INVESTIGATION OF a LYSIMETER USING THE SIMULATION TOOL siwapro DSS AND ADAPTATION OF THIS PROGRAM TO VIETNAMESE REQUIREMENTS

Figures and pictures Figure 1: Ranges in water solubility of some organic compound classes 10 Figure 3: Experimental and predicted value for mixture ethanol – Figure 9: Solubility of A

HANOI UNIVERSITY OF SCIENCE TECHNICAL UNIVERSITAT DRESDEN

PHAM THI BICH NGOC

INVESTIGATION OF A LYSIMETER

USING THE SIMULATION TOOL SiWaPro

DSS AND ADAPTATION OF THIS PROGRAM

TO VIETNAMESE REQUIREMENTS

MASTER THESIS

Tutor:

Prof Dr Ing habil Peter Wolfgang Graeber

Dipl Ing Rene Blankenburg

Technical University Dresden

Institute of Waste Management and Contaiminated Site Treatment

HANOI – VIETNAM, DECEMBER 2008

TECHNISCHE UNIVERSITÄT DRESDEN

INSTITUTE OF WASTE MANAGEMENT AND CONTAMINATED SITE TREATMENT

Master Thesis

Pollutant mixtures: Investigation of resulting changes in the

single compounds water solubility

Supervisor: Dipl.-Ing Dipl.-Ing Jens Fahl

TU Dresden, Institute for Waste Management and Contaminated Site Treatment

Hanoi, 2008

Acknowledgment

First of all, I would like to express my thankfulness for Jens Fahl, my supervisor for your knowledge and enthusiasm Without your encouragement and advice I can not complete this work I also gratefully acknowledge Dr Axel Fischer for all you have done for me Special thanks for Marene, you are very kind and patient for me Thanks for Stefan, Claudia, I'm very grateful for your support

I would like to thank Prof Dr Bilitewski, Prof Dr Nguyen Thi Diem Trang and Assc Prof Dr Bui Duy Cam for great effort to establish and develop this program

I also would like express my gratitude to the following organizations for supporting me throughout the course

- The Committee on Overseas Training Project- Ministry of Education and Training of Vietnam

- Hanoi University of Science - Vietnam National University

- Institute for Waste Management and Contaminated Site Treatment – TU Dresden

- German Academic Exchange Service (DAAD)

Warmly thanks to Mai, Christian, Hai Minh for your help Thanks to all my colleagues who shared a good time with me Finally, thanks to my family, my parent, my mother in law, my husband and my little son who always along with me, encourage and share difficulties and pleasure as well

Hanoi, 10th December, 2008

Vu Huyen Phuong

Table of contents

Acknowledgment 3

Table of contents 4

Abbreviations 6

Figures and pictures 7

Tables 8

Summary 10

1 INTRODUCTION 11

1.1 Some important definition related to solubility 16

1.2 Factors influencing solubility 17

1.2.1 Temperature effects: 17

1.2.2 Pressure effects 19

1.2.3 Salting out effect 20

1.2.4 Cosolvent effects 20

1.3 Estimation of solubility 21

2 MATERIALS AND METHODS 27

2.1 Materials 27

2.2 Experimental procedure 30

2.3 Analyzing method 33

2.3.1 Ethylbenzene and Toluene 33

2.3.2 Anthracene and Naphthalene 33

2.3.3 Phenol 34

2.3.4 Tetradecane 34

2.4 Assessment of experimental data 37

3 RESULTS AND DISCUSSIONS 39

3.1 Preliminary experiments 39

3.2 Water solubility of studied organic compounds in pure form 45

3.2.1 Solubility of Ethylbenzene in water 46

3.2.2 Solubility of Phenol in water 50

3.2.3 Solubility of Anthracene and Naphthalene in water 52

3.3 Water solubility of studied organic compound mixtures 55

3.3.1 Mixture of Ethylbenzene and Toluene 56

3.3.2 Mixture of Ethylbenzene and Phenol 58

3.3.3 Ethylbenzene – Anthracene – Naphthalene Mixture 60

3.3.4 Ethylbenzene – Toluene - Anthracene – Naphthalene Mixture 61

3.3.5 Phenol - Tetradecane Mixture; Naphthalene – Tetradecane Mixture and

Special Mixture 64

4 PROSPECT 66

5 CONCLUSIONS 67

6 References 68

7 Statement under oath 71

8 Appendix 72

Abbreviations

HOC: Hydrophobic Organic Chemical

PMOS: Partially Miscible Organic Solvent

IUPAC: International Union for Pure and Applied Chemistry

VOC: Volatile Organic Compound

PAH: Polycyclic Aromatic Hydrocarbon

UNIFAC: Universal Quasi Chemical Functional Group Activity Coefficient

BTEX: Benzene – Toluene – Ethylbenzene – Xylene

HPLC: High Performance Liquid Chromatograph

Figures and pictures

Figure 1: Ranges in water solubility of some organic compound classes 10

Figure 3: Experimental and predicted value for mixture ethanol –

Figure 9: Solubility of Anthracene in water of selected data 53

Tables

Table 1: Chemical/physical properties of selected substances in this work 12

Table 5: Concentration of Ethylbenzene and Anthracene at different times 39 Table 6: Ethylbenzene concentrations (mg/l) in stirring and non-stirring condition 41 Table 7: Anthracene concentrations (μg/l) in stirring and non-stirring condition 41 Table 8: Solubility of Ethylbenzene at different temperature (mg/l) 46 Table 9: Comparison of experimental data and literature data of Ethylbenzene 46 Table 10: Solubility of Toluene at different temperature (mg/l) 48 Table 11:Comparison of experimental data and literature data of Toluene 48 Table 12: Solubility of Phenol at different temperature (mg/l) 50

Table 14: Solubility of Naphthalene and Anthracene at 20oC 52 Table 15: Comparison of experimental data and literature data of Antharacene at 20oC 52 Table 14: Comparison between experimental data and literature data of Naphthalene at

Table 22: Accuracy of experimental values for components in the mixture

Ethylbenzene – Anthracene – Naphthalene

61

Table 23: Aqueous concentration of Ethylbenzene – Toluene - Anthracene –

Naphthalene in the mixture at 20oC

62

Table 24: Aqueous concentration of Ethylbenzene – Toluene - Anthracene –

Naphthalene in the mixture at 5oC

62

Table 25: Accuracy of experimental values of component of mixture Ethylbenzene –

Anthracene – Naphthalene

63

Table 26: Comparison of experimental and calculated solubility of each component in

mixture Ethylbenzene – Toluene - Anthracene – Naphthalene at 5oC

63

Table 27: Aqueous concentration of components of the mixture Phenol - Tetradecane

and Naphthalene and Tetradecane at 20oC

65

Table 28: Aqueous concentration of components in Special Mixture at 5oC and 20oC 65

This work presents briefly theory of solubility, researches relating to water solubility of single compound and mixture, how to calculate water solubility of components in a mixture

This work determined the water solubility of six substances including Ethylbenzene, Toluene, Anthracene, Naphthalene, Phenol and Tetradacane at temperatures 5-10-20oC Water solubility of mixtures of these substances was observed at temperatures 5 and

20oC Solubility of single compounds compared to those in literature for determining accurate and precise received data Water solubility of single compounds and mixture also compared them each other The difference between these data was explained following solubility’s theory Water solubility of some mixtures was calculated and compared to experimental value Behaviours of components in the mixture also predict from experimental data

1 INTRODUCTION

Water solubility is one of the most important properties of compounds Water solubility

is defined as the concentration of a compound dissolved in water when that water is both

in contact and at equilibrium with the pure chemical Solubility represents an equilibrium distribution of a solute between water and the solute phase [1] It is found various range

of water solubility from hundred grams to only few ppb for organic substances Some compounds are completely soluble in water such as methanol Figure 1 shows range in water solubility of some organic compound classes in mol/liter

Figure 1: Ranges in water solubility of some organic compound classes [2]

Water solubility of almost substances was studied and listed in handbooks However, in some cases, solubility of organic compounds in the pure form has not been determined, in references it is mentioned as “not soluble”, “insoluble”, “miscible”, “slightly soluble” or

“moderate soluble” Water solubility of some substances studied in this work is given as

an example of this fact, and is shown on Table 1

Thus, water solubility is very important factor for controlling manufacture process, a valuable data in pharmaceutical study field and for controlling fate and transport of contaminants If a highly soluble substance is quickly distributed, and diluted, an insoluble substance is more likely to adsorb on solids, or accumulate in biota So, water solubility indicates the tendency of a chemical to be removed from soil to reach the surface water or ground water, to precipitate at the surface soil [2]

Present techniques for assessing or modelling the contaminant transport to environmental components typically rely on data such as solubility and the octanol-water partition

coefficient for the calculation of bioconcentration factors, sediment adsorption coefficients, toxicity, and biodegradation rates.

Simple example, if the amount of seepage water is known, the substance mass in the soil and their water solubility, mass of the contaminating substance which will be transported over the time to the groundwater can be calculated And the lifetime of this soil contamination can also estimated

Table 1: Chemical/physical properties of selected substances in this work

Substance Ethylbenzene(1) Toluene (1) Phenol (1) Anthracene (1) Naphthalene (1) Tetradecane (2)

None (at 20°C)

Moderate (at 20°C) (g/100 ml at 0.00013

20oC)

None (at 25oC)

Data is cited from Physical Properties of International Chemical Safety Card of

Ethylbenzene, Toluene, Phenol, Anthracene and Naphthalene [3]

(2)

Data is cited from Material Safety Data Sheet of N-Tetradecane [4]

In fact, a substance is rarely found in the pure form in the nature, it is usually mixed with

other substances and modified different from its origin Especially, contaminated sites

where substances have been become intermixed through careless dumping procedures or

through failure to segregate waste steam [5] In general, behavior of mixture of these

substances is very complicated If the mixture comes in contact with aqueous phase and

form a solution, water solubility value of the single compounds from this mixture will not

be the same like the value which listed in literature Because these values are typically

validate only for the solution of a single substance in pure water under laboratory

conditions

Water solubility in both synthetic and environmental mixtures has been carrying out by

scientists over the world Relating to the selected compounds for this study, some

researches have been found and used in this as a literature source Sujit Banerjee spent many years for researching on water solubility of components in liquid-liquid mixture, liquid-solid mixture and solid- solid mixture Many his works have been publicized He investigated solubility of many organic compounds and organic mixtures as well [6] For example, solubility at 25oC of several chlorobenzenes, some mixtures of chlorobenzene, mixture of benzyl alcohol with several chlorobenzenes, mixture benzyl alcohol and toluene, ethyl acetate were determined This work found that mixture of hydrophobic liquid is near ideal in the organic phase, in the aqueous phase the activity coefficient of a component was unaffected by the presence of cosolute Increasing hydrophobicity of the solutes led to deviations from ideality in the organic phase For the mixtures of solids which did not interact, the components tended to be behave independently of one other, and their solubility ware approximately additive

Clayton McAuliffe [7] determined the solubility in water at room temperature of 65 hydrocarbons including Paraffin and Branched-Chain Paraffin Hydrocarbons, Olefin Hydrocarbons, Acetylene Hydrocarbons, Cycloparaffin, Cycloolefin, and Aromatic Hydrocarbons by using a gas-liquid partition chromatographic technique This work found branching increases water solubility for paraffin, olefin, and acetylene hydrocarbons, but not for cycloparaffin, cycloolefin, and aromatic hydrocarbons For a given carbon number, ring formation increases water solubility Double bond addition to the molecule, ring or chain, increases water solubility The addition of a second and third double bond to a hydrocarbon of given carbon number proportionately increases water solubility A triple bond in a chain molecule increases water solubility to a greater extent than two double bonds

Coyle, Harmon and Suffet [8] measured solubility of hydrophobic organic chemicals (HOC), including Naphthalene, Biphenyl, PCB-47, PCB-153, in water saturated with partially miscible organic solvents (PMOS), including methylene chloride and chloroform Generator Column Technique was used for solubility measurement in mixed solution The author concluded that solubility of Naphthalene was not much impacted by the solvents, while that’s of Biphenyl decreased slightly with increasing solvent’s

concentration In aqueous phase, chloride and chloroform, PCB-47 concentration in aqueous phase were reduced about 25% and 15%, respectively, of its aqueous solubility The solubility depression increased with increasing chemical hydrophobic of both HOC and solvents Through the research results, the authors also explain behaviors of organic mixture and contaminant transport in soil and groundwater The association of the solvents like methylene chloride and choroform with HOC phase will retard the transportations of this relatively mobile solute through sediments contaminated with HOC And the presence of nearly saturated solution of PMOS will reduce the apparent solubility and therefore the mobility of the HOC

Aqueous solubility of PAH was determined by Donald Mackay and Wan Ying Shiu (1977) The solubility of 32 PAHs has been measured in water at 25oC The results of ten

of the compounds compare satisfactorily with literature values Aqueous solubility can then be calculated directly for hydrocarbons which are liquid at 25oC [9]

Ghanima K Al-Sharrah, Sami H Ali and Mohamed A Fahim (2001) measured solubility

of anthracene in two mixed solvents toluene and 2-propanol and toluene and heptane is studied in the temperature range 20– 50oC The comparison between experimental and predicted solubility by two models - UNIQUAC and modified UNIFAC is quite reasonable with an average prediction coefficient between 0.995 and 0.971 [10] Other work of this group author (2005) investigated solubility of pyrene and phenanthrene in

toluene solvent mixture of iso-octane and heptane over a temperature range from

20-50oC The experimental solubility data were used to predict the interaction parameters for seven different solid–liquid equilibrium models [11]

The solubility of several n-paraffins (from Dodecane C12 to Hexadecane C26) in both distilled water and seawater has been determined by Chris Sutton and John A Calder (1974) The results shown these n-paraffins have very low water solubility in ppb range But n-paraffin is less soluble in seawater than in distilled water This work also indicates importance of salting out effect on water solubility This fact explains transportation and fate of paraffins in seawater and estuaries area [12]

The solubility of normal paraffins from methane to decane (C10) has been investigated

by Mc.Auliffe (1969) This work found that the solubility at 25oC of the normal alkanes decrease with increasing carbon number (solubility of C9 is 220 ppb and C10 is 52 ppb) [13]

An important database on solubility - IUPAC Solubility Data Series, containing solubility originally published in International Union for Pure and Applied Chemistry is now available online There are over 67,500 solubility measurements There are about 1800 chemical substances in the database and 5200 systems, of which 473 have been critically evaluated Solubility and liquid-liquid equilibrium of binary, ternary and quaternary systems are presented Typical solvents and solutes include water, sea water, heavy water, inorganic compounds, and a variety of organic compounds such as hydrocarbons, halogenated hydrocarbons, alcohols, acids, esters and nitrogen compounds For many systems, sufficient data were available to allow critical evaluation Data are expressed as mass and mole fractions as well as the originally reported units [14]

1.1 Some important definition related to solubility

Solubility is referred as the ability for a given substance, call the solute (solute can be a

solid, liquid or gas), to dissolve in a solvent It is measured in terms of the maximum

amount of solute dissolved in a solvent at equilibrium [3]

A solution is a liquid or solid phase containing more than one substance, when for

convenience one of the substances, which is called the solvent, and may itself be a mixture, is treated differently than the other substances, which are called solutes If the

sum of the mole fractions of the solutes is small compared to unity, the solution is called

a dilute solution [3]

A mixture is describes a gaseous, liquid or solid phase containing more than one

substance, where the substances are all treated in the same way [3]

Activity coefficient (γ) of a substance is defined as the chemical potential of its in liquid

or solid mixture An activity coefficient is a factor used in thermodynamics to account for deviations from ideal behavior in a mixture of chemical substances [15]

For pure compound dilute in water, activity coefficient of this solute in the solute phase is unity But in mixture many components interact within the mixture, had led to changes of mixture’s solubility In general, interaction takes place between solute in the organic phase, rather than in the aqueous phase Hydrophobic solutes tend to be diluted in the aqueous phase to interact significantly each other Liquid solute are usually mix each other resulting to they are able to interact within the organic phase Solid solutes tend not

to mix with other ones and they behave independently each other In this case, mixture’s solubility of solids is frequently the sum of the solubility of its components [1]

It is said that water solubility represents equilibrium of a solute between water and solute

phase The following will discuss more details about type of solute and solute phase, the

way of solute and solute effects on solubility

There are three type of solute including liquid solute, gaseous solute and solid solute For liquid solutes, the ideal solution tends to be formed if the solute and solvent molecules are very similar in size and in the nature of their intermolecular interactions Solutions of n-heptane in hexane, toluene in benzene or carbon tetrabromide in carbon tetracholoride are very nearly ideal Other case, the solute and solvent molecules are similar polarity but have great difference of molecule size, the solution of them is considered as an ideal mixture

For solid solute, it is necessary to account for the inhibitory effect of crystal structure upon solubility It is well known that the solubility of a crystalline solute in any solvent depends on properties of the crystals which is given by the van’ Hoff equation

Gaseous behavior is explained by Henry’s Law which says the solubility of a gas in a liquid is proportional to the pressure of the gas

1.2 FACTORS INFLUENCING SOLUBILITY

1.2.1 Temperature effects:

Aqueous solubility is a function of temperature Increasing temperature reduces water- water, water – solute and solute – solute interactions [1] Figure 2 shows temperature effects on solubility of some compounds

For solid solutes, the effect of temperature is important The solubility generally increases with temperature, in the temperature range from about room temperature to 100°C About 95% solid solute obeys this rule of thumb However, some of solid only have solubility increase in a certain range of temperature [1] The detail of this fact will be discussed later For most gaseous solutes, the water solubility decreases with increasing temperature That means as the temperature is raised gases usually become less soluble in

water Many organic liquids exhibit minima in solubility at room temperature In general, solubility of solids is much more sensitive to temperature effect than liquids [1]

Figure 2: Water solubility as a function of temperature [2]

Temperature effects on solubility can be different, depending on the temperature range Evidence of this fact is shown in Table 2 Solubility of some organic compounds only slightly depends on temperature in certain range Some of compounds have complex behaviors, for example Benzene solubility decreases with increasing temperature below

~15°C, but increases with increasing temperature above ~20°C [2]

Table 2: Difference of solubility in different temperature [1]

10oC 20oC 25oC 30oC 40oC 50oC m-

Table 3: Effect of pressure on the solubility of Xylene [1]

Pressure (MPa) Percent increase in solubility

In case of Xylene, solubility intensively influenced by pressure but only occurs at extremely high pressure The table shows the solubility increases significantly, reaches to maximum point and then falls down

1.2.3 Salting out effect

The aqueous solubility of different kinds of compounds such as proteins, volatile organic compounds, gases, detergents, etc decrease in the presence of inorganic salts, this is called the salting-out effect The solubility decrease is quantified by the classical Setschenow equation, named a scientist [16]

(1)

where S0 is the solubility of the non-electrolyte (solute) in pure water,

S is the solubility in the presence of a salt,

γ is the activity coefficient of the non-electrolyte

KS (salt, solute) is the Setschenow constant

c is the salt concentration

The salting-out effect is known to be influenced by the polarity (dipole moment) of the non-electrolyte Substances more polar are salted out from a given salt solution to a smaller degree

log S=log Sw+σf (2)

where S and Sw are the solubility in the co solvent–water mixture and water,

respectively

f the fraction of the co solvent

σ the solubilization capacity and can be defined by the following equation

using the octanol–water partition coefficient (log Kow)

The log–linear model was demonstrated that a linear relationship exists between σ and the logarithm of the solute's partition coefficient (log Kow) [18] This explains how strongly a solute is solubilized and how hydrophobic the compound is In essence, the more hydrophobic the solute, the more it will be solubilized by cosolvent addition

1.3 Estimation of solubility

Estimation of solubility in water of organic compounds is not easy, especially for mixtures of organics In case of pure compound seem to be less complex But in mixture many components interact within the mixture, had led to changes of mixture’s solubility

Some methods have been researched and developed for estimation of aqueous solubility

of mixture According to Sujit Baneejee [1] calculated solubility for mixtures obeyed

these following equations The different between experimental data and calculated data was pointed out in some his work which will be discussed later

When a hydrophobic liquid is equilibrated with water, its solubility is given by equation (3)

χorg γorg

χaq = _ (3)

γaq

χaq: mole fraction of the compound in aqueous phase

χorg: mole fraction of the compound in organic phase

γaq: activity coefficient of the compound in aqueous phase

γorg: activity coefficient of the compound in organic phase

If organic phase is pure form of the substance, χorg, γorg both approximate unity, equation (3) reduce to equation (4)

(χip)aq : solubility in water of the pure ith component

(γip)aq : activity coefficient of the pure ith component

(χi)org : mole fraction of itch component in organic phase

(γi)org : activity coefficient of ith component in organic phase

Equation (6) is more conveniently expressed as equation (7)

Ci (χi)org (γi)org (γip)aq

= (7)

Where Ci: equilibrium molar concentration of the itch component in the mixture

Si: water solubility of itch component in its pure form

If interaction in the aqueous phase is small and (γi)aq = (γip)aq, equation (7) reduces to equation (8):

Equation (9) is the simplest and applied for near ideal mixture

Equation (8) corrects for activity coefficient in the organic phase

Equation (7) corrects for activity coefficient in both organic and aqueous phase

Here, activity coefficient (γ) is calculated by UNIFAC (Universal Quasi Chemical Functional Group Activity Coefficients) methods which developed by Prausnitz and co-

workers [15] This method is well-known as a Group Contribution Method has been used

to estimate the appropriate activity coefficients for mixtures In group contribution methods, it is assumed that the mixture does not consist of molecules, but of functional groups Activity coefficients are calculated from constants reflecting the sizes and surface areas of individual functional groups, and parameters representing energetic interactions between groups Size and area parameters for groups were evaluated from pure-

component, molecular structure data Group interaction parameters were evaluated from

phase equilibrium data for mixtures containing paraffins, olefins, aromatic hydrocarbons, water, alcohol, ketones, amines, esters, ethers, aldehydes, chlorides, nitriles, and other organic liquids [15] From activity coefficient of the functional groups of both solute and solvent in the mixture, they are reassembled to obtain the activity coefficient of the mixture This method has been successful for predict phase equilibrium, for estimating pure-component properties such as liquid densities, heat capacities, and critical constants [19] This method was applied for calculation of activity coefficients in a large number of binary and multicomponent mixtures can be estimated with good accuracy [20]

However, UNIFAC method is an approximation and has some weaknesses such as poor results for activity coefficients at infinite dilution or excess enthalpies and systems with compounds very different in size The reason is contribution of a group in one molecule

is not necessarily the same as that in other Furthermore no quantitative information about the temperature dependence was used So, modified UNIFAC method has been developed

The main differences compared to original UNIFAC are:

• an empirically modified combinatorial part is introduced (In the UNIFAC method, the activity coefficients are calculated from a combinatorial and a residual part Whereas the combinatorial part takes into account the size and form of the molecule, the residual part considers the enthalpic interactions)

• temperature-dependent group interaction parameters are used; and

• additional main groups (e.g., for cyclic alkanes, formic acid, etc.) were added [20]

Comparison of experimental and predicted value by UNIFAC and modified UNIFAC method is described in Table 4

(1/T: function of temperature, ln γ: logarithms of the activity coefficients)

Figure 3: Experimental and predicted value for mixture ethanol – cyclohexane [20]

At the present, activity coefficient is computerized by software program which bases on UNIFAC and modified UNIFAC method Dortmund Data Bank (DDB) was established was in 1973 at the University of Dortmund is the largest computerized data bank for thermodynamic pure component and mixture properties DDB contains data from the open literature, also a large number of data from private communications or company data These include more than 1000 data points for mixtures containing ionic liquids [21]

Solubility can be calculated from Raoult's Law which says the partial vapor pressure of a component in a mixture is equal to the vapor pressure of the pure component at that temperature multiplied by its mole fraction in the mixture [22]

For solution of a non-volatile solute, this Law is demonstrated by equation (10)

(10)

In which: P o is the vapor pressure of the pure solvent at a particular temperature

x solv is the mole fraction of the solvent, exactly it is the fraction of the total number of moles present which is solvent

For a mixture of two volatile liquids A and B, equation (10) can be written by equation (11):

PA and PB are the partial vapor pressures of the components A and B

XA, XB are the mole fraction of the component A and B

So, XA and XB may be regarded as solubility of XA, XB in the solution at certain PA and

PB and can be calculated from pressure of it’s in the pure form

However, Raoult's Law only works for ideal solutions These are mixtures of two very closely similar substances And Raoult's Law only works for solutes which don't change their nature when they dissolve

So, the ideal mixture will always obey Raoult’s Law and Equation (9) And solubility can

be calculated from mole fraction of solute in the mixture and its pressure and solubility in pure form

(11)

2 MATERIALS AND METHODS

2.1 Materials

In this work, six organic substances with various range of solubility were studied These are Ethylbenzene and Toluene – volatile organic compounds (VOC); two Polycyclic Aromatic Hydrocarbons (PAHs) – Anthracene and Naphthalene, Tetradecane – a straight chain alkane and Phenol

Ethylbenzene and Toluene belong to BTEX group - acronym for Benzene, Toluene, Ethylbenzene, and Xylene This group of volatile organic compounds (VOCs) is found

in petroleum hydrocarbons, such as gasoline They are common industrial organic solvents, intermediate chemical for synthetic of other chemicals Ethylbenzene is used

as a solvent in paints and lacquers and in the rubber and chemical manufacturing industries Ethyl benzene is soluble in water, ethanol, diethylether and most other organic solvents [23] Toluene is a commercially-important intermediate chemical produced throughout the world in enormous quantities It is produced both in the isolated form and as a component of mixtures Toluene produced in the form of a mixture is used to back-blend gasoline Isolated toluene produced in the production of paints, thinners, adhesives, inks, pharmaceutical products [24]

Phenol is widely used in manufacture of many products such as insulation materials, adhesives, lacquers, paint, rubber, ink, dyes, illuminating gases, perfumes, soaps and toys In the environment, phenol obtains from coal tar, or as a degradation product of benzene The compound has moderate solubility in water and is soluble in most organic solvents [25]

Anthracene and Naphthalene both belong to the group of polycyclic aromatic hydrocarbons (PAHs) However, Naphthalene contains two fused aromatic rings and Anthracene has three PAHs are hydrophobic with low solubility in water, but solubility

is quite different between Anthracene and Naphthalene Most PAH enter the environment via the atmosphere from incomplete combustion processes, such as: oil refining, coal gasification, coking and so on [26], [27]

Tetradecane belongs to group of hydrocarbons, commonly known as straight chain alkanes (n-alkanes) It is light oily hydrocarbon (C14H30), so called from the fourteen carbon atoms in the molecule In nature alkanes are found in natural gas and petroleum

In some researches, they found that Tetradecane has very low solubility in water [4]

These substances used in this work have high purity, meet demands for chromatography Purity of studied substances is shown on Table 5

Equilibration of the studied compounds was occurred in close environment The compound was weighted or taken an exact volume by micropipette and placed on glass vessels Depending on each substance, glass vessels with different volume were used However, the ratio between the amount of the substances and water volume is correlative Due to establishing close system, reducing interference factors from outside environment, the following three kinds of glass vessels were chosen, glass vial 20ml with special silicone septum, glass vessel 100ml and 500ml with rubber cap Picture 1,

2, 3 will show these vessels Other reason for choosing vessels is to take to pierce with a cannula of a syringe through the rubber cover and take a sample from aqueous phase

Table 4: Purity of studied substances

Substance Formula Molecular mass Purity (%) Supplier Ethylbenzene C8H10 /

Picture 1: Glass vial 20ml with special silicone septum

Picture 2: Glass vessel 100ml with special rubber cap

Picture 3: Glass vessel 500ml with special rubber cap

Double distilled water was used as a solvent for studied substances All glassware was rinsed with water and then distilled water and dry at least 3 hours or whole the night in oven at 200oC The clean glassware was kept in close chamber until prior to use Aqueous sample was taken through silicon septum by Hamilton microliter syringe 50μl The syringes were cleaned carefully many times with distilled water and methanol after each use Some samples were taken by disposalable plastic syringe 2ml with needle 0.8x40 mm of TERUMO Corporation

2.2 Experimental procedure

For the water solubility studies, amount of each compound equilibrating with water need to be much greater than its solubility to ensure obtaining the maximum water solubility For water solubility determination of single compounds in pure form, experiments were made as the following describe Ethylbenzene and Toluene were taken by micropipet and separately place on 20ml glass tube with 15ml of water 5g Phenol was weighted and 10ml water were put in to glass vial 20ml Naphthalene and Anthracene were weighted separately and 75ml water added in to glass bottle 100ml Mixture experiments have been created with the same amount of each compound and the same procedure which were made for single compound experiments

Vessels with organic phase is lighter than water phase, keep in upside down position and tightly closed by rubber cover The rubber of the cover is only in contact with water and the organic phase is above the water After waiting for a certain time for reach equilibrium of the compound in the water phase, aqueous phase is sampled to analyse

A syringe can pierce through the rubber cover and take an exact volume of aqueous phase and dilute in to suitable volume for analysing Water solubility of single compounds were studied at 3 different temperatures, at 5°C, 10°C and 20°C, for mixture studied at two temperature, 5oC and 20oC Picture 4, 5, 6 will show experiments are under these temperatures Each experiment with single compound and mixture at each temperature has two or three parallel bottles The water in each bottle was sampled at least in duplicate

Picture 4: Samples is kept at 20oC

Picture 5: Store samples in room 5oC Picture 6: Store samples in room 10oC

Taking sample procedure is very important to get the correct analyzing results During

the handling it is needed to prevent the needle of the syringe from touching the surface

or the bottom layer Because droplet from solvent layer above in the water layer, solid

particle or liquefied solid in the bottom of the vessel can go inside the syringe, this had

led to significant deviation of analyzing results In case of Phenol, droplets may

distribute in the aqueous phase, the vial was shaken gently so that droplets sunk in the

bottom phase Before taking sample, the glass vials were allowed to clearly separate

phase, syringe went slightly through the rubber septum and aqueous phase is extracted

with exact volume In the next part, experimental data demonstrate the possibility for

prevention of droplet by taking sample Sampling activities are presented in picture 7, 8

Picture 7: Taking sample by microliter syringe 50μl Picture 7: Taking sample by syringe 2ml

2.3 Analyzing method

2.3.1 Ethylbenzene and Toluene

Ethylbenzene and Toluene concentration in aqueous phase were quantified by Gas Chromatograph (Hewlett Packard GC System HP 6890 Series) equipped with split/splitless injector, fitted with a Perkin-Elmer HS 40 XL autosampler, flame ionization detector (FID) and a capillary column (Agilent DB-624; 30.0 m, 0.53µm i.d., 3.0µm film thickness) The GC/FID was supplied with helium (4.0ml/min) as carrier gas and nitrogen (25ml/min) as make-up gas as well as oxygen (65.0 mL/min) and hydrogen (35ml/min) as detector gases 10ml of water samples were added to 22ml headspace vials, sealed with caps (silicon/ PTFE) and kept in an oven (thermostat) at 70°C for 180 minutes Afterwards, a gas space sample was injected automatically (injection time 0.1 min., split ratio 2.5, split flow 10ml/min, constant flow) into the GC/FID and analyzed The temperature settings were as follows: injector temperature 250°C, oven temperature programme: 80°C (10.5 min.), 5°C/min., 140°C (0 min.), postrun 250°C (2.5 min.), and detector temperature 300°C

To analyze Ethylbenzene and Toluene, 50µl water sample is taken, 9.9ml distilled water and 50µl Sodium Nitrite (Na3N) used as a disinfectant added in to headspace glass vial 22ml, then introduced for GC

Quantification of Ethylbenzene and Toluene follow MTBE and TBA method using external standard calibration The detection limits were 5µg/L and 75µg/L, respectively Retention time of Toluene is 12 minute, of Ethylbenzene is 16.5 minute Peak of Ethylbenzene is compared to calibration curve with concentration in range 100µg/l; 300µg/l; 500µg/l; 800µg/l and 1000µg/l Calibration curve of Toluene in range 1000µg/l; 2000µg/l, 4000µg/l

2.3.2 Anthracene and Naphthalene

Anthracene and Naphthalene concentration in aqueous phase were determined by High Performance Liquid Chromatograph WATERS 2695 with Detector Photodiode Array WATERS 99 (for naphthalene and anthracene at 220 nm) and Fluorescence WATERS

474 (for naphthalene with excitation wave length: 280 nm, emission wave length: 340 nm), for anthracene with excitation wave length: 235 nm, emission wave length: 430

nm; Column oven: Jetstream plus; Separation column: MZ-PAH C18, particle size 5

µm, column length = 25 cm, inner diameter = 2.1 mm Mobile phase are water (Milli pore) and acetonitrile (gradient grade, MERCK)

0 up to 7 minutes: 50:50 (pressure: ≈1100 psi)

23 up to 39 minutes: 0:100 (pressure: ≈500 psi)

43 up to 60 minutes: 50:50 (pressure: ≈1100 psi)

Steady phase: silica gel with chemically bounded octadecyl phase

Injection volume: 10µl, volume of the HPLC vials: 1.5ml

Column temperature: 40°C

Equilibration time: 20 min

1.5ml water sample containing Anthracene was taken and directly analysed by HPLC 30µl of water sample with Naphthalene was sampled by Hamilton micro syringe, fill with 1470 µl Acetonitrile and introduced for HPLC

2.3.3 Phenol

Phenol concentration was quantified by using Spectrometer (Specord 50 of Analytik Jena Company) at wave length λ = 271 nm Calibration curve was made at concentration 1 mg/l, 5 mg/l and 10 mg/l 50µl aqueous sample containing Phenol was taken and first step dilute by distilled water with factor 100 (50µl dilute up to 5ml) The second dilution step is to take 50µl of this solution and dilute with factor 100

2.3.4 Tetradecane

Tertradecane concentration in aqueous phase was quantified by Gas Chromatograph Shimadzu GC-2010 / autosampler AOC 5000 / FID detector Mobile Phase: N2; Stationary Phase (column): Crossbond® RTX®-5 mit 5% Diphenyl – 95% Dimethylpolysiloxane

Injection pressure (at 60°C): 14.9 kPa

Standard temperature program column oven: 60°C (1min)  20K/min auf 170°C

 50K/min auf 300°C (2min)

50ml aqueous phase containing Tetradecane plastic was taken from experimental bottle

by syringe 50ml with needle 0.8 x 40 mm of TERUMO Corporation Because of very low solubility of Tetradecane in water, it is necessary to up concentration of Tetradecane in sample The procedure for up concentration is described as following: 50

ml of water sample will be extracted 2 times with 5ml Heptane, the received 10 ml Heptane are given over a column of Na2SO4 and Fluorisil The column passed n-Heptane will be evaporated in a rotation evaporator to less than 1ml and after refilled with internal standard in n-Heptane to exactly 1 ml

n-Quantification of Tetradecane method used internal standard - Dodecane Calibration curve of Tetradecane concentration in range 10, 20, 50, 75, 100µg/l Calibration curve of internal standard Dodecane in range 50, 100, 1.000, 10.000µg/l

Sample preparation and analytical equipments are shown in Picture 9,10,11,12, 13, 14 Calibration curve of the methods mentioned above in attached in appendix