Ionic diffusion coefficients in the membrane are needed for the modelling of ion transport in ion‐exchange membranes (IEMs) with the Nernst‐Planck equation. We have determined the ionic diffusion coefficients of Na+, OH−, H+, Cl−, SO42−, NaSO4−, and HSO4− from the diffusion experiments of dilute NaCl, NaOH, HCl, Na2SO4, and H2SO4 solutions through IEMs and the membrane conductivity measured in these solutions, using electrochemical impedance spectroscopy. The order of diffusion fluxes across the anion‐exchange membrane is found to be as H2SO4>HCl>NaCl>Na2SO4>NaOH, whereas for the cation‐exchange membrane it was NaOH>NaCl>Na2SO4≥H2SO4. Special attention is given to sulfates because of the partial dissociation of bisulfate and NaSO4−, which makes the use of the Nernst‐Hartley equation, that is, splitting the electrolyte diffusion coefficient into its ionic contributions, impossible. The expression of the diffusion coefficient of sulfates taking into account the dissociation equilibrium has been derived and the corresponding Fick equation has been integrated. In addition, for sulfates, finite element simulations with COMSOL Multiphysics, applying a homogeneous membrane model, were done to give estimates of their ionic diffusion coefficients. This work offers a convenient approach to finding diffusion coefficients of various ions inside IEMs.
The lockdown restrictions during the COVID-19 pandemic provided a 'path' of reinstatement of the air quality globally. Despite several financial challenges, air quality improvement positively impacted the environment due to lockdown in the worst pandemic situations. The present study assessed the air pollution scenario in the post lockdown phase in the seven major metropolises of Rajasthan, namely, Jodhpur, Alwar, Jaipur, Kota, Pali, Ajmer, and Udaipur, in the recent pandemic year 2020. The air pollution scenario is determined with the help of the Air Quality Index (AQI) and the concentration level of PM2.5, PM10, NO2, and SO2. This study reveals that most cities of Rajasthan are violating India's national ambient air quality standards (NAAQS). It is found that Jodhpur is on rank first in terms of pollution levels, followed by Alwar, Jaipur, Pali, and Udaipur. The pollution level was higher before the lockdown period then reduced to a certain level due to restricted activities in lockdown. The pollution level is not rapidly increased after lockdown due to rainfall from the southwest monsoon. Winter season consists of higher concentration levels of pollutant and higher than before lockdown period. The study shows the significant impact of lockdown in reducing air pollution levels in cities. But imposing lockdown in a city or country is not a permanent solution to curb air pollution. So, regulating agencies and stakeholders should implement better control and reduction technologies for Indian cities.
The present study estimates the long-term and short-term health impacts of particulate matter on humans in Alwar, Rajasthan (India), with the help of AirQ+ software. The annual concentration of particulate matter violates the Indian and WHO standards. The PM2.5 induced long-term estimated number of attributable cases (ENACs) for mortality due to all-natural causes in adults, LC, ALRI, COPD, IHD, and stroke were 12867, 2225, 634, 1089, 4671, and 4353, respectively, while short-term ENACs for hospital admission due to respiratory disease, cardiovascular disease, and all-cause mortality in adults were 4399, 174, and 2333, respectively. The PM10 induced long-term ENACs for post-neonatal infant mortality, chronic bronchitis in adults, and the prevalence of bronchitis in children were 878494, 32698, and 700, respectively, while short-term ENACs for incidence of asthma symptoms in asthmatic children were 1799. The estimated human health risk assessment results are terrifying and require immediate actions from policymakers for mitigation.
The most common environmental concern in metropolitan cities worldwide is noise pollution. Kota metropolis (India) is also suffering from the problem of the increased noise level in the urban environment. Kota metropolis has been selected for the assessment of noise pollution. The main reasons behind the increasing level of noise in the city are increased population, rapid urbanization and industrialization, increased transportation facilities, urban development, construction and demolition works etc. The noise levels were recorded for day-time (6 am to 10 pm) as per Indian standard time for 96 days. Sixteen sampling points are made within the city depending upon the category of area/zone such as industrial, residential, silence and commercial. Six days were prescribed for each sampling location for noise level measurement. Noise descriptors such as Lmax, Lmin, L10, L50, L90, NC (noise climate), Lnp (noise pollution level), Leq (equivalent noise level), and NEI (noise exposure index) were computed with the observed data. Noise descriptors are very useful to indicate the physiological and psychological effects of noise pollution associated with noise levels. It makes regulating agency to take necessary actions in high noise areas for noise vulnerable groups such as Childs, old persons etc. Noise levels were recorded with the digital sound level meter " HTC SL-1350". Obtained equivalent noise levels were in between 65 dB(A) to 85 dB(A). The results were then compared with the WHO standards of community noise levels, and Indian noise pollution standards. It is noticed that the noise levels in all monitoring stations were well above the limits of the standards prescribed by the WHO and CPCB. Small variations in noise levels were observed for all sampling locations i.e. noise levels were almost similar at sampling locations. Noise levels were distinct in magnitude for morning and evenings hours. Noise Exposure Index (NEI) was greater than 1 which shows significant high noise levels in all the sampling locations. Kota metropolis desperately needs new strategies to reduces the high noise level in the city. Regulating agencies should take necessary action before things get out of control. Some immediate actions are suggested in the study.
The present study analyses the current PM10 and PM2.5 pollution scenarios for Kota City (India) to evaluate human health and ecological environment risks associated with particulate matter pollution exposure. Particulate matter concentration revealed a falling trend during the research period, but PM10 and PM2.5 exceeded the Indian NAAQS and WHO standards. The dust ratio (PM10/PM2.5) has been increased over the years from 0.36 to 0.51. and continue to overgrow for Kota City, showing that fine particulates share more than 45% of total particulate matter. Kota exhibits a high exposure of population towards pollution compared to other megacities of the state. The ecological environment and health risk assessment showed the greater vulnerability of the people to potential risks caused by particulate matter as the risk level remained more than one throughout the research period. The exposure presents important conclusions to stakeholders and policymakers for the proper adoption of mitigation measures.
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