Amine Resin Research Articles

Synthesis of some anion exchange resins for selective separation of 99Mo and 131I: A comparative study

ABSTRACT Amination of styrene-divinylbenzene (SDVB) copolymers is a traditional process for preparing strong anion exchange resins that can greatly improve their performance and applications. In the present investigation, poly(styrene-co-divinyl benzene) copolymers functionalized by various amino groups were synthesized by the amination route. The performance of synthesized exchange resins for the separation and recovery of active Mo(VI) and I(I) isotopes from their aqueous solutions was compared to that of three commercial ion exchange resins, used in the actual production of these radioisotopes in the Radioisotopes Production Facility. The morphology and structural properties of the synthesized copolymers as well as the commercial reference resins were characterized using FT−IR, SEM, TG, and XPS. The results demonstrate that the copolymer was successfully functionalized with amino groups, where trimethylamine produced amination greater than triethylamine. Furthermore, the thermal stability of synthesized anion exchanges was significantly higher than that of commercial beads. The synthesized polymer networks presented excellent radiation stability under applied experimental conditions. Compared to the reference resins, the synthesized co-polymeric beads showed enhanced adsorption capability for MoO4 2− and I− ions from an aqueous solution. Further, the uptake affinity of the networks aminated with trimethylamine for both radioisotopes, in optimal conditions, was greater than that of triethylamine aminated beads. The sorption mechanism was inferred through FT−IR and XPS analysis, and the results clarified that the separation of both radioisotopes was substantially related to the amine functional groups on the resin framework. The spectroscopic analysis illustrated that one molybdenum ion (in the form of MoO4 2−) was subjected to an ion-exchange interaction and two Cl− ions in the amine resin. A similar exchange mechanism was predicted for I− with Cl− ions. Further, the enhanced sorption of Mo(VI) could be additionally attained through coordination interactions with N atoms in the amine groups that have good chelating capability toward metal ions. The reusability performance of the synthesized exchange resins is better than that of the commercial reference resins, where they could be effectively regenerated for up to five cycles. Finally, this study presents a new technique for the separation and recovery of Mo(VI) and I(I) from irradiated low-enriched U-targets by employing highly promising amino-modified polystyrene-divinyl benzene microspheres.

Trypsin Digestion Conditions of Human Plasma for Observation of Peptides and Proteins from Tandem Mass Spectrometry.

Previous meta-analysis indicated that plasma or serum proteome groups using various experimental conditions detected different peptides from the same plasma proteins, which is strong evidence for the veracity of blood fluid LC-ESI-MS/MS but also evidences that the trypsin digestion step is a key source of variation in plasma proteomics. Agreement between different digestion conditions and MS/MS algorithms may serve as an independent confirmation of the validity of the LC-ESI-MS/MS analysis of plasma peptides. Plasma contains a high percentage of albumin held together by multiple disulfide bonds; hence, reduction and/or alkylation may greatly enhance the digestion efficiency of albumin. Plasma proteins were precipitated in 90% acetonitrile, collected over quaternary amine resin, and eluted in NaCl prior to digestion treatments. To determine the effect of trypsin digestion methods, the plasma proteins were digested in 600 mM urea and 5% acetonitrile with trypsin alone, or reduced with 2 mM DTT followed by trypsin, or DTT followed by 15 mM iodoacetamide and then trypsin. The resulting peptides were analyzed by LC-ESI-MS/MS with a linear quadrupole ion trap (LIT). The MS/MS spectra were directly fit to peptides by the X!TANDEM and SEQUEST algorithms. Blank noise injections served as the analytical control, and 30 million random MS/MS served as the statistical control. Digesting human plasma with DTT reduction, or reduction and alkylation, resulted in a dramatic increase in the number and observation frequency of albumin peptides. In contrast, digestion with trypsin alone suppressed the observation of albumin, and instead, many low abundance plasma and cellular proteins showed higher observation frequency. Digestion with trypsin alone increased the observation frequency of APOC1, ACAN, ATRN, CPB2, GP2, GPX3, HBA1, PAPD5, PKD1, and many cellular proteins. After correction against noise and random controls, SEQUEST showed good agreement with the true positive plasma proteins identified by X!TANDEM and resulted in an R-squared of 0.5238 with an F-statistic of 10,930 on 9,935 protein gene symbols with a p-value < 2.2e-16. Digestion of plasma with trypsin alone avoids the complete digestion of albumin and permits the enhanced detection of some other cellular proteins from plasma. Different digestion approaches were complimentary and together resulted in a more comprehensive plasma proteome. The protein FDR q-values, the modest effect of background and Monte Carlo correction, and the significant STRING analysis were all consistent with the high fidelity of the rigorous X!TANDEM algorithm. In contrast, SEQUEST required significant correction against noise and statistical controls and selection of high cross correlation (XCorr) scores to show good agreement with X!TANDEM. There was qualitative and quantitative agreement between plasma proteins digested without alkylation from the orbital ion trap (OIT) versus the LIT instrument that showed highly significant regression against the X!TANDEM OIT monoisotopic results, those from heavy isotopes and other masses from X!TANDEM, and with those from MaxQuant. There was significant qualitative and quantitative agreement between the complementary digestion conditions consistent with the good fidelity of plasma analysis by LC-ESI-MS/MS with a sensitive linear ion trap.

A DOPO-eugenol linear siloxane as a highly effective liquid flame retardant also imparting improved mechanical properties to an epoxy amine network

A liquid bio-derived eugenol-containing phosphorus silicone hybrid molecule (EGDS-DOPO) that endows excellent flame-retardancy and enhanced mechanical performance to an epoxy amine network at low levels of addition was successfully synthesized and characterised. The EGDS-DOPO significantly improved the flame retardancy requiring only 5 wt% of EGDS-DOPO to achieve a limiting oxygen index (LOI) of 34.9 % and a UL 94 V-0 rating. Cone calorimetry measurements reveal a reduction of the peak heat release rate, the total heat release, and total smoke production by 62.2 %, 34.0 % and 47.5 %, respectively when EGDS-DOPO concentration was 20 wt%, compared to the unmodified epoxy network. Viscosity remained low throughout cure, and despite some retardation of reactivity, the epoxy amine resin remains fast curing and suitable for liquid moulding composite fabrication technologies. Moreover, the modified EGDS-DOPO epoxy networks display a glass transition temperature (Tg) between 218.5 °C and 174.1 °C, a hydrophobic surface with water contact angle of 97.5°–106.6°, a low moisture ingress of 2.35 %–2.91 %, and improved overall mechanical properties in flexure (maximum 39.8 % increase in flexural strength and 27.0 % in flexural modulus), compression (maximum 24.5 % and 35.0 % increase in compressive strength and modulus, respectively), and fracture toughness (maximum 28.0 %).

Cytotoxicity and cell migration evaluation of a strontium silicate-based root canal sealer on stem cells from rat apical papilla: an in vitro study

BackgroundCalcium silicate-based bioceramics have been applied in endodontics as advantageous materials for years, many chemical components and new synthesizing methods were used to improve the base formulation of the materials for positively affecting the sealers properties. Recently, a novel biomaterial formulation, grounded in strontium silicate, has been introduced to the market, offering potential advancements in the field.ObjectiveTo comparatively analyze the cytotoxicity and cell migration effects of a novel strontium silicate-based bioceramic material (CRoot SP) and those of calcium silicate-based (iRoot SP) and epoxide amine resin (AH Plus) sealers on stem cells derived from rat apical papilla(rSCAPs).MethodsrSCAPs were isolated and characterized in vitro and subsequently cultured in the presence of various concentrations of CRoot SP, iRoot SP and AH Plus extracts. Cytotoxicity was assessed by CCK-8 assay, and cell-migration capacity was assessed by using wound healing assays .ResultsNo significant differences in cell viability were observed in the 0.02 mg/mL and 0.2 mg/mL sealer groups. The cell viability of CRoot SP was consistently greater than that of iRoot SP at concentrations of 5 mg/mL and 10 mg/mL across all time points. Maximum cytotoxic effect was noted on day 5 with 10 mg/mL AH Plus.The scratch was partly healed by cell migration in all groups at 24 h, and the 0.02 mg/mL, and 0.2 mg/mL CRoot SP exerted beneficial effects on rSCAPs migration.ConclusionsCRoot SP exhibited less cytotoxic than the iRoot SP and AH Plus extracts after setting. A lower concentration of CRoot SP thus promotes the cell migration capacity of rSCAPs, and it may achieve better tissue repair during root canal treatment.

Improving tensile properties of glass fiber-reinforced epoxy resin composites based on enhanced multiphase structure: The modification of resin systems and glass fibers

Glass fiber-reinforced polymer (GFRP) composites have been widely used as reinforced materials in marine engineering due to their good corrosion resistance and economic benefits. However, the mechanical properties of GFRP are lower than that of composites reinforced by carbon and aramid fibers etc. Methods to improve the mechanical properties of GFRP received ongoing attention. GFRP have various mechanical properties due to the characteristics of its multiple phases. This study developed an optimized processing method based on multiphase structures for GFRP composites, significantly enhancing the tensile properties of GFRP laminates. The modified GFRP can be produced efficiently by this method to meet more utilization situations in marine engineering. The influence of curing agents, silane coupling agents (SCA)-treated glass fibers (GFs), and nanomaterials on GFRP's tensile properties was investigated. The findings reveal a 10.64 % increase in the characteristic load of GF bundles due to the improved bonding between fibers by SCA. Besides, the contact angle between SCA-treated GFs and epoxy resin shows a significant reduction (26.69 %). Variations in ply thickness and resin system distinctly influence the tensile properties and failure modes of GFRP laminates. Laminates with 4-ply GF fabrics facilitate more effective load transfer across the matrix-fiber boundary, yielding optimal tensile properties for GFRP. Epoxy/phenolic amine resin system with more reactive functional groups (-OH) enhances the fiber-resin bonding, further improving the tensile properties of GFRP. The enhancement mechanism of the multiphase structure in GFRP was elucidated by microscale characterization, indicating that the multiphase structures in GFRP, enhanced by SCA, nanomaterials, and functional curing agents, significantly improve its tensile properties.

A DOPO modified cyclosiloxane reactive diluent as an effective flame retardant for a high-performance epoxy network

A novel phosphorus-siloxane containing liquid flame retardant epoxy resin was synthesized and incorporated into an epoxy amine network, maintaining low viscosity and rapid cure characteristics, good mechanical and thermal properties, and affording excellent flame retardancy at low concentration. The synthesized flame retardant incorporated a tetra-functional glycidyl ether cyclosiloxane substructure which was substituted with two DOPO segments to obtain a liquid bi-functional flame-retardant epoxy resin (BGTS-DOPO). At only 10 wt% BGTS-DOPO, the modified epoxy amine resin had a viscosity of less than 210 mPa s at 90 °C, gelled rapidly at 150 °C, (9.3 min at 150 °C), exhibited a Tg of 198.7 (extrapolated onset of E’) and 233.0 °C (tan δ max), and possessed improved flexural strength (4.5 %), modulus (4.1 %), strain (7.7 %) and fracture toughness (26.1 %). The self-extinguishing behaviour easily achieved a UL-94 V0 rating, exhibited a maximum limiting oxygen index of 36.7 %, while cone calorimetry produced a 24 % improvement in combustion behaviour of the carbon fibre composite. Presented here therefore is a new highly fire-retardant epoxy resin system that exhibited fast cure, low viscosity and excellent mechanical and thermal properties.

The effect of bioactive glass-based, bioceramic based and epoxy amine resin based root canal sealers on post-obturation pain: A double blinded randomized controlled trial.

The aim of this study was to compare the effect of two calcium silicate-based and an epoxy resin-based root canal sealers on postoperative pain and analgesic intake following single-visit root canal treatment. Ninety patients with at least one first or second molar tooth diagnosed as symptomatic irreversible pulpitis and symptomatic apical periodontitis were selected and allocated into three groups (n=30) according to the sealer used. Root canals were prepared using Protaper Gold instruments (Dentsply Sirona) in a crown down technique and irrigated with 2.5% NaOCl (Calyx, India) and saline solution. Root canal filling was then accomplished with a single cone obturation technique and treated in a single visit by the same endodontist. Patients were told to use a Visual Analog Scale (VAS) to rate their postoperative pain severity as none, minimal, moderate, or severe after 6 h, 24 h, 48 h, 5 days and 7 days following obturation using the appropriate sealers. The need for analgesic intake was also recorded. The data were statistically analyzed. Results showed a significant difference among the studied groups. Bio-C Sealer Ion+ reported the least pain score followed by Nishika Canal Sealer BG and AH plus sealer at all the time intervals recorded. The intergroup analysis, revealed was a significant difference in postoperative pain at 6 h (p=0.000) and 24 h (p = 0.028), but not at 48 h, 5 day or 7 days (P > 0.05). VAS ratings for all the three groups decreased over time. Also, there were significant differences between the means of analgesic intake among 3 groups (p=0.022). Analgesic intake in group BIO-C Sealer Ion+ is significantly lesser than AH Plus and Nishika Canal Sealer BG group. Calcium silicate-based sealer (Nishika Canal Sealer BG and Bio-C Sealer Ion+) resulted in significantly lower levels of pain as compared to epoxy resin-based sealer (AH Plus) at 6h and 24-h interval, there was no significant difference in postoperative pain occurrence at 48-h, 5 day and 7-day period. The analgesic intake in Bio-C Sealer Ion+ group is significantly lesser than Nishika Canal Sealer BG and AH Plus group.

Extraction of naturally occurring peptides versus the tryptic digestion of proteins from fetal versus adult bovine serum for LC-ESI-MS/MS

The naturally occurring peptides and digested proteins of fetal versus adult bovine serum were compared by LC-ESI-MS/MS after correction against noise from blank injections and random MS/MS spectra as statistical controls. Serum peptides were extracted by differential precipitation with mixtures of acetonitrile and water. Serum proteins were separated by partition chromatography over quaternary amine resin followed by tryptic digestion. The rigorous X!TANDEM goodness of fit algorithm that has a low error rate as demonstrated by low FDR q-values (q ≤ 0.01) showed qualitative and quantitative agreement with the SEQUEST cross correlation algorithm on 12,052 protein gene symbols. Tryptic digestion provided a quantitative identification of the serum proteins where observation frequency reflected known high abundance. In contrast, the naturally occurring peptides reflected the cleavage of common serum proteins such as C4A, C3, FGB, HPX, A2M but also proteins in lower concentration such as F13A1, IK, collagens and protocadherins. Proteins associated with cellular growth and development such as actins (ACT), ribosomal proteins like Ribosomal protein S6 (RPS6), synthetic enzymes and extracellular matrix factors were enriched in fetal calf serum. In contrast to the large literature from cord blood, IgG light chains were absent from fetal serum as observed by LC-ESI-MS/MS and confirmed by ELISA.

Effect of Surface Hydrophilized Plastic Waste Aggregates Made by Mixing Various Kinds of Plastic on Mechanical Properties of Mortar.

The surface hydrophilization of mixed plastic waste aggregates (MPAs) was conducted to improve the bond between an MPA and the surrounding cement matrix using two types of coating agents: a silicone amine resin and acrylic binders. The coating agents formed a physical bond with the MPAs, and the results of contact angle measurement also revealed that the surface of MPAs was hydrophilic. The workability of a mortar mix increased by up to 1.47 times with the surface hydrophilization of MPAs. Meanwhile, the compressive and flexural strengths of mortar mixes decreased by 29~43% and 72~86%, respectively, at 28 days with the surface hydrophilization of MPAs. Namely, the surface hydrophilization of MPAs was successively conducted, and the workability of mortar mixes was improved accordingly, but the compressive and flexural strengths of mortar mixes decreased as the physical bond was partially separated from not only the MPA but also the surrounding cement matrix and the surface friction was decreased.

Role of Fe Complexes as Initiators in the Oxidative Degradation of Amine Resins for CO2 Capture: Molecular Modeling and Experimental Results Compared

Role of Fe Complexes as Initiators in the Oxidative Degradation of Amine Resins for CO₂ Capture: Molecular Modeling and Experimental Results Compared

Harnessing a Biocatalyst to Bioremediate the Purification of Alkylglycosides.

As the world moves towards net-zero carbon emissions, the development of sustainable chemical manufacturing processes is essential. Within manufacturing, purification by distillation is often used, however this process is energy intensive and methods that could obviate or reduce its use are desirable. Developed herein is an alternative, oxidative biocatalytic approach that enables purification of alkyl monoglucosides (essential bio-based surfactant components). Implementing an immobilised engineered alcohol oxidase, a long-chain alcohol by-product derived from alkyl monoglucoside synthesis (normally removed by distillation) is selectively oxidised to an aldehyde, conjugated to an amine resin and then removed by simple filtration. This affords recovery of the purified alkyl monoglucoside. The approach lays a blueprint for further development of sustainable alkylglycoside purification using biocatalysis and, importantly, for refining other important chemical feedstocks that currently rely on distillation.

The Crosslinking Mechanism of Camellia Oleifera Protein Adhesive with Amine Resins by 13C-NMR and ESI-MS

The Crosslinking Mechanism of Camellia Oleifera Protein Adhesive with Amine Resins by 13C-NMR and ESI-MS

Hydrophobic functionalized amine-impregnated resin for CO2 capture in humid air

Water vapor in air significantly affects the CO2 separation performance of solid amine sorbents. Although moisture benefits the CO2 adsorption process, the co-adsorbed H2O in amine sorbents leads to extra regeneration energy consumption, which challenges the application of solid amine sorbents for direct air capture. Reducing H2O adsorption and improving the CO2/H2O selectivity of solid amine sorbents are fundamental solutions. This work clarified the more prominent hydrophilic contribution of polyethylenimine (PEI) layers than support resins for amine-impregnated sorbents. Then, we identified the phenyl group as the preferred additive to enhance the hydrophobic properties of PEI-impregnated sorbents using an orthogonal test. The introduction of hydrophobic phenyl groups reduced the average water vapor adsorption per amine group by more than 50% and increased the CO2/H2O selectivity of the amine resin sorbents by 68%–89%, resulting in lower heat requirement caused by H2O desorption. Despite the modification reduced CO2 uptake, a modest CO2 capacity of 1.47–1.6 mmol/g was detected of BZ13.5–40%R20 in a representative air condition (28 °C, relative humidity 50%). In addition, BZ13.5–40%R20 showed stable CO2 capacity in 10 consecutive temperature swing adsorption cycles (desorption at 70 °C, N2 stripping) in laboratory.

Influence of Upcycled Post-Treatment Bark Biomass Addition to the Binder on Produced Plywood Properties

The valorization of tree bark through chemical treatment into valuable products, such as bark acid, leads to the formation of process residues with a high solids content. Since they are of natural origin and are able to be suspended in water and acid, research was carried out on the recycling of suberic acid residues (SAR) as a bi-functional component of binder mixtures in the production of plywood. The 5%–20% (5%–30% for curing time) mass content of SAR has been investigated with urea-formaldehyde (UF) resin of about 66% of dry content. The results show that the curing time of the bonding mixture can be reduced to about 38% and 10%, respectively, for hot and cold curing, of the initial curing time for the lowest SAR content. The decreasing curing time of the tested binder mixtures with the increase in SAR content was caused by the increasing amount of acidic filler, since amine resins as UF require acidification hardening, and the curing dynamics are strongly dependent, among others, on the content of the acid medium (curing agent). In the case of hot curing, a SAR content of about 20% allowed us to achieve the curing time of bonding mass with an industrial hardener. Investigations into the mechanical properties of examined panels showed a significant modulus of elasticity (MOE) increase with filler content increase. Similar conclusions can be drawn when analyzing the results of the modulus of rupture (MOR) investigations; however, these were only significant regarding hot-pressed samples. The shear strength of the plywood samples increased with the SAR rise for both cold- and hot-pressed panels. The in-wood damage of samples with SAR filler, hot-pressed, rose up to about 30% for the highest SAR filler content. For cold-pressed samples, no in-wood damage was found. The positive effect of veneer impregnation limiter by resin was identified for SAR acting as a filler. Moreover, a higher density of SAR-containing bonding lines was reached for hot-pressed panels. Therefore, the results confirmed the ability to use the SAR as an upcycled component of the bonding mixture for plywood production.

Insight into thermal regulation of supercapacitors via surface-engineered phase change microcapsules.

Constructing efficient thermal management system to settle the thermal runaway of energy storage devices via employing phase change microcapsules (MEPCMs) is of great significance. However, it is still a challenge that the conventional MEPCMs go against the electrochemical performance and hardly be homogenously fixed in the electrodes. In order to conquer these long-standing critical issues, we designed a novel electrochemically active double-shell phase change microcapsule by introducing polypyrrole on the surface of dense amine resin shell of the conventional inert MEPCM. The active MEPCMs@PPy are uniformly immobilized on the surface of the electrode material using reduced graphene oxide to ensure the stable and efficient operation of the flexible supercapacitor. The assembled all-solid-state supercapacitor containing MEPCMs@PPy (SCs@MEPCMs@PPy) lagged 103s to 55°C than the SCs@00 without the added phase change material. At a high temperature of 55°C and a scan rate of 50mVs-1, SCs@MEPCMs@PPy exhibits an areal specific capacitance of 110.6mAcm-2, which is higher than that of the original SCs@MEPCMs. A capacitance retention of 79.8% and coulombic efficiency of 98.4% can be reached after 3000 cycles. This study opens a new avenue for developing applicable microencapsulated phase change materials in temperature-regulated electrode systems for supercapacitors and alkaline-ion batteries.

Moisture influence on solid wood bonded with modified starch

Moisture influence on solid wood bonded with modified starch. A growing and developing population is contributing to the ever-increasing global warming, which is caused, among other things, by the heavy use of chemicals. Most of them are crude oil-based, which is a non-renewable source. That is why the population tries to find organic substitutes in every area, even in the wood industry. Here, the most common and popular binders - amine resins, are subjected in research to partial or full replacement by more natural binders, non-formaldehyde, made of renewable raw materials, preferably plant-based. In this project, the studies were carried out on the possibility of starch-based glue application in wood bonding and its effect on glued birch wood (Betula L.) under various environmental storage conditions of bonded samples. The results show, that the samples at room temperature and normal humidity, as well as another – additionally dried, have a very similar shear strength. In-wood damages, on the other hand, are much more varied. The research also included moistened samples, which gave poorer results. Based on the results, it can be concluded, that modified starch is a very good organic glue, that can potentially replace some chemical products in certain applications.

Novel Styrene-Based Polyamine Sorbent for Efficient Selective Separation of Molybdenum.

Tungsten (W) and molybdenum (Mo) are important strategic resources but the two coexist in both primary ore and waste. Before a single metal product is obtained, it is often necessary to separate the two. In this work, we reported two new polyamine resins (D301@PA and D301@TA), which can be obtained by an assembled amine (primary amine or tertiary amine) and traditional D301 resin by the dipping method. Then, the sorption experiments with the amine resins were carried out, and the selectivity and sorption capacity of the two new polyamine resins for MoS42– have been significantly improved. Among them, D301@TA showed the highest sorption capacity of 414 mg·g–1 and a separation factor of 108. Finally, the sorption mechanism can be inferred through scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, and X-ray photoemission spectroscopy (XPS); the Cl– ions in the amine resin and the MoS42– ions were subjected to ion exchange. This work provides a green and efficient approach for separating tungsten and molybdenum.

Investigation of the processability, thermal, mechanical and flame retardant properties of bisoxazoline composites

Presented here is an investigation into the cure kinetics, thermal and mechanical properties, and fire resistance of a carbon fibre composite using a polymer matrix blend composed of 1,3 phenylene bisoxazoline, a phenolic resin and dodecylbenzene sulfonic acid . This polymer matrix is further modified with a benzoxazine, a tetra-functional epoxy amine resin and the engineering thermoplastic , polyether sulfone (PES) to explore their effect on the reaction mechanism and final properties of the composite after cure and post-cure. The modifiers reduce the reactivity of polymerisation and the final glass transition temperature of the network as shown by the rate constants, determined from the Kissinger and Sestak–Berggren models. Subsequent post-curing of the composite increases the glass transition temperature, thermal stability, interlaminar shear strength , and fire performance as determined by UL-94 vertical burn test. Ensuring the network is fully cured is clearly critical to optimum performance of the composite. The high char yields of the bisoxazoline polymer networks , particularly after post-cure illustrate great potential for applications where high temperature resistance is required.

Property and mechanism on sorption of molybdenum from tungstate solution with a porous amine resin

The sustainable development of tungsten and molybdenum resources requires a new clean and recyclable separation technology. This work proposes a recyclable clean separation technology of tungsten and molybdenum with a porous amine resin. The resin was well prepared by assembling amine groups on trioctylamine (TOA) and the porous resin matrix D301 by the dipping method. Here, pH 7.8, temperature 25 °C, and reaction time 240 min was used as optimum condition, resulting in the highest sorption capacity 236 mg g−1, and it has a good cycle performance, exhibiting a retention rate of 90% after five cycles. Experimental spectroscopy combined theoretical calculation confirmed that this sustainable sorption behavior is substantially related to the amine functional groups on the resin. Experimental spectroscopy illustrated that the Cl− ions in the amine resin and the MoS42− ions were subjected to ion exchange. Theoretical investigations further confirm that the sorption site is at the N atoms, the sorption behavior is chemical binding with the binding energy −0.055 Ha, and the bonding method is the s orbit of the N atoms in the amine resin hybridized with the s orbit of the S atoms in the amine resin. Owing to such an excellent performance in the selective sorption of molybdenum from the tungstate solution, the amine resin is greatly promising in the tungsten and molybdenum waste recovery field.

Adsorption properties of macroporous exchangers functionalized with various weak-base groups for aromatic acids: Coupling DFT simulation with batch experiments

Anion exchange resin has an excellent effect on the removal of aromatic acids in wastewater, while the adsorption affinities of the resins with different functional groups are various. In this work, six macroporous weak-base anion exchange resins were synthesized, and the adsorption characteristics of the resins for three typical aromatic acids including benzenesulfonic acid (BSA), benzoic acid (BA), phenol (PH) were investigated. The results showed that the adsorption performance for BSA and BA on these resins were more sensitive to pH than that for PH. The adsorption capacities of the secondary amine resins to aromatic acid in salt-rich environment were higher than that of the tertiary amine resins. In the binary system, when the adsorption mechanisms of the two adsorbates are overlapped to some extent, the competition between them on the resins was more significant. Density functional theory (DFT) simulations confirmed that the adsorption of BSA by the resins was mainly due to electrostatic interaction, and the adsorption of PH was attributed to hydrogen bond, while BA adsorption was the synergism of these two interactions. The functional resins with high binding energies and high natural bond orbital (NBO) charge transfer had good salt resistances. Furthermore, NaCl aqueous solution was suitable for desorption of BSA on the resins, while the proper desorbent for BA and PH was ethanol. These results indicated that DFT could guide the selection of the functional groups and provided an effective method for the design of selective separation materials for aromatic acids in wastewater.