Solvent Pollution Research Articles

Advanced superhydrophobic polylactic acid fibers with high porosity and biodegradability for efficient solvent recovery

The conventional oil-absorbing materials utilized for addressing oil and organic solvent pollution are plagued by the issue of secondary pollution. In this study, biodegradable porous polylactic acid (PLA) fiber materials were prepared using centrifugal spinning technology, with PLA and polyvinyl butyral (PVB) as raw materials. PVB was utilized as a pore-forming agent to fabricate multi-layered porous PLA fiber materials. When the content of PVB in the spinning solution was 14 %, the porous PLA fibers exhibited the maximum specific surface area of 60.7 m2/g and a porosity of up to 85.4 %, interior of the fiber contained numerous mesopores. Additionally, the porous PLA fibers demonstrated excellent superhydrophobic oil absorption properties, with a water static contact angle of 137.8° and oil or organic solvent absorption capacities ranging from 10 to 17.7 g/g. Furthermore, porous PLA fiber materials exhibited outstanding biodegradability, with a degradation mass loss rate of 42.3–45.1 %. Therefore, superhydrophobic and oleophilic biomass-based PLA fiber materials prepared in centrifugal spinning show promising applications in the recovery of organic solvents and oily substances.

In-situ synthesis of superhydrophobic PLA-UiO-66-NH2@MS melamine sponge composite for high efficiency oil/water separation

In recent years, oil and organic solvent pollution of water bodies have deteriorated water quality, harmed ecosystems, and presented serious concerns to human health and biodiversity. Traditional oil/water separation technologies are inefficient, consume a lot of energy, and are difficult to operate. As a result, finding efficient, environmentally beneficial, and long-term separation solutions to manage water pollution is challenging. This paper proposes UNP@MS, a MOF-based sponge material to achieve superhydrophobicity and super lipophilicity, the material is developed on a melamine sponge loaded with UiO-66-NH2 and grafted with a polylactic acid (PLA) component. It achieves a remarkable oil/water separation efficiency of 99% even under difficult conditions (such as acidic or alkaline solutions) and displays exceptional separation efficiency for various oils. Furthermore, the oil absorption capacity maintains at 85% after ten cycles of oil absorption, exhibiting outstanding stability.

Improving structural and functional properties of starch-catechin-based green nanofiber mats for active food packaging by electrospinning and crosslinking techniques

The hydrophilic and low mechanical properties limited the application of starch-based films. In this work, a hydrophobic starch-based nanofiber mat was first successfully prepared from aqueous solution at room temperature by using electrospinning and glutaraldehyde (GTA) vapor phase crosslinking techniques for active packaging applications. Catechin (CAT) was immobilized in the nanofibers by electrospinning, resulting in higher thermal stability (Tdmax = 315.23 °C), antioxidant (DPPH scavenging activity = 94.31 ± 2.70 %) and antimicrobial (inhibition zone diameter = 15.6 ± 0.3 mm) of the fibers, which further demonstrated hydrogen bonding and electrostatic interaction between CAT and fibers. Nanofibers after GTA vapor phase crosslinking exhibited enhanced hydrophobicity (water contact angle: 15.6 ± 1.5° → 93.5 ± 2.3°) and mechanical properties (tensile strength: 1.82 ± 0.06 MPa → 7.64 ± 0.24 MPa, elastic modulus: 19.35 ± 0.63 MPa → 45.34 ± 0.51 MPa). The results demonstrated that preparation of starch-based electrospun nanofiber mats in aqueous system at room temperature overcame the challenges of organic solvent pollution and thermosensitive material encapsulation, while GTA vapor phase crosslinking technique improved the hydrophobicity and mechanical properties of nanofiber mats, which facilitated the application of starch-based materials in the field of packaging.

Ternary deep eutectic solvents for esterification of 2-methylpropenoic acid with alcohols.

In this paper, a set of novel ternary deep eutectic solvents (T-DESs) is synthesized and applied in the esterification of 2-methylpropenoic acid with alcohols. T-DESs have multiple functions, serving as a catalyst, polymerization inhibitor, and solvent, and demonstrate excellent catalytic esterification reaction activity (up to 96% yield). The optimal T-DESs 1 can be recycled 14 times without any decrease in its catalytic activity, thus solving the problems of methacrylate product separation with a polymerization inhibitor, catalyst recovery, and organic solvent pollution.

Deep‐Blue CsPbBr3 Perovskite Quantum Dots via Green Polar Solvent and Short Ligand Engineering towards Highly Efficient Light‐Emitting Diodes

AbstractTo date, researchers face a huge challenge in synthesizing blue perovskite quantum dots (PQDs) with short‐chain ligands since the short‐chain ligands increase the polarity and decrease solubility in common non‐polar solvents during syntheses. The use of polar solvents to replace non‐polar ones may solve the solution problem, but polar solvents will decompose PQDs. So, the key to successful synthesis of PQDs with short‐chain ligands is to find polar solvents that can dissolve short‐chain ligands well and do not destroy perovskites concurrently. Herein, a room‐temperature synthesis method for deep‐blue CsPbBr3 PQDs with short‐chain ligands is proposed by using eco‐friendly ethyl acetate polar solvent. CsPbBr3 PQDs with an average size of 3.87 nm and a peak wavelength of 454 nm are synthesized with a photoluminescence quantum yield of 48.4%. With an interlayer modification to the hole transport layer, the deep‐blue perovskite light‐emitting diodes realize a maximum external quantum efficiency of 4.39% and half‐lifetime of 4.5 min at a maximum brightness of 72 cd m−2. This work offers a novel eco‐friendly avenue for the preparation of effective PQDs including blue ones, which will accelerate commercialization of PQDs in lighting and HD full‐color displays as well as reduce discharge of solvent pollutants and protect the global environment.

Highly swollen ROMP-based gels

The leakage of organic solvent during the transportation and storage is one of the major threats to the environment. Networks/gels acting as the absorbing materials for organic solvents are the most promising solution for the organic solvent pollution. Here, we report the synthesis of highly swollen networks/gels in high yield (≥95%) via ring opening metathesis polymerization (ROMP) using Grubbs’ first generation catalyst/initiator (G1), a crosslinker (1,1′-(methylenedi-4,1-phenylene)bis-exo-7-oxanorbornenecarboximide) and monofunctional monomer/diluent (exo-N-phenyl-7-oxanorbornenecarboximide). The mesh size of the network was varied by keeping the concentration of monomer constant while changing the concentrations of crosslinker and G1 (initiator). The swelling capacity of the network in N,N-dimethylformamide (DMF) solvent increased from 41 to 53 and to 61 with the increase of theoretical mesh size (molar ratio of monomer to crosslinker) from 20 to 40 and to 60, respectively. By further increasing the mesh size from 60 to 80 there was no significant change in swelling capacities (63). Thus, the gel with the mesh size of 60 was selected for swelling capacity analysis in other polar organic solvents such as dimethyl sulfoxide (DMSO), dichloromethane (DCM), chloroform and lithium-ion battery electrolyte solution (1.0 M LiPF6 in ethylene carbonate (EC)/diethyl carbonate (DEC) = 50/50 (v/v)). They showed the decreased swelling capacity value from 61 to 57, 40, 31 and 5, respectively. For a controlled mesh size ROMP-based gel, we observed the highest swelling capacity values to date.

Carbon nanofibers derived from cellulose via molten-salt method as supercapacitor electrode

Carbon nanofibers (CNFs) have been paid much attention as supercapacitor electrode due to outstanding chemical stability, high electron transfer rate and large specific surface area. However, the preparation process of CNFs is always stalemated in electrospinning, heat stabilization and carbonization. The problems of solvent pollution in the electrospinning process, complex process and high energy consumption in conventional carbonization process can't be solved. Herein, CNFs have been innovatively prepared from nanofibrillated cellulose by the molten-salt method (NaCl/NaOH). Molten salt penetrates between the fibers, separates and activates the fibers. The obtained carbon nanofibers remain developed branching structures and have a large specific surface area (899 m2 g−1). The electrical properties are tested in a symmetrical two-electrode system. The specific capacitance is 150 F g−1 at the current density of 1 A g−1. Low equivalent series resistance (1.13 Ω) indicates that it has high electrode conductivity. This study has taken into account energy conservation, environmental protection, recyclability and simplified preparation process, which has a very far-reaching significance for the industrial production of CNFs.

Sustainable Carbon Nanofibers Derived from Cellulose Via Molten-Salt Method as Supercapacitor Electrode

Carbon nanofibers have been paid much attention as supercapacitor electrode due to outstanding chemical stability, high electron transfer rate and large specific surface area. However, its preparation process is always stalemated in electrospinning, heat stabilization and carbonization. The problems of solvent pollution in electrospinning process, complex process and high energy consumption in carbonization process cannot be solved. Herein, carbon nanofibers have been innovatively prepared from nanofibrillated cellulose by molten-salt method. Molten salt effectively prevents hydrogen bonding, adhesion and agglomeration between fibers. The obtained carbon nanofibers remained developed branching structure and have a large specific surface area (899 m 2 g -1 ). The electrical properties were also tested in a three-electrode system. The specific capacitance is 145 F g -1 at the current density of 1 A g -1 . Low equivalent series resistance (1.07 Ω) indicates that it has high electrode conductivity. This study has taken into account energy conservation, environmental protection, recyclability and simplified preparation process, which has a very far-reaching significance for the industrial production of CNFs.

Fluorescent-brightener-mediated thiol-ene reactions under visible-light LED: A green and facile synthesis route to hyperbranched polymers and stimuli-sensitive nanoemulsions

LED-triggered polymerization is a well-known technique for the production of polymers, which requires less energy consumption and can resolve the issue of solvent pollution. Obtaining stimuli-responsive latexes especially within the nanoscale, however, is quite challenging via this low intensity photopolymerization method. Here, we demonstrate a one-pot synthetic strategy that integrates a visible-light LED-triggered photopolymerization and a thiol-ene click reaction: (i) the bulk form of which allows the facile formation of hyperbranched polymers in an efficient manner, (ii) the emulsion form of which contributes to the construction of a simpler and eco-friendlier preparation platform toward the synthesis of smart nanoparticles with pH-, redox- and UV-responsive properties, wherein the fluorescent brightener-based photoinitiating system is particularly critical for this synthetic approach. In parallel with retaining the robustness of step-growth polymerization, this approach simultaneously brings along two new features: visible light and aqueous reaction conditions, besides, which possesses the superiorities of low-energy, high-performance, photocatalyst-free, VOC-free and easy set-up.

Combining continuous monitoring and High-Precision altitude measurements in forensic groundwater surveys: a case study of chlorinated solvent pollution in an urban context

This paper describes a forensic investigation of groundwater in an urban context in Italy. The present case study was conducted to detect the hydraulic flow path between a sportfishing pond and a nearby industrial plant’s contaminated groundwater site. The investigation was performed to evaluate the potential for diffusion of contaminants through groundwater flow into a fishing pond located downstream from a chemical factory. High-precision altitude measurements of monitoring stations combined with continuous water level monitoring were crucial to understand the groundwater flow dynamics and define the hydrogeological conceptual model. The study verified that the fishing pond, dug in low-permeability volcanic rock, was not hydraulically connected to the groundwater flow. The presence of contaminants in the pond may be related to the periodic topping-up activity performed using water from an existing well. The identified groundwater flow paths were consistent with the possible contaminant migration from the chemical factory to the water well near the fishing pond.

Directional, super-hydrophobic cellulose nanofiber/polyvinyl alcohol/montmorillonite aerogels as green absorbents for oil/water separation.

Nowadays, the problem of oil spill and organic solvent pollution has become more and more serious, and developing a green and efficient treatment method has become a research hotspot. Herein, the preparation of porous super‐hydrophobic aerogel by directional freezing with cellulose nanofibre (CNF) as the base material, polyvinyl alcohol (PVA) as the cross‐linking agent and montmorillonite (MMT) as the modifier and filler, followed by hydrophobic treatment with chemical vapour deposition is reported. The prepared composite aerogel presented three‐dimensional inter‐perforation network structure, low density (26.52 mg⋅cm−3), high porosity (96.1 %) and good hydrophobicity (water contact angle of 140°). Notably, the composite aerogel has a good adsorption effect on different oils and organic solutions, and its adsorption capacity can reach 40–68 times of its initial weight. After complete adsorption, the aerogel could be easily collected. More importantly, the composite aerogel had high strength, whose compressive stress at 70 % strain reached 0.15 MPa and could bear over 1290 times its weight without deformation after 2 weeks. A new, green, simple and efficient absorbent for the adsorption of oils and organic solvents is provided.

An Intrinsic Photothermal Liquid for Light Detection and Energy Storage.

Photothermal materials (PTMs) have been intensively investigated in the fields of photothermal conversion. Superior to solid PTMs, liquid PTMs are leading the trends in satisfying the demands of high flexibility and easy recycling. Successful examples of liquid PTMs are mostly formulated by dispersing solid PTMs in solvents, but suffer from the problems of phase segregation and solvent pollution. In this work, a low-cost formulation is proposed, which involves an oxidative product of ethyl oleate by iodine. It is an intrinsic liquid PTM, preserving the fluidic nature as well as possessing considerable ability for photothermal conversion. In addition to understanding the mechanism of light absorption in the visible and even near infrared windows, two examples are presented to demonstrate the great potential of liquid PTMs in broad areas such as light sensing and energy storage.

Sensitive and selective detection of metal ions and small molecules in aqueous media using a hydrolytically stable amide-functionalized metal–organic framework

With the increase in human activities, the issue of environmental pollution is currently more and more serious, such as metal ions and chemical solvent pollutants which deeply influenced the human health and the environment. Herein, microporous MOF, TMU-22, with amide-decorated pores was employed for the detection of Al3+ and Fe3+ ions in aqueous media. The results demonstrated high selectivity to these ions especially Fe3+, with no interference from other metal ions. This MOF shows fast recognition of Al3+ and Fe3+ with a response time of <1 min and detection limit of 1.2 µM and 3 µM, respectively. More importantly, the KSV constant of Fe3+ was 65184 M−1, which is higher than other MOFs reported in the previous literature. Further luminescent studies revealed that TMU-22 exhibits a high-sensitivity sensing response to tetrahydrofuran with a response time of <1 min and the detection limit of 0.09%. This work would open up a new door for MOF applications in the detection of metal ions and THF in complex environments.

Study on affecting factors of curing rate in ultraviolet curing adhesives containing modified acrylic ester prepolymers

Ultraviolet (UV) curing adhesives have been extensively utilized in fields of health care and electronic components due to low energy consumption and solvent pollution. The most used system is modified acrylic ester system whose merits are low cost, high reliability and tensile strength. However, higher UV curing rate is still pursued especially in field of quick dry adhesives as well as influencing factors of curing rate are very complex. For clarifying affecting factors of curing rate as well as achieving higher curing rate, in this work, several UV curing adhesives with acrylic photosensitive resin prepolymers modified by epoxy and polyurethane were prepared. The impacts of class and content of radical photo-initiators, prepolymers and reactive diluents on UV curing rate were deeply researched. Moreover, the influence of oxygen polymerization inhibition on curing rate was discussed as well. The significantly elevated curing rates were obtained in as-prepared adhesives, in comparison with commercial ones. This work might offer a facile and effective strategy to obtain the promising high-performance modified acrylic ester prepolymer bearing UV curing adhesives with a significantly elevated high curing rate by well controlling these investigated affecting factors.

Fast curing velocity, low volume shrinkage and high heat resistance achieved in novel ultraviolet curing adhesives

Nowadays, Ultraviolet (UV) curing adhesives have been extensively researched in the fields of health care and electronic components thanks to their high curing rate, low energy loss, no solvent pollution and excellent properties. UV curing systems bearing modified acrylate prepolymers have been widely utilized in the field of electric industry packaging. The advantages are low cost, high reliability, quick curing velocity, high mechanical trait and strong solvent endurance. For further optimizing the curing rate, curing volume shrinkage and thermal resistance of UV curing adhesives, in present work, two kinds of novel UV curable adhesives bearing epoxy and polyurethane modified acrylate prepolymers were designed and fabricated. Adhesive properties and thermal resistance of two adhesives were studied firstly. Boiling and solvent tolerances as well as bin stability of adhesives were discussed. Finally, over-all performances of as-prepared adhesive and purchased commercial adhesive were compared. High curing rate, low curing volume shrinkage and high heat resistance were achieved. This work might offer a facile and practical route to prepare the high-performance UV curable adhesives with significantly improved over-all properties by formula design.

Synthesizing promising epoxy acrylate prepolymers applied in ultraviolet cured adhesives based on esterification reaction

Ultraviolet (UV) cured adhesives have attracted wide attention and investigation in the fields of health care and electronic components due to their quick curing rate, low energy consumption and solvent pollution. At present, the adhesive systems bearing epoxy acrylate components have prevailed in the field of electronic industry packaging. These systems show some advantages such as low cost, high reliability, excellent mechanical traits and fine solvent resistance. However, the affecting factors of the noumenal esterification reaction to synthesize epoxy acrylate prepolymers have hardly been reported. In order to clarify the affecting factors, in this work, the key pre-polymer components in application of UV cured adhesives were designed and further prepared based on noumenal esterification between epoxy resin and acrylic acid. Three kinds of varied epoxy resins were employed to prepare desired epoxy acrylate pre-polymers. Impacts of reaction temperature, epoxy resin type, catalyst content, catalyst class and raw material feed ratio on noumenal esterification reaction were deeply studied. Some valuable conclusions were achieved. This work might open the door to the large-scale synthesis of promising epoxy acrylate pre-polymers to construct high-performance UV curing adhesives by regulating noumenal esterification.

Micro- and nanoporous materials capable of absorbing solvents and oils reversibly: the state of the art

Treatment of petroleum spills and organic solvent pollution in general is an important issue; several techniques are under development to remove oil from water. The use of absorbents is one of the most common techniques to tackle this problem. These absorbents can be classified based on their characteristics of recyclability into irreversible and reversible ones. In this review, we discuss the application of several materials as oil absorbents, according to their classification and characteristics such as hydrophobicity, surface area and oil absorption capacity. Also, the fabrication methods for some materials are presented and analyzed.

Investigation of chlorinated solvent pollution with resistivity and induced polarization

Globally, an enormous number of polluted areas are in need of remediation to prevent adverse effects on health and environment. In situ remediation and especially the monitoring thereof needs further development to avoid costly and hazardous shipments associated with excavation. The monitoring of in situ remediation actions needs easier and cheaper nondestructive methods for evaluation and verification of remediation degree and degradation status of the contaminants. We investigate the Direct Current resistivity and time-domain Induced Polarization tomography (DCIP) method and its use within the context of a DNAPL (Dense Non-Aqueous Phase Liquids) contaminated site in Varberg, Sweden, where an in situ remediation pilot test has been performed by stimulated reductive dechlorination by push injection. Our results show that the DCIP technique is an emerging and promising technique for mapping of underground structures and possibly biogeochemical spatial and temporal changes. The methodology could in combination with drilling, sampling and other complementary methods give an almost continuous image of the underground structures and delineation of the pollutant situation. It can be expected to have a future in monitoring approaches measuring time lapse induced polarization (IP), if more research is performed on the parameters and processes affecting the IP-signals verifying the interpretations. The IP technique can possibly be used for verification of the effectiveness of in situ remediation actions, as the current sampling methodology is inadequate.

Enhanced oils and organic solvents absorption by polyurethane foams composites modified with MnO2 nanowires

The severe environmental and ecological problems, derived from oil spills and organic solvents leakage, have occurred in many parts of the world. It is urgent to seek appropriate ways to resolve oily wastewater and organic solvent pollution. A versatile oil-absorbing material which can separate the oily wastewater effectively and quickly is in high demanded for this issue. In this work, we report a facile and inexpensive to fabricate an effective and recyclable oil-absorbent, namely MnO2 nanowires/polyurethane (PU) foam composites, using a PU sponge as a porous substrate and MnO2 nanowires as modifiers. The hydrothermal method is employed to synthesize MnO2 nanowires and then foaming technology is used to fabricate MnO2 nanowires/PU foam composites. In order to enhance the hydrophobic and oleophilic properties, the surfaces of MnO2 nanowires are chemically modified using silane coupling agent (KH 570). The present MnO2 nanowires/PU foam composites not only effectively separate oils from water as expected, but also possess a very high absorption capacity for the removal of organic solvents from water up to 40.15 times its own weight. More importantly, the obtained MnO2 nanowires/PU foam composites is demonstrated to have excellent oil recoverability and absorbent regenerability, making them versatile and comprehensive absorbents to satisfy various practical oily wastewater and organic solvent separation requirements.

Sorption behavior of slightly reduced, three-dimensionally macroporous graphene oxides for physical loading of oils and organic solvents

High pollutant-loading capacities (up to 319 times its own weight) are achieved by three-dimensional (3D) macroporous, slightly reduced graphene oxide (srGO) sorbents, which are prepared through ice-templating and consecutive thermal reduction. The reduction of the srGO is readily controlled by heating time under a mild condition (at 1 10^&#x2212;2 Torr and 200&#x2103;). The saturated sorption capacity of the hydrophilic srGO sorbent (thermally reduced for 1 h) could not be improved further even though the samples were reduced for 10 h to achieve the hydrophobic surface. The large meso- and macroporosity of the srGO sorbent, which is achieved by removing the residual water and the hydroxyl groups, is crucial for achieving the enhanced capacity. In particular, a systematic study on absorption parameters indicates that the open porosity of the 3D srGO sorbents significantly contributes to the physical loading of oils and organic solvents on the hydrophilic surface. Therefore, this study provides insight into the absorption behavior of highly macroporous graphene-based macrostructures and hence paves the way to development of promising next-generation sorbents for removal of oils and organic solvent pollutants.