Enhanced Ca2+ binding with sulfonic acid type polymers at increased temperatures

Scalable Fabrication of Ionic-Conductive Covalent Organic Framework Fibers for Capturing of Sustainable Osmotic Energy

High-performance covalent organic framework (COF) fibers are demanded for an efficient capturing of blue osmotic power because of their excellent durability, simple integration, and large scalability. However, the scalable production of COF fibers is still very challenging due to the poor solubility and fragile structure of COFs. Herein, for the first time, it is reported that COF dispersions can be continuously processed into macroscopic, meter-long, and pure COF fibers using a wet spinning approach. The two presented COF fibers can be directly used for capturing of osmotic energy, avoiding the production of composite materials that require other additives and face challenges such as phase separation and environmental issues induced by the additives. A COF fiber exhibits power densities of 70.2 and 185.3 W m-2 at 50-fold and 500-fold salt gradients, respectively. These values outperform those of most reported systems, which indicate the high potential of COF fibers for capturing of blue osmotic energy.

Adsorption mechanism of Ca2+, Mg2+, Fe3+, and Al3+ ions in phosphoric acid-nitric acid solution on 001 × 7 and S957 resins

Selective removal of Ca2+ and Mg2+ ions using the 001 × 7 resin and Fe3+ and Al3+ ions using the S957 resin is able to achieve the deep purification of the phosphoric acid-nitric acid solution, but the adsorption behaviors of Fe3+ and Al3+ ions are seriously suppressed by phosphoric acid. In order to understand the interaction mechanism of separation processes and the influence of phosphoric acid, we first studied the bonding form of Ca2+, Mg2+, Fe3+, and Al3+ ions on 001 × 7 and S957 resins using FT-IR and XPS techniques; subsequently, quantum chemistry computation was carried out to further explore the bonding mechanism between the functional groups on resins and metal ions. FT-IR and XPS results reveal that for the adsorption process on the 001 × 7 resin, hydroxyls from sulfonic acid groups combine with Ca2+ and Mg2+ ions. Whereas Fe3+ and Al3+ ions are adsorbed on the S957 resin through an exchange reaction with hydroxyls on the phosphonic acid group but not on the sulfonic acid group. Quantum chemistry computation results reveal that the phosphonic acid group has a larger binding energy with Fe3+ and Al3+ ions. Thus, the S957 resin still presents great adsorption performance for Fe3+ and Al3+ ions despite the influence of dihydrogen phosphate ions in the phosphoric acid-nitric acid solution.

Inhibition of Poly(ethylenediaminetetraacetic acid-diethanolamine) on Deposition of Calcium Sulfate Crystal in Simulated Industrial Water

Calcium sulfate scale is a typical deposit on the equipment pieces or pipes of an industrial water system. Scale inhibitors could obviously reduce the precipitation of calcium sulfate crystal. The development and research of late-model environmentally friendly polymer inhibitors are often urgent problems to be addressed. A water-soluble poly(ethylenediaminetetraacetic acid-diethanolamine) (PEDTA-DEA) was successfully synthesized by thermal polycondensation of ethylenediaminetetraacetic acid (EDTA) with diethanolamine (DEA). The polymer product was characterized by Fourier infrared spectrum (FTIR) and the molecular weight was measured by gel chromatography, which confirms the polymerization of the two monomers. The inhibition effect of the polymer against calcium sulfate deposition was studied by static scale inhibition tests. When the Ca2+ concentration is 3000 mg/L, and the dosage of the polymer inhibitor is 10 mg/L, the inhibition effect exceeds 90%. The results show that PEDTA-DEA can inhibit the precipitation of calcium sulfate and reduce the deposition of calcium sulfate scale. The precipitate of calcium sulfate collected from the static scale inhibition test solution was analyzed by FTIR, scanning electron microscope (SEM) and X-ray diffraction (XRD). The results revealed that the addition of the polymer significantly changes the calcium sulfate crystal’s growth shape. Therefore, PEDTA-DEA is a potential calcium sulfate precipitation inhibitor for the industrial water system.

A Systematic Investigation on the Properties of Silica Nanoparticles "Multipoint"-Grafted with Poly(2-acrylamido-2-methylpropanesulfonate-co-acrylic Acid) in Extreme Salinity Brines and Brine-Oil Interfaces

Nanoparticles (NPs) may have great potential for various subsurface applications, including oil and gas recovery, reservoir imaging, and environmental remediation. One of the important challenges for these downhole applications is to achieve colloidal stability in subsurface media at high salinity and high temperature. It has been previously shown that several functional NPs "multipoint"-grafted with anionic poly(2-acrylamido-2-methyl-1-propanesulfonate-co-acrylic acid; AMPS-co-AA) exhibited remarkable colloidal stabilities in specific environments mimicking the harsh subsurface aquatic media, such as the American Petroleum Institute (API) brine. However, many important properties of such particles, other than the colloidal stabilities, must be studied in a more systematic fashion for a wide range of salt concentrations (C_s). Herein, we investigate various properties of the silica (SiO₂) NPs multipoint-grafted with poly(AMPS-co-AA), SiO₂-g-poly(AMPS-co-AA), in NaCl and CaCl₂ solutions across a range of salinities. The brush behavior of the grafted random copolymers was investigated in both salt solutions from salt-free conditions up to extreme salinities. The particles displayed brine-oil interfacial activity with increasing C_s, stabilizing oil-in-brine emulsions as Pickering emulsifiers. A high internal phase emulsion (HIPE) with an internal oil phase of up to 80 vol % could be formed in CaCl₂ solutions at high C_s, which exhibited gel-like behaviors.

Polyelectrolyte-grafted Ti3C2-MXenes stable in extreme salinity aquatic conditions for remediation of contaminated subsurface environments

Polyelectrolyte-grafted Ti₃C₂-MXenes display high colloidal stability and low adsorption to mineral substrates in extreme salinity aquatic media, while maintaining decent removal efficiency for aqueous organic dyes.

Calcium carbonate nucleation driven by ion binding in a biomimetic matrix revealed by in situ electron microscopy

The characteristic shapes, structures and properties of biominerals arise from their interplay with a macromolecular matrix. The developing mineral interacts with acidic macromolecules, which are either dissolved in the crystallization medium or associated with insoluble matrix polymers, that affect growth habits and phase selection or completely inhibit precipitation in solution. Yet little is known about the role of matrix-immobilized acidic macromolecules in directing mineralization. Here, by using in situ liquid-phase electron microscopy to visualize the nucleation and growth of CaCO3 in a matrix of polystyrene sulphonate (PSS), we show that the binding of calcium ions to form Ca-PSS globules is a key step in the formation of metastable amorphous calcium carbonate (ACC), an important precursor phase in many biomineralization systems. Our findings demonstrate that ion binding can play a significant role in directing nucleation, independently of any control over the free-energy barrier to nucleation.