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Magnesium incorporated bentonite clay for defluoridation of drinking water
No full textLow cost bentonite clay was chemically modified using magnesium chloride in order to enhance its
fluoride removal capacity. The magnesium incorporated bentonite (MB) was characterized by using
XRD and SEM techniques. Batch adsorption experiments were conducted to study and optimize various
operational parameters such as adsorbent dose, contact time, pH, effect of co-ions and initial fluoride
concentration. It was observed that the MB works effectively over wide range of pH and showed a maximum
fluoride removal capacity of 2.26mgg−1 at an initial fluoride concentration of 5mg L−1, which is
much better than the unmodified bentonite. The experimental data fitted well into Langmuir adsorption
isotherm and follows pseudo-first-order kinetics. Thermodynamic study suggests that fluoride adsorption
onMBis reasonably spontaneous and an endothermic process.MBshowed significantly high fluoride
removal in synthetic water as compared to field water. Desorption study of MB suggest that almost all
the loaded fluoride was desorbed (∼97%) using 1M NaOH solution however maximum fluoride removal
decreases from 95.47 to 73 (%) after regeneration. From the experimental results, it may be inferred that
chemical modification enhances the fluoride removal efficiency of bentonite and it works as an effective
adsorbent for defluoridation of water
Assessment of In-Plant Particulate Matter and its Toxic Metals Contents of Sponge Iron Industry in Goa, India
No full textThe present study attempted to assess toxic metal contents (Arsenic, Cadmium, Copper, Cobalt, Chromium, Iron, Manganese, Nickel, Lead and Zinc) in Total Suspended Particulate (TSP) and Particulate Matter less than ten micron (PM10) in three sponge iron industries in Goa (India), one of the famous tourist place on the World map. TSP and PM10 average concentration in all three sponge iron industries were found to be in the range 401–485 lg/m3 and 135–270 lg/m3 respectively. Amongst all the metals, concentration of iron was the highest in TSP as well as in PM10. Statistical results indicate that proportion of specific metals were found higher in PM10 as compared to the ratio of PM10/TSP ratio. Value of correlation coefficient was found to be significant for Cr–Pb indicating coal burning was the major source contributor
Immobilized Carbonic Anhydrase for the Biomimetic Carbonation Reaction
No full textCarbonic anhydrase (CA) has been immobilized on surfactant-modified silylated chitosan (SMSC) for the
carbonation reaction. CA immobilized on SMSC was characterized using a scanning electron microscope,
energy-dispersive X-ray and X-ray diffraction spectroscopy, and Fourier transform infrared analysis. The
effect of various parameters, such as pH, temperature, and storage stability, on immobilized CA was
investigated using a p-nitrophenyl acetate (p-NPA) assay. The optimum pH and temperature were
determined to be 7 and 35 �C, respectively. Kinetic parameters of immobilized and free CA (Km and Vmax
values) were also evaluated. For immobilized CA, the Km value was 4.547 mM and the Vmax value was
1.018 mmol min-1mg-1, whereas for the free CA, theKm value was 1.211mMand theVmax value was 1.125
mmol min-1 mg-1. It was observed that immobilized CA had longer storage stability and retained 50% of
its initial activity up to 30 days. Proof of concept has been established for the biomimetic carbonation
reaction. TheCO2 sequestration capacity in terms of conversion ofCO2 to carbonate was quantified by gas
chromatography (GC). It was 10.73 and 14.92 mg of CaCO3/mg of CA for immobilized and free CA,
respectively, under a limiting concentration of CO2 (14.5 mg of CO2/10 mL)
Arsenic Contamination in Groundwaters of Village Koudikasa in Rajnandgaon District (Chhattisgarh)
Get PDFExcessive intake of arsenic can lead to health problems. More than 800 water samples collected from hand pumps and dug wells from Chowki block were analyzed for arsenic and some other physico-chemical parameters. Out of the total samples analyzed the highest consentration of 1890ugAs/L was found in one of the hand pumps at the Koudikasa village. The paper present results of groundwater samples with special reference to arsenic contamination in village Koudikasa. Short term and long term course of action have also been delineated in the present paper
Emission Inventory of evaporative emissions of VOCs in Four metro cities In India.
No full textHigh concentrations of volatile organic
compounds (VOCs) in ambient air of urban areas
stress the need for the control of VOC emissions
due to the toxic and carcinogenic nature of
many VOCs commonly encountered in urban air.
Emission inventories are an essential tool in the
management of local air quality, which provide a
listing of sources of air pollutant emissions within
a specific area over a specified period of time.
This study intended to provide a level IV emission
inventory as par the United States Environmental
Protection Agency (USEPA) definition for evaporative
VOC emissions in the metro cities of India
namely Delhi, Mumbai, Chennai, and Kolkata.
The vehicular evaporative emissions are found
to be the largest contributor to the total evaporative
emissions of hydrocarbons followed by
evaporative losses related to petrol loading and
unloading activities. Besides vehicle-related activities,
other major sources contributing to evaporative
emissions of hydrocarbons are surface
coating, dry cleaning, graphical art applications,
A. Srivastava (B) · D. (née Som) Majumdar
National Environmental Engineering Research
Institute, Kolkata Zonal Centre, i-8, Sector C,
East Kolkata Area Development Project,
P.O East Kolkata Township, Kolkata 700107, India
e-mail: [email protected], [email protected]
printing (newspaper and computer), and the use
of consumer products. Various specific preventive
measures are also recommended for reducing the
emissions
Nanosized materials for environmental and energy related applications
No full textEfforts are being made to develop nanomaterials for addressing
issues related to energy, environment and resource conservation. In this
connection, research is being conducted at Environmental Materials Unit
in the area of development of nanosized structural analogues related
to molecular sieves and zeolites, surface functionalised zeolites, pervoskite
based catalytic materials, multifunctional metals/metal oxide materials, carbon
and photocatalytically active materials. Several environmental and energy
technologies have emerged with substantial benefits from nanotechnology,
which include reduction in waste and improved energy efficiency,
environmentally benign composite structures, waste remediation and energy
conversion. Some of the key research areas include carbon capture,
water-splitting reaction for hydrogen generation, biomimetic sequestration
of CO2, and Diesel Particulate Filter (DPF) regeneration
Synthesis of La-incorporated chitosan beads for fluoride removal from water
No full textIn this study, lanthanum incorporated chitosan beads (LCB) were synthesized using precipitation
method and tested for fluoride removal from drinking water. The effect of various parameters like
complexation and precipitation time, lanthanum loading and ammonia strength on fluoride removal
have been studied. It is observed that the parameters for the synthesis of LCB have significant influence
on development of LCB and in turn on fluoride removal capacity. The optimal condition for synthesis of
LCB includes lanthanum loading: 10 wt%, complexation time: 60 min, precipitation time: 60 min, drying
temperature: 75 8C for 72 h. The maximum fluoride adsorption capacity of LCB was found to be 4.7 mg/g
and negligible release of lanthanum ion was observed. XRD analysis shows the presence of lanthanum
hydroxide and amorphous nature of LCB. SEM of LCB shows the presence of oval lanthanum hydroxide
particles spread over the chitosan matrix. Fluoride adsorption capacity has been calculated by applying
Langmuir and Freundlich isotherms. The comparative study suggests that LCB shows four times greater
fluoride adsorption capacity than the commercially used activated alumina
Heavy metal resistance in Arthrobacter ramosus strain G2 isolated from mercuric salt-contaminated soil.
No full textPresent study describes isolation of a multiple metal-resistant Arthrobacter ramosus strain from mercuric salt-contaminated soil. The isolate was found to resist and bioaccumulate several metals, such as cadmium, cobalt, zinc, chromium and mercury. Maximum tolerated concentrations for above metals were found to be 37, 525, 348, 1530 and 369 microM, respectively. The isolate could also reduce and detoxify redox-active metals like chromium and mercury, indicating that it has great potential in bioremediation of heavy metal-contaminated sites. Chromate reductase and mercuric reductase (MerA) activities in protein extract of the culture were found to be 2.3 and 0.17 units mg(-1) protein, respectively. MerA enzyme was isolated from the culture by (NH(4))(2)SO(4) precipitation followed by dye affinity chromatography and its identity was confirmed by nano-LC-MS/MS. Its monomeric molecular weight, and optimum pH and temperature were 57kDa, 7.4 and 55 degrees C, respectively. Thus, the enzyme was mildly thermophilic as compared to other MerA enzymes. K(m) and V(max) of the enzyme were 16.9 microM HgCl(2) and 6.2 micromol min(-1)mg(-1) enzyme, respectively. The enzyme was found to be NADPH-specific. To our knowledge this is the first report on characterization of MerA enzyme from an Arthrobacter sp
Sea water intrusion studies near Kovaya limestone mine, Saurashtra coast, India
No full textThe Kovaya Limestone Mine is situated on the Saurashtra coast of India. Though the mine is dependent on the desalination plant installed in the plant for its domestic and industrial water requirements, there is significant withdrawal of groundwater by the large number of bore wells
and open wells, which are present in the agricultural
fields lying in and around the leased area of the mine. The heavy withdrawal of groundwater has led to intrusion of seawater. The present work entails study of possible seawater intrusion by chemical analysis of major cations and anions in selected groundwater samples. Very high total
dissolved solids in the range of >1,000 mg/l and high chloride in the range of 103 mg/l to 3,899 mg/l have been measured in the groundwater samples. ‘Resistivity Imaging Survey’ has also been carried out on selected profiles in the study area. The Electrical Resistivity Tomography images indicate very low resistivity zones (∼0–3 � m) in the
bottom portion of the resistivity depth sectio