Iminodiacetic acid-functionalized porous polymer for removal of toxic metal ions from water

Facile synthesis of anthranilic acid based dual functionalized novel hyper cross-linked polymer for promising CO2 capture and efficient Cr3+ adsorption

A novel hyper cross-linked polymer of 2-Aminobenzoic acid (HCP-AA) is synthesized for the adsorption of Cr3+ and CO2. The Brunauer-Emmett-Teller surface area of HCP-AA is 615 m2 g-1. HCP-AA of particle size 0.5 nm showed maximum adsorption of Cr3+ for lab prepared wastewater (93%) while it was 88% for real industrial wastewater. It is might be due to electrostatic interactions, cation-π interactions, lone pair interactions and cation exchange at pH 7; contact time of 8 min; adsorbent dose 0.8 g. The adsorption capacity was calculated 52.63 mg g-1 for chromium metal ions at optimum conditions. Freundlich isotherm studies R2 = 0.9273 value is the best fit and follows pseudo second order kinetic model (R2 = 0.979). The adsorption is found non-spontaneous and exothermic through thermodynamic calculations like Gibbs free energy (ΔG), enthalpy change (ΔH) and entropy change (ΔS) were 6.58 kJ mol-1, - 60.91 kJ mol-1 and - 45.79 kJ mol-1 K-1, respectively. The CO2 adsorption capacity of HCP-AA is 1.39 mmol/g with quantity of 31.1 cm3/g (6.1 wt%) at 273Kwhile at 298 K adsorption capacity is 1.12 mmol/g with quantity 25.2 cm3/g (5 wt%). Overall, study suggests that carboxyl (-COOH) and amino (-NH2) groups may be actively enhancing the adsorption capacity of HCP-AA for Cr3+ and CO2.

Aminopoly(carboxylic acid)-Functionalized PolyHIPE Beads toward Eliminating Trace Heavy Metal Ions from Water

Many advanced materials are designed for the removal of heavy metal ions from water. However, materials for eliminating trace heavy metal ions from wastewater to meet drinking water standards remain a major challenge. Herein, epoxy group-functionalized open-cellular beads are synthesized by UV polymerization of a water-in-oil-in-water system. The epoxy groups are further transformed into diethylenetriaminepentaacetic acid (DTPA) with hexamethylene diamine as a bridging agent. The resulting material (DTPA@polyHIPE beads) can eliminate trace Cu(II), Cr(III), Pb(II), Fe(III), or Cd(II) from water. When 0.15 g of DTPA@polyHIPE beads are used to adsorb metal ions of 20 mg in 100 mL of water, the residue concentrations of Cu(II), Cr(III), Pb(II), Fe(III), and Cd(II) are reduced to 0.08, 0.06, 0.02, 0.09, and 0.07 mg/L, respectively. The adsorption efficiencies of the beads for these ions are all higher than 99.55%. The adsorbent is durable and exhibits good recyclability by retaining an adsorption capacity of ≥91% after 5 cycles. The negative values of ΔG in the adsorption process indicate that the adsorption is feasible and spontaneous. The chemical adsorption follows the Freundlich adsorption model, indicating a multilayer heterogeneous adsorption. The DTPA@polyHIPE beads have a great potential application in dealing with trace heavy metal ion polluted water.

Thiol-Ene Click Reaction Modified Triazinyl-Based Covalent Organic Framework for Pb(II) Ion Effective Removal

As a common water pollutant, Pb2+ has harmful effects on the nervous, hematopoietic, digestive, renal, cardiovascular, and endocrine systems. Due to the drawbacks of traditional adsorbents such as structural disorder, poor stability, and difficulty in introducing adsorption active sites, the adsorption capacity is low, and it is difficult to accurately study the adsorption mechanism. Herein, vinyl-functionalized covalent organic frameworks (COFs) were synthesized at room temperature, and sulfur-containing active groups were introduced by the click reaction. By precisely tuning the chemical structure of the sulfur-containing reactive groups through the click reaction, we found that the adsorption activity of the sulfhydryl group was higher than that of the sulfur atom in the thioether. Moreover, the incorporation of flexible linking groups was observed to enhance the adsorption activity at the active site. The maximum adsorption capacity of the postmodified COF TAVA-S-Et-SH for Pb(II) reached 303.0 mg/g, which is 2.9 times higher than that of the unmodified COF. This work not only demonstrates the remarkable potential of the "thiol-ene" click reaction for the customization of active adsorption sites but also demonstrates the remarkable potential of the "thiol-alkene" click reaction to explore the structure-effect relationship between the active adsorption sites and the metal ion adsorption capacity.

Thiophene-based porphyrin polymers for Mercury (II) efficient removal in aqueous solution

Development of novel sulf-functionalized porous organic polymers (POPs) for Mercury (II) (Hg2+) removal is of great significant, but the adsorbents always suffered by the low adsorption capacity, stability, and efficiency for the reason that the common construction of functionalized POPs from the functionalized monomers or post-functionalization of the POPs always sacrifice the porosity. In this paper, porphyrin-based POPs with different heteroatoms were constructed through the aldehyde monomer (benzene, 2,5-thiophenedicarboxaldehyde and thieno[3,2-b]thiophene-2,5-dicarboxaldehyde) and pyrrole according to the Adler-Longo method. In this way, nitrogen (N) in pyrrole and sulfur (S) in thiophene structures were embed into the backbone structure of the polymers. The functional structures not only act as the linking building block into the stable cross-linking structure, but also offer abundant uncovered functional sites for Hg2+ adsorption, resulting the porphyrin-based POPs high Hg2+ capacity (1049 mg/g), removal efficiency (more than 99.9%), good reusability and selectivity for its highest heteroatoms contents. The adsorption mechanism confirmed the cooperative coordination of N in porphyrin and S in thiophene with Hg2+. This work confirmed the functional groups play more important role in heavy metal adsorption, and the embedded functional sites into backbone also promotes the stability and the adsorption performance.

PEI-modified chitosan/activated carbon composites for Cu(II) removal from simulated pyrophosphate plating rinsing wastewater

It is a challenging task to remove heavy metal ions efficiently from the wastewater containing high concentrations of complexants. In this work, a novel PEI-modified chitosan/activated carbon composite adsorbent (PCA) was prepared and applied to the removal of Cu(II) from pyrophosphate plating rinsing wastewater. The main species of Cu(II) in the pyrophosphate wastewater was [Cu(HP2O7)2]4- or [Cu(P2O7)2]6-, which were denoted as [Cu(II)-PP] anions. The maximum adsorption capacity of PCA for Cu(II) reached 1.41 mmol g-1 under the condition of pH = 8 and molar ratio of pyrophosphate to Cu(II) = 4:1. The adsorption kinetic behavior of Cu(II) on PCA followed the Elovich model best and PCA attained adsorption equilibrium within 36 h. The thermodynamic studies showed that the adsorption process of Cu(II) by PCA was endothermic and spontaneous. The PCA fixed bed column was used to remove Cu(II) from simulated pyrophosphate plating rinsing wastewater. After three consecutive adsorption-desorption cycles, the adsorption performance, hydraulic conductivity, and mechanical stability of PCA column did not decrease. The FTIR and XPS analysis results indicated that [Cu(II)-PP] anions can be adsorbed on PCA by electrostatic attraction with protonated amine groups or coordination with the amine groups of PCA via ligand substitution.

Peroxidase-like oxidative activity of cobalt-based 1D coordination polymer; experimental and theoretical investigations

CONTEXT

The present work describes the synthesis, structural characterization, and catalytic activity of a Co(II)-based one-dimensional coordination polymer (CP1). To validate the chemotherapeutic potential of CP1, in vitro DNA binding assessment was carried out by employing multispectroscopic techniques. Moreover, the catalytic activity of CP1 was also ascertained during the oxidative conversion of o-phenylenediamine (OPD) to diaminophenazine (DAP) under aerobic conditions.

METHODS

The molecular structure of CP1 was solved with the olex2.solve structure solution program using charge flipping and refined with the olex2.refine refinement package by using Gauss-Newton minimization. The DFT studies were performed by utilizing ORCA Program Version 4.1.1 to calculate the electronic and chemical properties of CP1 by calculating the HOMO-LUMO energy gap. All calculations were carried out at B3LYP hybrid functional using def2-TZVP as the basis set. Contour plots of various FMOs were visualized by using Avogadro software. Hirshfeld surface analysis was carried out by Crystal explorer Program 17.5.27 to examine the various non-covalent interactions which are crucial for the stability of crystal lattice. In addition, molecular docking studies of CP1 with DNA were performed by using AutoDock Vina software and AutoDock tools (version 1.5.6). Discovery studio 3.5 Client 2020 was used for visualization of the docked pose and binding interactions of CP1 with ct-DNA.

Porogen Concentration Effect on the Pore Structure and Properties Evolution of Polymer Monolith Based on Oligocarbonate Dimethacrylate OCM-2

Porous polymer monolith materials of 2-mm thickness were obtained by visible light-induced radical polymerization of oligocarbonate dimethacrylate (OCM-2) in the presence of 1-butanol (10 to 70 wt %) as a porogenic additive. The pore characteristics and morphology of polymers were studied by mercury intrusion porosimetry and scanning electron microscopy. Monolithic polymers with both open and closed pores up to 100 nm in size are formed when the alcohol content in the initial composition is up to 20 wt %. The pore structure in such materials is a system of holes in the bulk of the polymer (hole-type pores). Open interconnected pores with a specific volume up to 2.22 cm³/g and modal pore size up to 10 microns are formed in the volume of the polymer with 1-butanol content of more than 30 wt %. Such porous monoliths are a structure of covalently bonded polymer globules (interparticle-type pores). The free space between the globules represents a system of open interconnected pores. In the transition region of 1-butanol concentrations (from 20 to 30 wt %), areas with both structures and intermediate frameworks, as well as honeycomb structures of polymer globules connected by bridges, are fixed on the polymer surface. It was found that the transition from one type of pore system to another is accompanied by a sharp change in the strength characteristics of the polymer. Approximation of experimental data using the sigmoid function made it possible to determine the concentration of the porogenic agent in the vicinity of which the percolation threshold is observed.

Synthesis of a Triazaisotruxene-Based Porous Organic Polymer and Its Application in Iodine Capture

A new triazaisotruxene-based porous organic polymer (POP) was designed and successfully synthesized by a FeCl₃-promoted crosslinking reaction. As a result of its porosity and good thermal stability, the designed POP can be utilized as a promising adsorbent for iodine, not only in the gaseous phase, but also in organic and aqueous solutions. Compared to its triazatruxene (TN) analogue, the ITN-based POP shows equal iodine uptake in the gaseous phase and in hexane solution, and better uptake in aqueous solution.

Zwitterionic iodonium species afford halogen bond-based porous organic frameworks

Porous architectures characterized by parallel channels arranged in honeycomb or rectangular patterns are identified in two polymorphic crystals of a zwitterionic 4-(aryliodonio)-benzenesulfonate. The channels are filled with disordered water molecules which can be reversibly removed on heating. Consistent with the remarkable strength and directionality of the halogen bonds (XBs) driving the crystal packing formation, the porous structure is stable and fully preserved on almost quantitative removal and readsorption of water. The porous systems described here are the first reported cases of one-component 3D organic frameworks whose assembly is driven by XB only (XOFs). These systems are a proof of concept for the ability of zwitterionic aryliodonium tectons in affording robust one-component 3D XOFs. The high directionality and strength of the XBs formed by these zwitterions and the geometrical constraints resulting from the tendency of their hypervalent iodine atoms to act as bidentate XB donors might be key factors in determining this ability.

A knitting copolymerization strategy to build porous polytriazolium salts for removal of anionic dyes and MnO4. Macromol Rapid Commun 2022;43:e2200170. [PMID: 35471590 DOI: 10.1002/marc.202200170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Although considerable efforts have been devoted, the development of novel ionic porous networks (IPNs) in a scalable manner to tackle the issues in pollutant treatment by adsorption remains an imminent challenge. Herein, inspired by natural spider webs, a knitting copolymerization strategy is proposed to construct analogue triazolium salt-based porous networks (IPN-CSUs). It is not only convenient to incorporate the cationic motifs into the network, but easy to control over the contents of ionic pairs. The as-prepared IPN-CSUs displays a high surface area of 924 m² g^-1 , a large pore volume of 1.27 cm³ g^-1 and abundant ionic sites, thereby exhibiting fast adsorption rate and high adsorption capacity towards organic and inorganic pollutants. The kinetics and thermodynamics study reveal that the adsorption followed a pseudo-second-order kinetic model and Langmuir isotherm model correspondingly. Specifically, the maximum adsorption capacity of the IPN-CSUs is as high as 1.82 mg mg^-1 for permanganate ions and up to 0.54 mg mg^-1 for methyl orange, which stands out among the previously reported porous adsorbents so far. We expect that the strategy reported herein can be extended to the development of other potential efficient adsorbents in water purifications. This article is protected by copyright. All rights reserved.

The Effect of the Synthesis Method on Physicochemical Properties of Selective Granular Polymer Sorbents

Investigation of the effect of the polymer synthesis method on physicochemical properties of sorbents is one of the topical problems in the chemistry of macromolecular compounds that has high scientific and practical interest. Determination of the optimal synthesis method will make it possible to create sorbents with physicochemical properties that led to the realization of effective sorption. In this work, we investigated the effect of synthesis methods (Pickering emulsion polymerization and precipitation polymerization in solution) of granular polymers based on 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate on physicochemical and sorption properties. The synthesis by Pickering emulsion polymerization led to improvement of the n-propyl alcohol diffusion into the polymer network and to the formation of more homogeneous and structurally stable polymer networks. Creating selective polymer networks by Pickering emulsion polymerization compared to precipitation polymerization in solution led to an increase in porosity, creation of more segregated surface of granules, improvement of binding sites availability at the temperature of 37 °C, and formation of the homogeneous sorption surface with high affinity to target molecules at 25 °C and 37 °C. Selective polymers synthesized by both polymerization methods had the largest values of available sorption surfaces areas for target molecules at 37 °C.

Preparation of biochar-interpenetrated iron-alginate hydrogel as a pH-independent sorbent for removal of Cr(VI) and Pb(II)

Herein, a pH-independent interpenetrating polymeric networks (Fe-SA-C) were fabricated from graphitic biochar (BC) and iron-alginate hydrogel (Fe-SA) for removal of Cr(VI) and Pb(II) in aqueous solution. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and scanning electron microscope (SEM) results demonstrated that graphitic BC interpenetration increased surface porosity and distorted surfaces of Fe-SA, which boosted availability of hydroxyl (-OH) group. Fe³⁺ as a cross-linking agent of the alginate endowed Fe-SA-C with positive surfaces (positive zeta potential) and excellent pH buffering capacity, while excessive Fe³⁺ was soldered on Fe-SA-C matrix as FeO(OH) and Fe₂O₃. Cr(VI) removal at pH of 3 by Fe-SA-C (20.3 mg g^-1) were 30.3% and 410.6% greater than that by Fe-SA and BC, respectively. Fe-SA-C exhibited minor pH dependence over pH range of 2-7 towards Cr(VI) retention. Greater zeta potential of Fe-SA-C over Fe-SA conferred a better electrostatic attraction with Cr(VI). FTIR and XPS of spent sorbents confirmed the reduction accounted for 98.5% for Cr(VI) removal mainly due to participation of -OH. Cr(VI) reduction was further favored by conductive carbon matrix in Fe-SA-C, as evidenced by more negative Tafel corrosion potential. Reductively formed Cr(III) was subsequently complexed with carboxylic groups originating from oxidation of -OH. Thus, Cr(VI) removal invoked electrostatic attraction, reduction, and surface complexation mechanisms. Pb(II) removal with excellent pH independence was mainly ascribed to surface complexation and possible precipitation. Thus, the functionalized, conductive, and positively-charged Fe-SA-C extended its applicability for Cr(VI) and Pb(II) removal from aqueous solutions in a wide pH range. This research could expand the application of hydrogel materials for removal of both cationic and anionic heavy metals in solutions over an extended pH range.

[Preparation of melamine-functionalized porous organic polymer and its adsorption properties for methyl orange]

In this work, a polymer precursor was first synthesized using p-terphenyl (TP) and terephthaloyl chloride (TC) as monomers. Then, cross-linking was realized by means of a Schiff base reaction with melamine (MA) as a modifier to obtain an amine-functionalized porous organic polymer TP-TC-MA. The synthesized polymers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and point of zero charge (pH_pzc) measurements, as well as on the basis of nitrogen adsorption-desorption isotherms. Adsorption experiments were carried out to evaluate the adsorption properties of TP-TC-MA for methyl orange (MO), a typical anionic azo dye that has widespread industrial application. The amount of MO adsorbed on TP-TC-MA was evaluated by ultraviolet-visible (UV-Vis) spectroscopy at a wavelength of 463 nm. Microscopic analysis revealed that the as-synthesized polymer had an aggregated particle-shaped structure. XRD spectra confirmed that TP-TC-MA was an amorphous polymer, consistent with the results of high-resolution TEM experiments. The Brunauer-Emmett-Teller (BET) specific surface area and total pore volume of TP-TC-MA were determined as 708.5 m ²/g and 0.556 cm³/g, respectively. The measured pH_pzc of TP-TC-MA was 4.0, probably because of the abundant nitrogen-containing groups provided by MA. The factors affecting adsorption, such as pH, adsorbent dosage, contact time, initial pollutant concentration, and ionic strength, were investigated. Because of the protonation of the N-atom in TP-TC-MA, the pH had a strong impact on the adsorption of MO. The removal efficiency could be maximized at the optimized pH of 3.0. The adsorption equilibrium isotherm, measured at 25 ℃ and a concentration of 50-500 mg/L, showed that the MO adsorption over TP-TC-MA followed the Langmuir isotherm, with a maximum adsorption capacity of 156.3 mg/g. The modeling of the experimental adsorption data was consistent with the pseudo-second-order kinetic model, which indicated fast adsorption and chemisorption as the dominant mechanism. With increasing ionic strength, the adsorption of MO slightly decreased, suggesting a partial antagonistic ion effect. Results of the selectivity study revealed that TP-TC-MA was more selective toward MO than methylene blue (MB), which indicated that electrostatic interactions played a significant role during the adsorption progress. Five adsorption-desorption cycles showed that TP-TC-MA could be regenerated without significant deterioration of its adsorption efficiency, indicating that it has good stability and reusability. The observed adsorption performance indicated that this MA-modified porous organic polymer offers prospects for further research and application in the treatment of dye-containing wastewaters.

Controllable preparation and performance of bio-based poly(lactic acid-iminodiacetic acid) as sustained-release Pb2+ chelating agent

The bio-based lactic acid (LA) and the common metal ion chelating agent iminodiacetic acid (IDA) are used to design and prepare a polymeric sustained-release Pb2+ chelating agent by a brief one-step reaction. After the analysis on theoretical calculation for this reaction, poly(lactic acid-iminodiacetic acid) [P(LA-co-IDA)] with different monomer molar feed ratios is synthesized via direct melt polycondensation. P(LA-co-IDA) mainly has star-shaped structure, and some of them have two-core or three-core structure. Thus, a possible mechanism of the polymerization is proposed. The degradation rate of P(LA-co-IDA)s can reach 70% in 4 weeks. The change of IDA release rate is consistent with the trend of the degradation rate, and the good Pb2+ chelating performance is confirmed. P(LA-co-IDA) is expected to be developed as a lead poisoning treatment drug or Pb2+ adsorbent in the environment with long-lasting effect, and this research provides a new strategy for the development of such drugs.

Facile synthesis of porous porphyrin-based polymers by solvent-crosslinking method

Three solvents were employed as crosslinkers to synthesise porous porphyrin-based polymers via Friedel–Crafts alkylation reaction.

Aminophosphonic Acid Functionalized Cellulose Nanofibers for Efficient Extraction of Trace Metal Ions

Cellulose nanofibers were covalently functionalized using diethylenetriamine penta (methylene phosphonic acid) and studied for the extraction of heavy metal ions. The surface-functionalized nanofibers showed a high adsorption capacity towards heavy metal ions as compared to bare nanofibers. The elemental composition and surface morphology of the prepared bio-adsorbent was characterized by X-ray photoelectron spectroscopy, attenuated total reflectance infrared spectroscopy, field emission scanning electron microscopy, and energy dispersive spectroscopy. The prepared material was studied to develop a column-based solid phase extraction method for the preconcentration of trace metal ions and their determination by inductively coupled plasma optical emission spectroscopy. The batch experimental data was well fitted to Langmuir adsorption isotherms (R2 > 0.99) and follows pseudo-second-order kinetics. The experimental variables such as sample pH, equilibrium time, column breakthrough, sorption flow rate, the effect of coexisting ions, and eluent type were systematically studied and optimized accordingly. The detection limit of the proposed method was found to be 0.03, 0.05, and 0.04 µg L-1 for Cu(II), Pb(II), and Cd(II), respectively. Certified Reference Materials were analyzed to validate the proposed method against systematic and constant errors. At a 95% confidence level, the Student's t-test values were less than the critical Student's t value (4.302). The developed method was successfully employed for the preconcentration and determination of trace metal ions from real water samples such as river water and industrial effluent.

Application of Hybrid Membrane Processes Coupling Separation and Biological or Chemical Reaction in Advanced Wastewater Treatment

The rapid urbanization and water shortage impose an urgent need in improving sustainable water management without compromising the socioeconomic development all around the world. In this context, reclaimed wastewater has been recognized as a sustainable water management strategy since it represents an alternative water resource for non-potable or (indirect) potable use. The conventional wastewater remediation approaches for the removal of different emerging contaminants (pharmaceuticals, dyes, metal ions, etc.) are unable to remove/destroy them completely. Hybrid membrane processes (HMPs) are a powerful solution for removing emerging pollutants from wastewater. On this aspect, the present paper focused on HMPs obtained by the synergic coupling of biological and/or chemical reaction driven processes with membrane processes, giving a critical overview and particular emphasis on some case studies reported in the pertinent literature. By using these processes, a satisfactory quality of treated water can be achieved, permitting its sustainable reuse in the hydrologic cycle while minimizing environmental and economic impact.