Gas-Liquid Equilibrium Data for Mixture Gas of Sulfur Dioxide Nitrogen with Poly(Ethylene Glycol)

Gas-Liquid Equilibrium Data for the Mixture Gas of Sulfur Dioxide+Nitrogen with Poly(ethylene glycol)Aqueous Solutions at298.15K and122.61kPa

Jianbin Zhang,*,?,?Fang Han,?Pengyan Zhang,§Guohua Chen,?and Xionghui Wei*,?

College of Chemical Engineering,Inner Mongolia University of Technology,Huhhot010051,China,Department of Applied Chemistry,College of Chemistry&Molecular Engineering,Peking University,Beijing100871,China,and Beijing Boyuan Hengsheng High-Technology Co.,Ltd.,Beijing100190,China

Isothermal gas-liquid equilibrium(GLE)data have been measured for the system SO2+N2+poly(ethylene

glycol)(PEG400)+water at298.15K and122.61kPa and SO2partial pressures in the range of(0to122)

Pa.Measurements were carried out by a saturation method using a glass absorption apparatus,which was

controlled at constant temperatures by a thermostatic circulation bath with Beckmann thermometer.The

GLE data were obtained with relative uncertainties within(2.5%for SO2concentration in the gas phase

and(0.6%for SO2concentration in the liquid phase.The measurement showed that the addition of water

into PEG decreased the solubility of SO2compared with pure https://www.360docs.net/doc/6315783290.html,pared with our previous work

(Zhang,J.B.;Wei,X.H.;et al.J.Chem.Eng.Data2008,53,2372-2374),the aqueous PEG400solutions

present stronger solubility to SO2than ethylene glycol(EG)aqueous solutions.The results of this work can

be used to provide important GLE data for the design and operation of the absorption and desorption process

in?ue gas desulfurization(FGD)with potential industrial application of PEG400aqueous solutions.

1.Introduction

Sulfur dioxide(SO2)is an important atmospheric pollutant, and therefore it is severe in environmental protection. Emissions of SO2into the atmosphere have increased steadily with industrial development.The combustion of coal,due to its high sulfur content,1means it is necessary to dedicate particular attention to eliminating the resulting emission of SO2.Among the many procedures employed to desulfurize exhaust gases,organic solvents used as absorbents have been identi?ed as an option among the regenerative processes2-6 because regeneration can be done by pressure reduction,by temperature increase,and by use of a carrier gas.Of the numerous organic solvents,alcohols show favorable absorp-tion and desorption capabilities for acid gases in industrial processes;7therefore,our research group has paid great attention to the alcohol+water system for SO2removal for several years.8-12

PEG400is a promising medium for?ue gas desulfurizaton (FGD)processes because of its high absorption capacity,its low-to-moderate vapor pressure for temperatures below373K, and its low toxicity.This work was mainly focused on providing GLE data for SO2+N2mixtures with various PEG400+water solutions(PEGWs)at298.15K and122.61kPa and on optimizing the composition of PEGW for the future FGD processes.

2.Experimental Section

Materials.The SO2gas(99.9%)and pure N2gas(>99.9 %),purchased from the Beijing Gas Center,Peking University (China),were employed to determine the GLE data for PEGWs with SO2in this work.The analytical grade PEG400with the number average molecular mass of400(380to420)was purchased from Beijing Reagent Company.It was used after drying over molecular sieves(type4A)and decompression ?ltration before measurements.The purity of the sample was checked by density and viscosity determination at298.15K. The density of PEG400at298.15K was found to be1.1218 g·cm-3,in good agreement with the literature.13Bidistilled water was used.

Apparatus and Procedure.The apparatus used in this work was based on a dynamic analytic method and is reported in previous work.11The concentrations of SO2in the gas phase were determined by a gas chromatograph on a2×3.2(m×mm)Porapak Q packed column using an Agilent6890N gas chromatograph(GC)and an FPD detector linked to an HP6890 workstation.In all cases,the injections were repeated at least seven times,and the average results were reported.To calibrate the GC FPD detector,the external standard method was used. The sulfur(IV)concentration in the liquid phase(C SO2)was determined according to ref14.The overall relative uncertainty in the determination of the sulfur(IV)concentration was estimated to be(0.6%.Experiments were carried out at298.15 K,kept at a constant temperature using a CS501thermostatted bath with a Beckmann thermometer purchased from Huanghua Meter Factory(Hebei province,China)with(0.02K,and inspected using an accurate thermometer purchased from Fuqiang Meter Factory(Hebei province,China)with the precision of(0.02K,and the total pressure of122.61kPa inspected by a pressure gauge purchased from Fuqiang Meter Factory(Hebei province,China)with(0.133kPa,using SO2 +N

2

mixtures in the SO2partial pressure range from(0to122) Pa.

*To whom correspondence should be addressed.Tel.:+86-010-********.

Fax:+86-010-********.E-mail:xhwei@https://www.360docs.net/doc/6315783290.html,(X.H.Wei);

tadzhang@https://www.360docs.net/doc/6315783290.html,(J.B.Zhang).

?Inner Mongolia University of Technology.

?Peking University.

§Beijing Boyuan Hengsheng High-Technology Co.,Ltd.

J.Chem.Eng.Data2010,55,959–961959

10.1021/je900392e CCC:$40.75 2010American Chemical Society

Published on Web07/06/2009

3.Results and Discussion

GLE Data for PEGWs with Dilute SO2.A series of GLE experiments for PEG+H2O+SO2+N2were performed at 298.15K and122.61kPa,and the GLE data are listed in Table 1.In this table,the mass fraction of PEG in PEGW(w1)was used in the actual operation,and PEG400and water were weighed using a Sartorius BS224S balance with a precision of (0.0001g to present accurate factual mass fraction of PEG

400.The GLE data were obtained with relative uncertainties within(2.5%for SO2concentration in the gas phase and( 0.6%for SO2concentration in the liquid phase.

In Table1,Φ3denotes the concentration of SO2in the gas phase asφ3≈(p SO2)/(p SO2+p H2O+p N2+p PEG))(p SO2/p total); p3and p total denote,respectively,the partial pressure of SO2in the gas phase and the total pressure of the GLE system;and C3 denotes the concentration of SO2in the liquid phase.

The GLE curves of PEGWs for SO2absorption at298.15K and122.61kPa are plotted in Figure1.Solubility of SO2in PEGWs when SO2volume fraction in the gas phase is designed atΦ3)5·10-4is shown in Figure2.

Figures1and2show that the addition of H2O into PEG400 decreased the solubilities of SO2in PEG400;meanwhile,w1)0.85exhibits an extreme minimum value to dissolve SO

2

, and the solubility is651mg·L-1when SO2concentration in the gas phase is designed atΦ3)5·10-4;w1)0.80PEGW shows a higher capability to dissolve SO2,and the solubility is 778mg·L-1when SO2concentration in the gas phase is designed atΦ3)5·10-4.In the entire composition range,the pure PEG400shows the strongest capability to dissolve SO2, and the solubility is1330mg·L-1when SO2concentration in the gas phase is designed atΦ3)5·10-4.The above results may be related to the excess properties of aqueous PEG400 solutions15and the hydrogen bonding and interactions among PEG400,H2O,and SO2,and the similar hydrogen bonding and interactions among EG,H2O,and SO2have been published in our previous work.16Compared with our previous work,12the PEG400aqueous solutions present stronger solubility to SO2 than ethylene glycol(EG)aqueous solutions in the entire composition range.The result gives us important information to optimize the composition of PEGWs for the SO2absorption processes.

4.Conclusion

This paper presents the results of fundamental investigations on isothermal GLE data of various aqueous solutions of PEG 400with SO2,which were determined as a function of composition at298.15K and122.61kPa.The GLE data show that the addition of water into PEG400decreased the solubility of SO2compared with pure PEG400.The experimental results showed that the w1)0.85PEG400presents the extreme minimum value solubility of651mg·L-1to SO2when the SO2 concentration in the gas phase was set atΦSO2)5·10-4;the

Table1.GLE for PEG(1)+H2O(2)+SO2(3)+N2(4)at298.15 K and122.61kPa

C3C3

100w110-6Φ3(mg·L-1)P3/Pa100w110-6Φ3(mg·L-1)P3/Pa 0.00 6.4061.80.78560.0177557195.1 0.0025.670.3 3.1460.01829598102 0.0053.877.6 6.5980.029.19400 1.13 0.0079.184.99.7080.0253.8554 6.59 0.0013794.616.880.0255.8561 6.84 0.0023411528.680.0295.156711.7 0.0038115346.780.022*******.7 0.0050217661.580.022*******.2 0.0058020071.280.023*******.4 0.0062721976.980.025*******.5 20.0123.9132 2.9380.025*******.4 20.0138.2135 4.6880.0269583785.2 20.0182.815310.280.029********

20.0112816315.785.0019.2265 2.35 20.0115417018.985.0035.3429 4.33 20.0117017220.885.0013949217.0 20.0125818731.685.0023753329.0 20.0138420947.185.0042462052.0 20.0142522152.185.0054967067.3 20.0153623765.785.0070976986.9 20.0160324574.085.00858844105 20.0164925379.690.0115.0197 1.84 20.0169226484.990.0132.8408 4.02 20.0188929510990.0152.8550 6.47 40.3928.2203 3.4590.0114958118.3 40.3934.8224 4.2790.0120369024.9 40.3964.92487.9590.0136174944.2 40.3984.225310.390.0137879346.3 40.3911027313.590.0145782456.1 40.3912027714.790.0159190172.5 40.3918729422.990.0164495078.9 40.3935730443.890.0176799894.0 40.3948832559.890.018271029101 40.3957033569.9100.008.89632 1.09 40.39893361110100.0038.0865 4.66 60.0111.878.7 1.45100.0057.68897.06 60.0123.6273 2.89100.0085.395710.5 60.0126.5362 3.25100.0089.596411.0 60.0143.7393 5.36100.0011598814.1 60.0172.94038.94100.00174102221.4 60.0112243114.9100.00267111132.8 60.0112444115.1100.00375122745.9 60.0121845126.7100.00450129955.2 60.0127047933.0100.00463130656.7 60.0139249948.1100.00509133662.4 60.0150752062.2100.00681153183.5 60.0154153366.3100.00695154885.2 60.0164755779.4100.00815165899.9Figure1.GLE curves for PEG400(1)+H2O(2)+SO2(3)+N2(4):0, w1)0;O,w1)0.20;?,w1)0.40;],w1)0.60;+,w1)0.80;×,w1 )0.85;2,w

1

)0.90;1,w

1

)1.00.

Figure2.Solubility of SO2in PEGWs when SO2concentration in the gas phase is designed atΦ1)5·10-4.

960Journal of Chemical&Engineering Data,Vol.55,No.2,

2010

solubility of SO2in w1)0.80PEGW is presented at778 mg·L-1;and the solubility of SO2in pure PEG400is1330 mg·L-1at the same gas phase composition. Acknowledgment

Thanks to Professor Hongcheng Gao and Professor Wenting Hua (Peking University,China)for their suggestions on the GLE researching processes.

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Received for review May2,2009.Accepted June17,2009.This work was?nanced by Yongfeng Boyuan Industry Co.,Ltd.(Jiangxi province, China).

JE900392E

Journal of Chemical&Engineering Data,Vol.55,No.2,2010961