Document Type
Dissertation
Date of Award
5-31-2024
Degree Name
Doctor of Philosophy in Environmental Science - (Ph.D.)
Department
Chemistry and Environmental Science
First Advisor
S. Mitra
Second Advisor
Edgardo Tabion Farinas
Third Advisor
Mengyan Li
Fourth Advisor
Yuanwei Zhang
Fifth Advisor
N. M. Ravindra
Abstract
Effective liquid phase separation is vital across industries, especially in aviation, chemicals, fuels, and textiles. Membrane technology offers advantages over traditional methods like distillation, with low energy consumption and protection for heat-sensitive molecules. Membrane performance is assessed based on factors such as materials, surface modification, and interactions. This research targets superhydrophobic membranes for liquid-liquid filtration and antiwetting omniphobic membranes for membrane distillation, focusing on properties like contact angle and thermal resistance.
This study presents a highly hydrophobic membrane achieved by immobilizing carbon nanotubes (CNTs) onto a PTFE microfiltration membrane. It's designed for dewatering organic-water mixtures with trace water content via cross-flow filtration. The impact of varying CNT concentrations on membrane characteristics like morphology, wettability, hydrophobicity, porosity, and permeability was systematically studied. The carbon nanotube immobilized membrane (CNIM) demonstrated exceptional separation efficiency for octane and heptane water systems. Water rejection was more pronounced at lower pressures and increased with CNT loading. This approach enables continuous removal of trace water content from solvents at low pressures, overcoming challenges of conventional techniques.
In another study, membrane filtration was employed to remove water at the ppm level from kerosene by using CNIM. The CNIM facilitated kerosene permeation through the membrane by wetting the CNT sidewalls at varying pressures. Surface roughness and water contact angles increased with higher CNT loading, enhancing hydrophobicity. Generally, water rejection increased with CNT loading while effective surface porosity and flux decreased.
The subsequent study focuses on the development of a carbon nanotube immobilized membrane (CNIM) for butanol dewatering through microfiltration. The CNTs enhance membrane hydrophobicity and butanol permeation through adsorption, leading to significant preconcentration. Different concentration zones (WIB, BIW, BWCM) affect separation efficiency, with BWCM showing significantly higher efficiency attributed to well-dispersed CNTs facilitating agglomeration of water droplets.
Chapter 6 represents innovative omniphobic membranes designed to separate high concentrations of bioethanol using membrane distillation (MD), a capability previously unattainable with standard membranes. The FAS-coated carbon nanotube immobilized membranes (FAS-CNIM) exhibit excellent omniphobic properties, surpassing conventional PTFE membranes in contact angles. Our study demonstrates superior performance in ethanol vapor flux, separation factor, mass transfer coefficient, and permeate separation index for FAS-CNIM membranes.
In conclusion, this thesis emphasizes the potential development of adsorption-influenced superhydrophobic/omniphobic membrane for diverse applications such as fuel purification, solvent recovery and wastewater treatment. The use of carbon nanotubes (CNTs) allows for substantial preconcentration and offers flexibility for hybrid separation processes.
Recommended Citation
Paul, Sumona, "Development of super hydrophobic membranes and their applications" (2024). Dissertations. 1844.
https://digitalcommons.njit.edu/dissertations/1844
Included in
Environmental Engineering Commons, Environmental Sciences Commons, Nanoscience and Nanotechnology Commons
