Chitosan-modified geopolymer sub-microparticles reinforced multifunctional membrane for enhanced removal of multiple contaminants in water

Development of moringa seed powder-modified slag geopolymers for enhanced mechanical properties and effective dye removal

Crystal violet (CV), a widely used dye in paints and textiles, poses a significant environmental threat due to its non-biodegradable nature. A modified slag-based geopolymer has been developed to address this issue by incorporating raw moringa seed powder (MSP), an agricultural waste. The geopolymers (SM1, SM2, and SM3) were created by adding different percentages of MSP (0.2%, 0.6%, and 1% by weight) to ground granulated blast furnace slag (GGBFS), using sodium silicate and 10 M sodium hydroxide as alkali activators. This combination enhances the geopolymer's mechanical and adsorbent properties, making it more effective for CV removal. The geopolymer composites were analyzed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Their mechanical properties were evaluated by conducting compressive strength and total porosity tests. Pore structure analysis was performed using nitrogen adsorption and desorption techniques, and the point of zero charges was determined. Additionally, batch experiments were carried out to investigate the adsorption of CV dye, employing two isotherm models and kinetic models for analysis. The SM1 mix, which is a modified slag-based geopolymer containing 0.2% MSP, exhibited the highest compressive strength at 73 MPa after 180 days, representing a 25.8% improvement compared to the control mix (100% slag). Furthermore, modified geopolymer mixes showed greater adsorption activity toward crystal violet compared to the control mix, with the SM3 mix achieving an adsorption capacity of up to 322.58 mg/g. The study demonstrates that adding MSP to slag-based geopolymer enhances mechanical strength and adsorption capacity. This indicates a positive impact on the composite's surface properties and highlights the environmental benefits of utilizing industrial and agricultural waste in wastewater treatment.

Pressure-Driven Membrane Processes for Removing Microplastics

The intense consumption of polymeric materials combined with poor waste management results in the dissemination of their fragments in the environment as micro- and nanoplastics. They are easily dispersed in stormwater, wastewater, and landfill leachate and carried towards rivers, lakes, and oceans, causing their contamination. In aqueous matrices, the use of membrane separation processes has stood out for the efficiency of removing these particulate contaminants, achieving removals of up to 100%. For this review article, we researched the removal of microplastics and nanoplastics by membrane processes whose driving force is the pressure gradient. The analysis focuses on the challenges found in the operation of microfiltration, ultrafiltration, nanofiltration, and reverse-osmosis systems, as well as on the innovations applied to the membranes, with comparisons of treatment systems and the peculiarities of each system and each aqueous matrix. We also point out weaknesses and opportunities for future studies so that these techniques, known to be capable of removing many other contaminants of emerging concern, can subsequently be widely applied in the removal of micro- and nanoplastics.

Microplastic interactions with co-existing pollutants in water environments: Synergistic or antagonistic roles on their removal through current remediation technologies

Composite water pollution, caused by microplastics (MPs) and co-occurring pollutants, is an emerging issue that induces synergistic toxicity. Multidimensional interactions occur between MPs and co-existing pollutants in a composite system, which alter the behavior of each component, resulting in unpredictable effects on the treatment processes. However, significant gaps exist in current review papers regarding MP‒pollutant interaction mechanisms and the corresponding synergistic or antagonistic effects on their removal processes. This review comprehensively describes the latest research in composite water pollution caused by MPs and various other pollutants with different compositions and states, systematically discusses their interaction mechanisms, and critically evaluates the impact of co-existing contaminants on the treatment performance of current remediation technologies. Based on current research progress and gaps, opportunities, challenges, and perspectives for future research directions are proposed. This review highlights state-of-the-art research related to composite water pollution caused by MPs and various pollutants, which is expected to inspire new strategies for the effective removal of multiple contaminants from the aquatic environment.

Miniaturized 3D-printed hand-operable dispersive sample pretreatment device with replaceable chitosan/polydopamine thin film metal sorbent for enhanced metal analysis

To address the increasing demand for sensitive and selective sample preparation methods for metal analysis; preconcentration of intended analyte from complex sample matrices before analysis is required to improve the performance of analysis instruments. In this study, we have engineered a sustainable and portable syringe-based hand-operable three-dimensionally (3D) printed sample pretreatment apparatus equipped with a replaceable bio-based thin- film metal sorbent. This device effectively addresses the challenges of sample matrix interference in metal analysis. A metal sorbent film composed of chitosan (CS) and polydopamine (PDA) leveraged the diverse functional groups in the CS/PDA matrix to significantly enhance the extraction efficiency for various metals. Our approach demonstrated excellent analytical performance, with coefficients of determination (R2) of 0.9982 for copper (Cu) and 0.996 for chromium (Cr). The method achieved low limits of detection (LOD) of 0.3 μg L-1 for Cr and 0.7 μg L-1 for Cu. Precision and practicality assessments using actual urine samples yielded satisfactory relative standard deviations (RSD%) ranging from of 1.6 %-8.5 % for both metals, indicating minimal interference from the sample matrix. Moreover, our approach exhibited robust performance even after seven consecutive extraction and desorption cycles, highlighting its sustainability and practical applicability for laboratory and on-site sample pretreatment.

Dielectrophoretic separation and purification: From colloid and biological particles to droplets

It is indispensable to realize the high level of purification and separation, so that objective particles, such as malignant cells, harmful bacteria, and special proteins or biological molecules, could satisfy the high precise measurement in the pharmaceutical analysis, clinical diagnosis, targeted therapy, and food defense. In addition, this could reveal the intrinsic nature and evolution mechanisms of individual biological variations. Consequently, many techniques related to optical tweezers, microfluidics, acoustophoresis, and electrokinetics can be broadly used to achieve micro- and nano-scale particle separations. Dielectrophoresis (DEP) has been used for various manipulation, concentration, transport, and separation processes of biological particles owing to its early development, mature theory, low cost, and high throughput. Although numerous reviews have discussed the biological applications of DEP techniques, comprehensive descriptions of micro- and nano-scale particle separations feature less frequently in the literature. Therefore, this review summarizes the current state of particle separation attention to relevant technological developments and innovation, including theoretical simulation, microchannel structure, electrode material, pattern and its layout. Moreover, a brief overview of separation applications using DEP in combination with other technologies is also provided. Finally, conclusions, future guidelines, and suggestions for potential promotion are highlighted.

Techniques for recovery and recycling of ionic liquids: A review

Due to beneficial properties like non-flammability, thermal stability, low melting point and low vapor pressure, ionic liquids (ILs) have gained great interest from engineers and researchers in the past decades to replace conventional solvents. The superior characteristics of ILs make them promising for applications in fields as wide-ranging as pharmaceuticals, foods, nanoparticles synthesis, catalysis, electrochemistry and so on. To alleviate the high cost and environmental impact of ILs, various technologies have been reported to recover and purify the used ILs, as well as recycling the ILs. The aim of this article is to overview the state-of-the-art research on the recovery and recycling technologies for ILs including membrane technology, distillation, extraction, aqueous two-phase system (ATPS) and adsorption. In addition, challenges and future perspectives on ILs recovery are discussed. This review is expected to provide valuable insights for developing effective and environmentally friendly recovery methods for ILs.

Lignin microparticles-reinforced cellulose filter paper for simultaneous removal of emulsified oils and dyes

The presence of multiple pollutants in wastewater, often with complex interactions, poses a significant challenge for conventional membranes to effectively remove multiple pollutants simultaneously. Herein, a lignin microparticles-reinforced cellulose filter paper (FP@AL-LS-DA) was fabricated via an aldol condensation between lignin and cellulose filter paper and cross-linking with dopamine hydrochloride (DA), which showed desired rejection of oil-in-water emulsions and dyes. Characterizations revealed that the addition of lignin and DA effectively narrowed the pore size (from 4.45 μm to 2.01 μm) and enhanced the rigidity and stability of the cellulose filter paper, thus making it not easily damaged in the water environment and showing excellent tolerance to strong acid and high-salt environments. The oil-in-water emulsions removal efficiency was higher than 99 % even after ten times usage, and the oil flux was kept stable at 52.54 L·m^-2·h^-1, indicating that FP@AL-LS-DA had outstanding reusability and stability. Remarkably, FP@AL-LS-DA showed excellent removal efficiency (>99 %) for complex pollutants containing dyes and oil-in-water emulsions. In this work, we demonstrate a lignin microparticles-reinforced cellulose filter paper that is simple to prepare and can efficiently separate oil-in-water emulsions and remove dyes.