Lei Xie

Lei Xie
Central South University | CSU · School of Minerals Processing and Bioengineering

Ph.D.

About

62
Publications
10,397
Reads
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1,739
Citations
Introduction
Research interest in colloid and interface, intermolecular forces, and polymer adhesion in engineering applications (e.g., minerals processing, water treatment) http://faculty.csu.edu.cn/xielei/zh_CN/index/191631/list/index.htm
Additional affiliations
December 2020 - present
Central South University
Position
  • Professor
February 2017 - November 2020
University of Alberta
Position
  • PostDoc Position
Education
September 2012 - January 2017
University of Alberta
Field of study
  • Chemical Engineering
September 2008 - June 2010
University of California, Riverside
Field of study
  • Chemical and Environmental Engineering
September 2004 - June 2008

Publications

Publications (62)
Article
Lamellar membranes of Nb2CTx nanosheets have received significant research interests as cost-effective and efficient materials for desalination, water purification, energy conversion and storage, and ion separation. However, the constructive strategies...
Article
To promote the separation and enrichment efficiency of oxide minerals from the sulfide-oxide ores through froth flotation has become a challenging issue. In this paper, the driving role of S-[(2-hydroxyamino)-2-oxoethyl]-N,N-dibutyl-dithiocarbamate (HABTC) in facilitating the aggregation of copper sulfide and oxide minerals particles was explored t...
Article
As non-renewable natural resources, minerals are essential in a broad range of biological and technological applications. The surface interactions of mineral particles with other objects (e.g., solids, bubbles, reagents) in aqueous suspensions play a critical role in mediating many interfacial phenomena involved in mineral flotation. In this work,...
Article
Flotation separation is determined by chemical additives which can enlarge the hydrophobicity difference of minerals. Herein, S-[(2-hydroxyamino)-2-oxoethyl]-N,N-dipropyl dithiocarbamate (HAPTC) was firstly developed for the flotation separation of galena and sphalerite. In situ AFM imaging elucidated a much stronger adsorption affinity of HAPTC to...
Article
Full-text available
Efficient enzymatic hydrolysis of cellulose in lignocellulose to glucose is one of the most critical steps for the production of biofuels. The nonproductive adsorption of lignin to expensive cellulase highly impedes the development of biorefinery. Understanding the lignin-cellulase interaction mechanism serves as a vital basis for reducing such non...
Article
Full-text available
Gas bubbles widely exist in nature and numerous industrial processes. The physicochemical characteristics of bubbles such as large specific surface area, low density, and hydrophobicity make them an ideal platform for developing colloidal and interfacial technologies. Over the past few decades, much effort has been devoted to investigating the prop...
Article
Freezing-tolerant and conductive hydrogels have attracted tremendous interest as promising materials for flexible sensors under the gelid condition. In this work, a freezing-tolerant, dual-responsive hydrogel sensor was developed by using an ionic-glycerol hybrid hydrogel. The fabricated hydrogel sensor was demonstrated to detect efficiently differ...
Article
Hypothesis: The anodic dissolution of chalcopyrite (CuFeS2) encounters the problem of surface passivation, which significantly affects the copper extraction efficiency. So far, there is no agreement on the passivation mechanism and composition of passive layer, which could be studied by using in-situ scanning electrochemical microscopy (SECM). Expe...
Article
Mussel-inspired polydopamine (PDA) can be readily deposited on almost all kinds of substrates and possesses versatile wet adhesion. Meanwhile, slippery surfaces have attracted much attention for their self-cleaning capabilities. It remains unclear how the versatile PDA adhesive would interact with slippery surfaces. In this work, both liquid-infuse...
Article
Functional slippery surfaces have broad applications in engineering and bioengineering processes, such as water harvesting, photocatalysis, wastewater treatment and food industry. In this work, for the first time, we report the fabrication of a novel type of functional slippery solid surfaces via the self-assembly of a non-fluorine small molecule,...
Article
The SARS-CoV-2 virus that causes the COVID-19 epidemic can be transmitted via respiratory droplet-contaminated surfaces or fomites, which urgently requires a fundamental understanding of intermolecular interactions of the coronavirus with various surfaces. The corona-like component of the outer surface of the SARS-CoV-2 virion, named spike protein,...
Article
Probing the interaction mechanism between organic molecules and material surfaces in the presence of metal ions is of great importance in many fields, such as mineral flotation. The collectability of benzohydroxamic acid (BHA) to spodumene (LiAl(SiO3)2) mineral surface during mineral flotation could be enhanced with the addition of metal ion activa...
Article
Hypothesis: Ion specificity is crucial in assembly and aggregation of polymers in water driven by hydrophobic interaction. An increasing number of studies have suggested that specific ion adsorption and consequent impact on interfacial water molecules should play an important role in modulating hydrophobic interaction. Experiments: Here, bubble pro...
Article
Humic substance is a ubiquitous class of natural organic matter (NOM) in soil and aquatic ecosystems, which severely affects the terrestrial and aquatic environments as well as water-based engineering systems by adsorption on solids (e.g., soil minerals, nanoparticles, membranes) via different interaction mechanisms. Herein, the chemical force micr...
Article
The conversion of selenium oxyanions to elemental selenium (Se0) of low solubility and bioavailability is an effective industrial approach for selenium management in wastewater treatment. The generated Se0 particles require further treatment with coagulants such as ferric ions to facilitate the precipitation of Se0 particles. In this work, settling...
Article
Molybdenite (MoS2) has attracted great attention in the field of advanced materials. MoS2 is normally separated from other minerals by selective flotation, and chemical reagents (so-called depressants) are required to lower the surface hydrophobicity of MoS2. Previous studies had controversial arguments on the adsorption of organic and inorganic de...
Article
Hydrophobic interaction is responsible for a variety of colloidal phenomena, which also plays a key role in achieving desired characteristics and functionalities for a wide range of interfacial applications. In this feature article, our recent advances in the quantification and modulation of hydrophobic interactions at both solid/water and air/wate...
Article
Energy-efficient process for water desalination and organic dye separation is urgently needed to meet the dramatically increasing demand for fresh water globally. Nb2CTx MXene, as one type of 2D transition metal carbides (TMDCs) family, has attracted tremendous research interest in the fields of separation technology over the past decade. However,...
Article
Hydrophobic interactions are ubiquitous in water-based systems, which play a central role in a variety of interfacial phenomena. Herein, the recent advances in the quantitative measurements of hydrophobic interactions at different solid/water, air/water, and oil/water interfaces using surface forces apparatus (SFA) and atomic force microscope (AFM)...
Article
3,4-Dihydroxyphenylalanine (Dopa) is a mussel-inspired, unique and versatile adhesive moiety, while zwitterions are well-known for their antifouling and repellent properties. It is still unclear whether zwitterionic surfaces could effectively prevent the adhesion of Dopa unit, and zwitterion-Dopa interaction mechanism may lead to development of a n...
Article
Understanding the self-assembly and lubrication behavior of confined nanoparticles (NPs) is of fundamental and practical importance for the wide applications of NPs (e.g., in nanotribology). In this work, a systematic study was conducted to probe the assembly and associated surface forces of spherical gold nano-particles (Au NPs, diameter ~ 5 nm) c...
Article
Hypothesis: Hydrophobic interaction is crucial in various colloidal phenomena and engineering processes involving air/water/solid systems where polar and nonpolar substances usually mingle with each other. The molecular-level heterogeneity of surface hydrophobicity could potentially disorder the interfacial water molecules and thus influence the h...
Article
Wetting phenomena of oil/water/solid systems are fundamentally governed by the stability of confined water film and interaction mechanism between oil droplet and solid surface in water. Herein, droplet probe AFM was used to quantify the surface forces of model oil droplets including toluene and heptol in presence of interfacial asphaltenes interact...
Article
Emulsions stabilized with asphaltenes are undesirable in oil production due to the challenges associated with fouling, corrosion and environment contaminations. To understand the stabilization mechanism, the interfacial behavior and interaction mechanism of pentol/water interface in the presence of asphaltenes were investigated by interfacial tensi...
Article
Ultrathin two-dimensional (2D) materials are emerging as a promising platform for next-generation applications in catalysis, energy storage and many engineering fields. 2D non-layered nanomaterials with abundant dangling bonds and unsaturated coordination sites promise excellent characteristics and functionalities. However, 2D non-layered nanosheet...
Article
Separation process facilitated by selective adsorption of chemical reagents can be modulated through an in-depth understanding of reagent-surface interaction, which is of both fundamental and practical importance in a wide range of industrial applications. Hydroxamate is a class of widely used reagents in chemical and mineral engineering that can s...
Article
Considerable amounts of fine solids retained in the bitumen product have been a challenging issue impeding the industrial application of the non-aqueous extraction (NAE) of oil sands ore. The undesired stable suspension of bitumen-coated fine solids in the bitumen-solvent mixture is generally considered as the origin of solid migration to the NAE b...
Article
Surface modification by chemical reagents is of profound importance to modulate the surface characteristic and functionality of materials, which has attracted tremendous interest in many research fields and industrial applications, such as froth flotation of minerals. In this work, a new reagent S-[(2-hydroxyamino)-2-oxoethyl]-O-octyl-dithiocarbona...
Article
Probing the adsorption and lubrication behavior of lubricin, also known as Proteoglycan 4 (PRG4), is important for understanding the ultra-low friction of cartilage lubrication. Most previous research has focused on native lubricin either purified from synovial fluid or articular cartilage explant culture media. In this work, the adsorption behavio...
Article
Many challenging issues are encountered along the petroleum production such as the wettability alteration of reservoir solids due to deposition of petroleum materials, stabilization/destabilization of water-in-oil and oil-in-water emulsions and treatment of tailings water. All these problems are essentially driven by the fundamental intermolecular...
Article
Stabilization and destabilization of emulsions play an important role in a wide range of engineering and environmental processes (e.g., oil-water separation, waste water treatment). The destabilization of water-in-oil (W/O) emulsions in the presence of asphaltenes, which form a protective interfacial layer to prevent the coalescence of emulsions, i...
Article
Full-text available
The anisotropic surface characteristics and interaction mechanisms of molybdenite (MoS2) basal and edge planes have attracted much research interest in many interfacial processes such as froth flotation. In this work, the adsorption of a polymer depressant [i.e., carboxymethyl cellulose (CMC)] on both MoS2 basal and edge surfaces as well as their i...
Article
Hydrophobic (HB) interaction plays a critical role in many colloidal and interfacial phenomena, biophysical and industrial processes. Surface hydrophobicity, characterized by water contact angle, is generally believed as the most dominant parameter determining HB interaction. In this work, we quantified the HB interactions of air bubbles and a seri...
Article
Hydrophobic (HB) interaction plays a critical role in many colloidal and interfacial phenomena, biophysical and industrial processes. Surface hydrophobicity, characterized by water contact angle, is generally believed as the most dominant parameter determining HB interaction. In this work, we quantified the HB interactions of air bubbles and a seri...
Article
This work reports a kind of novel, robust, multifunctional covalent-bonded polymer nanofilms based on highly efficient spin-assisted layer-by-layer (LbL) assembling, with a wide range of engineering and bioengineering applications. An active-ester block copolymer, polypentafluorophenylacrylate-block-polystyrene (PPFPA-b-PS) and an amine-rich polyme...
Article
Fluorite is the most important mineral source for producing fluorine-based chemicals and materials in a wide range of engineering and technological applications. In this work, atomic force microscope (AFM) was employed, for the first time, to probe the surface interactions and adhesion energy of model oleic acid (a commonly used surface modificatio...
Article
Full-text available
Humic acid (HA) has been studied as a potential selective depressant for molybdenite in the flotation separation of molybdenite and talc in this paper. In the single mineral flotation tests, HA has shown good depression ability to molybdenite over the entire pH range tested from pH 3-11, while the floatability of talc was only affected by HA under...
Article
Full-text available
Surface interactions involving deformable air bubbles have attracted tremendous interest in a wide range of engineering applications, such as mineral flotation and bitumen extraction. In this work, for the first time, the interaction forces between air bubbles and bitumen surfaces in complex aqueous media of varying pH, salinity and salts were dire...
Article
Due to the limited availability of fresh water sources, recycled water and sea water, generally with high salinity, have been widely used in mining industry in arid regions, which can significantly affect the interactions of mineral particles, chemical additives and air bubbles in mineral processing (e.g., flotation). In this work, the surface forc...
Article
In this work, bubble probe atomic force microscope (AFM) was employed to quantify the interactions between two air bubbles and between an air bubble and an octadecyltrichlorosilane (OTS)-hydrophobized mica under various aqueous conditions. The key parameters (e.g. surface potentials, decay length of hydrophobic attraction) were obtained by analyzin...
Article
Surface functionalization by alkylsilanes has been widely used in many engineering applications. In this work, a systematic investigation was conducted on the deposition behaviors of octadecyltrichlorosilane (OTCS) on freshly cleaved mica surfaces that possess low density of reactive sites (i.e., silanol groups) via a vapor deposition method. The d...
Article
Full-text available
Hydrophobic effect plays an important role in a wide range of natural phenomena and engineering applications, such as mineral froth flotation. In this work, atomic force microscope (AFM) force mapping was employed, for the first time, to probe the nanoscale heterogeneity of surface hydrophobicity and surface interactions on the sphalerite mineral s...
Article
Full-text available
The surface characteristics of molybdenite (MoS2) such as wettability and surface interactions have attracted much research interest in a wide range of engineering applications, such as froth flotation. In this work, a bubble probe atomic force microscope (AFM) technique was employed to directly measure the interaction forces between an air bubble...
Article
Full-text available
The interactions of emulsion drops and gas bubbles in complex fluids play important roles in a wide range of biological and technological applications, such as programmable drug and gene delivery, formation of emulsions and foams, and froth flotation of mineral particles. In this feature article, we have reviewed our recent progress on the quantifi...
Article
Adsorption of interfacially active components at water/oil interface plays critical roles in determining the properties and behaviors of emulsion droplets. In this study, droplet probe atomic force microscopy (AFM) technique was applied, for the first time, to quantitatively study the interaction mechanism between water-in-oil (W/O) emulsion drople...
Article
The outstanding water wettability and the capability of polyelectrolyte surfaces to spontaneously clean oil fouling are determined by their wetting mechanism in the surrounding medium. Here, we have quantified the nanomechanics between three types of polyelectrolyte surfaces (i.e. zwitterionic, cationic, and anionic) and water or oil drops using an...
Article
The most engineering application for the molecular self-assembly of sulfydryl compounds on solid surfaces is froth flotation. In this work, the hydrophobic mechanism of 3-hexyl-4-amino-1,2,4-triazole-5-thione (HATT) on chalcopyrite (CuFeS2) was first investigated by in situ atomic force microscopy (AFM), in situ scanning electrochemical microscopy...
Article
Full-text available
The interactions between asphaltene surfaces in aqueous media play important roles in many interfacial processes and phenomena in oil production and waste water treatment. In this study, the interaction mechanisms between asphaltene surfaces in aqueous solutions were investigated using a surface forces apparatus (SFA) and an atomic force microscope...
Article
The outstanding water wettability and the capability of polyelectrolyte surfaces to spontaneously clean oil fouling are determined by their wetting mechanism in the surrounding medium. Here, we have quantified the nanomechanics between three types of polyelectrolyte surfaces (i.e. zwitterionic, cationic, and anionic) and water or oil drops using an...
Article
Full-text available
Colloidal stability governed by various surface interactions finds wide application in many engineering processes, such as mineral froth flotation. In this work, electrochemical atomic force microscope (EC-AFM) was employed to modulate the interfacial chemical reaction and simultaneously probe the evolution of surface characteristics (i.e., morphol...
Article
Water management and treatment of mineral tailings and oil sands tailings are becoming critical challenges for the sustainable development of natural resources. Polymeric flocculants have been widely employed to facilitate the flocculation and settling of suspended fine solid particles in tailings, resulting in the separation of released water and...
Article
The interactions between air bubbles and hydrophobic polymer surfaces in aqueous media play important roles in many industrial and engineering processes. In this work, the interaction forces between air bubble and a model hydrophobic polymer - polystyrene (PS) in NaCl solutions (1 mM to 1000 mM) were directly measured using a bubble probe atomic fo...
Article
Understanding the surface interactions between elemental selenium (Se0) and solid substrates are of both fundamental and practical importance in biological systems, water treatment processes, and microelectromechanical/nanoelectromechanical systems where Se0 is present. In this work, for the first time, surface interactions between a Se0 sphere and...
Article
Emulsions with interface-active components at oil/water interface have long been of fundamental and practical interest in many fields. In this work, the interaction forces between two oil droplets in water in the absence/presence of asphaltenes were directly measured using droplet probe atomic force microscopy (AFM) and analyzed using a theoretical...
Article
The adsorption of amyl xanthate on sphalerite in NaCl solutions of different concentrations and in saline water (viz. simulated sea water) and the surface properties of treated minerals were investigated. The interactions between xanthate treated sphalerite particles and air bubbles were examined using induction time measurement, which revealed tha...
Article
Full-text available
The interaction between air bubbles and solid surfaces plays important roles in many engineering processes, such as mineral froth flotation. In this work, an atomic force microscope (AFM) bubble probe technique was employed, for the first time, to directly measure the interaction forces between an air bubble and sphalerite mineral surfaces of diffe...
Article
A combination of atomic force microscopy (AFM) and reflection interference contrast microscopy (RICM) was used to measure simultaneously the interaction force and the spatiotemporal evolution of the thin water film between a bubble in water and mica surfaces with varying hydrophobicity. Stable films, supported by the repulsive van der Waals-Casimir...
Article
Understanding the surface properties and interactions of non-spherical particles is of both fundamental and practical importance in rheology of complex fluids in various engineering applications. In this work, natural chrysotile, a phyllosilicate composed of 1:1 stacked silica and brucite layers which coil into cylindrical structure, was chosen as...

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Projects (2)
Project
We are organizing a special issue that may be of interest to you, "Studies on Colloidal Chemistry and Intermolecular Forces of Minerals" for Minerals. The topics of interest of this Special Issue include but are not limited to characterization of mineral surfaces using advanced analytical tools, adsorption of chemical reagents (e.g., collector, depressant, flocculant) on mineral surfaces, co-aggregation/hetero-aggregation of mineral particles, rheology of mineral particles, bubble–mineral attachment, coagulation, flocculation, exfoliation of natural minerals, and mineral-based interfacial application (e.g., adsorption, catalysis, medication). Both experimental investigations and theoretical modelings related to colloid chemistry, surface characteristics, intermolecular forces, and interaction mechanisms of minerals are welcome. We warmly invite you to make valuable contributions to this Special Issue, and please find the detailed information on: https://www.mdpi.com/journal/minerals/special_issues/CCIFM Dr. Lei Xie Dr. Wenjihao Hu Dr. Yuesheng Gao Guest Editors
Project
Anisotropic surface properties of mineral crystals, the interfacial interaction among mineral surface/reagent/aqueous solution, and the screen&design of selective reagents.