Hemant Kumar | Indian Institute Of Technology, Roorkee (original) (raw)
Presently I am working on Emulsion Fuels as a PhD research scholar IIT Roorkee. Past I have Teaching experience in Chemical Engineering field to undergraduate and graduate students (masters). I have experience of working on heavy metal and toxic organic compounds removal from wastewater and published some work.
Address: Roorkee, Uttarakhand, India
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Papers by Hemant Kumar
Formation of water-in-diesel oil (w/o) nano-emulsion has been achieved by a low-energy emulsifica... more Formation of water-in-diesel oil (w/o) nano-emulsion has been achieved by a low-energy emulsification
method by stabilizing a new combination of nonionic sorbitan esters surfactants, that is PEG20-sorbitan
monostearate and sorbitan monooleate in mixed proportions. Different combinations of the surfactants
(T6 þ S8) have been tested and the best possible combination of mixed surfactants is found at a
surfactants ratio of 35:65 (wt/wt) for T6:S8 at hydrophile–lipophile balance (HLB) ¼ 8.01, which resulted in
smaller droplet size of 44.87 nm. A phase diagram study is performed to identify the zones of formation
of transparent, translucent, and opaque emulsions (44 nm < droplet size < 700 nm). The mechanism
responsible for the instability of emulsion is explained by Ostwald ripening, with inference describing a
decrease in particle size with the Ostwald ripening rate. In case of nano-emulsion of droplet size
64.28 nm, the Oswald ripening rate is found as 0.0874 � 10
27 m3 · s
1
. Comparison of Ostwald ripening
rate with other sets of surfactants obtained by different authors showed the lowest rate among them,
indicative of enhanced stability. A rheological study of the tested set of nano-emulsions depicts the
Newtonian behavior (1.0371<n <1.0826) over a wider range of shear rates (10–1000 s-1) at different
temperatures (25–40°C)
Biowaste materials obtained from Azadirachta indica plant have shown potential towards adsorption... more Biowaste materials obtained from Azadirachta indica plant have shown potential towards adsorption of heavy metals like copper. In this work, Cu (+2) ion was adsorbed from synthetically made copper salt solution on chemically activated Neem sawdust (Azadirachta indica). Effect of Initial concentration of copper ions on percent removal and adsorption capacity was studied at four concentrations viz. 25, 50, 75 and 100 mg L-1 at constant adsorbent loading of 4 g L-1
and stirring speed of 150 rpm. The high value of adsorption capacity of 21.875 mg Cu (+2) per gram of adsorbent was obtained at 100 mg L-1at 301K. Three different equilibrium isotherms namely Freundlich, Langmuir and Temkin were fitted and the best models representing the experimental results were founded as Langmuir and Temkin models with regression coefficients as 93 and 92% , respectively where Langmuir model represents monolayer adsorption of copper ions and Temkin model confirms the physical adsorption by the heat of adsorption b=288.04 J. mol-1. The Kinetics of the adsorption
process was best described by pseudo first order.
Books by Hemant Kumar
Diesel engines are used in heavy transportation vehicles and heavy machineries as they produce hi... more Diesel engines are used in heavy transportation vehicles and heavy machineries as they produce higher torque at low speeds for a given power meeting the primary requirement for a heavy engine. Moreover, diesel engines provide higher compression ratio and, if gasoline has to be used in bigger engines, they will produce higher knocking due to preignition. Therefore, the use of diesel in heavy vehicles is indispensable; however, exhaust gases emerging from the engine contain pollutants predominantly nitric oxides (NO) and particulate matter (PM). Nowadays, there is an extensive focus toward improving emission characteristics and enhanced combustion properties with pure diesel oil in an IC engine. One of the recent ways to achieve the similar characteristics is to develop a water-in-diesel oil (W/D) nanoemulsion that reduces the pollutants and at the same time enhances combustion properties. Therefore, the proposed chapter is aimed to discuss the advancement and opportunities in W/D nanoemulsion fuel preparation using different surfactants and additives that provide improved emission characteristics and engine performance.
Formation of water-in-diesel oil (w/o) nano-emulsion has been achieved by a low-energy emulsifica... more Formation of water-in-diesel oil (w/o) nano-emulsion has been achieved by a low-energy emulsification
method by stabilizing a new combination of nonionic sorbitan esters surfactants, that is PEG20-sorbitan
monostearate and sorbitan monooleate in mixed proportions. Different combinations of the surfactants
(T6 þ S8) have been tested and the best possible combination of mixed surfactants is found at a
surfactants ratio of 35:65 (wt/wt) for T6:S8 at hydrophile–lipophile balance (HLB) ¼ 8.01, which resulted in
smaller droplet size of 44.87 nm. A phase diagram study is performed to identify the zones of formation
of transparent, translucent, and opaque emulsions (44 nm < droplet size < 700 nm). The mechanism
responsible for the instability of emulsion is explained by Ostwald ripening, with inference describing a
decrease in particle size with the Ostwald ripening rate. In case of nano-emulsion of droplet size
64.28 nm, the Oswald ripening rate is found as 0.0874 � 10
27 m3 · s
1
. Comparison of Ostwald ripening
rate with other sets of surfactants obtained by different authors showed the lowest rate among them,
indicative of enhanced stability. A rheological study of the tested set of nano-emulsions depicts the
Newtonian behavior (1.0371<n <1.0826) over a wider range of shear rates (10–1000 s-1) at different
temperatures (25–40°C)
Biowaste materials obtained from Azadirachta indica plant have shown potential towards adsorption... more Biowaste materials obtained from Azadirachta indica plant have shown potential towards adsorption of heavy metals like copper. In this work, Cu (+2) ion was adsorbed from synthetically made copper salt solution on chemically activated Neem sawdust (Azadirachta indica). Effect of Initial concentration of copper ions on percent removal and adsorption capacity was studied at four concentrations viz. 25, 50, 75 and 100 mg L-1 at constant adsorbent loading of 4 g L-1
and stirring speed of 150 rpm. The high value of adsorption capacity of 21.875 mg Cu (+2) per gram of adsorbent was obtained at 100 mg L-1at 301K. Three different equilibrium isotherms namely Freundlich, Langmuir and Temkin were fitted and the best models representing the experimental results were founded as Langmuir and Temkin models with regression coefficients as 93 and 92% , respectively where Langmuir model represents monolayer adsorption of copper ions and Temkin model confirms the physical adsorption by the heat of adsorption b=288.04 J. mol-1. The Kinetics of the adsorption
process was best described by pseudo first order.
Diesel engines are used in heavy transportation vehicles and heavy machineries as they produce hi... more Diesel engines are used in heavy transportation vehicles and heavy machineries as they produce higher torque at low speeds for a given power meeting the primary requirement for a heavy engine. Moreover, diesel engines provide higher compression ratio and, if gasoline has to be used in bigger engines, they will produce higher knocking due to preignition. Therefore, the use of diesel in heavy vehicles is indispensable; however, exhaust gases emerging from the engine contain pollutants predominantly nitric oxides (NO) and particulate matter (PM). Nowadays, there is an extensive focus toward improving emission characteristics and enhanced combustion properties with pure diesel oil in an IC engine. One of the recent ways to achieve the similar characteristics is to develop a water-in-diesel oil (W/D) nanoemulsion that reduces the pollutants and at the same time enhances combustion properties. Therefore, the proposed chapter is aimed to discuss the advancement and opportunities in W/D nanoemulsion fuel preparation using different surfactants and additives that provide improved emission characteristics and engine performance.