Biometamaterials application for solar steam generation device

LIST OF FIGURESPage Figure 1.1: Drought in Vietnam left, warning of saline intrusion in Ben Tre province, and Vinh Long province on the television news...2 Figure 2.1: Fresh pomelo a and

VIETNAM NATIONAL UNIVERSITY, HANOI

VIETNAM JAPAN UNIVERSITY

VU TIEN DUNG

BIOMETAMATERIALS APPICATION FOR SOLAR STEAM GENERATION

DEVICES

MASTER'S THESIS

VIETNAM NATIONAL UNIVERSITY, HANOI

VIETNAM JAPAN UNIVERSITY

VU TIEN DUNG

BIOMETAMATERIALS APPICATION FOR SOLAR STEAM GENERATION

DEVICES

MAJOR: NANOTECHNOLOGY

CODE: 8440140.11QTD

RESEARCH SUPERVISOR:

Dr PHAM TIEN THANH

Dr BUI NGUYEN QUOC TRINH

Hanoi, 2020

Firstly, I would like to extend my sincere thanks to Dr Pham Tien Thanh, and Dr.Bui Nguyen Quoc Trinh, my supervisors, working for Vietnam Japan University, fortheir enthusiasm, encouragement, and patient guidance during the preparation of mymaster thesis

Moreover, I would also like to express my great appreciation to Prof Dr KotaroKajikawa, working for the Tokyo Institute of Technology, who gives me a lot ofvaluable suggestions and teaches me with the necessary knowledge about thescience

I take this chance to acknowledge the support provided by Assoc Prof Dr Do DanhBich, Dr Nguyen Duc Cuong, Dr Nguyen Viet Hoai, and Mr Nguyen Minh Tuan.The advice given by them has been a great help in my research

Finally, I especially wish to thank my mom, my dad, my brother, and friends, whoare always by my side, have supported and encouraged me throughout my life Mylife will be incomplete without them Thanks

Vu Tien DungHanoi, 2020

TABLE OF CONTENTS

Page

ACKNOWLEDGMENTS i

TABLE OF CONTENTS ii

LIST OF FIGURES iii

LIST OF TABLES v

LIST OF ABBREVIATIONS vi

CHAPTER 1: INTRODUCTION 1

1.1 Clean water and Salination Issue + Desalination method 1

1.2 Solar Steam Generation 2

1.2.1 Mechanism of SSG 2

1.2.2 Absorber Material 3

1.2.3 Purpose of this master thesis 5

CHAPTER 2: EXPERIMENTAL METHOD 7

2.1 Carbonized pomelo peel synthesis and characteristics 7

2.1.1 Fabrication procedure 7

2.1.2 Carbonized pomelo peel characteristics 8

2.2 SSG System construction and evaluation 9

2.2.1 Construction of the SSG system 9

2.2.2 SSG system evaluation 9

CHAPTER 3: RESULTS AND DISCUSSION 15

3.1 Carbonized pomelo peel 15

3.1.1 Physical characteristics of carbonized pomelo peel 15

3.1.2 Absorption properties 20

3.1.3 Solar heating behavior of materials under the sunlight 24

3.2 Solar steam generation system ability 27

3.2.1 Vapor steam creation capacity 27

3.2.2 Desalination and purification capacity of the SSG system 33

CHAPTER 4: CONCLUSION 35

LIST OF FIGURES

Page Figure 1.1: Drought in Vietnam (left), warning of saline intrusion in Ben Tre

province, and Vinh Long province on the television news 2

Figure 2.1: Fresh pomelo (a) and (b), and Fresh pomelo peel (c) 7

Figure 2.2: Pomelo peel and carbonized pomelo peel 8

Figure 2.3: Light absorber and converter and water supply 9

Figure 2.4: System to calculate the evaporation rate in the laboratory 10

Figure 2.5: Mechanism of the system in the real condition 11

Figure 3.1: Porous Structure and Tube Structure of Fresh Pomelo Peel (left) and Carbonized Pomelo Peel 15

Figure 3.2: Changes in structural dimensions before and after carbonization process (a), (b), (c): Fresh Pomelo Peel; (d), (e), (f): Carbonized Pomelo Peel 16

Figure 3.3: Water Capacity Ability of Carbonized Pomelo Peel 17

Figure 3.4: XRD spectrum of Carbonized Pomelo Peel 18

Figure 3.5: Raman Spectrum of Carbonized Pomelo Peel 18

Figure 3.6: FTIR spectra of Fresh Pomelo Peel and Carbonized Pomelo Peel 19

Figure 3.7: Absorption properties of carbonized pomelo peel with 1 hour of annealing time 20

Figure 3.8: Absorption properties of carbonized pomelo peel with 2 and 3 hours of annealing time 21

Figure 3.9: Absorption properties of carbonized pomelo peel and fresh pomelo peel in the UV-Vis-IR region 22

Figure 3.10: Absorption spectrum of carbonized pomelo peel samples before being hydrated and after being hydrated 23

Figure 3.11: Temperature of Fresh Pomelo Peel and Carbonized Pomelo Peel Samples under an artificial sun 24

Figure 3.12: Infrared image of sample carbonized pomelo peel placed under artificial sunlight 25

Figure 3.13: Temperature of Fresh Pomelo Peel and Carbonized Pomelo Peel Samples under some real conditions (a): affected by wind; (b): affected by solar intensity; and (c): affected by cloud 26

Figure 3.14: Vapor steam creation ability under an artificial sun 27

Figure 3.15: Vapor steam creation ability with different conditions of thickness under an artificial sun (a): Mass change within 1 hour; (b): Evaporation Rate within 1 hour; (c) Carbonized pomelo peel’s infrared photos when exposing to the sunlight 28 Figure 3.16: Vapor steam creation capacity under the real condition 30

Figure 3.17: Vapor steam creation capacity under different power intensity 31Figure 3.18: Vapor steam creation capacity after 30 days 32Figure 3.19: Cation concentration (top), and Anion concentration (bottom) of Seawater and Purified water compared to the Standard of drinking water 33Figure 3.20: Wastewater Purification Application 34

LIST OF TABLES

PageTable 2.1: Some equipment used in this master thesis 11Table 4.1: The comparison of evaporation rate for each material and itsdisadvantages 35

CHAPTER 1: INTRODUCTION

1.1 Clean water and Salination Issue + Desalination method

In the recent time, one of global problem is crisis of the clean water Water iseverywhere, but clean water is lacking According to the World Economic Forum

2019, the clean water crisis is one of four global threats that have a great impact onthe lives of human beings [21] Moreover, Water Center, University of Twente(2016) showed us that over 65% of the world's population, have to face to theshortage of clean water for at least one month a year as a result of climate changeand drought [14] Vietnam is one of the country’s most vulnerable to climate changeand is currently facing a serious shortage of freshwater and irrigation due to droughtand especially surface intrusion over the years According to Vietnam DisasterManagement Authority, in the Mekong Delta, nearly 160,000 households are usingpolluted water, saline intrusion affects 40% of the fruit land area [19] Figure 1.1reveals drought and saline intrusion in several provinces in Vietnam Thesalinization (water with salinity of > 4‰) is alarming, and in some areas the salineinstruction occurs 80-100 km from the coast Several predictions affirm thatVietnam's GDP will be reduced by 10% by 2030 because of drought and salineintrusion Therefore, constructing a system to product the clean water from the seawater is expected to be a valuable solution to face with the situation of clean waterscarcity

Figure 1.1: Drought in Vietnam (left), warning of saline intrusion in Ben Tre

province, and Vinh Long province on the television news

To find a solution with this situation, a lot of technologies for producing fresh waterfrom the saline water have been developed and applied, such as distillation, ionexchange, membrane filtration, and so on [4], [7], [18] However, these methodshave limitations, such as high cost, high consumption of materials and lowperformance because of the sea water’s corrosion and salt precipitation Nowadays,technology for producing the clean water from the saline water using solar energy isreceiving much attention The potential of this technology is to create an eco-friendly, cheap, high-performance system

1.2 Solar Steam Generation

The solar energy is a kind of green energy which available in the nature Moreover,

it is an endless source of energy for human life However, we have not used thesolar energy optimally According to California Institute of Technology, the amount

of sunlight energy that reaches the earth in 1 hour is equal to the total amount ofenergy that humans use within 1 year [22] In the world, Vietnam is one of thecountries with a lot of sunshine hours in a year (around 2000 to 2600 hours/year,equivalent to 6-7 hours/day), which is a huge source of energy coming from the sun.This is an extremely good condition, giving Vietnam many advantages when setting

up devices that use solar energy Solar Steam Generation (SSG) is a system that usessolar energy to turn water into steam That steam is passed through a condensationsystem to obtain the clean water SSG system has many advantages, such as noelectricity in use, no CO2 emissions, simplicity, and competitive price With thesunshine hours of 6-7 h/d as in the South of Vietnam, a normal device can produce15-30 L/h, equivalent to the minimum water demand of a household per day [25]

Absorber material receives sunlight and converts that energy into heat energy Thesurface temperature of the material goes up extremely high The water supplytransports the water from the bottom to the surface of the absorber material through

a water transport system (usually a capillary system) A sufficient amount of waterwhen reaching the surface, will exchange heat with the absorber and convertersystem, to receive energy to transform the state from liquid to vapor Steam isinvolved in the condensation process by a refrigeration device Finally, clean water

is collected The above process is operated continuously Water is constantly beingtransferred up to a specified amount so that the absorber layer’s surface temperature

is always at maximum The performance of the system depends on the thermal energy conversion efficiency of the absorber layer In order to achieve thehighest photo-thermal conversion efficiency, light absorber materials must havestrong absorption in the sunlight range (from 300 nm to 3000 nm) Many categories

photo-of materials have been used for developing light absorbers, such as metalnanoparticles [2], [3], metal oxides [17], polymers [11], [20], semiconductors [6],[26], bio-inspired materials [5], [10], [24], etc The photo-thermal materials havebeen designed with the porous and capillary structures or bio-inspired structures

1.2.2 Absorber Material

Photo-thermal conversion (PTC) process has classified into 3 main types The firsttype is PTC based on the plasmonic localized heating of metals There are two mainkind of materials that operate on this mechanism, metals nanoparticles and metaloxides Several metals with nanostructures such as gold, silver, and copper havebeen utilized for absorber layer [1], [8] They exhibit extremely strong absorptiondue to the resonant effect of free electrons on the surface excited by theelectromagnetic of the incident light Yang et al showed SSG system with coppernanoparticles, which is a scalable and eco-friendly system [13] The coppernanoparticles exhibited strong absorption (around 97,7%) in the region of 200 nm to

1300 nm The SSG based on Cu NPs had high efficiency up to 73% at 2 sun(equivalent with P= 2 kW.m-2 ) illumination Naomi et al developed the SSG usingSiO2/Au nano-shells particles [15] This material strongly absorbs the light range

from 500 nm to 1200 nm, leading to the system’s conversion efficiency reached up

to 80% at 1 sun However, the SSG system using these materials has limitations,such as: complicated fabrication procedure, expensive, and so on Constructing thissystem on an industrial scale is an uneconomical option For the metal oxides,several groups published some initial results in the construction of the SSG system

By using WO2.9 , SSG system manufactured by Wang et al can absorb more than90% of sunlight [16] PTC efficiency of the system reached over 85%, higher thanthat of nanoparticles Deng et al constructed the absorber layer by generation Fe3O4nanoparticles on the surface of graphene [17] The temperature of the watercontained this material rose to 10000C when exposing to sunlight The photo-thermal materials based on metal oxides had higher light absorbability and greaterconversion efficiency than metal nanoparticles Those materials get same limitations

of metal nanoparticles

The second type of PTC is non-radiative relaxation of semiconductor.Semiconductor materials absorb light to transfer electrons from the valence band tothe conduction band At the conduction band, electrons perform non-radiativerelaxation before returning to the valence band These relaxation causes thetemperature of the material to heat up, making the evaporation process faster Hu et

al developed an SSG system using a membrane with CuFeSe2 nanoparticlesdecorated wood [12] CuFeSe2 had a narrow bandgap (0.45 eV) so it can absorb allphotons with energy greater than 0.45 eV (equivalent to wavelength shorter than

2755 nm) This SSG system achieved a solar thermal efficiency of 86.2% under 5sun illumination The evaporated water amount obtained with anothersemiconductor materials was from 0.85 to 1.3 kg.m-2.h SSG system using thesemiconductor as a photo-thermal material will be difficult to fabricate with highprice and be complicate to deal with large-scale system

The third type of PTC is thermal vibration of molecules Several materials haveextremely high absorption, and all absorbed photon energy will be converted tothermal energy in the form of vibrations of the molecules of the material through thephoto-thermal conversion Especially, carbon-based materials with zero band

gap can absorb sunlight as a black body They are cheap, stable and easy tofabricate Carbonization process, which can turn any material with a specificstructure into carbon-based materials with the same structure, plays an importantrole in making carbon-based materials Lin et al synthesized SSG system byannealing to make the carbonized melamine foams, realizing highly efficient SSGwith a water evaporation rate of 1.270 kg.m-2.h-1 and an energy conversionefficiency of 87.3% under 1 kW.m-2 solar illumination [9] Zhu et al developed theSSG devices based on the natural materials, such as mushroom, wood, so on [24].The mushroom was carbonized at high temperatures As a result, the surface of themushroom turned into black and the absorbance of the carbonized mushroomincreased to above 95% in the wavelength range of 30-3000 nm The SSG deviceperformed a high photo-thermal conversion efficiency as above 85%, and anevaporation rate of 1.47 kg.m-2.h-1 The evaporated water quality met the standards

of WHO for the drinking (or clean) water Carbonization material provides a goodperformance for SSG system, simple fabrication process, environmentally friendly,promising to be a key material for setting up SSG system In particular,carbonization materials of biological origin (naturally occurring) -named bio-metamaterials- are currently receiving much attention Constructing the SSG systemusing bio-metamaterial materials is a potential, and feasible direction

1.2.3 Purpose of this master thesis

The pomelo is the most common fruit in Vietnam The pomelo is not only a kind of human food, other components of the pomelo also have many application in our life.Pomelo's outer skin contains many essential oils, those essential oils are used as a remedy for hair loss, sinusitis, etc Pomelo peel is used as some traditional folk dishes and also have applications in medicinal healing In this master thesis, pomelo peel have been considered because of their porous structure With the porous

structure of the pomelo peel, the carbonized pomelo peel (CPP) promises not only the good light-absorber material, but also the good ability to transport water onto the surface itself Carbonized pomelo peel promises to be a good bio-metamaterial for constructing the SSG system We hope that the SSG using the carbonized

pomelo peel as PTC material will have high absorbance, high efficiency of thermal conversion, good ability in desalination and purification.

photo-This master thesis aims at:

• Fabricating the photo-thermal conversion (PTC) material from natural sources by the carbonization method

• Studying on the PTC characteristics

• Evaluating the absorption of bio-metamaterial under the sunlight

• Developing a SSG system, using bio-metamaterial as a absorber layer (will

mention in the chapter 2)

• SSG system evaluation:

• Assessing the evaporation capacity of the system

• Demonstration in producing clean water from saline water using the Solar SteamGeneration system, which is based on solar energy, bio-inspired materials with lightabsorbability and one-dimensional capillary sheets with high efficiency

CHAPTER 2: EXPERIMENTAL METHOD

2.1 Carbonized pomelo peel synthesis and characteristics

20 mm

Figure 2.1: Fresh pomelo (a) and (b), and Fresh pomelo peel (c)

• Pomelo peel slices were washed by the solution of domestic water and absolute ethanol 3 times with the stirrer at 200 rpm for 30 minutes at room temperature

• After that, they were dried at 4000C for 12 hours The moderate temperature helps the water evaporate while keeping the sample from bending after drying

• Dried-pomelo peel was taken part in a carbonization process at controllabletemperature and time in the nitrogen atmosphere The carbonization process wasperformed as follows:

1. Put the pomelo peel sample into the annealing tube, the lock the valve

2. Vacuum for 5 minutes Then blow nitrogen into the tube until the pressure isequal to atmospheric pressure Do this step at least 3 times to make the annealingtube clean.

3. Blow nitrogen so that the pressure is maintained at 1.5 atmospheres

4. Increase the temperature with the speed of 500 per minute

5. When the system reaches the desired temperature, keep the system at that

temperature for a specified time

6. Stop heating the system, wait until the system temperature returns to roomtemperature, then take the sample Figure 2.2 shows a sample of carbonized pomelopeel

7. Store the sample in a dry condition

Figure 2.2: Pomelo peel and carbonized pomelo peel

2.1.2 Carbonized pomelo peel characteristics

• To study the structure and composition of materials, the following methods were used:

1. SEM to observe the material morphology

2. XRD, FTIR, Raman to study on the structure and composition of materials

• To investigate other properties of the material:

1. Absorption properties of carbonized pomelo peel

2. Solar heating behavior of carbonized pomelo peel.

3. The stability of materials

2.2 SSG System construction and evaluation

2.2.1 Construction of the SSG system

Figure 2.3 describes the structure of light absorber and converter part and watersupply part of the SSG system Carbonized pomelo peel is placed at the top of thebeaker containing water The area of the sample is designed to be equal to thesurface area of the beaker Separating the water supply and carbonized pomelo peelhas a Polystyrene Foam sheet This sheet helps prevent the heat exchange betweenmaterials and the water supply Surrounding the foam sheet is a gauze pad, thegauze pad acts as a water transport channel, transport water from the water supply tothe carbonized pomelo peel Water is transported to the surface through the porousstructure and tube structure of the material Finally, the baker is wrapped aroundwith aluminum foil

Figure 2.3: Light absorber and converter and water

supply 2.2.2 SSG system evaluation

•To study the SSG system evaluation, the following methods were used:

1 Evaluate the evaporation index of the system

Figure 2.4 shows the experimental diagram for determining the evaporation rate ofthe SSG system The beaker (constructed in section 2.2.1) is placed on theelectronic balance The mass of the system will be collected at different times, todetermine the amount of evaporated water After that, the evaporation rate of thesystem is equal to the lost mass divided by the illuminated sample area.

Figure 2.4: System to calculate the evaporation rate in the laboratory

2 Evaluate the desalination and purification ability

For the desalination and purification processes, all experiments are done in the realcondition The baker containing the carbonized pomelo peel is placed into a sealedglass box designed as in Figure 2.5 The sun shines on the system, and makes thewater evaporate That vapor will exist in a sealed glass box A cooling system,placed next to that glass case (dry ice), leading to the condensation of the steaminside the box Finally, the steam condenses into water and flows out through thehole at the bottom of the box For the desalination, sea water will be selected as asource of input water After taking enough amount of purified water, the ionconcentration of both solutions is analyzed via SW-846 Test Method 6010D byusing Skalar ++ CP-OES For the purification process, crystal violet and methylorange solutions are pick as the wastewater The color and transparency of thepurified solution will be assessed to evaluate the performance of the system

Figure 2.5: Mechanism of the system in the real

condition 2.3 Equipment

Table 2.1 shows some equipment used in measurement in the thesis

Table 2.1: Some equipment used in this master thesisEquipment

UV-Vis Lambda 950 forobserving theabsorption properties ofmaterials in the range of

200 nm to 2500 nm

UV/Vis Jasco V670(Jasco, Japan) forobserving theabsorption properties

of materials in the

11

X-ray Diffraction(XRD Mini Flex 600,Rigaku, Japan) spectra

of sample wereobtained using aBruker AXN model

Fourier- transforminfrared (FTIR-4600,Jasco, Japan) spectra

of samples wererecorded on a Nicole

380 spectrometer

Raman Labram evolution (Horiba)

12

FLIR infrared camerafor calculating thesurface temperature of

material

Ion concentration of solutions wereobtained via SW-846 Test Method6010D by using Skalar ++ CP-OES

Annealing equipment forcarbonization process

13

SEM for observingthe materialmorphology

HOBO pyranometerfor measuring thesunlight intensity

14