Ionic liquid decorated MXene/Poly (N-isopropylacrylamide) composite hydrogel with high strength, chemical stability and strong adsorption

Organic phenolic pollutants in industrial wastewater cause severe environmental pollution and physiological damage. Poly (N-isopropylacrylamide) (PNIPAM) hydrogels generally have poor mechanical strength and are also intrinsically frangible, limiting their widespread applications in wastewater treatment. Combining them with 2-dimensional materials can also only improve the mechanical properties of hydrogels. Here, we report a high-strength, chemical stability and strong adsorption MXene/poly (N-isopropylacrylamide) (PNIPAM) thermosensitive composite hydrogel for efficient removal of phenolic pollutants from industrial wastewater. Ionic liquids (ILs) were grafted onto the surface of MXenes and introduced into NIPAM monomer solution to obtain composite hydrogels by in-situ polymerization for improved mechanical strength and adsorption capacity of the composite hydrogel. Compared with the MXene/PNIPAM composite hydrogel, the introduction of ILs simultaneously improves the mechanical and adsorption properties of the composite hydrogel. The ILs bind to the surface of MXene flakes through electrostatic interactions, which improved the thermal stability and oxidation resistance of MXenes while maintaining its good dispersion. Using 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) modified MXene (MXene-EMIMBF4) did not change significantly were observed after aging for 45 days. As-prepared composite hydrogels demonstrated excellent mechanical properties, reusability, and high adsorption capacity for p-Nitrophenol (4-NP). The MXene-EMIMBF4/PNIPAM hydrogel could recover after ten 95% strain compression cycles under the synergistic effect of chemical bonding and electrostatic attraction. Its maximum adsorption capacity for 4-NP was 200.29 mg g^-1 at room temperature, and the adsorption capacity maintained at ∼90% of its initial value after five adsorption cycles, which was related to the introduction of EMIMBF4 to form a denser network structure. The adsorption data followed the pseudo-second-order kinetics and Freundlich models.

Tumor microenvironment-responsive, high internal phase Pickering emulsions stabilized by lignin/chitosan oligosaccharide particles for synergistic cancer therapy

HYPOTHESIS

The stability of anti-cancer drugs and the adverse drug reactions (ADRs) caused by drug-drug interactions (DDIs) are two major challenges of combination chemotherapy. In this work, hydrophilic drug loaded lignin-based nanoparticles were applied to stabilize high internal phase Pickering emulsions (HIPPEs) containing hydrophobic drug in the oil phase, which not only improved the stability of anti-cancer drugs, but also reduced the risk of DDIs.

EXPERIMENTS

Highly biocompatible enzymatic hydrolysis lignin/chitosan oligosaccharide (EHL/COS-x) nanoparticles were prepared and used to load hydrophilic cytarabine (Ara-C). The morphology, loading capacity, encapsulation efficiency and emulsifying properties of nanoparticles were characterized and predicted. Subsequently, these nanoparticles were applied to stabilize HIPPEs with soybean oil containing hydrophobic curcumin as dispersed phase. The effects of the morphology, amphipathy and concentration of nanoparticles and oil/water ratio on the microstructure and stability of HIPPEs were investigated. Meanwhile, the controlled release, protective performance, cytotoxicity and bio-activity of HIPPEs were also evaluated.

FINDINGS

EHL/COS-x nanoparticles loaded with Ara-C could stabilize HIPEs with 85 vol% soybean oil containing curcumin. The two drugs were separately loaded in same delivery system, which effectively lowered the risk of DDIs. Meanwhile, HIPPEs provided outstanding UV, thermal and oxidation protection for these two environmentally sensitive anti-cancer drugs. In addition, HIPPEs displayed a good pH-responsive release in a tumor environment. In vitro experiments show that the killing efficiency of two drugs co-loaded HIPPEs against the leukemia cell is two times higher than that of single drug loaded systems. This strategy can be extended to the synergistic therapy of two or more drugs with different physicochemical properties.

Recent advances in separation applications of polymerized high internal phase emulsions

Polymerized high internal phase emulsions as highly porous adsorption materials have received increasing attention and wide applications in separation science in recent years due to their remarkable merits such as highly interconnected porosity, high permeability, good thermal and chemical stability, and tailorable chemistry. In this review, we attempt to introduce some strategies to utilize polymerized high internal phase emulsions for separation science, and highlight the recent advances made in the applications of polymerized high internal phase emulsions for diverse separation of small organic molecules, carbon dioxide, metal ions, proteins, and other interesting targets. Potential challenges and future perspectives for polymerized high internal phase emulsion research in the field of separation science are also speculated at the end of this review.

Neutral fabrication of UV-blocking and antioxidation lignin-stabilized high internal phase emulsion encapsulates for high efficient antibacterium of natural curcumin

By adjusting the polarity and conformation via the sulfomethylation modification, the bio-renewable enzymatic hydrolysis lignin (EHL) combined with alkyl polyglucoside (APG) was used as an emulsifier to stabilize the oil-in-water (O/W) high internal phase emulsions (HIPEs) for the first time under neutral conditions. The structure and sulfonation degree of the sulfomethylated lignin (EHL-XS) were characterized using gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS) and an automatic potentiometric titrator. The effects of the EHL-XS concentration, sulfonation degree and oil/water ratio on the microstructure and stability of HIPEs were investigated using an optical microscope and a rheometer. The results suggest that commercial lignosulfonates (LS) could not to stabilize HIPEs due to their high hydrophilicity. However, by using EHL-XS with sulfonation degree between 0.89 and 1.05 mmol g-1, up to 2.0 wt% of EHL-XS with the assistance of 3.5 wt% APG could stabilize HIPEs containing 80 vol% of internal oil phase, which were super stable and displayed no significant microstructure changes over one month. Rheological investigation indicated that HIPEs with smaller droplet size and higher oil/water ratio exhibited higher surface elasticity and stability due to the tighter overall droplet packing. In addition, the EHL-XS stabilized O/W HIPEs could be used as encapsulates for the protection and delivery of the environmentally sensitive curcumin. It was found that such HIPEs encapsulation system exhibited superior UV protection of at least 30% higher than curcumin dispersed in bulk oil after 72 h of UV irradiation or 30 days at room temperature, respectively. Meanwhile, such HIPEs within curcumin also demonstrated good inhibitory activity against S. aureus.

Equilibrium and Kinetic Studies of Biosorptive Removal of 2,4,6-Trichlorophenol from Aqueous Solutions Using Untreated Agro-Waste Pine Cone Biomass

The present work discusses the adsorptive removal of a phenolic pollutant, i.e., 2,4,6-trichlorophenol (TCP), using low cost untreated agricultural waste pine cone powder (PCP). The present biosorbent was thoroughly characterized with the help of FTIR, SEM, XRD, and CHN analysis. The presence of amine (-NH2), hydroxyl (-OH) and carbonyl (C=O) functional groups was detected by the FTIR analysis. The important biosorption factors like agitation time, biomass dosage, initial adsorbate concentration, and the initial pH were examined by batch studies. The biosorption kinetic process was fast, reaching equilibrium in 75 min. The experimental kinetic data revealed an excellent agreement with the pseudo second order (PSO) model. On the other hand, the Langmuir isotherm model best described the equilibrium data with the maximum biosorption capacity (qmax) of 243.90 mg/g. These values are better than the adsorption capacities of most agro-based untreated adsorbents previously reported in the literature. Owing to fast removal rates and high biosorption capacity, PCP can be used for cost-effective treatment of TCP from aqueous streams.

Silver-modified porous polystyrene sulfonate derived from Pickering high internal phase emulsions for capturing lithium-ion

Adsorption separation based on porous polystyrene sulfonate is an important method of extracting lithium ion (Li⁺). In this work, silver-modified porous polystyrene sulfonate (PHIPEs-SS-Ag) derived from Pickering high internal phase emulsions was fabricated for the selective binding of Li⁺. PHIPEs-SS-Ag possessed porous polymer matrix, sufficient sulfonic acid functional groups, and uniformly immobilized silver particles, which were beneficial for improving mass transfer, binding amount and antifouling performance. In batch mode experiments, the adsorption capacity reached a maximum value (i.e. 14.09 mg g⁻¹) under alkaline conditions, and the adsorption mechanism between PHIPEs-SS-Ag and Li⁺ was electrostatic attraction. PHIPEs-SS-Ag exhibited fast binding kinetics at 25 °C (i.e. 300 min), and the maximum monolayer adsorption amount from the Langmuir model for Li⁺ are 59.85 mg g⁻¹, 35.06 mg g⁻¹, and 27.09 mg g⁻¹ at 15 °C, 25 °C, and 35 °C, respectively. Moreover, PHIPEs-SS-Ag displayed excellent selectivity for Li⁺ in the presence of K⁺, Mg²⁺, and Na⁺, and maintained 80.71% of the initial adsorption capacity after seven sequential cycles of adsorption–regeneration. Therefore, this work opened up a universal route for the development of composite adsorbents for the specific separation of Li⁺.

Adsorption separation based on porous polystyrene sulfonate is an important method of extracting lithium ion (Li⁺).