Bishnupada Mandal

Absorption of carbon dioxide into aqueous blends of 2-amino-2-methyl-1-propanol and diethanolamine

Abstract This work presents an experimental and theoretical investigation of CO2 absorption into aqueous blends of 2-amino-2-methyl-1-propanol (AMP) and diethanolamine (DEA). The CO2 absorption into the amine blends is described by a combined mass transfer–reaction kinetics–equilibrium model, developed according to Higbies penetration theory. The model predictions have been found to be in good agreement with the experimental rates of absorption of CO2 into (AMP+DEA+H2O). The good agreement between the model predicted rates and enhancement factors and the experimental results indicate that the combined mass transfer–reaction kinetics–equilibrium model with the appropriate use of model parameters can effectively represent CO2 mass transfer for the aqueous amine blends AMP/DEA.

Removal of carbon dioxide by absorption in mixed amines: modelling of absorption in aqueous MDEA/MEA and AMP/MEA solutions

This work presents an investigation of CO 2 absorption into aqueous blends of methyldiethanolamine (MDEA) and monoethanolamine (MEA), as well as 2-amino-2-methyl-1-propanol (AMP) and monoethanolamine (MEA). The combined mass transfer-reaction kinetics-equilibrium model to describe CO 2 absorption into the amine blends has been developed according to Higbies penetration theory following the work of Hagewiesche et al. (Chem. Eng. Sci. 50 (1995) 1071). The model predictions have been found to be in good agreement with the experimental rates of absorption of CO 2 into (MDEA + MEA + H 2 O) of this work and into (AMP + MEA + H 2 O) reported by Xiao et al. (Chem. Eng. Sci. 55 (2000) 161), measured at higher contact times using wetted wall contactor. The good agreement between the model predicted rates and enhancement factors and the experimental results indicate that the combined mass transfer-reaction kinetics-equilibrium model with the appropriate use of model parameters can effectively represent CO 2 mass transfer for the aqueous amine blends MDEA/MEA and AMP/MEA.

Removal of Cr(VI) from aqueous solution using Bael fruit (Aegle marmelos correa) shell as an adsorbent

In this study, a new activated carbon prepared from non-usable Bael fruit shell (BS) has been used as an efficient low cost adsorbent to remove the Cr(VI) toxic metal from aqueous phase. Batch mode experiments have been performed as a function of initial pH of solution, agitation time, adsorbate concentration and adsorbent dosage. Maximum chromium removal was found at pH 2.0 in an equilibrium time of 240 min by adsorption-coupled reduction. The sorption data fitted satisfactorily with Langmuir as well as Freundlich adsorption model. Evaluation using Langmuir equation gave the monolayer sorption capacity as 17.27 mg/g. Chromium uptake (adsorption-coupled reduction) by Bael fruit shell activated carbon (BSAC) was best described by pseudo-second-order chemisorption model. The progressive changes on surface texture and the confirmation of chromium binding on adsorbent surface at different stages were obtained by the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectrometer (FT-IR) analysis. Phosphoric acid activation played a significant role to develop the well defined pores on adsorbent surface. The results obtained in this study illustrate that the BSAC is expected to be an effective and economically viable adsorbent for Cr(VI) removal from aqueous system.

Selective absorption of H2S from gas streams containing H2S and CO2 into aqueous solutions of N-methyldiethanolamine and 2-amino-2-methyl-1-propanol

Selective absorption of H2S from N2 streams containing H2S and CO2 into aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) as well as N-methyldiethanolamine (MDEA) was investigated in a 2.81×10−2 m o.d. stainless steel wetted-wall column at atmospheric pressure and constant feed gas ratio. In the range of gas flow rates studied (90–180×10−6 m3/s), the effect of gas-phase resistance on the absorption of H2S was significant. The rates of absorption of H2S and the selectivity factor decreased with the contact time for both alkanolamine solutions. With increasing amine concentration in the range 2.0–3.0 kmol/m3, the rates of absorption of both CO2 and H2S increased, but relatively more for CO2, resulting in a consequent decrease in the selectivity factor. In the temperature range 293–313 K, the rates of absorption of CO2 increased marginally with the increase in temperature while the rates of absorption of H2S and the selectivity factor decreased. The maximum selectivity observed in this work was 17.57 and 23.02 for AMP and MDEA, respectively. The acid gas mass transfer has been modelled using equilibrium-mass-transfer-kinetics-based combined model for CO2 and gas-phase transport equation-based approximate model for H2S considering negligible interaction between CO2 and H2S in the liquid phase. The experimental and model results have been found to be in good agreement.

Adsorption of chromium(VI) and Rhodamine B by surface modified tannery waste: Kinetic, mechanistic and thermodynamic studies

In this study, various activation methods have been employed to examine the potential reuse of tannery residual biomass (TRB) obtained from vegetable tanning process for the removal of Cr(VI) and Rhodamine B (RB) from aqueous solution. The maximum BET surface area (10.42 m(2)/g), honey comb pore distribution and uptake of both Cr(VI) and RB were achieved when only 3-fold volume of HCl was used to activate the biomass. The pH and temperature experiment showed that they have considerable impact on the adsorption capacity of the used adsorbent. The presence of other ions (Na(+), Ca(2+) and NH(4)(+)) significantly reduces the metal uptake but marginal enhancement in the dye removal was observed when Na(+) and NH(4)(+) ions were present in the solution. The equilibrium data fitted satisfactorily with the Langmuir model and monolayer sorption capacity obtained as 177-217 and 213-250 mg/g for Cr(VI) and RB at 30-50°C, respectively. The sorption kinetics was found to follow the pseudo-second-order kinetic model. The increase in adsorption capacity for both metal and dye with increase in temperature indicates that the uptake was endothermic in nature. The results indicate that the HCl modified TRB (A-TRB) could be employed as a low cost adsorbent for the removal of both Cr(VI) and RB from the aqueous solution including industrial wastewater.

Effect of physical parameters, carbon and nitrogen sources on the production of alkaline protease from a newly isolatedBacillus pseudofirmus SVB1

The effect of process physical parameters (initial pH of the medium, temperature and rpm of the shaking incubator) on the production of alkaline protease from a newly isolatedBacillus pseudofirmus SVB1 was studied using central composite design technique. The individual optimum levels of initial pH of the medium, temperature and rpm of the shaking incubator were found to be 9.2, 27.3 °C and 195, respectively for the production of alkaline protease (specific activity, u/mg of protein) and 11, 28.9 °C and 210, respectively for cell growth. By applying multiresponse analysis method of generalized distance approach for production and growth, the optimal levels were found to be 9.9, 28.1 °C and 202, for initial pH of the medium, temperature and rpm of the shaking incubator, respectively. After optimization, the production of alkaline protease and cell growth were enhanced by 36.23 and 44.29%, respectively. Also, the various nutritional parameters, which have significant effect on the production of alkaline protease, are delineated in the present study. Alkaline protease production was found to be influenced by media components,viz., types of C/N source and presence of metal ions. Finally an overall 6.2 fold increase in the production was achieved using casein as both carbon and nitrogen source.

Effect of Adsorbent History on Adsorption Characteristics of MIL-53(Al) Metal Organic Framework

Structural transformation of MIL-53(Al) metal organic framework from large pore to narrow pore form (lp → np) or vice versa is known to occur by adsorption of certain guest molecules, by temperature change or by applying mechanical pressure. In this work, we perform a systematic investigation to demonstrate that adsorbent history also plays a decisive role in the structural transitions of this material (and hence on its adsorption characteristics). By changing the adsorbent history, parent MIL-53(Al) is tuned into its np domain at ambient temperature such that it not only exhibits a significant increase in CO2 capacity, but also shows negligible uptake for CH4, N2, CO, and O2 at subatmospheric pressure. In addition, for the high pressure region (1-8 bar), we propose a method to retain the lp form of the sample to enhance its CO2 uptake.

Modeling and Simulation for Post-Combustion Carbon Dioxide Capture from Power Plant Flue Gas with Economic Analysis

In this study three configurations, viz. conventional MEA, interstage absorber, and interstage absorber with two stripper configuration have been techno-economically evaluated for the optimized result by carrying out simulations using ASPEN PLUS. An economic model defined for carbon capture using 30 wt% MEA to reduce CO2 in flue gas to 0.5 mol% of 550 MWe coal fired power plant resulted in increase in COE of power plant by 20.6, 17.4, and 15.6 percents for the three configurations, respectively. The CO2-avoided cost for the three configurations are 65.94, 64.05, and 63.09 (

Graphene-Incorporated Biopolymeric Mixed-Matrix Membrane for Enhanced CO2 Separation by Regulating the Support Pore Filling

/tonne of CO2 avoided), respectively.

Experimental and theoretical studies on efficient carbon dioxide capture using novel bis(3-aminopropyl)amine (APA)-activated aqueous 2-amino-2-methyl-1-propanol (AMP) solutions

The CO2 separation performance by a membrane is influenced essentially by film thickness, temperature, moisture, and pressure. Pore formation on the active layer and pore clogging of the membrane support are critical factors that impedes the CO2 separation performance. This study involves the development of a novel nanocomposite membrane (CS/SF/GNP) consisting of chitosan (CS), silk fibroin (SF), and graphene nanoparticles (GNP). The CS acts as the matrix, SF contributes to the CO2 facilitated transport by its inherent amines as carriers, and GNP helped in counteracting the support pore blockage during the gas separation test. The positive effect of GNP in the CS/SF/GNP was further apparent in the CO2 permeance inconsequential drop of ∼7% during the initial 12 h in the presence of moisture and pressure. The detailed characterizations including FESEM, AFM, and swelling were performed for the membranes. The effect of sweep water flow rate, temperature, and feed absolute pressure on CO2 separation performance from binary gas were performed. The CS/SF/GNP membrane exhibited CO2 permeance of 159 GPU and CO2/N2 selectivity of 93 at 90 °C and a feed absolute pressure of 2 bar having a sweep side water flow rate of 0.05 mL/min. Further, when CS/SF/GNP membrane was tested to separate CO2 from ternary gas mixture (CO2/N2/H2), it displayed excellent CO2 permeance of 126 GPU and selectivity for CO2/N2 and CO2/H2 as 104 and 52, respectively. The TGA isotherm and XPS analysis of CS/SF/GNP membrane suggested a thermal stability of the prepared membrane that establishes its suitability for the gas permeation at different temperature.