Performance analysis of hydrated Zr(IV) oxide nanoparticle-impregnated anion exchange resin for selective phosphate removal

Selective extraction of phospholipids from human milk using glass fabric modified with zirconium-based metal organic framework

Phospholipids (PLs) are important and complex trace lipids in milk, which have positive effects on the infants' nervous and immune system development. Herein, a new method for selective extraction of PLs using glass fabric @ MOF-808 was proposed. Based on Lewis acid-base interaction, MOF-808 containing abundant Zr-OH groups was selected as the adsorption body, and glass fabric was used as a substrate to make the adsorbent easy to remove and reuse. The influencing factors such as loading solution, extraction time, eluent and elution time were further investigated. The adsorbent showed high adsorption capacity (3.31-6.54 mg/g for PLs) and good reusability (reused at least five times). The method showed low detection limits (1.61 μg/L - 10.24 μg/L) and quantification limits (5.24 μg/L-51.21 μg/L) for eight classes of PLs. The analysis of PLs in human milk at different lactation stages by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry could obtain up to 206 PLs, indicating that the method has extremely high extraction and anti-interference capabilities. This work is the first time to introduce MOF materials to selectively extract PLs and use glass fabric as a substrate for MOF-808, which has the advantages of easy recovery and high sensitivity. It provides technical support for the discovery of more PL species and has potential applications in phospholipidomics.

Optimization of phosphate oxygen isotope pretreatment measurement method based on phosphate in situ enrichment blanket

Phosphate oxygen isotope analysis is an effective tool for investigating phosphorus migration and transformation in water bodies. Unfortunately, current pretreatment methods for this technology are significantly limited due to their demanding sample amount requirements, complex operation, and limited scope of application. In order to enhance the efficiency of the pretreatment process, hydrated zirconia was synthesized through liquid-phase precipitation. Zeolite, D001 macroporous resin, activated carbon, and ceramsite were chosen as possible candidate materials for loading purposes. The optimal zirconium loading material was identified through a combination of field enrichment and laboratory elution experiments. The ideal in situ enrichment duration, material dosages, and elution time were ascertained using response surface methodology. The findings showed that D001 resin exhibited superior selective adsorption and elution capacity for phosphate. The response surface optimization yielded the optimal parameters for the in situ phosphate-enrichment blanket: a mass of 13 g for zirconium-loaded D001 resin, an enrichment period of 360 min, and an elution period of 853 min. The attainment of a bright yellow Ag3PO4 solid after purification served as proof of the reliability of the optimization method. The obtained results provide a fundamental basis for the preparation and application of phosphate oxygen isotope analysis in freshwater ecosystem.

A novel glucose-based highly selective phosphate adsorbent

Industrial wastewater discharge leads to serious eutrophication of water bodies, but most of the adsorbents are difficult to selectively remove phosphorus and are difficult to use multiple times, therefore, developing an efficient and reusable material for removal phosphate is extremely necessary. In this work, a kind of highly selective phosphate adsorbent, microporous carbon material (MCM), based on glucose was synthesized by hydrothermal and activation method. The MCM were characterized by SEM, XPS, BET, element analysis, et al. The phosphate adsorption mechanism of MCM were investigated by batch adsorption experiment and model calculation. Results showed that MCM had a high adsorption capacity for phosphate in a wide range of pH (1.5-10). Langmuir model and pseudo-second-order kinetic revealed that the process was endothermic and involved both physical and chemical adsorption. The main phosphate adsorption mechanisms of MCM are electrostatic attraction, ion complexation, hydrogen bonding, and physical adsorption. The ions competition simulation experiment indicated that the MCM was highly selective for phosphate removal. Furthermore, the phosphate adsorption tests were carried out on five kinds of water, and the removal rates were all above 99.98%. The 20 regenerative cycles experiment revealed that the MCM had high reusability. Therefore, this kind of novel glucose-based highly selective phosphate adsorbent with multi-cycle phosphorus removal performance can improve the eutrophication of water. This study provides a new idea for phosphate removal and expands the application range of glucose-based carbon materials.

Copper Rich Composite Materials Based on Carboxylic Cation Exchangers and Their Thermal Transformation

The effect of a cupric deposit (Cu2+, CuO) on the thermal decomposition of carboxylic cation exchangers (CCEs) is not known, and such studies may have practical significance. CCEs have a very high ion exchange capacity, so an exceptionally large amount of CuO (which is a catalyst) can be precipitated inside them. Two CCEs, macroreticular (Amberlite IRC50) and gel-like (Amberlite IRC86), served as a polymeric support to obtain copper-rich hybrid ion exchangers. Composites with CuO particles inside a polyacrylic matrix (up to 35.0 wt% Cu) were obtained. Thermal analyses under air and under N2 were performed for CCEs in the H+ and Cu2+ form with and without a CuO deposit. The results of sixteen experiments are discussed based on the TG/DTG curves and XRD patterns of the solid residues. Under air, the cupric deposit shifted the particular transformations and the ultimate polymeric matter decomposition (combustion) toward lower temperatures (even about 100-150 °C). Under N2, the reduction of the cupric deposit to metallic copper took place. Unique composite materials enriched in carbonaceous matter were obtained, as the products of polymeric matrix decomposition (free radicals and hydrogen) created an additional amount of carbon char due to the utilization of a certain amount of hydrogen to reduce Cu (II) to Cu0.

Layered zinc hydroxide as an adsorbent for phosphate removal and recovery from wastewater

At present, phosphate removal and recovery from wastewater is gaining wide attention due to the dual issues of eutrophication, caused by the increased production of algae, and universal phosphorus scarcity. In this study, a layered zinc hydroxide (LZH) was synthesized by a simple precipitation method and characterized via various techniques. Experiments investigating the effect of contact time, pH, LZH dose, initial phosphate concentration, and co-existing ions on phosphate adsorption were conducted. LZH exhibited a high phosphate adsorption capacity (135.4 mg g⁻¹) at a neutral pH. More than 50% of phosphate was removed within the first 60 s of contact time at an initial phosphate concentration of 5 mg L⁻¹. Phosphate removal using the as-prepared LZH adsorbent was also tested in real treated sewage effluent reducing the residual phosphate amount to levels inhibiting to the growth of algae. Furthermore, phosphate desorption from LZH was investigated using acetic acid and sodium hydroxide regenerants which showed to be very effective for phosphate recovery.

This study demonstrates a novel LZH adsorbent synthesized, characterized and applied for high phosphate removal and recovery from wastewater.

Weakly Hydrated Anion Exchangers Doped with Cu2O and Cu0 Particles-Thermogravimetric Studies

Hybrid ion exchangers (HIXs) containing fine Cu₂O and Cu⁰ particles were subjected to thermal analysis in order to determine their hygroscopic water content (with regard to their anomalously low porosity) and to determine the effect of the oxidation state of the copper atom in the deposit on the thermal properties of composite materials. Commercially available anion exchangers, Amberlite IRA 900Cl (macroreticular, M) and Amberlite IRA 402OH (gel-like, G), were used as supporting materials. M/Cu₂O, G/Cu₂O, M/Cu and G/Cu, containing 4.3–8.4 wt% Cu, were subjected to thermal analysis under respectively air and N₂. TG/DTG curves revealed that dry M/Cu and G/Cu contained as little as 7.2% and 4.3% hygroscopic water, while M/Cu₂O and G/Cu₂O contained respectively 10.6% and 9.4% (Cu⁰ was a stronger water repellent than Cu₂O). The oxidation state of the copper atom in the deposit was found to affect the amount of the forming char, and also Cu⁰ was found to contribute to the formation of more char than in the pyrolysis of the pure resin (the anion exchanger with no copper deposit). Under air the two kinds of particles transformed into CuO, while under N₂ metallic copper and char (from the resin phase) made up the solid residue. This means that in the pyrolysis of the HIXs the inorganic phase participated in char formation and it also transformed itself (undergoing reduction when possible). The above findings provide a basis for in-depth research aimed at the innovative use of copper-containing HIXs and at obtaining usable composite materials with a designed (organic-inorganic) composition.