Removal of aniline from air and water by polymers of intrinsic microporosity (PIM-1) electrospun ultrafine fibers

Polymers of Intrinsic Microporosity Based on Dibenzodioxin Linkage: Design, Synthesis, Properties, and Applications

The development of polymers of intrinsic microporosity (PIMs) over the last two decades has established them as a distinct class of microporous materials, which combine the attributes of microporous solid materials and the soluble nature of glassy polymers. Due to their solubility in common organic solvents, PIMs are easily processable materials that potentially find application in membrane-based separation, catalysis, ion separation in electrochemical energy storage devices, sensing, etc. Dibenzodioxin linkage, Tröger's base, and imide bond-forming reactions have widely been utilized for synthesis of a large number of PIMs. Among these linkages, however, most of the studies have been based on dibenzodioxin-based PIMs. Therefore, this review focuses precisely on dibenzodioxin linkage chemistry. Herein, the design principles of different rigid and contorted monomer scaffolds are discussed, as well as synthetic strategies of the polymers through dibenzodioxin-forming reactions including copolymerization and postsynthetic modifications, their characteristic properties and potential applications studied so far. Towards the end, the prospects of these materials are examined with respect to their utility in industrial purposes. Further, the structure-property correlation of dibenzodioxin PIMs is analyzed, which is essential for tailored synthesis and tunable properties of these PIMs and their molecular level engineering for enhanced performances making these materials suitable for commercial usage.

Recent advances in porous organic frameworks for sample pretreatment of pesticide and veterinary drug residues: a review

Rapid and accurate detection of pesticide and veterinary drug residues is a continuing challenge because of the complex matrix effects. Thus, appropriate sample pretreatment is a crucial step for the effective extraction of the analytes and removal of the interferences. Recently, the development of nanomaterial adsorbents has greatly promoted the innovation of food sample pretreatment approaches. Porous organic frameworks (POFs), including polymers of intrinsic microporosity, covalent organic frameworks, hyper crosslinked polymers, conjugated microporous polymers, and porous aromatic frameworks, have been widely utilized due to their tailorable skeletons and pores as well as fascinating features. This review summarizes the recent advances for POFs to be utilized in adsorption and sample preparation of pesticide and veterinary drug residues. In addition, future prospects and challenges are discussed, hoping to offer a reference for further study on POFs in sample pretreatment.

Amidoxime modified polymers of intrinsic microporosity/alginate composite hydrogel beads for efficient adsorption of cationic dyes from aqueous solution

Polymers of intrinsic microporosity (PIM-1) has demonstrated great potential in adsorption and separation fields. In this study, PIM-1 was structured into an applicable and efficient adsorbent using a facile way. PIM-1 was first modified by amidoxime, and then the amidoxime modified PIM-1 (AOPIM-1) was mingled into alginate (Alg) hydrogel to obtain composite hydrogel beads. The AOPIM-1/Alg composite beads were further employed for removal of malachite green (MG) from aqueous solution and the effects of doped ratio, adsorbent dosage, contact time, and initial dye concentration on the MG adsorption performance were systematically investigated. The MG adsorption capacity of pure Alg beads was substantially enhanced after incorporating AOPIM-1. Furthermore, isothermal, kinetic and thermodynamic studies were performed to explore the fundamental adsorption behavior. Both Freundlich isotherm and Langmuir isotherm models can fit the adsorption isotherm data well, and the adsorption kinetics is well described by Pseudo-second-order. The adsorption process is feasible, spontaneous and endothermic. In addition, mixed dyes adsorption measurements indicate that AOPIM-1/Alg beads are highly selective to adsorb cationic dyes from anionic/cationic mixed dyes solution. The regeneration test shows that above 90% of the adsorption capacity of the composite beads can be maintained after 10 cycles of MG adsorption/desorption. These findings point that AOPIM-1/Alg composite hydrogel beads are an efficient, up-and-coming and recyclable adsorbent for cationic dyes adsorption from aqueous solution.

Removal of Antibiotics from Water by Polymer of Intrinsic Microporosity: Isotherms, Kinetics, Thermodynamics, and Adsorption Mechanism

Traces of antibiotics within domestic and industrial effluents have toxic impact on human health as well as surrounding flora and fauna. Potential increase in antibiotic resistance of microorganisms is likely to rise due to the incomplete removal of antibiotics by traditional wastewater processing, methods such as membrane filtration and biological treatment. In this study, we investigated a novel class of material termed Polymer of Intrinsic Microporosity (PIM) that is based on amorphous microporous organic materials for the application of antibiotic removal form aqueous environments. The adsorption of four commonly used antibiotics (doxycycline, ciprofloxacin, penicillin G, and amoxicillin) was evaluated and found that at least 80% of the initial concentrations was eliminated under the optimized conditions. Langmuir and Freundlich models were then employed to correlate the equilibria data; the Freundlich model fit well the data in all cases. For kinetic data, pseudo-first and second order models were examined. Pseudo-second order model fit well the kinetic data and allowed the calculation of the adsorption rate constants. Thermodynamic parameters were obtained by conducting the adsorption studies at varied reaction temperatures. Surface potential, adsorption at various solution pHs, thermogravimetric analysis (TGA), Infrared spectroscopy (IR), and surface area experiments were conducted to draw possible adsorption mechanisms. The removal of antibiotics from water by PIM-1 is likely to be governed by both surface and pore-filling adsorption and could be facilitated by electrostatic interactions between the aromatic rings and charged functional groups as well as hydrogen bond formation between the adsorbent and adsorbate. Our work shows that the application of such novel microporous material could contribute to the removal of such challenging and persistent contaminants from wastewater with further optimizations of large-scale adsorption processes.

Binder-free preparation of ZSM-5@silica beads and their use for organic pollutant removal

Organic structure directing agent (OSDA)- and binder-free preparation of ZSM-5@silica beads and their use for aniline removal.

Synthesis of anionic ionic liquids@TpBd-(SO3)2 for the selective adsorption of cationic dyes with superior capacity

Anionic ionic liquids@covalent organic materials for the selective adsorption of cationic dyes.

Highly selective surface adsorption-induced efficient photodegradation of cationic dyes on hierarchical ZnO nanorod-decorated hydrolyzed PIM-1 nanofibrous webs

Selectivity of catalysts toward harmful cationic pollutants in industrial wastewater remains challenging but is of crucial importance in environmental remediation processes. Here, we present a complex network of a hydrolyzed polymer of intrinsic microporosity (HPIM)-based electrospun nanofibrous web with surface functional decoration of ZnO nanorods (NRs) as a hierarchical platform for selective and rapid degradation of cationic dyes. Over a single species or binary mixtures, cationic dyes were selectively adsorbed by the HPIM surface, which then rapidly degraded under simultaneous photoirradiation through the ZnO NRs. Both HPIM and ZnO exhibited high electronegative surfaces, which induced the selectivity towards the cationic dyes and rapidly degraded the pollutants with the production of reactive oxygen species under photoirradiation. Further, as a free-standing web, the catalytic network could be easily separated and reused without any significant loss of catalytic activity after multiple cycles of use. The hierarchical platform of ZnO/HPIM-based heterostructures could be a promising catalytic template for selective degradation of synthetic dyes in mixed wastewater samples.

Atomic Layer Deposition of NiOOH/Ni(OH)2 on PIM-1-Based N-Doped Carbon Nanofibers for Electrochemical Water Splitting in Alkaline Medium

Portable and flexible energy devices demand lightweight and highly efficient catalytic materials for use in energy devices. An efficient water splitting electrocatalyst is considered an ideal future energy source. Well-aligned high-surface-area electrospun polymers of intrinsic microporosity (PIM-1)-based nitrogen-doped carbon nanofibers were prepared as a free-standing flexible electrode. A non-noble-metal catalyst NiOOH/Ni(OH)₂ was precisely deposited over flexible free-standing carbon nanofibers by using atomic layer deposition (ALD). The morphology, high surface area, nitrogen doping, and Ni states synergistically showed a low onset potential (η_HER =-40 and η_OER =290 mV vs. reversible hydrogen electrode), small overpotential at η₁₀ [oxygen evolution reaction (OER)=390.5 mV and hydrogen evolution reaction (HER)=-147 mV], excellent kinetics (Tafel slopes for OER=50 mV dec^-1 and HER=41 mV dec^-1 ), and high stability (>16 h) towards water splitting in an alkaline medium (0.1 m KOH). The performance was comparable with that of state-of-the-art noble-metal catalysts (e.g., Ir/C, Ru/C for OER, and Pt/C for HER). Post-catalytic characterization with X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy further proved the durability of the electrode. This study provides insight into the design of 1D-aligned N-doped PIM-1 electrospun carbon nanofibers as a flexible and free-standing NiOOH/Ni(OH)₂ decorated electrode as a highly stable nanocatalyst for water splitting in an alkaline medium.

Stability, Stimuli-Responsiveness, and Versatile Sorption Properties of a Dynamic Covalent Acylhydrazone Gel

Gel adsorbents are promising for pollutant removal from the wastewater. Herein, an acylhydrazone gel is developed from acylhydrazide-terminated pentaerythritol (PAT) and 2,4,6-triformylphloroglucinol (TFP) based on dynamic covalent acylhydrazone chemistry. PAT-TFP gel is stable under various conditions, while it shows reversible Cu2+ adsorption and desorption. PAT-TFP gel is studied as a versatile adsorbent for the capture of a range of (bulky) organic contaminants and heavy metal ions from aqueous solutions. Fast and good adsorption capacities are achieved for various dyes (rhodamine B and methyl orange), amines (aniline, p-chloroaniline, 4-methylaniline, and p-aminobenzoic acid), phenols (phenol, 1-naphthol, p-methylphenol, and bisphenol A), and metal ions (Cu2+, Cr3+, and Hg2+). The maximum adsorption capacity is 107.5 mg g-1 for Cu2+ and the equilibrium adsorption time is 30 min. PAT-TFP gel can be regenerated efficiently and used repeatedly.