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Dinesh Mohan

Publications and source records attributed to Dinesh Mohan.

At least 19 recordsLinked to original sources
PubMed2006

Activated carbons and low cost adsorbents for remediation of tri- and hexavalent chromium from water.

Hexavalent chromium is a well-known highly toxic metal, considered a priority pollutant. Industrial sources of Cr(VI) include leather tanning, cooling tower blowdown, plating, electroplating, anodizing baths, rinse waters, etc. The most common method applied for chromate control is reduction of Cr(VI) to its trivalent form in acid (pH approximately 2.0) and subsequent hydroxide precipitation of Cr(III) by increasing the pH to approximately 9.0-10.0 using lime. Existing overviews of chromium removal only cover selected technologies that have traditionally been used in chromium removal. Far less attention has been paid to adsorption. Herein, we provide the first review article that provides readers an overview of the sorption capacities of commercial developed carbons and other low cost sorbents for chromium remediation. After an overview of chromium contamination is provided, more than 300 papers on chromium remediation using adsorption are discussed to provide recent information about the most widely used adsorbents applied for chromium remediation. Efforts to establish the adsorption mechanisms of Cr(III) and Cr(VI) on various adsorbents are reviewed. Chromium's impact environmental quality, sources of chromium pollution and toxicological/health effects is also briefly introduced. Interpretations of the surface interactions are offered. Particular attention is paid to comparing the sorption efficiency and capacities of commercially available activated carbons to other low cost alternatives, including an extensive table.

Adsorption↗
PubMed2006

Removal and recovery of metal ions from acid mine drainage using lignite--A low cost sorbent.

Acid mine drainage (AMD), has long been a significant environmental problem resulting from the microbial oxidation of iron pyrite in presence of water and air, affording an acidic solution that contains toxic metal ions. The main objective of this study was to remove and recover metal ions from acid mine drainage (AMD) by using lignite, a low cost sorbent. Lignite has been characterized and used for the AMD treatment. Sorption of ferrous, ferric, manganese, zinc and calcium in multi-component aqueous systems was investigated. Studies were performed at different pH to find optimum pH. To simulate industrial conditions for acid mine wastewater treatment, all the studies were performed using single and multi-columns setup in down flow mode. The empty bed contact time (EBCT) model was used for minimizing the sorbent usage. Recovery of the metal ions as well as regeneration of sorbent was achieved successfully using 0.1 M nitric acid without dismantling the columns.

Acids↗
PubMed2006

Single, binary, and multicomponent sorption of iron and manganese on lignite.

Acid mine drainage (AMD) has long been a significant environmental problem resulting from the microbial oxidation of iron pyrite in the presence of water and air, affording an acidic solution that contains toxic metal ions. The main objective of this study was to remove metal ions [Fe(II), Fe(III), Mn(II), Zn(II)] from AMD using lignite, a low-cost adsorbent. The lignite sorbent was utilized for the sorption of ferrous, ferric, manganese, zinc, and calcium ions in aqueous solutions. Studies were performed at different pH to find optimum pH. Equilibrium isotherms were determined to assess the maximum adsorption capacity of lignite for different metal ions. Sorption capacities were compared in single, binary, ternary, and multicomponent systems. The sorption data are correlated with Freundlich and Langmuir isotherms in each system. Both Freundlich and Langmuir isotherms fit the data reasonably well in terms of regression coefficients. Sorption studies were also performed at different temperatures to obtain the thermodynamic parameters of the process. The maximum lignite adsorption capacities at 25 degrees C were 34.22, 25.84, and 11.90 mg/g for Fe(II), Mn(II), and Fe(III), respectively. Adsorption of Fe(2+) (24.70 mg/g at 10 degrees C and 46.46 mg/g at 40 degrees C) increased with increased temperature, while Mn(2+) adsorption (28.11 mg/g at 10 degrees C and 7.70 mg/g at 40 degrees C) decreased with increased temperature.

Journal Article↗
PubMed2006

Trivalent chromium removal from wastewater using low cost activated carbon derived from agricultural waste material and activated carbon fabric cloth.

An efficient adsorption process is developed for the decontamination of trivalent chromium from tannery effluents. A low cost activated carbon (ATFAC) was prepared from coconut shell fibers (an agricultural waste), characterized and utilized for Cr(III) removal from water/wastewater. A commercially available activated carbon fabric cloth (ACF) was also studied for comparative evaluation. All the equilibrium and kinetic studies were conducted at different temperatures, particle size, pHs, and adsorbent doses in batch mode. The Langmuir and Freundlich isotherm models were applied. The Langmuir model best fit the equilibrium isotherm data. The maximum adsorption capacities of ATFAC and ACF at 25 degrees C are 12.2 and 39.56 mg/g, respectively. Cr(III) adsorption increased with an increase in temperature (10 degrees C: ATFAC--10.97 mg/g, ACF--36.05 mg/g; 40 degrees C: ATFAC--16.10 mg/g, ACF--40.29 mg/g). The kinetic studies were conducted to delineate the effect of temperature, initial adsorbate concentration, particle size of the adsorbent, and solid to liquid ratio. The adsorption of Cr(III) follows the pseudo-second-order rate kinetics. From kinetic studies various rate and thermodynamic parameters such as effective diffusion coefficient, activation energy and entropy of activation were evaluated. The sorption capacity of activated carbon (ATFAC) and activated carbon fabric cloth is comparable to many other adsorbents/carbons/biosorbents utilized for the removal of trivalent chromium from water/wastewater.

Adsorption↗
PubMed2006

Evaluation of groundwater quality in northern Indo-Gangetic alluvium region.

The northern Indo-Gangetic alluvium region is known for intensive agricultural and industrial activities. Groundwater is the main source used for drinking, irrigation and industrial purposes in this region. Groundwater quality assessment is an essential component for its safer use. Thus, the measurements on various water quality parameters were carried out on surface water and groundwater samples of dug wells, bore wells and hand pumps at different sites spread over an area of about 2150 km(2). Influence of soil on hydrochemistry of groundwater was investigated through analyzing soil characteristics at selected sites in the region. Water quality classification was investigated through calculating the base-exchange, meteoric genesis, Langelier saturation and Ryznar stability indices. Groundwater sources were evaluated according to various criteria for their drinking and domestic, irrigation (salinity, chlorinity and sodicity), and industrial (saturation index) uses. Soil-water interactions and impact on groundwater quality was evaluated using ion flux coefficient (cf). Results of this study show that the groundwater in the study region is mainly of Na-HCO(3) and shallow meteoric water percolation type. Low cf values observed for NO(3), PO(4), Ca and metals indicate their lower mobility from soil matrix to groundwater. About 4-19% of the groundwater samples showed levels of TDS, hardness, alkalinity, Cl, F, SO(4), Ca, Mn, Pb, Cr and Fe above their respective permissible limits. Majority of samples violating the drinking water guidelines belong to shallow depth aquifer. Correlations between various parameters lead to interpretation of the results of analysis and suggesting the ionic species present in the groundwater sources. Contamination of some groundwater aquifers with F, Pb and Cr indicates natural and anthropogenic influences.

Adsorption↗
PubMed2005

Studies on the interaction of some azo dyes (naphthol red-J and direct orange) with nontronite mineral.

The adsorption of two azo dyes, namely naphthol red-J and direct orange, on nontronite mineral was studied as a function of pH and temperature. All the sorption studies were conducted in batch mode. The Langmuir and Freundlich isotherm models were applied. The isotherms are Langmuirian in nature, while the Freundlich equation is only valid over the low concentration range. The adsorption of the two dyes increases with increased temperature and decreases with increased pH. The data have been explained in terms of the area of contact of the dye molecule on the clay platelet vis-à-vis the area per anion exchange site. Estimated area per anion exchange site of the mineral and area associated per anionic dye molecule at nontronite surface was 642 and 454 A2 for naphthol red-J and 642 and 440 A2 for direct orange respectively. This has been further supported by X-ray measurements. Thermodynamic parameters of the process were evaluated.

Journal Article↗
PubMed2005

Single, binary and multi-component adsorption of copper and cadmium from aqueous solutions on Kraft lignin--a biosorbent.

A new biosorbent for removing toxic metal ions from water/industrial wastewater has been investigated using by-product lignin from paper production. Lignin was extracted from black liquor waste, characterized and utilized for the removal of copper and cadmium from aqueous solutions in single, binary and multi-component systems. Adsorption studies were conducted at different temperatures, lignin particle sizes, pHs and solid to liquid ratios. All the studies were conducted by a batch method to determine equilibrium and kinetic parameters. The Langmuir and Freundlich isotherm models were applied. The Langmuir model fits best the equilibrium isotherm data. The maximum lignin adsorption capacities at 25 degrees C were 87.05 mg/g (1.37 mmol/g) and 137.14 mg/g (1.22 mmol/g) for Cu(II) and Cd(II), respectively. Adsorption of Cu2+ (68.63 mg/g at 10 degrees C and 94.68 mg/g at 40 degrees C) and Cd2+ (59.58 mg/g at 10 degrees C and 175.36 mg/g at 40 degrees C) increased with an increase in temperature. Copper and cadmium adsorption followed pseudo-second order rate kinetics. From kinetic studies, various rate and thermodynamic parameters such as effective diffusion coefficients, activation energy, and activation entropy were evaluated. Adsorption occurs through a particle diffusion mechanism at temperatures 10 and 25 degrees C while at 40 degrees C it occurs through a film diffusion mechanism. The sorption capacity of black liquor lignin is higher than many other adsorbents/carbons/biosorbents utilized for the removal of Cu(II) and Cd(II) from water/wastewater in single and multi-component systems.

Adsorption↗
PubMed2005

Removal of alpha-picoline, beta-picoline, and gamma-picoline from synthetic wastewater using low cost activated carbons derived from coconut shell fibers.

In the present study the ability of activated carbons developed from coconut shell fibers to remove alpha-picoline, beta-picoline, and gamma-picoline from aqueous solution in the broad range of concentrations (1-100 mg/L) is investigated. The derived carbons are designated as FAC (activated carbon derived from coconut shell fibers without any treatment) and ATFAC (activated carbon derived from acid treated coconut shell fibers). Systematic equilibrium and kinetic adsorption studies at different pH, temperatures, particle size, and solid-to-liquid ratio were carried out to determine various parameters necessary to establish the fixed bed reactors. The Langmuir and Freundlich models were applied and the data are not fitted well by the Freundlich and Langmuir equations, but the Langmuir model has an edge over Freundlich model. The monolayer adsorption capacity (Q0) as calculated using Langmuir adsorption isotherm of the activated carbons viz., FAC and ATFAC is found to increase with an increase in temperature confirming the endothermic process. The ATFAC has a higher sorption capacity than FAC. Overall the adsorption of alpha-picoline, beta-picoline, and y-picoline on FAC and ATFAC follow the order FACalpha-picoline < ATFACalpha-picoline < FAC gamma-picoline < ATFACbeta-picoline < FACbeta picoline < ATFAC gamma-picoline. The adsorption of alpha-,beta-, and gamma-picoline followed the pseudosecond-order rate kinetics. On the basis of these studies, various parameters such as effective diffusion coefficients, activation energy, and entropy of activation were evaluated to establish the mechanisms. It was concluded that the adsorption occurred through particle diffusion at low temperatures viz., 10 degrees C and 25 degrees C (except alpha-picoline where it was film diffusion), while at 40 degrees C it occurred through film diffusion. Similarly at concentrations of 25 and 50 mg/L the adsorption was particle diffusion controlled (except for alpha-picoline where it was film diffusion), while at > 50 mg/L it was film diffusion controlled.

Adsorption↗
PubMed2005

Effect of tractor driving on hearing loss in farmers in India.

BACKGROUND: Indian tractor drivers operate their tractors and other implements/equipment in an environment which can have extreme temperatures and high level of suspended particulate matter. In addition, Indian tractors do not have adequate vibration and noise attenuating designs features. This cross-sectional study compares the hearing status of tractor driving farmers (TDFs) (study group) and non-tractor driving farmers (NTDFs) (control group) matched for age, sex, generic/ethnic group, land holding, education levels, and work routines. METHOD: Two groups of 50 experienced tractor-driving farmers and 50 non-driving farmers were selected from 2 villages, 50 km from Delhi. All participants were interviewed for details of work routine and noise exposures. An audiogram was performed and noise measurements taken on tractors and other machines. RESULTS: Self-reported hearing problems were similar (4 cases each) in both the groups of 50 farmers. However, audiogram analysis showed higher prevalence of abnormalities in TDFs. TDFs (24) had more often high frequency hearing loss when compared to NTDFs (14). The noise levels observed on tractors in different operations were in the range of 90-110 dB (A). CONCLUSIONS: Tractor noise levels exceeded the recommended safe limits of OSHA and NIOSH prescribed standards. TDFs had higher high frequency hearing loss than NTDFs. The mechanism of damage and prevention needs to be studied further.

Adult↗
PubMed2005

Status of heavy metals in water and bed sediments of river Gomti--a tributary of the Ganga River, India.

The concentrations of cadmium, chromium, copper, iron, lead, manganese, nickel, and zinc in water and bed sediments of river Gomti have been studied in a fairly long stretch of 500 km from Neemsar to Jaunpur. Grab samples of water (October 2002-March 2003) and bed sediments (December 2002 and March 2003) were collected from 10 different locations following the standard methods. The river water and sediment samples were processed and analyzed for heavy metals viz., Cd, Cr, Cu, Fe, Pb, Mn, Ni, and Zn, and using ICP-AES. The heavy metals found in the river water were in the range: Cd (0.0001-0.0005 mg/L); Cr (0.0015-0.0688 mg/L); Cu (0.0013-0.0.0043 mg/L); Fe (0.0791-0.3190 mg/L); Mn (0.0038-0.0.0973 mg/L); Ni (0.0066-0.011 mg/L); Pb (0.0158-0.0276 mg/L); and Zn (0.0144-0.0298 mg/L) respectively. In the sediments the same were found in the range: Cd (0.70-7.90 /microg/g); Cr (6.105-20.595 microg/g); Cu (3.735-35.68 microg/g); Fe (5051.485-8291.485 micorg/g); Mn (134.915-320.45 microg/g); Ni (13.905-37.370 microg/g); Pb (21.25-92.15 microg/g); and Zn (1 5.72-99.35 microg/g) of dry weight respectively. Some physico-chemical parameters viz., pH, total solids, total dissolved solids, total suspended solids, dissolved oxygen, biological oxygen demand, chemical oxygen demand, hardness etc. were estimated as these have direct or indirect influence on the incidence, transport and speciation of the heavy metals. Based on the geoaccumulation indices, the Gomti river sediments from Neemsar to Jaunpur are considered to be unpolluted with respect to Cr, Cu, Fe, Mn, and Zn. It is unpolluted to moderately polluted with Pb. In case of Cd it varies from moderately polluted to highly polluted. As far as Ni is concerned the sediment is very highly polluted at Barabanki and Jaunpur D/s. No correlation was found between enrichment factor and geoaccumulation index.

Environmental Monitoring↗
PubMed2004

Impact assessment of treated/untreated wastewater toxicants discharged by sewage treatment plants on health, agricultural, and environmental quality in the wastewater disposal area.

Studies were undertaken to assess the impact of wastewater/sludge disposal (metals and pesticides) from sewage treatment plants (STPs) in Jajmau, Kanpur (5 MLD) and Dinapur, Varanasi (80 MLD), on health, agriculture and environmental quality in the receiving/application areas around Kanpur and Varanasi in Uttar Pradesh, India. The raw, treated and mixed treated urban wastewater samples were collected from the inlet and outlet points of the plants during peak (morning and evening) and non-peak (noon) hours. The impact of the treated wastewater toxicants (metals and pesticides) on the environmental quality of the disposal area was assessed in terms of their levels in different media samples viz., water, soil, crops, vegetation, and food grains. The data generated show elevated levels of metals and pesticides in all the environmental media, suggesting a definite adverse impact on the environmental quality of the disposal area. The critical levels of the heavy metals in the soil for agricultural crops are found to be much higher than those observed in the study areas receiving no effluents. The sludge from the STPs has both positive and negative impacts on agriculture as it is loaded with high levels of toxic heavy metals and pesticides, but also enriched with several useful ingredients such as N, P, and K providing fertilizer values. The sludge studied had cadmium, chromium and nickel levels above tolerable levels as prescribed for agricultural and lands application. Bio-monitoring of the metals and pesticides levels in the human blood and urine of the different population groups under study areas was undertaken. All the different approaches indicated a considerable risk and impact of heavy metals and pesticides on human health in the exposed areas receiving the wastewater from the STPs.

Crops, Agricultural↗
PubMed2004

Multivariate statistical techniques for the evaluation of spatial and temporal variations in water quality of Gomti River (India)--a case study.

This case study reports different multivariate statistical techniques applied for evaluation of temporal/spatial variations and interpretation of a large complex water-quality data set obtained during monitoring of Gomti River in Northern part of India. Water quality of the Gomti River, a major tributary of the Ganga River was monitored at eight different sites selected in relatively low, moderate and high pollution regions, regularly over a period of 5 years (1994-1998) for 24 parameters. The complex data matrix (17,790 observations) was treated with different multivariate techniques such as cluster analysis, factor analysis/principal component analysis (FA/PCA) and discriminant analysis (DA). Cluster analysis (CA) showed good results rendering three different groups of similarity between the sampling sites reflecting the different water-quality parameters of the river system. FA/PCA identified six factors, which are responsible for the data structure explaining 71% of the total variance of the data set and allowed to group the selected parameters according to common features as well as to evaluate the incidence of each group on the overall variation in water quality. However, significant data reduction was not achieved, as it needed 14 parameters to explain 71% of both the temporal and spatial changes in water quality. Discriminant analysis showed the best results for data reduction and pattern recognition during both temporal and spatial analysis. Discriminant analysis showed five parameters (pH, temperature, conductivity, total alkalinity and magnesium) affording more than 88% right assignations in temporal analysis, while nine parameters (pH, temperature, alkalinity, Ca-hardness, DO, BOD, chloride, sulfate and TKN) to afford 91% right assignations in spatial analysis of three different regions in the basin. Thus, DA allowed reduction in dimensionality of the large data set, delineating a few indicator parameters responsible for large variations in water quality. This study presents necessity and usefulness of multivariate statistical techniques for evaluation and interpretation of large complex data sets with a view to get better information about the water quality and design of monitoring network for effective management of water resources.

Data Collection↗
PubMed2004

Evidence-based interventions for road traffic injuries in South Asia.

Injuries and deaths due to road traffic injuries (RTI) have become one of the most serious health problems in most countries of South Asia. Young adults are more likely to die in a serious road traffic crash than from most other diseases. Systematic reviews of international scientific literature provide insights for the South Asian road safety community. Detailed information about proven effective interventions is provided in this paper. For example, education programmes are usually, in themselves, insufficient to change overall behaviour, red light cameras reduce red light violations and intersection crashes by 25-40%. Helmet use reduces bicycle and motorcycle related head and facial injuries for all ages involved in all types of crashes, including those involving motor vehicles. Use of seat belts and equipping cars with airbags can reduce car occupant fatalities by over 30%. Traffic calming techniques, the use of roundabouts and the provision of pedestrian and bicycle facilities in urban areas provide significant safety benefits.

Accidents, Traffic↗
PubMed2003

Equilibrium uptake and sorption dynamics for the removal of a basic dye (basic red) using low-cost adsorbents.

Waste carbon slurries (generated in fertilizer plants) and blast furnace slag (generated in steel plants) have been converted into low-cost potential adsorbents. The adsorbents have been characterized and tried for the removal of the dye basic red from wastewater. Studies were performed at different pH to find the pH at which maximum adsorption occurs. Equilibrium isotherms were determined to assess the maximum adsorption capacity of the adsorbents. Adsorption capacities are compared for activated carbon developed from fertilizer waste and activated slag developed from blast furnace waste. The adsorption data are correlated with Freundlich and Langmuir isotherms in each system. The kinetics of adsorption depends on the adsorbate concentration and the physical and chemical characteristics of the adsorbent. Studies were conducted to delineate the effect of pH, temperature, initial absorbate concentration, particle size of the adsorbent, and solid-to-liquid ratio. The adsorption of basic red was found to be endothermic and first-order in nature.

Journal Article↗
PubMed2002

War on the roads.

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Accidents, Traffic↗