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The complex nature of the hydrothermal liquefaction (HTL) of lignin product downstream requires an effective separation strategy. In this study, the use of adsorption separation was undertaken using deep eutectic solvent (DES)-modified amberlite XAD-4 adsorbents to achieve this goal. XAD-4 was modified with a choline chloride: ethylene glycol DES and characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the Brunauer–Emmett–Teller (BET) test. In addition, the HTL product was characterized using Gas Chromatography with Flame Ionization Detection (GC-FID). The performance of unmodified and DES-modified adsorbents was initially tested on the model compounds of guaiacol, phenol and catechol, followed by the HTL product in a batch adsorption system. The Freundlich model best described the model compound adsorption system with a preferential affinity for guaiacol (kf = 12.52), outperforming phenol and catechol. Adsorption experiments showed an increase in capacity and selectivity for all species when the DES-modified adsorbents were used at all mass loadings. GC-FID analytics showed the DES-modified XAD-4 (300 mg) as having the highest selectivity for guaiacol, with an equilibrium concentration of 121.45 mg/L representing an 85.25% uptake, while catechol was the least favorably adsorbed. These results demonstrate the potential of DES-functionalized XAD-4 adsorbents in selectively isolating high-value aromatics from the HTL of the lignin product stream.

The present work reports studies on the effective removal of Rhodamine-B (RhB) using Aliquat-336 modified Amberlite XAD-4 resin in the fixed-bed columns in series. The effect of flow rate (Q = 2 to 6 mL·min−1), bed height (h = 3.5 to 7 cm) and initial RhB dye concentration (Cin = 10 to 20 mg·L−1) was studied. When a single column was used, 93% RhB dye was removed in 3 h at Q= 2 mL·min−1, Cin = 10 mg·L−1, and h = 7 cm. When three columns in series were used, almost 100% dye was removed until 80 h. The maximum breakthrough time (142 h) and saturation time (244 h) were found by keeping Q= 2 mL·min−1, h = 7 cm of each column and Cin = 10 mg·L−1. Mathematical modeling of the breakthrough curves was done by using Yoon-Nelson, Clark, Wolborska, and pore diffusion models. The Clark model best fitted the experimental data. The possible interaction mechanism between Aliquat-336 and RhB dye was proposed. The column was regenerated in continuous mode using 1 M HCl solution and maintaining a flow rate of 2 mL·min−1.

Long-term cultivation practices, in which mineral fertilizers are the only amendments made to crop-supporting soils, are giving rise to the degradation of soil structures in the world’s most fertile soils. This leads to erosion and to the loss of productivity and may well become a greater threat than that of global warming. Humic substances (structurally related compounds), and humin (which no longer falls within the modern definitions of humic substances), are major transformation or humification components of organic matter entering the soil, with varying resistance to biological degradation, and properties vastly contributing to soil fertility. There is considerable discussion on the macromolecular structures arising from associations or supramolecular structuring of some components of humic substances. The compositions, structures, shapes, sizes, and surface properties of these molecular components determine their intra- and inter-molecular associations, their interactions with the soil particles, and particularly with the soil inorganic colloids. Such interactions play a vital role in soil aggregates’ formation, which is important for soil health and productivity. In this work, an outline is given of modern methods for the isolation of broadly defined soil organic components, of what is known of their origins (plant or microbial), compositions, sizes and shapes, of how they interact to promote soil structure and productivity, and how the materials composing the hydrophobic fraction form strong associations with the inorganic colloids. A better understanding should be sought of how these interactions and associations take place giving rise to the structured systems that are characteristic of fertile soils.

Aryl diazonium salt chemistry offers a robust and versatile approach for the modification of material surfaces via the covalent immobilization of reactive functional groups under mild conditions. In this study, this strategy was successfully applied to graft the chelating agent 4-(2-pyridylazo)resorcinol (PAR) onto Amberlite XAD-4 resin. Initially, 4-nitrobenzenediazonium tetrafluoroborate (NBDT) was covalently anchored onto the resin surface using hypophosphorous acid as a reducing catalyst to introduce aryl nitro groups. These nitro groups were subsequently reduced to aniline functionalities, enabling diazo coupling with PAR. The successful modification of the resin was confirmed by ATR-FTIR spectroscopy, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The synthesized chelating resin exhibited sorption capacities of 0.152, 0.167, and 0.172 mM g−1 for Co(II), Ni(II), and Cu(II), respectively. The functionalized resin was packed into standard SPE cartridges and employed as a selective sorbent for the extraction and preconcentration of trace metals from groundwater samples collected from Dhalamah Valley, Al-Madinah Al-Munawwarah, prior to quantification by inductively coupled plasma mass spectrometry (ICP-MS). These results demonstrate the effectiveness of rapid diazonium-based surface functionalization for the preparation of selective polymeric metal chelators suitable for the extraction of trace metals from complex groundwater matrices.

The novel core–shell type polymeric supports with accessible phosphorus groups were synthesised in the search for new reactive materials designed for the synthesis of functional resins. Amberlite XAD-4 adsorbent was impregnated with tri octyl phosphine oxides (Cyanex 921), which were then polymerized in the polymer carrier structure. The syntheses were evaluated by capturing FT-IR spectra, SEM micrographs, and analysing the sorption process. Batch studies were conducted to study the influence of some factors like pH, contact time, the metal ions concentration, and temperature on sorption efficiency of La (III) ions. The results showed that the optimum conditions were at pH equal to 0.5 and an equilibrium contact time of 30 min. According to the results of the sorption data analysis, the pseudo-second-order and Langmuir models were better fitted than the other estimated models. The sorption capacity of La (III) ions into impregnated resin as adsorbent martial was 54.25 mg g −1 . The results revealed that the used adsorbent has been used successfully as a promising material for the elimination and recovery of La ions from the aqueous solutions. The impregnated resin exhibits a high chemical stability, reusability and fast equilibration. Further, the above procedure has been successfully employed for the application of real sample.

The aim of this study was to extract pomegranate peel waste, a by-product of the fruit juice industry, and enrich it with ellagic acid using cost-effective, scalable physical separation methods. To achieve this, ultrafiltration was employed as a pre-enrichment technique. The results showed that ellagic acid was selectively concentrated in the retentate fraction, with an 118% increase in purity when a 10 kDa cut-off membrane was used. Subsequently, the adsorption efficiency of two adsorbents, Amberlite XAD-4 resin and activated charcoal, was evaluated for ellagic acid enrichment. Adsorption experiments were performed using adsorbent concentrations of 0.5%, 1%, 2%, and 4%, followed by testing the desorption steps separately with 70% ethanol, methanol, and absolute ethanol for 24 h. Static adsorption tests revealed that 2% activated carbon and 4% Amberlite XAD-4 resin achieved the highest adsorption efficiencies, with 100% and 99.3% for ellagic acid, respectively. These cost-effective and environmentally friendly processes significantly enhanced the ellagic acid concentration in pomegranate peel-derived polyphenols, reaching 17.4 g/100 g dry weight (DW). This demonstrates their potential for the sustainable valorization of fruit waste. The methodology presented here offers an efficient and scalable approach for the recovery of ellagic acid, supporting the development of a circular bioeconomy by converting agricultural by-products into high-value bioactive compounds.

Gamma-decalactone (GDL) is a fragrance compound obtained in the process of β-oxidation of ricinoleic acid, which is derived from the hydrolysis of castor oil. The biotechnological method of the synthesis of this lactone has been improved for over two decades, but the vast majority of research results have been based only on determining the concentration of the lactone by chromatographic methods without separating it from the biotransformation medium. In this study, we attempted to separate GDL from the medium in which the lactone was synthesized by Yarrowia lipolytica from castor oil. The effectiveness of liquid–liquid extraction, hydrodistillation, and adsorption on the porous materials (zeolite, vermiculite and resin Amberlite XAD-4) was compared. The influence of the solvent on the efficiency of GDL extraction, the influence of the acidity of the medium on the amount of GDL in the distillate, and the level of lactone adsorption on the above-mentioned adsorbents were compared by calculating the initial adsorption rate. The adsorption isotherm was determined for the most effective adsorbent. Among the five solvents tested, the most effective was diethyl ether, used at the ratio of 1:1. The extraction was characterized by higher efficiency than hydrodistillation; the difference in GDL determinations by these two methods ranged from 12.8 to 22%. The purity of the distillates was much higher than that of the extracts at 88.0 ± 3.4% compared to 53.0 ± 1.8%. The acidification of the biotransformation medium increased the concentration of the lactone in both the reaction mixture and the distillate. GDL was most efficiently adsorbed on Amberlite XAD-4 resin, for which the lactone isotherm adsorption was linear. The amount of lactone adsorbed on Amberlite XAD-4 within 1 h was approx. 80% (2.45 g), of which 1.96 g was then desorbed with ethanol. In the context of industrial applications, adsorption of GDL on Amberlite XAD-4 seems to be the most appropriate method due to material costs, the ease of the process, and low environmental burden.

Bacillus vallismortis and Bacillus mojavensis were loaded onto Amberlite XAD-4 resin and used for solid phase extraction (SPE) of uranium(VI). A quick and simple UV–Vis spectrophotometric method was used to determine U(VI) ion. The best experimental conditions were determined as being a pH of 5.0; a sample flow rate of 2.0 mL min−1; 200.0 mg of biosorbent; 800 mg of Amberlite XAD-4, and 5.0 mL of 1 mol L−1 HCl as desorption solution for both immobilized bacteria. The preconcentration factors were achieved as 80 for both solid phase extractor. The developed methods were validated by applying to reference water and tea samples.

A new solid phase extraction method was developed for the preconcentration and determination of the rare earth elements (REEs) Pr, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu at trace levels using a mini-column packed with 8-hydroxy-2-quinolinecarboxaldehyde functionalized Amberlite XAD-4 resin. The REE ions were adsorbed onto the resin and then eluted with 2 mL of 1.0 mol L −1 HNO 3 solution and determined using inductively coupled plasma-optical emission spectrometry (ICP-OES). In order to achieve the best performance for the method, the effects of several parameters such as sample pH, sample and eluent flow rate, sample volume, and matrix ions on the method efficiency were investigated. Under the optimum conditions, detection limits between 0.010 and 0.420 μg L −1 for a preconcentration factor of 12.5 were achieved. The sorption capacities for the resin were found to range between 49.6 μmol g −1 (for Yb) and 112.4 μmol g −1 (for Pr). In order to verify the accuracy of the developed method, a certified reference material (SPS-SW2 Batch 127 surface water) was analyzed, and the results obtained were in good agreement with the certified values. The method was also successfully applied to the determination of REEs in water samples with recoveries in the range of 88.4–100.5 % being obtained.

Safety and appropriate management of nuclear waste are of major importance in radioisotope production. Radioiodine has been identified as one of the most dangerous radioelements in terms of radiological effects in case of accidental release; accordingly substantial efforts are made to optimize the iodine capture in liquid effluents to avoid any possible iodine gas release from liquid waste during storage. The IRE (National Institute for Radioelements) produces radioelements such as Mo-99 for nuclear medicine. Its production process results in highly acidic and oxidizing effluents containing iodine which might thus be present in various oxidation states and species. This needs to be taken into account for the development of a decontamination process for these effluents. CL Resin (TrisKem International) is an extraction chromatographic resin showing high selectivity for noble metals over a large number of other elements. The CL Resin retains silver over a wide pH range including high acid concentrations. It was further shown, after being loaded with silver, to strongly retain iodine species forming insoluble complexes with silver making it well suited for use in the given context; XAD-4 Resin (Sigma-Aldrich) on the other hand is known to retain elemental iodine. A mixed bed column based on silver loaded CL Resin and XAD-4 resin was developed and optimized for iodine removal from IRE’s process effluents. Prepared mixed bed columns were evaluated by treating multi-curies production process solutions at the IRE. These columns showed high iodine removal from elevated effluent volumes (>10 L) even at flow-rates up to >180 mL min−1.