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Desalination of synthetic seawater by microfluidic solvent extraction / Alvin Teo Hua Huang

By:

Alvin Teo, Hua Huang [author.]

Material type: Text

text

Media type:

unmediated

Carrier type:

volume

ISBN:

THE0010370 (Local)

Subject(s):

Dissertation note: Thesis (Master of Science) -- Universiti Malaysia Pahang - 2025 Abstract: Water shortage is an imminent issue in the foreseeable future. The existing desalination techniques such as thermal desalination techniques are energy intensive while fouling propensity is a well-known issue for membrane desalination technologies. Custom-made polydimethylsiloxane (PDMS) – glass microfluidic device is fabricated via direct writing lithography with microchannel depth and length of 100 μm and 161 mm respectively while the width is varied from 400 - 800 μm. This study investigates a membrane-less low-temperature technique known as directional solvent extraction (DSE) desalination in a serpentine microchannel at 45, 50, 55, 60 and 65 °C. Two short-chain fatty acids, heptanoic acid (HeptA) and nonanoic acid (NonA) were used as the solvents to recover water from a 35000 ppm total dissolved solids (TDS) seawater (constant at 5 mL/h) at 2, 3, 4 and 5 organic to aqueous flowrate ratios (O: aq) to generate different flow type. It was found that the channel with 600 μm width is the best for the current process. Droplets were generated during the extraction process to maximize diffusion by using a 90° T-junction where the organic solvent is the continuous phase and seawater is the dispersed phase. When finely dispersed flow was generated at the highest process temperature, a maximum product water yield, Yw of 4 % v/v and 1.9 % v/v was achieved by HeptA and NonA respectively. The salinity of the product is measured by a salinity meter while the solvent concentration is determined by a UV-Vis spectrometer. The product water recovered from HeptA and NonA has salinity as low as 0.01% and 0.08%, respectively. The HeptA system produces water containing higher solvent residuals than the NonA system. HeptA is a better solvent as it can extract approximately two times more water than NonA under the same operating conditions. Both solvents are reusable as they did not degrade during the extraction process.

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Holdings ( 2 )
Title notes ( 4 )

Holdings
Item type	Current library	Call number	Status	Date due	Barcode
Thesis	UMPLIB GAMBANG	FTKKP .A48 2025 r Thesis (Browse shelf(Opens below))	Not for loan		T000004046
Thesis	UMPLIB GAMBANG	CD13935 (Browse shelf(Opens below))	In Transit		T000004047

Faculty of Chemical and Process Engineering Technology

Thesis (Master of Science) -- Universiti Malaysia Pahang - 2025

Includes bibliographical references

Water shortage is an imminent issue in the foreseeable future. The existing desalination techniques such as thermal desalination techniques are energy intensive while fouling propensity is a well-known issue for membrane desalination technologies. Custom-made polydimethylsiloxane (PDMS) – glass microfluidic device is fabricated via direct writing lithography with microchannel depth and length of 100 μm and 161 mm respectively while the width is varied from 400 - 800 μm. This study investigates a membrane-less low-temperature technique known as directional solvent extraction (DSE) desalination in a serpentine microchannel at 45, 50, 55, 60 and 65 °C. Two short-chain fatty acids, heptanoic acid (HeptA) and nonanoic acid (NonA) were used as the solvents to recover water from a 35000 ppm total dissolved solids (TDS) seawater (constant at 5 mL/h) at 2, 3, 4 and 5 organic to aqueous flowrate ratios (O: aq) to generate different flow type. It was found that the channel with 600 μm width is the best for the current process. Droplets were generated during the extraction process to maximize diffusion by using a 90° T-junction where the organic solvent is the continuous phase and seawater is the dispersed phase. When finely dispersed flow was generated at the highest process temperature, a maximum product water yield, Yw of 4 % v/v and 1.9 % v/v was achieved by HeptA and NonA respectively. The salinity of the product is measured by a salinity meter while the solvent concentration is determined by a UV-Vis spectrometer. The product water recovered from HeptA and NonA has salinity as low as 0.01% and 0.08%, respectively. The HeptA system produces water containing higher solvent residuals than the NonA system. HeptA is a better solvent as it can extract approximately two times more water than NonA under the same operating conditions. Both solvents are reusable as they did not degrade during the extraction process.