation process of soil contaminated with Chromium metal. This study was conducted at a laboratory scale by setting up an experiment in a container holding soil contaminated with chromium. This setup represents actual field conditions where remediation process could be applied and monitored for the removal of toxic metals like Cr. For generation of LIBS spectrum, the plasma was produced by focusing a pulsed Nd: YAG laser at 1064 nm on the soil contaminated with chromium under remediation process. The evaluation of the potential and capabilities of LIBS as a rapid tool for remediation process of contaminated sites is discussed in detail. Optimal experimental conditions were evaluated for improving the sensitivity of our LIBS system for monitoring of remediation process through parametric dependence study. The minimum detection limit of our spectrometer for chromium in soil matrix was 2 mg Kg(-1).
[Show abstract][Hide abstract] ABSTRACT: This paper describes a constructed wetland treatment system designed to treat wastewater from oil refinery. In 2003, to promote the practical development of constructed wetlands (CWs) used for industrial wastewater treatment in Pakistan, a series of investigations was conducted to evaluate the feasibility of using constructed treatment wetlands to remove pollutants from refinery wastewater. The main objective of the research was to quantify the effect of different filter media on the treatment performance of vertical flow wetlands in the prevailing climate of Pakistan. Wastewater produced from the oil refinery contains high concentrations of organic and inorganic pollutants; therefore it cannot be discharged directly into river without any treatment. Phragmites karka were planted in both containers as a vertical flow wetland to evaluate their efficiencies in the purification of wastewater and their growth in wetlands fed with oil refinery wastewater. The results from a 1-year treatment showed that the purifying efficiency of constructed wetlands for oil-refined wastewater was low at the beginning but it improved gradually with the growth of plants and biofilm. Thus, a gravel-filled wetland and organic compost filled wetland were operated identically with primarily treated refinery wastewater at a hydraulic loading rate of 0.100 m d−1, intermittently. According to the results, the removal efficiencies for the compost and gravel wetland cells varied as follows during the experimental period of 1 year: total suspended solids (TSS) (51–73% and 39–56%), chemical oxygen demand (COD) (45–78% and 33–61%), biological oxygen demand (BOD) (35–83% and 35–69%) and significant removal of heavy metals, i.e. Fe2+, Cu2+ and Zn2+, was observed. The treatment performances of the compost-filled wetland were better than that of the gravel-filled wetland in terms of removal of COD and BOD. Since this study was a pioneer for implementation of vertical flow constructed wetlands in Pakistan using local sources, it has proved that this eco-technology could also be used effectively for water quality enhancement in Pakistan.
[Show abstract][Hide abstract] ABSTRACT: Study of various binding materials like potassium bromide, poly(vinyl alcohol), starch, silver and aluminum has been carried out using laser-induced breakdown spectroscopy (LIBS). The role of matrix effects using these five binders on LIBS signal intensity was investigated for better performance of LIBS technique as a quantitative analytical tool. For comparative study of different binders, the signal intensity of different Mg lines at 518.3, 517.2, 383.8 and 279.5nm wavelengths were recorded for pellets prepared with known concentrations of Mg in these binders. The influence of laser energy on ablated mass under different binding materials and its correlation with LIBS signal intensity has been explored. Optical scanning microscopy images of the ablated crater were studied to understand the laser ablation process. The study revealed that the binding material plays an important role in the generation of LIBS signal. The relative signal intensity measured for a standard Mg line (at 518.3nm) were 735, 538, 387, 227 and 130 for potassium bromide, starch, poly(vinyl alcohol), silver and aluminum as binders, respectively. This indicates clearly that potassium bromide is better as a binder for LIBS studies of powder samples.
[Show abstract][Hide abstract] ABSTRACT: Laser-induced breakdown spectroscopy (LIBS) has been applied for the determination of nutrients in the green house soil samples. We determined appropriate spectral signatures of vital nutrients and calibrated the method to measure the nutrients in a naturally fertilized plot, cultivated with tomato and cucumber plants. From the calibration curves we predicted the concentrations of important nutrients such as Ca, K, P, Mg, Fe, S, Ni and Ba in the soil. Our measurements proved that the LIBS method rapidly and efficiently measures soil nutrients with excellent detection limits of 12, 9, 7, 9, 7, 10, 8 and 12 mg/kg for Ca, K, P, Mg, Fe, S, Ni and Ba respectively with a precision of approximately 2%, The unique features of LIBS for rapid sample analysis demonstrated by this study suggests that this method offers promise for precision measurements of soil nutrients as compared to conventional methods in short span of time.
[Show abstract][Hide abstract] ABSTRACT: Laser induced breakdown spectroscopy (LIBS) was applied for the elemental analysis of Arabian crude oil residue samples. The spectra due to trace elements such as Ca, Fe, Mg, Cu, Zn, Na, Ni, K and Mo were recorded using this technique. The dependence of time delay and laser beam energy on the elemental spectra was also investigated. Prior to quantitative analysis, the LIBS system was calibrated using standard samples containing these trace elements. The results achieved through this method were compared with conventional technique like inductively coupled plasma.
[Show abstract][Hide abstract] ABSTRACT: Three aqueous oxidants, Hydrogen peroxide, Sodium Hypochlorite and Calcium Hypochlorite were employed independently in oxidizing Chromium (III) containing tannery wastewaters to soluble chromate (CrO42-) under alkaline conditions. The amount of chromate recovered was determined via spectrophotometry. Hydrogen peroxide was potentially a suitable oxidant as it could recover chromate (CrO42-) up to 98% (from synthetic Cr3+ solution) and 88% (from effluent I). The percentage recoveries by the hypochlorites were lower than those by hydrogen peroxide i.e. for NaOCl the recoveries were up to 94% (from synthetic Cr3+ solution) and 67% (from effluent I), similarly for Ca(OCl)2 90% (from synthetic Cr3+ solution) and 49% (from effluent I). For all three oxidants complete (100%) recovery could not be achieved despite different experimental conditions (temperatures and oxidation time). The results clearly indicate that hydrogen peroxide is the most efficient among the three oxidants.
Journal of Applied Sciences and Environmental Management Vol. 7(2) 2003: 5-8
[Show abstract][Hide abstract] ABSTRACT: Boiling of water, for purification, commonly practiced in the world, has many problems associated with it like danger of scalding, scaling in the vessels, removal of useful minerals and blandness of taste etc. Water can be made safe for drinking simply by heating at 65 degrees C for 6 minutes. A colour indicating strip was developed which changes colour from red to purple at 67 degrees C. Use of this strip can help in pasteurizing water without the above problems and with considerable energy saving.
Journal of Environmental Sciences 12/2003; 15(6):863-4. · 1.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel photoacoustic spectrometer (PA) has been developed for
in-situ detection of SF<sub>6</sub> leaks in low concentrations. The
developed system is equipped with a sound alarm system and has been
tested in the laboratory for very minute SF<sub>6</sub> leaks. This
newly developed SF<sub>6</sub> detection device utilizes a high quality
factor resonant photoacoustic cell and continuous wave (CW) line tunable
CO<sub>2</sub> laser at 10.55 μm wavelength. Whenever SF<sub>6</sub>
is detected an acoustic signal is generated and no signal appears from
ambient air if there is no leakage of SF<sub>6</sub>. An electret
microphone is used for the detection of these acoustic signals. The
system is capable of detecting leaks of the order of 3.5 ppbv (parts per
billion by volume) concentration. This device has been proved to have
significant applications to industrial organizations that have electric
power gas insulated systems (GIS). It could be also applied for other
applications such as monitoring of environmental pollutants with minimal
IEEE Transactions on Dielectrics and Electrical Insulation 07/2002; 9(3-9):421 - 427. DOI:10.1109/TDEI.2002.1007706 · 1.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A national park is comparatively a large area of outstanding scenic merit and natural interests with the primary objective of protection and preservation of flora and fauna in natural state to which access for public, education and research may be allowed. The management zoning of national park based on different environmental factors is the prime objective of the present research. In order to carry out this study, satellite image (SPOT-5) of year 2007 was classified into three different classes named as forest land, possess land and degraded land using maximum likelihood algorithm in ERDAS IMAGINE 9.1 software. Major environmental factors considered for zoning of national park were slope, land use, elevation, distance from community, roads and river/streams. These factors were ranked according to their significance for the national park. The study area was categorized into three management zones after weighted overlay analysis in Arc GIS software. Area calculated for service zone, primitive zone, and recovery zone, is nearly 14.3%, 11.0%, 34.4%, respectively. The result can be used as an input for effective management of the park in order to preserve the natural resources and to ensure a sustainable ecology. Management zoning can also be utilized as guide lines and suggestions for where an activity shall be located in future. For example when the park officers want to enlarge the recreational area, they would consider the area of high suitability for this class as the first priority, so that critical areas of the NP are least disturbed.
[Show abstract][Hide abstract] ABSTRACT: Constructed wetlands have proven their effectiveness for treatment of a variety of wastewaters in developed countries and little work has been done in developing countries where concept of constructed wetlands for wastewater treatment is still a relatively new idea. CWTSs are engineered wastewater treatment systems comprised of cells filled with porous media and planted with emergent wetland plants such as cattails, bulrushes and reeds. The systems are designed to maximize the physical, chemical and biological abilities of natural wetlands to reduce the biochemical oxygen demand (BOD), total suspended solid (TSS), total nitrogen (TN), phosphorus, and pathogens as wastewater flows slowly through the vegetated subsurface. Bioaccumulation, biotransformation and biodegradation of metals are also possible. The mechanisms of pollutant removal in CWTSs include both aerobic and anaerobic microbiological conversions, sorption, sedimentation, volatilization and chemical transformations. There are over 300-constructed wetland wastewater treatment systems in the United States and Canada, and over 500 in Europe. This is need of time that constructed wetland should be used as treatment facility for wastewater because their performance is comparable to conventional wastewater treatment plants.
[Show abstract][Hide abstract] ABSTRACT: A series of experiments was carried out to assess the viability of treating refinery wastewater using coarse sand for the removal of heavy metals. Typha lattifolia was planted in two containers to evaluate the treatment efficiencies of vertical flow constructed wetlands. The results demonstrated low treatment efficiency of constructed wetlands during the initial stage but with the growth of plants and bio-film improved gradually. Vertical flow constructed wetland filled with coarse sand was operated for treatment of refinery wastewater at hydraulic loading rate of 1.21, 1.44 and 1.71 m 3 /m 2 day −1 , at regular intervals. The results showed high removal efficiencies for iron (Fe) (49%), copper (Cu) (53%) and zinc (Zn) (59%) in the coarse sand filled wetlands. The coarse sand filled constructed wetland showed good treatment performance at hydraulic loading rate of 1.21 m 3 /m 2 day −1 . It is concluded that that constructed wetland can be used as economical option for wastewater quality enhancement in developing countries.
[Show abstract][Hide abstract] ABSTRACT: Recovery of chromium from tannery wastewater is attractive not only environmentally but also economically. Chromium III containing wastewaters were oxidized independently in alkaline conditions with three aqueous oxidants i.e. Hydrogen peroxide, Sodium Hypochlorite and Calcium Hypochlorite to soluble chromate. Hydrogen peroxide was potentially a suitable oxidant as it could oxidize a suspension of Cr(OH) 3 to chromate to 98% (synthetic solution) and 88% (wastewater). The percentage recoveries by the hypochlorites were lower than those by hydrogen peroxide. For all three oxidants complete recovery could not be achieved despite different experimental conditions (temperatures and oxidation time). The amount of chromate recovered was determined by spectrophotometry. The results clearly indicate that hydrogen peroxide is the most efficient among the three oxidants. INTRODUCTION Leather tanning is one of the main sectors in Pakistan's leather industry (consisting of tannery, shoemaking, furs, and leather products). About 90% of its products are exported in finished form (CCP) 1. There are some 600 tanneries in the formal sector and an equally large number of tanneries in the informal sector. Leather tanneries in Pakistan produce all three categories of waste: wastewater, solid waste and air emissions. However, wastewater is by far the most important environmental challenge being faced by Pakistan's tanneries (Iqbal 1998)2. Although the exact quantity varies widely between tanneries, a normal requirement of around 50-60 litres of water per kilogram of hide is suggested (Iqbal 1998)2. Tannery wastewater is highly polluted in terms of biochemical oxygen demand (BOD), chemical oxygen demand (COD), suspended solids, settleable solids, total kjeldhal nitrogen, conductivity, sulphate, sulphide and chromium (Iqbal 1998)2. The values of these parameters are very high as compared to the values mentioned in the National Environmental Quality Standards (NEQS) set by the Government of Pakistan (CCP 1999)3. In about 80% of the cases untreated tannery effluent is discharged directly into recipient water bodies or onto open land and only 115 is discharged into municipal sewers that also drain into natural water bodies without any treatment. Traditionally 60 – 70% chrome applied in the form of BCS (Basic Chromium Sulphate) are absorbed by the hides and skins during process and the remaining is discharged as waste.