Resin Treatment Research Articles

Recent advances in Fenton-like treatment of radioactive ion exchange resins

Ion exchange resins (IERs) are widely used to remove radioactive contaminants from various commercial nuclear power plant systems. After the completion of their useful life cycle, IERs are removed from the nuclear facility and are known as spent resins. In the past few decades, the development of Fenton/Fenton-like treatments for the management of spent resins has received considerable attention because of their potential to completely break down the IER structure into harmless compounds (e.g., carbon dioxide, water, and inorganic salts). In addition, after Fenton-like treatments, the resulting solutions containing radionuclides can be easily immobilized to stable waste. In this review, we critically discuss the key developments in Fenton/Fenton-like dissolution, degradation, and mineralization of spent resins. We describe the important reaction parameters (initial pH, resin dosage, catalyst type and dosage, hydrogen peroxide dosage, flow rates of the catalyst and oxidant, reaction temperature, treatment time, and other specific parameters) for various Fenton/Fenton-like treatments of spent resins. Moreover, this review focuses heavily on the major reaction intermediates generated in Fenton-like treatments. In the final section of this review (conclusions and perspectives), we discuss the major challenges and suggest future research directions need to be addressed to improve the efficiency of Fenton-like treatments of spent resins.

Efficient Extraction of Flavonoids from Lotus Leaves by Ultrasonic-Assisted Deep Eutectic Solvent Extraction and Its Evaluation on Antioxidant Activities

The discovery of a green extraction solvent for natural plants could promote related research. In this study, deep eutectic solvents (DES) were used as green solvents coupled with an ultrasound-assisted extraction method (UAE) to extract flavonoids from lotus leaves. Thirty-four different DES were performed and choline chloride/urea with 40% water was chosen as the most promising one, and the related parameters in the procedures were optimized, resulting in the highest extraction amount of flavonoids in lotus leaves. D-101 was selected from four macroporous resins to separate the flavonoids from DES. Moreover, DES could be recycled and efficiently reused four times with satisfactory performances. In addition, the lotus leaf flavonoids from the DES extract exhibited antioxidant activities in five kinds of assays including DPPH, ABTS, Fe3+ reducing, FRAP, and Fe2+ chelating. It also showed antibacterial activities on Staphylococcus aureus and Escherichia coli bacterial strains with minimal inhibitory concentrations at 1666 μg/mL and 208 μg/mL, respectively. In the HPLC analysis, the three main components in the DES extract were identified as astragalin, hyperoside, and isoquercitrin. In conclusion, the developed UAE-DES followed by macroporous resin treatment could become an efficient and environmentally friendly extraction and enrichment method for flavonoids from lotus leaves and other natural products.

Influence of oxygen equivalent on molten salt oxidation efficiency of mixed resin in Li2CO3-Na2CO3-K2CO3 melt

The disposal of spent radioactive ion exchange resin generated during the operation of nuclear facilities has always been a conundrum. The molten salt oxidation (MSO) for the treatment of mixed resin (MR) shows obvious superiority. In this work, ternary carbonate (Li2CO3-Na2CO3-K2CO3) and MR was used as the molten salt system and the oxidation target, respectively. The oxidation behavior of MR was analyzed by varying the temperature and oxygen equivalent during the MSO process. By studying the effect of different oxygen equivalents on the oxidation efficiency, the oxygen equivalent of 125% could make the oxidation efficiency of MR reach 99.99% at 800 °C. The composition of C, N and S containing exhaust gas produced through MSO process of MR with temperature were almost consistent with the simulation results. The exhaust gas was successfully adsorbed by molten carbonate to produce nitrate and sulfur compounds. The carbonate has good absorption to harmful gases such as SO2, CO, NO, etc. The content of SO2 from the highest 0.32% to 0, and 71.23% of sulfur in MR was trapped by molten carbonate as the form of sulfate. This work has important implications for reducing the potential harm of radioactive waste resin to the environment.

The effect of air on oxidation decomposition of uranium-containing cationic exchange resins in Li2CO3-Na2CO3-K2CO3 molten-salt system.

With the development of nuclear energy, spent cationic exchange resins after purification of radioactive wastewater must be treated. Molten-salt oxidation (MSO) can minimize the disposal content of resins and capture SO2. In this work, the decomposition of uranium-containing resins in carbonate molten salt in N2 and air atmospheres was investigated. Compared to N2 atmosphere, the content of SO2 released from the decomposition of resins was relatively low at 386-454 °C in an air atmosphere. The SEM morphology indicated that the presence of air facilitated the decomposition of the resin cross-linked structure. The decomposition efficiency of resins in an air atmosphere was 82.6% at 800 °C. The XRD analysis revealed that uranium compounds had the reaction paths of UO3 → UO2.92 → U3O8 and UO3 → K2U2O7 → K2UO4 in the carbonate melt, and sulfur elements in resins were fixed in the form of K3Na(SO4)2. The XPS result illustrated that peroxide and superoxide ions accelerated the conversion of sulfone sulfur to thiophene sulfur and further oxidized to CO2 and SO2. Besides, the ion bond formed by uranyl ions on the sulfonic acid group was decomposed at high temperature. Finally, the decomposition of uranium-containing resins in the carbonate melt in an air atmosphere was explained. This study provided more theoretical guidance and technical support for the industrial treatment of uranium-containing resins.

Effects of Petroleum Resins and Ultrasonic Treatment on the Properties of Petroleum Paraffin Solutions in n-Decane and on the Structural-Group Composition of Precipitated Resins

Effects of Petroleum Resins and Ultrasonic Treatment on the Properties of Petroleum Paraffin Solutions in n-Decane and on the Structural-Group Composition of Precipitated Resins

Проведение опытной работы по снижению активности отработавших ионообменных смол

High level decontamination is seen as a method providing the reprocessing of ion-exchange resins: they are treated with specifically selected solutions to achieve high degree of radionuclide elution. In 2021, Research Manufacturing Technological Bureau Onega launched an experimental study aimed at reducing the activity of spent ion-exchange resins unloaded from ships undergoing maintenance. Under the study, a few experiments were performed to select appropriate regenerating solutions, optimal methods for spent ion-exchange resin processing and treatment of regenerating solutions on sorbents of NZрS and TsMPA types. Based on the study, a method was proposed with an appropriate processing flowchart developed to manage spent ion-exchange resins at the ship repair site Zvezdochka.

Strategies for the sensorial optimization of alcohol-free wines

De-alcoholized wines are currently experiencing an increasing demand, but are also being discussed very controversially at this time. The de-alcoholization process is usually carried out by distillation processes under vacuum. The treatment is accompanied by a series of changes in terms of analytical and sensory parameters of the wines. Ethanol has a very complex and far ranging influence on the wine sensory character. Even more, the de-alcoholization process goes along with certain losses of aroma components. Several strategies were assessed to buffer and balance the effect of de-alcoholizing wines below 0.5% v/v. Compared to the addition of tannins and mannoproteins, sweetening showed clearer results on the panelist’s preference. The assessment of a commercial resin treatment to recover aroma from de-alcoholization process showed promising results.

Effects of Compression Ratio and Phenolic Resin Concentration on the Properties of Laminated Compreg Inner Oil Palm and Sesenduk Wood Composites

Due to its inferior properties, oil palm wood (OPW) extracted from the inner layer of the oil palm (Elaeis guineensis) trunk, referred as inner OPW in this study, is frequently regarded as a waste. Phenolic resin treatment and lamination of inner OPW with other hardwoods may be an excellent way to improve the properties of the inner OPW. In this study, inner OPW were treated with two different concentrations (15% and 20%) of low molecular weight phenol formaldehyde resin (LmwPF) and compressed at different compression ratios (10%, 20%, and 30%). The physical and mechanical properties of the modified inner OPW’s were evaluated according to British Standards (BS) 373: 1957. The results revealed that inner OPW treated with the highest compression ratio (30%) and resin concentration (20%) exhibited the highest weight percent gain, polymer retention and density. In the following phase of the research, the treated inner OPW was used as the core layer in the fabrication of a three-layer laminated compreg hybrid composites, with untreated and treated sesenduk (Endospermum diadenum) wood serving as the face and back layers. The compression ratios of 10% and 20% and resin concentrations of 10% and 20% were used in this phase of study as laminated boards made with 30% compression ratio failed. The findings showed that resin concentration had a significant impact on both the inner OPW and the laminated compreg hybrid panels. Markedly, higher resin concentrations (20%) resulted in improved physical properties, i.e., thickness swelling and water absorption, as well as enhanced mechanical properties (modulus of rupture and modulus of elasticity). Although compression ratios had no significant effect on the properties of the laminated products, those compressed at higher compression ratios (20%) performed slightly better than the panels compressed at lower compression ratios (10%).

Experimental study on treatment of mixed ion exchange resins by supercritical water gasification

Nuclear power acts as a significant role in the current world energy supply system. The treatment of radioactive waste from nuclear station is a considerable issue and has attracted more and more attention. Spent ion exchange resins used in nuclear power plants are typical organic nuclear waste which are difficult to deal with. Supercritical water gasification could offer an efficient and clean treatment to spent ion exchange resins. In this study, Supercritical water gasification of mixed ion exchange resins was carried out in a batch reactor with various conditions. Effects of reaction parameters such as temperatures (550oC–750 °C), concentrations (5 wt%-15 wt%), catalysts (K2CO3, Na2CO3, KOH and NaOH) and residence times (10 min–60 min) were investigated. Results showed that high temperature, low concentration, K2CO3 addition and long residence time promote the gasification result. And the carbon gasification efficiency reached up to 97.2% with 10 wt% concentration and K2CO3 catalyst addition at 750 °C. The main intermediate organic component residues in liquid products were trimethylamine, benzene, toluene, ethylbenzene p-xylene styrene benzene, 1-ethyl-4-methyl- and naphthalene. Reaction pathways in supercritical water have been discussed and proposed. And the conversion pathways and distributions of sulfur and nitrogen were disclosed.

Removal and destruction of perfluoroalkyl ether carboxylic acids (PFECAs) in an anion exchange resin and electrochemical oxidation treatment train

Perfluoroalkyl ether carboxylic acids (PFECAs) are a group of emerging recalcitrant contaminants that are being developed to replace legacy per- and polyfluoroalkyl substances (PFAS) in industrial applications and that are generated as by-products in fluoropolymer manufacturing. Here, we report on the removal and destruction of four structurally different PFECAs using an integrated anion exchange resin (AER) and electrochemical oxidation (ECO) treatment train. Results from this work illustrated that (1) flow-through columns packed with PFAS-selective AERs are highly effective for the removal of PFECAs and (2) PFECA affinity is strongly correlated with their hydrophobic features. Regeneration of the spent resin columns revealed that high percentage (e.g., 80%) of organic cosolvent is necessary for achieving 60-100% PFECA release, and regeneration efficiency was higher for a macroporous resin than a gel-type resin. Treatment of spent regenerants showed (1) >99.99% methanol removal was achieved by distillation, (2) >99.999% conversion of the four studied PFECAs was achieved during the ECO treatment of the still bottoms after 24 hours with an energy per order of magnitude of PFECA removal (EE/O) <1.03 kWh/m3 of total groundwater treated, and (3) >85% of the organic fluorine was recovered as inorganic fluoride. Trifluoroacetic acid (TFA), perfluoropropionic acid (PFPrA), and perfluoro-2-methoxyacetic acid (PFMOAA) were confirmed via high-resolution mass spectrometry as transformation products (TPs) in the treated still bottoms, and two distinctive degradation schemes and four reaction pathways are proposed for the four PFECAs. Lastly, dissolved organic matter (DOM) inhibited uptake, regeneration, and oxidation of PFECAs throughout the treatment train, suggesting pretreatment steps targeting DOM removal can enhance the system's treatment efficiency. Results from this work provide guidelines for developing effective separation-concentration-destruction treatment trains and meaningful insights for achieving PFECA destruction in impacted aquatic systems.

Effects of oxygen content on gaseous and solid products during molten salt oxidation of cation exchange resins.

Molten salt oxidation (MSO) is an advanced method for waste resins treatment; nevertheless, the research about gas product variations of resins under different stoichiometric air feed coefficient (α) is rare. The optimal working condition of hazardous waste disposal is obtained through thermodynamic equilibrium calculation, and the method to improve the treatment efficiency is found to guide the optimization of the actual experiment. In this paper, Fact Sage was used to calculate the oxidation products of cation exchange resins (CERs) at different temperatures and α, focusing on the similarities and differences through the contents of CO, CH4, CO2, and SO2 during the oxidation of CERs, the MSO of CERs, and the theoretical calculation. The results indicated that the gas products of the calculation and reality of the oxidation process of CERs are quite different, while the CO contents of CERs during MSO are close to the calculated values. The main reason for this consequence is that in the oxidation process of CERs, the S in the sulfonic acid group will form thermally stable C-S with the styrene-divinylbenzene skeleton. Moreover, the introduction of carbonate can promote the destruction of C-S and absorb SO2 as sulfate, weakening the influence of C-S on the oxidation products of CERs. The gas chromatograph results indicated that the SO2 content is reduced from 0.66% in the process of CERs oxidation to 0.28% in MSO of CERs. When 1.25 times stoichiometric air feed coefficient is fed, the sulfate content in the carbonate is the highest at 900°C, which is 23.4%.

Radiological safety analysis of a newly designed spent resin mixture treatment facility during normal and abnormal operational scenarios for the safety of radiation workers

The radiological safety of workers in a newly developed microwave-based spent resin treatment facility was assessed based on work location and operational scenarios. The results show that the remote-operation room worker was exposed to maximum annual dose of 3.19E+00 mSv, which is 15.9% of the dose limit, thereby confirming radiological safety. Inside the pathway, annual doses in the range of 7.87E-02–2.07E-01 mSv were measured initially at the mock-up tank and later at the point between the spent resin separation and treatment parts. The dose of emergency maintenance workers was below the dose limit (4.08E-03–4.99E+00 mSv); however, before treatment (separation and microwave), the dose of maintenance and repair workers exceeded the dose limit. The doses of the effluent removal workers at the zeolite and activated carbon storage tank and spent resin storage tank were the lowest at 2.79E-01–2.87E-01 mSv and 9.27E-01 mSv in “1 h” and “4–5 h of operation”, respectively. The immediately lower and upper layers of the facility room exhibited the highest annual doses of 1.84E+00 and 3.22E+00 mSv, respectively. Through this study, a scenario that can minimize the dose considering the movement of spent resin through the facility can be developed.

Recovery of Naringin-Rich Flavonoid Extracts from Agroresidues with Anxiolytic- and Antidepressant-like Effects in Mice

Citrus paradisi species belong to the Rutaceae family, and it is commonly known as grapefruit. Grapefruit consumption involves a large amount of waste that goes to landfills and produces significant pollution affecting the human health. To examine this phenomenon, we designed an efficient chemical method that recovers naringin-rich flavonoid extracts from the fresh waste of grapefruits, by using the solvent impregnation resin method (SIR) with XAD-4 amberlite and either methanol or water as elution systems. Additionally, we focused on evaluating these extracts' anxiolytic- and antidepressant-like effects in behavioral predictive paradigms in mice. According to direct Principal Component Analysis (PCA) by NMR, and Direct Injection Electrospray Ionization-Mass Spectrometry (DIESI-MS), methanol extracts obtained after resin treatment were free of coumarin compounds and evinced had a high content of naringin. Poncirin, phenylalanine, chrysin 5,7-dimethyl ether, 5,7-dimethoxy-4'-hydroxyflavanone, 2,3-dihydro-2-(4-hydroxyphenyl)-5,6,7,8-tetramethoxy-4H-1-benzopyran-4-one, tetrahydrocurcumin, corchoionoside C, 6'-coumaroyl-1'-O-[2-(3,4-dihydroxyphenyl) ethyl]-β-D-glucopyranoside were also detected. Naringin-rich methanol extract caused a clear anxiolytic-like effect in the Elevated Plus Maze (EPM) and the Hole-Board (HBT) Tests, increasing oral doses of this extract did not produce a sedative effect. A single oral dose caused an antidepressant-like effect in the Tail Suspension Test (TST), while repeated administrations of the methanol extract elicited a robust antidepressant effect in the Forced Swimming Test (FST) in mice. Our evidence highlights the importance of bioprospecting studies of organic waste with therapeutic potentials, such as anxiety and depression disorders.

Spherical TiO2 /Cr2O3 Composites Synthesized Using Ion-Exchange Resins as a Template

Two samples of TiO2 /Cr2O3 composites were synthesized as spherical grains by stepwise thermal treatment of ion-exchange resins, which were preliminarily saturated with chromium cations Cr3+ and dichromate anions Cr2O7 2– and covered with a film-forming solution of titania. The modes of calcination were based on thermal analysis and determined by the type of ion-exchange resin chosen as a template. The obtained composites consist mostly of the α-Cr2O3 phase, while the content of the TiO2 phase does not exceed 4 %. The composites retain the spherical grain shape of the initial ion-exchange resins with the size from 370 to 660 μm. Grains of the sample based on cationite, which adsorbs Cr3+ ions, have a pore structure with swells and voids. Grains of the sample based on anionite have fractures and cracks over the entire surface due to nonuniform distribution of adsorbed Cr2O72– anions in the initial anionite. The composites exhibit the catalytic activity in the complete oxidation of p-xylene. The sample based on cationite is more active. This may be related to a smaller accessible specific surface area of titania in the anionite-based sample due to formation of the Ti3+ solid solution in α-Cr2O3.

Influence of Phenol–Formaldehyde Resin Oligomer Molecular Weight on the Strength Properties of Beech Wood

The objective of this study was to determine the effects of four phenol–formaldehyde (PF) resin treatments with different molecular weights at four different concentrations (5, 10, 15, and 20%) in treated beech wood. The mechanical properties of untreated and treated beech wood were evaluated. After impregnation with PF resin, all modified beech wood at all PF resin concentrations exhibited an increase in weight percent gain compared with that in untreated beech samples. PF resins with lower molecular weights more easily penetrate the wood cell wall, leading to increased bulking of the wood structure, which in turn improves the dimensional stability of the wood. The PF resin treatment with a molecular weight of 305 g/mol showed better impregnation ability than that of the other PF resins. The impact bending strength of PF-treated wood was considerably reduced because PF-cured resins formed inside the wood and are rigid and brittle. Additionally, PF resin treatments at all concentrations decreased the modulus of elasticity of the wood. Scanning electron microscopy and light microscopy revealed that the PF resins were comparatively well fixed in the wood samples. The results indicate that the large molecular weight PF resins are more uniformly distributed in the fiber lumens.

Effect of Resin Finishing on Some Properties of 100% Cotton Light Weight Woven Fabric

In this study, experimental investigation was conducted to assess the wrinkle-resistance performance of resin-treated 100% cotton light-weight fabric. Resin (Dimethyloldihydroethylene urea, DMDHEU) was used for treating 100% cotton light-weight fabric with different treatment parameters (resin concentration: 30 g/L, 45 g/L, 60 g/L; pick-up: 60%, 70%, 80%; drying temperature: 110 °C, 120 °C; and curing time: 2 min, 2.5 min, 3 min). After resin treatment, wrinkle properties, as well as the tearing strength and dimensional stability, of the resin treated fabrics were evaluated. Experimental results revealed that the resin concentration, pick-up, drying temperature, and curing time are inter-related, which could affect the final performance of the 100% cotton light-weight woven fabric. Thus, the effects of different parameters on the performance of the 100% cotton light-weight woven fabric were compared and discussed. Generally speaking, the resin finishing improved the wrinkle properties and dimensional stability but reduced the tearing strength of 100% cotton light-weight woven fabric.

Thermal decomposition and oxidation of cation exchange resins with and without Na2CO3–K2CO3 salt

Owing to the capability of trapping sulfur and reducing the formation of sulfur bridges, the addition of carbonate salt is one of the ideal destruction technologies for the treatment of cation exchange resins (CERs). The oxidation processes of CERs with and without Na 2 CO 3 –K 2 CO 3 salt were investigated using TG, FT-IR and XPS. The results of these analyses indicate that in addition to the evaporation process, the oxidation process of CERs can be described as: during the thermal decomposition of the sulfonic acid groups, there are direct destruction of functional groups and the dehydration of functional groups. In addition to the destruction of styrene-divinylbenzene copolymer, the continuous oxidation process includes the direct thermal decomposition of sulfonyl bridges and the formation of sulfur bridges, which decompose at high temperature. The elemental analysis results confirmed that the presence of carbonate salt reduced the formation of sulfur bridges in residue. The SO 2 can be effectively adsorbed by carbonate salt to form sulfate in the salt. Moreover, the content of sulfate ions in waste salt were determined by ICP-MS, which proves that oxidation with Na 2 CO 3 –K 2 CO 3 at 550 °C for 1 h is the optimal oxidation condition to form the sulfate in carbonate salt. • The Na 2 CO 3 –K 2 CO 3 salt can effectively promote the oxidation of resins. • Carbonates can convert the sulfur bridge structure in residue into sulfate. • Four oxidation processes of resin are described by quantifying S content.

Investigation on the simultaneous loss of saccharides in pre-hydrolysis liquor during an efficiently combined process towards lignin removal

Generally, lignin separation from prehydrolysis liquor (PHL) is accompanied by sugar removal, making the purification of PHL challenging. However, how sugar loss from PHL can be minimized in PHL purification is still unclear. In this work, a method for removing lignin from PHL was attested, which included treatments of PHL with poly aluminum chloride (PAC), activated carbon, and XAD-4 resin. The results exhibited that the PAC could form complexation with lignin facilitating lignin removal from PHL. At the PAC concentration of 15 mg/L, 10% of lignin was removed, while no significant sugar loss was observed. Subsequently, by treating PHL with activated carbon, 87% of the remaining lignin was removed from the PHL, while sugar loss was identified to be 14%. XAD-4 resin treatment could slightly improve the lignin removal from 87% to 92%. However, the XAD-4 was unselective in sugar removal and led to an increased sugar loss (from 14% to 37%). Interestingly, removing colloidal lignin by PAC benefited the subsequent activated carbon process for improving lignin removal. In other words, PAC removed not only colloidal lignin but also facilities lignin isolation (i.e., an increase from 81% to 87%) and prohibited sugar loss (a drop from 27% to 6%) in the subsequent activated carbon treatment.

Properties Enhancement of Oil Palm Trunk Plywood against Decay and Termite for Marine Applications.

Oil palm trunk (OPT) veneers have the potential to be used in the production of plywood for marine applications. However, OPT is not resistant to fungal decay and termites, limiting its use in the production of marine plywood. As a result, in this study, phenolic resin treatment was used to improve the biological durability of OPT and produce marine grade equivalent (MGE) plywood. The OPT veneer was treated with medium molecular weight phenol formaldehyde (MmwPF) resin. The results showed that MmwPF resin with a solid content of 30% resulted in higher weight percent gain and polymer retention. Veneers treated with 30% MmwPF resin were then pressed for more than 10 min at temperatures above 140 °C. Dimensional stability, shear strength, bending strength, fungal decay resistance, and termite resistance were all tested on the plywood produced. The results of this study revealed that MGE plywood has satisfactory bonding quality and excellent biological durability. Good bending strength was recorded for the MGE plywood with modulus of rupture and modulus of elasticity ranged between 31.03 and 38.85 MPa and 4110 and 5120 MPa, respectively. Rubberwood, as a reference sample in this study, is not durable (Class 5) against white rot fungi and is moderately durable (Class III) against subterranean termite attacks. Interestingly, MGE plywood produced in this study was found very durable (Class 1) against white rot fungi. It is also durable (Class II) and very durable (Class I) against termite attacks, depending on the pressing parameters employed. Based on their outstanding bonding quality, bending strength, and biological durability, the study confirmed the feasibility of OPT plywood for marine applications.

Investigation on fiber coating and treatment on mechanical properties of fiber composites

The purpose of this project is to investigate on mechanical properties of fibre coated reinforced composites. Tensile properties of the coated flax fabrics tested at different resin treatment. The tensile test is to evaluate the effect of the epoxy coating on the strength of the flax fiber and to predict the behavior of the coating how influence the mechanical properties of the composites. The results show that the epoxy-coated flax fiber considerably higher tensile properties compared with the non-coated flax fiber reinforced composite materials. The tensile strength of the reference sample, i.e., flax fiber without coating is 18.7 MPa is compared low to the value of the coated fiber value of 19.3 MPa. It is important to consider, that there is a large number of factors affecting mechanical properties of coated fiber, for curing temperature, resin combination, fiber arrangement etc. Consequently, it is not possible to compare accurately the achieved values with the literature. To the best of authors’ knowledge there is no previously published work on effect of fiber coating on flax fiber using high modulus. So, this latter assumption should be checked in a separate study.