Devendra Mohan

Preparation and application of effective different catalysts for simultaneous control of diesel soot and NOX emissions: An overview

Soot particulates and nitrogen oxides (NOX) from diesel engine exhaust have been causing serious problems to human health and the global environment. NO contributes not only to the production of acid rain but also to the production of photochemical smog in a reaction with hydrocarbons while under the influence of sunlight. Fine soot particulates (C8H to C10H), which contain mutagenic hydrocarbons, can easily reach far down into lung tissues when inhaled and therefore have a detrimental impact on human health. Diesel engines are the primary power source of vehicles used in heavy duty applications. These include two wheelers, buses, large trucks, and inside-highway construction and mining equipment. Furthermore, diesel engines are becoming an increasing part of the light duty vehicle market worldwide. In India, 100% of heavy duty vehicles, 60% of light-duty commercial vehicles and 20% of passenger cars are diesel powered. Diesel exhaust is inherently low in the concentration of CO and unburned HC, for NO and particulate matter are being objectionable to be removed from the exhaust. Since the reduction of both NO and soot particulate emissions to the allowed level cannot be accomplished by engine modifications alone, after-treatment activity for the simultaneous reduction of emissions should be developed.

Modified Cenospheres as an Adsorbent for the Removal of Disperse Dyes

The main objective of this investigation was to use modified cenospheres for the removal of disperse blue 79:1 (DB) and disperse orange 25 (DO) dyes from aqueous solution by batch adsorption process under different conditions (pH, adsorbent dose, adsorbate concentration, agitation speed, contact time, and temperature). Modified cenosphere was capable of removing up to 78% of DB and 81% of DO dyes from aqueous solutions of 40 mg/L dyes concentration. The investigated data was explained by the Langmuir isotherm. The experimental data were found to follow the pseudo-second-order kinetic model. The results of this study suggested that modified cenospheres could be used as a low-cost alternative to expensive adsorbents like activated carbon in wastewater treatment for the removal of disperse dyes.

Adsorptive capacity of sawdust for the adsorption of MB dye and designing of two-stage batch adsorber

Abstract The use of low-cost locally available adsorbent, sawdust for the removal of methylene blue (MB) dye in a batch adsorber system has been investigated. The experimental data fitted best in Langmuir isotherm as compared to Freundlich and Temkin isotherms, showing maximum adsorption capacity of 76.92 mg/g. The study revealed that the adsorption of MB dye onto sawdust follows pseudo-second-order kinetic model and the same has been used in design of a two-stage batch adsorber by minimizing total contact time to attain a fixed percentage of MB dye removal. The minimum contact time required for the removal of MB dye with 99% efficiency has been found as 37.54 min.

An Efficient Removal of Disperse Dye from Wastewater Using Zeolite Synthesized from Cenospheres

AbstractIn the present work, cenospheres were modified to synthesize zeolite in order to improve their adsorption capacity. The synthesized zeolite was characterized by attenuated total reflectance...

Simultaneous abatement of diesel soot and NOX emissions by effective catalysts at low temperature: An overview

ABSTRACT The diesel engine generally achieves the highest fuel, energy, and thermal efficiency due to its very high compression/expansion ratio (14:1 to 25:1). Diesel engines can have a thermal efficiency that exceeds 50%. The main problem is that they emit more pollution like fine black soot particulates (C8H to C10H) and nitrogen oxides (NOX). These pollutants have been causing serious problems for human health and the global environment and also impacts on the engine. There are many types of catalysts investigated for simultaneous control of these two pollutants, i.e., platinum group metals (PGM; Pt, Pd, Rh, and Ir) based, spinel-type oxides, hydrotalcite, rare earth metal oxides, mixed transient metal oxides, etc. The high raw material cost of PGM catalysts has become a significant issue, so developing non-PGM catalysts are one of the promising challenges. There are no extra reductants required because soot catalytically oxidizes itself in the presence of NOX at a faster rate than molecular oxygen and simultaneously NOX is reduced to nitrogen. The order of oxidation potential of NOX to oxidized soot in comparison to molecular oxygen is as follows: NO2 > NO > O2. To meet the very strict EPA US 2010 and Euro VI regulations of particulate matter (PM) and NOX for heavy-duty and light-duty vehicular stringent emission, it is very important to apply the integrated catalytic systems to significantly remove PM and NOX simultaneously. Many papers related to simultaneous control of soot and NOX over different catalysts have been published but till now some of effective catalysts showing high conversion at low temperatures (possibly within the range typical of diesel exhaust: 150–450°C) have not been reviewed. Thus, this article provides a summary of published information regarding the effective catalysts, their preparation methods, properties, and application for simultaneous control of diesel soot and NOX.

Utilization of Water Treatment Plant (WTP) Sludge for Pretreatment of Dye Wastewater Using Coagulation/Flocculation

Water treatment plants generate large amounts of sludge during the coagulation and flocculation of raw water that poses a challenge in the disposal. Potential savings in coagulant dosage could be achieved through the recovery of coagulant from sludge or reusing the sludge during the treatment. Current research focuses on the reuse of WTP sludge for the treatment of dyeing wastewater. The study area, i.e. Varanasi, is famous for its Banarasi Saree industries, most of which are small to medium scale in magnitude. Dyes being used have been polluting nearby water bodies such as Ganga, Varuna and Assi. At present, there is an immediate need for the development of low-cost methods to treat the coloured wastewater as commonly adopted methods are costly that cannot provide an economical treatment option for such small- and medium-scale industries. Therefore, use of low-cost materials like WTP sludge for pretreatment could be a feasible option for achieving the desired results after final treatment. The study was conducted using coagulation and flocculation by WTP sludge for the treatment of Acid Red 94, Acid Yellow 1, Direct Green 26 and Reactive Blue 21 dyes because these were frequently used in dyeing units in and around Varanasi city. The maximum removal for Acid Red 94, Acid Yellow 1, Direct Green 26 and Reactive Blue 21 dyes was found to be at the sieve size of 90–125 µm, and the corresponding values were 41.5, 27, 43.5 and 26.2%, respectively.

Phototrophic cultivation of NaCl-tolerant mutant of Spirulina platensis for enhanced C-phycocyanin production under optimized culture conditions and its dynamic modelling

Commercial cultivation of Spirulina sp. is highly popular due to the presence of high amount of C‐phycocyanin (C‐PC) and other valuable chemicals like carotenoids and γ‐linolenic acid. In this study, the pH and the concentrations of nitrogen and carbon source were manipulated to achieve improved cell growth and C‐PC production in NaCl‐tolerant mutant of Spirulina platensis. In this study, highest C‐PC (147 mg · L−1) and biomass (2.83 g · L−1) production was achieved when a NaCl‐tolerant mutant of S. platensis was cultivated in a nitrate and bicarbonate sufficient medium (40 and 60 mM, respectively) at pH 9.0 under phototrophic conditions. Kinetic study of wildtype S. platensis and its NaCl‐tolerant mutant was also done to determine optimum nitrate concentrations for maximum growth and C‐PC production. Kinetic parameter of inhibition (Haldane model) was fitted to the relationship between specific growth rate and substrate concentration obtained from the growth curves. Results showed that the maximum specific growth rate (μmax) for NaCl‐tolerant mutant increased by 17.94% as compared to its wildtype counterpart, with a slight increase in half‐saturation constant (Ks), indicating that this strain could grow well at high concentration of NaNO3. C‐PC production rate (Cmax) in mutant cells increased by 12.2% at almost half the value of Ks as compared to its wildtype counterpart. Moreover, the inhibition constant (Ki) value was 207.85% higher in NaCl‐tolerant mutant as compared to its wildtype strain, suggesting its ability to produce C‐PC even at high concentrations of NaNO3.

The choice of precursors in the synthesizing of CuMnOx catalysts for maximizing CO oxidation

The hopcalite (CuMnOx) catalyst is a well-known catalyst for CO oxidation at a low temperature and it is synthesized by the co-precipitation method with different types of precursors. Activity of the CuMnOx catalysts for CO oxidation is strongly dependent upon the combination of precursors, ranking in order {Mn(Ac)2 + Cu(NO3)2} > {Mn(Ac)2 + Cu(Ac)2} > {Mn(NO3)2 + Cu(NO3)2} > {Mn(NO3)2 + Cu(AC)2}. All the precursors were precipitated by KMnO4 solution and the precursors mostly comprised of MnO2, Mn2O3 and CuO phases. Keeping the same precipitant while changing the precursors caused a change in the lattice oxygen mobility which influenced the CO oxidation activity. The calcination strategy of the precursors has great influence on the activity of resulting catalysts. The reactive calcination (RC) conditions produce multifarious phenomena of CO oxidation and the precursor decomposition in a single-step process. The activity order of the catalysts for CO oxidation was as follows: reactive calcination (RC) > flowing air > stagnant air. Therefore, we recommended that the RC route was the more appropriate calcination route for the production of highly active CuMnOx catalysts. All the catalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller analysis, X-ray photoelectron spectroscopy and scanning electron microscopy technique. The influence of precursors on the structural properties and the catalytic activity of co-precipitation derived binary CuMnOx catalysts for CO oxidation has been investigated.

Emerging approaches for industrial sustainability and feasible applications in India

Over the past few decades, emerging economies like India have seen unprecedented growth in industrialisation. Improper planning has resulted in pollution and environmental risks due to excessive consumption of natural resources. For a developing country like India, establishment of industrial clusters on the concepts of industrial symbiosis has enormous potential to curtail resource utilisation and environmental degradation. As in case of nature, there is continuous flow of materials and energy through various levels, industrial ecology also involves somewhat similar approach involving exchanges of materials and energy at different levels amongst participating industries. The paper discusses about the emerging approaches to achieve industrial sustainability that can be applied to industrial sectors such as thermal power plant (TPP), sugar and cement production industries. The paper will also discuss about the complexities involved and the considerations required, while planning the development of such industrial complexes in Indian scenario.

Impacts Assessment of Municipal Solid Squander Dumping in Riparian Corridor Using Multivariate Statistical Techniques

Crumbling soil quality and reduction in vegetation plenitude are grave outcomes of open squanders dumping which have brought about growing public concern. The center of the present study is to assess the contribution of open squander dumping in riparian soil contamination and its impact on plant assorted qualities in riparian corridor of river Varuna. Surface soil sample (n = 6 + 2) was gathered from both the open squander dumping and control site. The assorted qualities of vegetation were learned at both sites. Significant changes were seen in the soil attributes of the dumping sites. Soils at the dumping indicated high pH, TDS and EC regime in contrast with control site. The assorted qualities of vegetation were also learned at both sites. A comparable pattern was seen in plant assorted qualities. Control site indicated differentiated assortment of plants, i.e., 12 plant species while this number decreased at the dumping sites. The principal component analysis created three significant components explaining 95.764 of the variance in the data attributable to open dumping effect. Hierarchical cluster analysis grouped six-dumping sites into three clusters having similar characteristics and source of contamination, i.e., moderate and highly polluted dumping sites.