Dr. Qilin Li’s lab, the Li Lab for Advanced Water Treatment Technologies, is at the forefront of research focused on innovative solutions for water treatment. The lab’s work encompasses the development of novel materials and processes, as well as system-level designs that enhance the energy efficiency and cost-effectiveness of utilizing both conventional and alternative water resources. These advancements aim to improve water supply systems across residential, municipal, and industrial sectors. By integrating cutting-edge technologies and interdisciplinary approaches, our lab seeks to address key challenges in water purification and resource management, contributing to sustainable and efficient water treatment solutions.
Selective Electrodialysis for Resource Recovery
Lithium Extraction using Selective Electrodialysis System
Concentrating and harvesting high-value metals such as lithium (Li) and copper (Cu) from water sources presents a promising avenue to address the increasing global demand for these essential materials. For instance, the lithium reserves in US geothermal brine alone have the potential to satisfy over 40% of the worldwide lithium demand. Despite this, direct extraction remains challenging due to the low concentrations of these metals and the complex composition of the water. Our research group is dedicated to overcoming these challenges by developing advanced materials with high selectivity. In conjunction with optimized process and system designs, we aim to achieve the selective extraction of high-value metals in a manner that is both energy-efficient and cost-effective.
The LiSED system, proposed and developed by Dr. Qilin Li’s research lab, is designed to harvest lithium sustainably and affordably in order to meet the growing lithium demand as the world transitions to a low-carbon economy. This technology has the potential to replace existing methods in lithium recovery by extracting lithium from untapped sources—such as lithium-containing geothermal brine and oil- and gas-produced water—at a fraction of the cost. The impact of lower-cost lithium sources could mean more affordable electric vehicles and solar and wind energies, as well as reduced dependence on foreign imports.
Cation Exchange Membrane Modification for Enhanced Rare Earth Element Recovery
Rare Earth Elements (REEs) are critical minerals and critical materials for sustainable energy transition. Among REEs, Nd, Pr, Tb, and Dy are of highest economic value. They are used in the NdFeB magnets, which are lead magnets for manufacturing wind turbines and electric motors. Importantly, REEs can be found in many waste streams associated with magnet scraps, electronics, and coal fly ashes. For example, the leachates of electronic wastes contain over 1000 ppm of REEs coexisting with other transition metal ions. Electrosorption is an electric potential driven adsorption process that separates ions from water using adsorbents. It is more advantageous compared to conventional adsorption, because the operating condition is mild, and the use of harsh chemicals is limited during the regeneration of adsorbents. However, the separation of ions during electrosorption is still based on electrostatic interactions and is non-selective. The selectivity of electrosorption towards REEs against other competing metal ions can enable effective REE extraction from industrial wastewater. Metal organic frameworks (MOFs), a class of adsorbent materials known for their highly porous and tunable properties. To achieve ion selectivity, MOFs can be grafted with different ligands that enable complexation with certain metal ions. For example, phosphoric-acid-based functional groups have been demonstrated in the solvent extraction and conventional adsorption processes for REE extraction. We are studying different ligand-modified MOF materials to achieve the ion selectivity towards REEs. The modified MOF materials, once proven successful, can be used as adsorbents in electrosorption processes, which recover REEs from a range of aqueous waste streams (e.g., leachates of scrap magnets).
Tunable Selectivity of Ion Exchange Membranes in ED Systems
Electrodialysis (ED) is gaining interest as a desalination technology. However, ion transport properties of existing ion exchange membranes (IEMs) used in ED are not ideal for many desalination and reuse applications. The higher permeability of divalent ions compared to monovalent ions often leads to depletion of hardness and alkalinity in the product water, and scale formation in the concentrate channel, requiring extensive pretreatment and post-treatment and increasing treatment cost. It is important to develop IEMs that provide the desired divalent ion/monovalent ion selectivity in order to minimize water recovery while ensuring product water quality with minimal pretreatment and posttreatment. Our research group is developing thin film composite ion exchange membranes (TFC-IEMs) with tunable monovalent/divalent selectivity to enhance water recovery while ensuring product water quality in ED processes.
Nanocomposite Electrodes for Selective Ionic Contaminant Removal
Electrodialysis (ED) is gaining interest as a desalination technology. However, ion transport properties of existing ion exchange membranes (IEMs) used in ED are not ideal for many desalination and reuse applications. The higher permeability of divalent ions compared to monovalent ions often leads to depletion of hardness and alkalinity in the product water, and scale formation in the concentrate channel, requiring extensive pretreatment and post-treatment and increasing treatment cost. It is important to develop IEMs that provide the desired divalent ion/monovalent ion selectivity in order to minimize water recovery while ensuring product water quality with minimal pretreatment and posttreatment. Our research group is developing thin film composite ion exchange membranes (TFC-IEMs) with tunable monovalent/divalent selectivity to enhance water recovery while ensuring product water quality in ED processes.
Novel Desalination and Water Purification Technologies
Nanophotonics Enabled Solar Membrane Distillation (NESMD):
Supported by NEWT and the SunShot Program from the Department of Energy, our group has developed Nanophotonics-enabled solar membrane distillation (NESMD) which is capable of utilizing solar energy to produce freshwater; this greatly reduces the operational cost of MD. By incorporating a thermally conductive coating onto a membrane, highly localized heating on the surface reverses temperature polarization (a prevalent limitation in MD systems) and greatly increases system efficiency. In our lab, we actively work on developing novel photothermal materials and optimizing process design to improve heat utilization and make NESMD cost effective.
Electrothermal Membrane Distillation (ETMD):
Diminishing freshwater availability has driven water users to consider unconventional sources for water recovery. Wastewater containing high salinity and high organic loads presents challenges for even the most industrially matured membrane processes, requiring extensive pretreatment. Membrane Distillation (MD) is a thermally driven water-recovering technology applicable to a wide range of salinity and exhibits a lower fouling propensity compared to pressure-driven membrane processes. However, MD’s innate thermodynamic limitations hinder its utilization in industrial applications. Electrothermal Membrane Distillation (ETMD) is a surface heating membrane distillation (SHMD) process that addresses several inherent limitations of conventional MD processes. Its capability to achieve both high flux and high-water recovery is attractive to wastewater reuse applications. However, it has not been demonstrated using real, complex wastewaters, and the impact of compound fouling by the various foulants in wastewater has not been investigated. In this work, we demonstrate the use of ETMD to recover ultrapure water from kidney dialysis effluent and investigate the impact of both organic and inorganic constituents on permeate flux as well as the fouling mechanisms involved.
Membrane Fouling: Mechanisms, Advanced Materials and Mitigation
Gypsum Nucleation on Substrates of Different Hydrophilicity
Membrane fouling, categorized as organic fouling, inorganic fouling and biofouling, is a major issue impeding the application of membrane technology to water treatment processes. It not only increases the mass transfer resistance but also causes deterioration of effluent quality and ultimately shortens the membrane’s useful life. Therefore, it is important to study the basic mechanisms fundamentally for the development of functionalized anti-fouling membranes.
Membrane scaling, known as inorganic fouling, is mainly caused by particulate matter deposition or the salts precipitation on the membrane surface. It has been the primary constraint especially in seawater desalination and brine water treatment. We devote to understand the fundamental mechanism of the scale formation process at the liquid-solid interface, aiming to empower the innovation in material development and process design.
Dynamic Coatings and Electrified Systems for Scaling Control
Stimuli responsive polymers(SRPs), or smart polymers, are capable of conformational or chemical changes responding to external stimulus, such as temperature, pH, light, electric or magnetic field. Such structual changes may have a potential in scaling control which is yet to be explored. Supported by Bureau of Reclamation, we propose to develop membrane coatings consisting of stimuli-responsive block copolymer brush (SRBCB)-nanomaterial complexes for active control of mineral scaling in membrane desalination systems using a periodic electrical or magnetic signal.
Sustainable Control Strategies for Membrane Biological Fouling
Due to the adaption and inevitable growth of microorganisms, biofouling is a critical issue in the operation and maintenance of membrane systems used for water and wastewater treatment. Our group has investigated and developed various sustainable biofouling control strategies over the years, which are icorporating nanoparticles (such as Ag, Cu etc.), employing biofouling control reagents such as D-amino acids, modulating the quorum sensing and introducing surface patterning on the materials.
Antibiotic Resistance and Control in Wastewater Treatment
Inactivation of Antibiotic Resistant Bacteria and Genes
Due to numerous causations including over-prescribing of antibiotics and over-use in farming, antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG) are found in various environments which eventually are concluded in wastewater treatment plants (WWTPs). Infected WWTP effluents are then dispersed to a variety of areas in the environment-leading to a greater spread of ARBs. Therefore, disinfection processes for ARBs and ARGs particularly in WWTPs is an area of critical focus. We aim to figure out effective disinfection method such as advanced oxidation processes, especially for the ARBs and ARGs.
Sustainable Urban Food, Energy and Water Infrastructures
Quantitative Modeling: Assessing Design and Performance of Water Systems
Safe and secure water supply is critical to the sustainability of cities. This goal, however, has become increasingly challenging due to rapid population growth, continuing urbanization and global climate change. A paradigm shift from centralized water supply to an integrated water and wastewater management approach has been proposed as a potential solution. We aim to develop quantitive models to assess urban water and wastewater infrastructure through decentralized direct potable reuse (DPR) of wastewater as a strategy to improve energy and water efficiency of urban water systems
