Development of gaseous trimethylamine trap tube using activated carbon for sampling of fish derived malodorous gases

VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY NGUYEN TUAN KHANG DEVELOPMENT OF GASEOUS TRIMETHYLAMINE TRAP TUBE USING ACTIVATED CARBON FOR SAMPLING OF FISH-DERIVED MALODOROUS GASES MASTER'S THESIS Hanoi, 2018 VIETNAM NATIONAL UNIVERSITY, HANOI VIETNAM JAPAN UNIVERSITY NGUYEN TUAN KHANG DEVELOPMENT OF GASEOUS TRIMETHYLAMINE TRAP TUBE USING ACTIVATED CARBON FOR SAMPLING OF FISH-DERIVED MALODOROUS GASES MAJOR: ENVIRONMENTAL ENGINEERING RESEARCH SUPERVISOR: PROF TAKASHI HIGUCHI ASSOC PROF TRAN HONG CON ASSOCIATE PROF TU BINH MINH Hanoi, 2018 ACKNOWLEDGEMENTS First of all, I would like to express my greatest thank to my supervisor, Professor Takashi Higuchi and Associate Professor Tran Hong Con for supporting me all the time It is my honor to be able to study and work with them They always willing to help me at any time a need throughout my study I gratefully acknowledge the financial support from Associate Professor Tran Hong Con With his support and good relationship, I am able to my thesis smoothly In addition, special thanks to Associate Professor Cao The Ha, Professor Jun Nakajima for the valuable working experiences and useful advices Thank Dr Nguyen Thi An Hang for being such a great mentor, a great friend that share me a lot of valuable advices Besides, It is a pleasure for me to show my gratitude to all members in Environmental Chemistry Laboratory, who instructed, supported, encouraged me during the completion of the thesis I would like to thank teachers in Environmental Engineering Program from Vietnam Japan University who gave me essential knowledge of environmental major Last but not least, I would like to thank my family, my classmate and my friends for encourage and support me throughout this process to complete my master degree Hanoi, June 15th 2018 Nguyen Tuan Khang i TABLE OF CONTENTS ACKNOWLEDGEMENTS i LIST OF FIGURES iv LIST OF TABLES v LIST OF ABBREVIATIONS vi INTRODUCTION .1 CHAPTER LITERATURE REVIEW 1.1 Trimethylamine Gas 1.1.1 Physical and Chemical properties 1.1.2 Human odor threshold of trimethylamine 1.1.3 Toxicity of trimethylamine 1.2 Overview of fish-derived malodorous gases .8 1.2.1 Fish processing activities 1.2.2 Fish-derived gases emissions 10 1.2.3 Vietnamese Regulation for organic malodorous gases 11 1.3 Review on Trimethylamine gas sampling and measurement methods 13 1.3.1 Colormetric Determination of TMA as the picrate salt 13 1.3.2 Thermal desorption with GC and time of flight mass spectroscopy 15 1.3.3 TMA adsorption of Activated Carbon .16 CHAPTER EXPERIMENT 18 2.1 Assessment of Activated Carbon material 19 2.2 Preparation of Activated Carbon tube .20 2.3 Generation of Odorless gas .22 2.4 Preparation of Trimethylamine operating gas samples 23 2.5 TMA gas sampling using Activated Carbon Tubes 26 2.6 In-situ sampling at fish-processing sites 28 2.7 TMA extraction from the AC adsorbent tube 29 2.8 Instrument analysis 31 CHAPTER RESULTS AND DISCUSSION 32 3.1 TMA calibration curve 32 3.2 Study of the TMA adsorption efficiency 33 3.3 Study of the TMA extraction efficiency 35 ii 3.3.1 Effect of different initial TMA concentration on the TMA extraction efficiency 35 3.3.2 Ethanol as an alternate solvents on the TMA extraction efficiency 37 3.3.3 Microwave as an alternate method for extraction techniques 37 3.4 In-situ sampling .38 CHAPTER CONCLUSION AND RECOMMENDATION 40 REFERENCES 41 iii LIST OF FIGURES Figure 1.1 An overlay of aromagram and chromatogram represent panelist’s perception on Trimethylamine and Dimethylsulfide with hedonic tone and qualifier (Caraway, 2007) Figure 1.2 Conventional fish sauce making process Figure 1.3 Breakthrough curve of Methyl mercaptan, Demethyl sulfide and Trimethylamine on Activated Carbon (Lee, 2010) 17 Figure 2.1 Experimental procedure 18 Figure 2.2 Scanning electron microscope (SEM) pictures of Tra Bac activated carbon 20 Figure 2.3 Activated Carbon adsorbent tube 22 Figure 2.4 Odorless gas generation procedure 22 Figure 2.5 Kitagawa detector tube’s structure 24 Figure 2.6 Kitagawa gas detector system procedure 25 Figure 2.7 Scheme of TMA sampling .27 Figure 2.8 Odor sampling at fish sauce incubation area 29 Figure 2.9 Diagram of TMA extraction experiments 30 Figure 3.1 Calibration curve of TMA .32 Figure 3.2 Comparison between estimated TMA and analyzed TMA results of T0.02A, T0.02B, T0.02C samples respectively .35 Figure 3.3 Comparison between estimated TMA and analyzed TMA results of T20A, T20B, T20C samples .36 Figure 3.4 TMA adsorption analyzed from samples Tm20A, Tm20B, Tm20C, T20A, T20B, T20C at 20ppmv initial adsorping concentration respectively 38 iv LIST OF TABLES Table 1.1 Chemical and physical properties of Trimethylamine(EPA, 2008) Table 1.2 Maximum allowed concentration of some harzardous gases in the ambient air (ENVIRONMENT, 2009) 11 Table 3.1 Standard solutions procedure 32 Table 3.2 TMA Adsorption rate measured by the inlet and outlet amount of samples 34 v LIST OF ABBREVIATIONS AC ACN TMA VOCs TMAO LC MS SEM Activated carbon Acetonitrile Trimethylamine Volatile organic compounds Trimethylamine N-oxide Liquid Chromatography Mass Spectrometry Scannnig electron microscope vi INTRODUCTION Research’s purpose and significance In the recent years, air pollution has been considered as an emerging problem that can directly cause adverse effects on both environmental and human health The sources of air pollution mostly come from anthropogenic activities: energy generation by burning fossil fuels, industrial producing/manufacturing and commercial activities, etc They all emit a tremendous amount of various chemical gases into the atmosphere Among different issues related to air pollution, the odor problems raise up as the top of air pollution complaints to governments around the world, especially in Vietnam An odor can be understood as a mixture of gases contained light and small chemical molecular, which can trigger human sense of smell if it is inhaled at a certain concentration(Brattoli, 2011) There are many chemical gases which have the odor properties to human sense, most of them are volatile organic compounds (VOCs) such as sulfurous compounds and amine compounds These gases may interfere with people normal behavior due to its annoying smell at low concentration, e.g feeling uncomfortable and losing attention to work At higher level, the health risks appear when a person get to inhale large amount of chemical gases or be exposed to them during a long period In Vietnam, there are many activities that can causes nuisance odor Recently, one of the most complaint issues related to smell comes from the fish-processing manufacturer, especially in the central areas of the country Miller et al (1993) used the liquid chromatography to determine several VOCs gases related to decayed fish including hydrogen sulfide, methylmercaptan, trimethylamine oxide, ammonia, etc Among those gases, trimethylamine (TMA) has been considered as a specific indicator of fish-processing emission, since its formation comes from the reduction of trimethylamine oxide (TMAO) through aerobic bacteria activities such as Alteromonaces and A putrefaciens (Caraway, 2007) Besides TMAO exists inside the tissues of almost any sea fish but not present in other animal Therefore, an appropriate procedure for TMA gas sampling and measurement is necessary in order to control the air quality at the fish-processing sites In the ambient environment, TMA gas usually exists at low concentration due to the diffusion of TMA into the air, plus the slow rate of TMA emission from fish muscles under the activities of bacteria On the other hand, TMA is known as the gas with very low odor threshold - 0.00026 ppmv for detection threshold or 0.0034 ppmv for recognition threshold(Caraway, 2007) As a result, people around the emission source can easily feel the malodor and suffer from it even though the TMA concentration at that time is still low The conventional method for TMA sampling is to pump the TMA sample into diluted sulfuric acid for absorption and then desorb it with base solution such as potassium hydroxide For in situ sampling, that method requires many chemical and equipment which is costly and inconvenient To overcome this difficulty, the activated carbon tubes or cartridges can be applied as a device for quick concentrating and sampling The activated carbon is well known for its ability to adsorb a wide range of chemical, including VOCs Besides it is also a cheap non-chemical material that can be made or purchased easily Moreover, the adsorption tube has a small size, no longer than 10cm, make it comfortable to carry to multiple areas Therefore, these activated carbon tube is a good approach for a more convenient, flexible and less costly sampling procedure Objective and scope This research is mainly focus on the sampling method for TMA gas using the Activated Carbon trap tube as a portable device In previous researches, the carbons have been chosen to be the effective material to isolate the VOCs gas in the air(Brewer, 2004) This trapping techniques were firstly employed for detection and analysis of VOCs released from swine finishing chamber and swine manure, now will be studied on TMA gas adsorption in laboratory experiment, followed by fishprocessing in situ malodor sampling After the adsorption process, both ends of the tube are sealed using PE layer The tubes are kept in refrigerator to avoid thermal desorption, diffusion and contamination In order to measure the adsorption efficiency of the AC tubes, the effluent gas from the tube are going to the impinger contained 10mL of the ACN:water solvent to trap the TMA that were not adsorption in the AC tube The solution from the impinger in each experiment are poured into 10mL vials, labeled as U0.02A, U0.02B, U0.02C, U20A, U20B, U20C respectively with adsorption tubes These vials are kept in refrigerator and also are analyzed to quantify the TMA passed through the AC tubes Additionally, a series of adsorbent tubes were also prepared with the similar sampling condition of the T20A tube, named as: Te20A, Te20B, Te20C, Tn20A, Tn20B, Tn20C, Tm20A, Tm20B, Tm20C These tubes were used for the investigation of the TMA extraction efficiency which will be described in detail in Section 2.6 2.6 In-situ sampling at fish-processing sites Location The chosen sites is a fish sauce processing site, which belonged to Cat Hai Joint Stock Company for Seafood processing, Hai Phong, Vietnam Apparatus - AC adsorbent tube - Kimoto handy sampler HS7 - Silicon tubes - Silicon caps Procedure The in-situ samplings are conducted at fish sauce incubation area The tube labeled S1 is installed with the sampler device, and the system was put under the shadow that kept the temperature remained constaintly at 33°C The position of the 28 system was 0.5m above the ground, and stayed at the downwind of the whole area to optimize the efficiency of sampling S1 was sampling at the flow rate of 0.5L/min, in the total of 30 minutes Then it was sealed using silicon caps This method was partly adopted from Kim’s method (2012) (Kim, 2012) Figure 2.8 Odor sampling at fish sauce incubation area 2.7 TMA extraction from the AC adsorbent tube Many previous researchers pointed out that TMA was very soluble in water and organic solvent Specifically, Flick (1991) and Neil (2006) claimed that, TMA was readily soluble to ethanol as it had very high solubility – 1mL of ethanol can solve 600mL of gaseous TMA(Flick, 1991, Neil, 2006) On the other hand, acetonitrile is well known as an convenient organic solvent and can be easily mix with water to create solvent solution Besides it also usually be utilized as a mobile phase of HPLC system Therefore in this research, those compounds are expected to be good extract solvents for desorbing TMA from AC bed The first three tubes named T0.02A, T0.02B, T0.02C were used to adsorp TMA gas samples at 0.02ppmv and they were desorped by vortex vibrating in 1mL mixture 29 solvent of ACN and water To investigate the appropriate extraction techniques for the AC tube, several experiments were carried out with main solvents: ethanol, pure acetonitrile, mixture of acetonitrile and water with 3:1 volumetric ratio Two different techniques: vortex machine and microwave extraction were also applied separately to evaluate the desorption efficiency of each method These experiments targeted on adsorbent tubes that had TMA initial concentration at 20ppmv The procedure of TMA extraction from the adsorbent tube can be explained by the figure below: Vortex shake in 10 minutes T0.02A, T0.02B, T0.02C 1mL ACN:W 3:1 Vortex shake in 10 minutes T20A, T20B, T20C 6mL ACN:W 3:1 Vortex shake in 10 minutes Te20A, Te20B, Te20C 6mL Pure Ethanol Microwave in hours Tm20A, Tm20B, Tm20C, S1 10mL ACN:W 3:1 Figure 2.9 Diagram of TMA extraction experiments The tubes after sampling were poured into small vials, then added a sufficient amount of desired solvent and bring to the vortex shaker for minutes or put into microwave device for hours, depend on different experiments 30 2.8 Instrument analysis For the analysis of Trimethylamine, an LC system (Shimadzu LC-19A) consisting of a preparative pump, a 10 µL sample loop injector and Tandem Mass Spectrometry (MS/MS) are employed After the injection of extracted TMA samples, the TMA was separated from other impurities and the solvent by a polar column The chosen working solvent for mobile phase which is 3:1 volumetric mixture of Acetonitrile (ACN) and distiled water was utilized to make a analysis of TMA concentration for the optimum separation 31 CHAPTER RESULTS AND DISCUSSION 3.1 TMA calibration curve TMA Calibration Curve 5,37 y = 0,0274x - 0,145 R² = 0,9989 Peak area x106 2,52 1,28 0 50 100 150 200 250 Concentration (ng/mL) Figure 3.1 Calibration curve of TMA The calibration curve was made from the standard solution provided by WAKO Pure Chemical Corporation This standard is Trimethylamine dissolved in ethanol with the concentration is 1µg/1mL, equal to 1000ppm According to this solution, lower concentration standards were made by accurate dilution Regarding the low concentration of TMA in all samples, 1ppm standard solution was prepared by injecting 100µL of the original standard into 100mL of water From then, standard solutions of TMA were made based on the procedure in table 3.1 Table 3.1 Standard solutions procedure Std Conc 200ppb 100ppb 50ppb Vwater (µL) 800 900 1900 V1ppm standard (µL) 200 100 100 Vtotal (mL) 1 32 3.2 Study of the TMA adsorption efficiency To measure the TMA adsorption efficiency, the amount of TMA that went into the adsorbent tube and the TMA that come out from the tube need to be quantified Adsorption rate = TMA inlet - TMA outlet × 100 (%) (3.1) TMA inlet The trimethylamine to be adsorbed into the AC bed was in gaseous phase The initial TMA concentration in the control gas samples was evaluated by the Kitagawa detector’s tube as ppmv From that the total amount of TMA pumped into the AC tube can easily be calculated The TMA inlet is measured by the equation 3.2: mTMA = Cini × Conversion factors × v × t (3.2) where - mTMA: the total mount of TMA pumped into adsorbent tube (µg) - Cini: Concentration of TMA in the gas samples - Conversion factors: 1ppmv = 2.42mg/m3 = 2.42µg/L (Pospischil) - v: Flow rate (L/min) - t: time of operation (min) According to the sampling procedure in section 2.4, we have: - The TMA inlet of samples T0.02A, T0.02B, T0.02C is: 0.02×2.42×0.15×6 = 0.04356 µg - The TMA inlet of samples T20A, T20B, T20C is: 20ì2.42ì0.15ì6 = 43.56 àg The TMA outlet can be measured by quantifying TMA that did not adsorb in the AC bed and captured by the mixture solvent in the impinger Due to the high solubility of TMA in organic solvent, TMA is assumed to be readily soluble in the solvent mixture of ACN and water This study was conducted on tube samples at two different initial TMA concentration: 0.02ppmv and 20ppmv, along with their corresponding solvent mixture’s vials They have similar extraction techniques, which are shaked by vortex 33 machine and desorbed by the mixture of ACN and water The results are shown in table 3.2 below: Table 3.2 TMA Adsorption rate measured by the inlet and outlet amount of samples Sample TMA inlet Sample (µg) TMA outlet Adsorption (µg) efficiency (%) T0.02A 0.04356 U0.02A N/D 100 T0.02B 0.04356 U0.02B N/D 100 T0.02C 0.04356 U0.02C N/D 100 T20A 43.56 U20A 0,5115 98,84 T20B 43.56 U20B 0,2774 99,37 T20A 43.56 U20C 0,2383 99,46 N/D: Not detected If we assume that the solvent mixture can absorb all the TMA gas passed through the AC tube, due to the high solubility of TMA in organic solvents, the data indicate that the AC bed adsorbed almost every TMA component from the gas samples At low initial concentration, the adsorption process was either completely 100% or the TMA in the outlet samples are under the limit of detection (LOD) of the analysis method Regarding the high initial concentration, the adsorption efficiency were also very high, over 98% This result has consolidated the state that AC is the material of choice for adsorption VOCs in general and for TMA gas in particular But in order to turn it into one ideal material for TMA sampling, it also requires good extraction method that is compatible with the existed instrument analysis methods In section 3.4, the efficiency of the TMA extraction process is investigated through different extraction procedure 34 3.3 Study of the TMA extraction efficiency 3.3.1 Effect of different initial TMA concentration on the TMA extraction efficiency To evaluate the TMA extraction efficiency at different initial concentration , the value of TMA estimated inlet amount in each AC tube and the analyzed TMA amount the same extracted tube were collected The targeted samples in this study also are samples that investigated in section 3.3, because they all share the same sampling condition as well as extraction techniques T0.02A, T0.02B, T0.02C samples 0,06 TMA amount (µg) 0,05 100% 91,83% 100% 101% 114,8% 100% 0,04356 0,04356 0,04356 0,04 0,044 0,05 0,04 0,03 0,02 0,01 Estimated inlet TMA Analyzed TMA Estimated inlet TMA Analyzed TMA Figure 3.2 Comparison between estimated TMA and analyzed TMA results of T0.02A, T0.02B, T0.02C samples respectively At 0.02ppmv initial concentration for adsorption, the analyzed TMA amounts of all samples are approximate to the estimated TMA amount T0.02A analyzed data was 8.2% low than the estimated data The difference may come from the incomplete adsorption of AC bed, or the TMA extract efficiency did not get optimum The T0.02B data showed equal results between the calculated one and the instrument’ analysis The T0.02C sample got the opposite results with T0.02A sample, where the analyzed TMA amount was 14.8% higher than the calculated one This can be explained that the actually concentration in this gas samples might higher than the 35 concentration calculated because of the experimental bias from the sampling procedure In general, despite some differences spotted from each samples, the average TMA extraction efficiency of low (0.02ppmv) concentration samples based on this data is 102.5%, which are very suitable T20A, T20B, T20C samples TMA amount (µg) 50 45 40 35 30 25 20 15 10 100% 100% 100% 1,01% 0,96% 0,3% Estimated inlet TMA 43,56 43,56 43,56 Analyzed TMA 0,42 0,444 0,132 Estimated inlet TMA Analyzed TMA Figure 3.3 Comparison between estimated TMA and analyzed TMA results of T20A, T20B, T20C samples As can be seen in Figure 3.3, the analyzed TMA value of the three samples were signicantly lower than the values which had been estimated TMA quantified by the instrument from the elution of T20A, T20B, T20C samples only reach under or equal to 1% of the calculated inlet of TMA This result implied one major problem – at high TMA concentration for adsorption, the solvent mixture can not overcome the adsorption forces from the activated carbon, and the TMA adsorbate still remains on the surface of the AC Therefore it is crucial to have more researchs on the technique of TMA extraction using organic solvents 36 3.3.2 Ethanol as an alternate solvents on the TMA extraction efficiency This study is designed to evaluate the TMA extraction capability of ethanol, since it is well known as a most common solvent for TMA according to many previous researchers that had already been notice in the literature review Three AC adsorbent tubes were prepared and sampling at the same condition with T20A sample, labled as Te20A, Te20B, Te20C These tubes were extracted using pure ethanol instead of the mixture of ACN and water as other samples After being analyzed, the TMA was not detected in any of these extracted samples The peaks coming out from the instruments showed that TMA concentration in these extracted sample were lower than the level of detection limit, while the T20A, T20B, T20C samples analysis gave data results, eventhough they were not good We can conclude that ACN and water mixture is the best choice in the limit of this research It is, however, very important to expand studies about the organic solvent the would be able to extract TMA out of AC material It also has meaning in the recycling and regenerate the AC after being used 3.3.3 Microwave as an alternate method for extraction techniques Due to the fact that TMA adsorption on the surface of the AC is physical adsorption, using the microwave is hope to increase the extraction efficiency of TMA from the AC The vibration from the microwave, theoretically makes the adsorbate molecules to detach from the pores or cracks on the surface of the AC That is why in this research, the microwave techniques is also tested Three samples Tm20A, Tm20B, Tm20C were sampling with the similar condition to T20A sample After that, instead of being shaked by the vortex device, the samples were put inside a microwave device for hours 37 TMA analyzed from samples 0,8 0,689 TMA amount (µg) 0,7 0,6 0,618 0,538 0,5 0,42 0,444 0,4 0,3 0,2 0,132 0,1 Figure 3.4 TMA adsorption analyzed from samples Tm20A, Tm20B, Tm20C, T20A, T20B, T20C at 20ppmv initial adsorping concentration respectively Although the value of TMA analyzed from Tm20A, Tm20B, Tm20C were still very small compared to the estimated value of these samples, the extraction efficiency increased noticeably Total amount of TMA analyzed from these tubes was 1.845µg, 84,9% higher than the TMA analyzed from T20A, T20B, T20C, at only 0.996µg Through this results, the microwave showed a great potential of improving the TMA extraction efficiency 3.4 In-situ sampling Recognizing that using ACN:water mixture and microwave are the best for TMA quantification, the in-situ samples, labled as S1, after being sampling as described in section 2.5, was then added 10mL of ACN:water mixture and put into the microwave champer in hours The result from the LC-MS/MS analysis was 1.14 µg TMA in the extracted solvent mixture Since the TMA concentration in the ambient air usually low, because of the turbulance of the wind and the diffusion into surrounded environment Based on the finding in section 3.3 and section 3.4, the adsorption efficiency of this sample which have low initial concentration should range from 99 to 100%, and the TMA extraction efficiency can be consider as 100%, 38 we can calculate the TMA concentration in the ambient air at the site following this equation 3.3: TMA Conc= TMA amount analyzed V sampling  conversion  adsorption efficiency  extraction efficiency = 1.14 µg = 0.032 (ppmv) (3.3) 15L  2.42 100%  99% 39 CHAPTER CONCLUSION AND RECOMMENDATION Conclusion The TMA adsorption efficiency was very high, accounted for 100% and 99.22% at the assigned initial TMA concentration, 0.02 and 20ppmv respectively The TMA desorption efficiency varied significantly depend on the initial TMA concentrations and the extraction techniques At 0.02ppmv gas samples, TMA extraction efficiency from the tube by using vortex vibration and mixture solvent of ACN:Water (3:1 volumetric ratio) was higher than 91% In contrast, extracion efficiency was very low, stayed below 1.01% for tube samples of 20ppmv initial TMA concentration The TMA analyzed from samples that used ethanol as its extracting solvent were not detected, emphasize that ethanol cannot desorp TMA from the AC bed The microwave extraction technique showed an 84.9% improvement in extraction efficiency compared to the vortex vibration When applying the method to Cat Hai Company at the fish sauce making sites, the results of TMA concentration in the air was 0.032 ppmv Recommendation This research was unable to conduct more experiment and find out the best organic solvent for desorp the analytes in the AC bed Besides the TMA measurement procedure in Vietnam is still very new, which leads to a difficulty in finding the good analyze condition and appropriate pretreatment process In future, there should be more research focus on TMA 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TUAN KHANG DEVELOPMENT OF GASEOUS TRIMETHYLAMINE TRAP TUBE USING ACTIVATED CARBON FOR SAMPLING OF FISH-DERIVED MALODOROUS GASES MAJOR: ENVIRONMENTAL ENGINEERING RESEARCH SUPERVISOR: PROF TAKASHI... threshold of trimethylamine 1.1.3 Toxicity of trimethylamine 1.2 Overview of fish-derived malodorous gases .8 1.2.1 Fish processing activities 1.2.2 Fish-derived gases. .. Activated Carbon tube .20 2.3 Generation of Odorless gas .22 2.4 Preparation of Trimethylamine operating gas samples 23 2.5 TMA gas sampling using Activated Carbon Tubes