Electrostatic Attraction Research Articles

Outstanding performance of magnetic La2O2CO3/Fe3O4 nanosheets for simultaneous removal of phosphate and arsenate from wastewater

The chemical similarities and co-occurrence of phosphate and arsenate contamination have heightened the focus on their efficient simultaneous removal. In this study, magnetically recoverable La2O2CO3/Fe3O4 nanosheets were synthesized through the calcination of La-Fe binary metal glycolate. Based on magnetic and adsorption properties, La2O2CO3/Fe3O4 nanosheets with a La to Fe molar ratio of 1:1 (La2O2CO3/Fe3O4-1) were selected for further exploration. Electron microscopy characterization revealed that the nanocomposites consist of stacked La2O2CO3 and Fe3O4 nanosheets. The La2O2CO3/Fe3O4-1 nanocomposites exhibited exceptional adsorption capacities of 114.6 mg P/g and 230.2 mg As/g. Additionally, the material exhibited rapid adsorption kinetics and maintained excellent adsorption performance within a pH range of 3.0 to 9.0, showing significant selectivity for phosphate and arsenate even in the presence of various coexisting ions. Adsorption-desorption cycling tests indicated good potential for recycling. When applied to the spring water of Yangzonghai Lake, the material efficiently reduced the concentrations of phosphate and arsenate from 0.725 mg P/L and 1.380 mg As/L to below 0.020 mg P/L and 0.010 mg As/L, respectively. Mechanistic studies suggest that La2O2CO3 facilitates the removal of phosphate and arsenate primarily through electrostatic attraction and ligand exchange. These findings indicate that La2O2CO3/Fe3O4 holds significant promise for the co-removal of phosphate and arsenate, even at low concentrations.

Preparation and characterization of polyphenol-loaded microcapsules based on zeaxylated protein

Pomegranate seeds are rich in polyphenols, known for their significant health benefits. In this study, we developed microcapsules to encapsulate pomegranate seed polyphenols (PSP) using a combination of zeaxylated protein (Zein) and chitosan (Cs). The optimization process involved a Zein to Cs volume ratio of 1:1, a chitosan concentration of 1.0 mg·mL−1, and a polyphenol concentration of 2.0 mg·mL−1. Scanning electron microscopy confirmed the formation of Zein/Cs/PSP complex coacervates, indicating the successful encapsulation. Fourier-transform infrared spectroscopy provided further evidence of electrostatic attraction between PSP and the Zein/Cs matrix. Differential scanning calorimetry analysis demonstrated the successful incorporation of PSP into the Zein/Cs wall material. Moreover, the encapsulated core material exhibited exceptional storage stability and retained its antioxidant activity. Notably, more than 85% of the encapsulated PSP remained intact after 5 hours of simulated intestinal fluid digestion. This study underscores the potential of pomegranate seeds for comprehensive utilization in food engineering.

Heavy metals remediation through alkali assisted ball-milling activation of copper smelting slag for resource utilization

This study describes the preparation of Silico-Calcium-adhesive (CS-SS) by alkali-assisted ball milling to activate copper smelting slag (CS) for the remediation of heavy metals contamination and consequent resource utilization. The adsorption behavior and mechanisms of Cd(II), Cu(II) and Pb(II) in mono-metallic and polymetallic coexisting systems were investigated. The adsorption capacities of CS-SS were 21.906mg/g, 30.893mg/g and 93.593mg/g for Cd(II), Cu(II) and Pb(II) at a pH of 6, respectively. Based on the experimental results of monometallic system indicated that CS-SS exhibited the highest adsorption capacity for Pb(II), followed by Cu(II) and Cd(II). In the polymetallic system, the inhibitory impact of Pb(II) was more potent compared to Cd(II) and Cu(II). The adsorption mechanisms included electrostatic attraction, chemical adsorption, physical adsorption, ion exchange, functional group complexation and surface precipitation. Simple economic estimates show that it costs about $4.72 to treat 1 m3 of Cd(II)-20 mg/L, Cu(II)-30 mg/L and Pb(II)-90 mg/L containing wastewater. Therefore, the CS treatment method proposed in this study has certain feasibility and economic applicability.

Sustainable Zn2+ removal using highly efficient, novel, and cost-effective chitosan-magnetic biochar composite.

This study focused on the development of a sustainable and low-cost adsorbent derived from the chitosan-biochar composite for the removal of Zn2+ from an aqueous solution. Biochar was prepared from cotton stalk residue by pyrolysis at 600°C for 2h, modified with FeCl3, and composed with chitosan in various ratios (1:3, 1:1, 3:1), leading to the formation of an efficient, thermally stable, and rich with functional groups chitosan-biochar composite denoted as CHB-Fe-CS. Functional groups (hydroxyl, carboxyl, and amine) were identified as key contributors to the adsorption mechanism. Langmuir isotherm (R2 = 0.99) and Pseudo-Second order (R2 = 0.99) were best fitted models with the experimental results indicating chemisorption-driven monolayer adsorption. The results revealed CHB-Fe-CS (3:1) composite obtained the highest adsorption capacity of 117.50mg/g for Zn2+ under optimal conditions viz., 180min batch time, 500mg/l metal concentration, 4g/l adsorbent dosage, 40°C solution temperature, and 5.0 pH. Regeneration of the used adsorbent was performed using 0.2mol/l HCl and obtained desorption efficiency of 67.48% and 51.48% after the 4th and 8th cycles. The adsorption mechanisms were dominated by ion exchange, surface complexation, and electrostatic attraction compared to intra-particle diffusion and physisorption. The CHB-Fe-CS demonstrated an economical, environment friendly, and good performing adsorbent for water decontamination.

Dynamic Electrostatic Interfacial Engineering for Block Copolymer Microparticles with Reversible Structures.

Responsive nanoparticle surfactants (NPSs) can dynamically and reversibly modulate the interfacial interactions between incompatible components, which are essential in the interfacial catalysis, corrosion, and self-assembly of block copolymers (BCPs). However, NPSs with stimuli-responsive behavior often involve tedious chemical synthesis and surface modifications. Herein, we propose a strategy to in situ construct a kind of dynamic and reversible NPSs by the interfacial electrostatic interaction between the negatively charged nanoparticles (NPs) and the positively charged homopolymers. The NPSs assembled at the oil/water interface reduce the interfacial tension and direct the confined assembly of BCP. Meanwhile, the dynamic NPSs can be disassembled by increasing the pH value or introducing competitive electrostatic attractions, which can dynamically and reversibly change the interfacial properties as well as the alignment of polymer chains, enabling BCP microparticles with reversibly switchable lamellar and cylindrical structures. Furthermore, by the introduction of aggregation-induced emission luminogens as tails to the NPSs, the reversible transformation of BCP microparticles can be visualized by fluorescence emission, which is dependent on the nanostructures of microparticles. This work establishes a concept for dynamically manipulating interfacial interactions and reversibly switching BCP microparticles without time-consuming NPS synthesis, showing promising applications in the fabrication of smart materials with switchable structures and properties.

Undiminished performance in simultaneous phosphorus and dye recovery via ring-opening Mg-assembled carbonitride

The multiple effects of eutrophication and refractory organic dye may pose serious environmental risks, whereas conventional adsorbents mostly suffer from the disadvantage of performance degradation in complex environments. Herein, we designed Mg-assembled carbonitride (MAC) that allowed for phosphorus (P) and selective dye recovery (methylene blue (MB) as model pollutants) simultaneously, and then successfully separated the two pollutants in a simple way to obtain pure dyes and phosphorus-containing compounds. The triazine ring conjugation framework and abundant functional groups of carbonitride facilitated the doping of Mg sites. The adsorption capacity of MAC for P (211.6 ± 2 vs 207.4 mg P·g−1) and MB (116.5 ± 3 vs 117.8 mg MB·g−1) in the binary-polluted system exhibited little difference from the individual, implying synchronous and undiminished adsorption on MAC. This was attributed to the ring-opening reaction triggered by NaOH etching and thermal decomposition, generating the two new active sites, where cyano groups (C N) interacted with P and Mg–N bonds responded with both target pollutants. Moreover, the favorable selective adsorption ability of MAC for different dyes was attributed to electrostatic attraction, surface complexation, hydrogen bonds and π-π interactions. This study provides a good reference for exploiting performance-stable multifunctional adsorbents for applications in wastewater resource recovery.

Synthesis of activated carbon from waste polyester fabric activated by ZnCl2 and its adsorption for organic dyes

In order to achieve the resource utilization of waste polyester (WPT), the WPT based activated carbon (WPT-AC) was prepared by ZnCl2 activation high-temperature pyrolysis method. The phase morphology, characteristic groups, pore structure of specific surface area and microstructure were characterized by TGA, XRD, FTIR, BET and SEM. The optimum preparation process of WPT-AC was determined by L9(34) orthogonal experiment, and the adsorption performance of WPT-AC for methylene blue (MB) was evaluated. WPT-AC showed a high specific surface area of 1037.62 m2/g, with rich pore structure, which provided the possibility for efficient adsorption. The pretreatment of ZnCl2 plays a key role in the formation of WPT-AC pore structure, and the abundant pore structure is conducive to improving the adsorption of pollutants. WPT-AC showed excellent performance in the field of organic dye adsorption, and the highest removal rate of MB reached 97.34%. The adsorption was mainly related to electrostatic attraction, hydrogen bonding and π–π conjugation. The analysis of adsorption kinetics and thermodynamics is conducive to a better understanding of the adsorption process.

Removal of Metribuzin and Bentazon by LDH-HA Modified Material: Kinetic and Equilibrium Study

ABSTRACT This study investigates the adsorption behavior of herbicides Metribuzin and Bentazon using a soil model incorporating Layered Double Hydroxide (LDH) and humic acid. Mg3AlCl-LDH, synthesized at pH 10, was combined with humic acid to produce two distinct materials: Mg3–5%HA and Mg3–10%HA. These materials were characterized using FTIR, XRD, and SEM techniques. The research confirms that humic acid adsorbs onto the LDH surface without altering its structure, resulting in negatively charged materials. While both materials fully adsorb Metribuzin at 20 mg/L, their adsorption capacities diverge at higher concentrations, with Mg3–10%HA exhibiting a higher capacity than Mg3–5%HA. In contrast, Bentazon’s adsorption is unaffected by humic acid content, displaying identical adsorption capacities in both materials at different concentrations. Both herbicides exhibit rapid adsorption kinetics, reaching equilibrium in 15 minutes. The Avrami model accurately predicts equilibrium adsorption capacities, with Metribuzin primarily adsorbed through electrostatic attraction and hydrogen bonding, while Bentazon’s adsorption is limited due to electrostatic repulsion. The adsorption of both herbicides by Mg3-HA materials is not influenced by pH variations, likely due to the surface charge of the materials. Metribuzin retention in soil containing LDH and humic acid is effective, increasing with higher humic acid concentrations, whereas Bentazon demonstrates greater mobility and resistance. These findings provide valuable insights for developing efficient water decontamination techniques, with implications for environmental protection and public health. Policymakers, researchers, and professionals in water management and pollution control should consider these findings to enhance current practices and technologies.

The heavy atom structure, "cis effect" on methyl internal rotation, and 14N nuclear quadrupole coupling of 1-cyanopropene from quantum chemical and microwave spectroscopic analysis.

The microwave spectrum of 1-cyanopropene (crotonitrile) was remeasured using two pulsed molecular jet Fourier transform microwave spectrometers operating from 2.0 to 40.0 GHz. The molecule exists in two isomer forms, E and Z, with respect to the orientation between the methyl and the cyano groups. The spectrum of the Z isomer is more intense. Due to internal rotation of the methyl group, doublets containing A and E torsional species were found for all rotational transitions. Hyperfine splittings arising from the 14N nuclear quadrupole coupling were resolved. The heavy atom structure of the Z isomer was determined by observation of 13C and 15N isotopologue spectra in natural abundances. The experimental results were supported by quantum chemistry. The complex spectral patterns were analyzed and fitted globally, and the barriers to methyl internal rotation are determined to be 478.325(28) cm-1 and 674.632(76) cm-1 for the Z and E isomers, respectively. The non-bonded intramolecular electrostatic attraction between the methyl group and the 1-cyano substituent overcomes steric hindrance, leading to higher stability of the Z isomer. The consequence is a slight opening of 3.2° of the C(1)-C(2)-C(3) angle and a radical decrease of the methyl torsional barrier in the Z isomer due to steric repulsion.

Influence of biochar on the removal of Microcystin-LR and Saxitoxin from aqueous solutions

The present study assessed the effective use of biochar for the adsorption of two potent HAB toxins namely, Microcystin-LR (MCLR) and Saxitoxin (STX) through a combination of dosage, kinetic, equilibrium, initial pH, and competitive adsorption experiments. The adsorption results suggest that biochar has excellent capabilities for removing MCLR and STX, with STX reporting higher adsorption capacities (622.53–3507.46 µg/g). STX removal required a minimal dosage of 0.02 g/L, while MCLR removal needed 0.4 g/L for > 90%. Similarly, a shorter contact time was required for STX removal compared to MCLR for > 90% of toxin removed from water. Initial pH study revealed that for MCLR acidic conditions favored higher uptake while STX favored basic conditions. Kinetic studies revealed that the Elovich model to be most suitable for both toxins, while STX also showed suitable fittings for Pseudo-First Order and Pseudo-Second Order in individual toxin systems. Similarly, for the Elovich model the most suited kinetic model for both toxins in presence of each other. Isotherm studies confirmed the Langmuir–Freundlich model as the best fit for both toxins. These results suggest adsorption mechanisms including pore filling, hydrogen bonding, π–π interactions, hydrophobic interactions, electrostatic attraction, and dispersive interactions.

Rock fines breakage by flow-induced stresses against drag: geo-energy applications

The paper presents a strength-failure mechanism for colloidal detachment by breakage and permeability decline in reservoir rocks. The current theory for permeability decline due to colloidal detachment, including microscale mobilisation mechanisms, mathematical and laboratory modelling, and upscaling to natural reservoirs, is developed only for detrital particles with detachment that occurs against electrostatic attraction. We establish a theory for detachment of widely spread authigenic particles due to breakage of the particle-rock bonds, by integrating beam theory of particle deformation, failure criteria, and creeping flow. Explicit expressions for stress maxima in the beam yield a graphical technique to determine the failure regime. The core-scale model for fines detachment by breakage has a form of maximum retention concentration of the fines, expressing rock capacity to produce breakable fines. This closes the governing system for authigenic fines transport in rocks. Matching of the lab coreflood data by the analytical model for 1D flow exhibits two-population particle behaviour, attributed to simultaneous detachment and migration of authigenic and detrital fines. High agreement between the laboratory and modelling data for 16 corefloods validates the theory. The work is concluded by geo-energy applications to (i) clay breakage in geological faults, (ii) typical reservoir conditions for kaolinite breakage, (iii) well productivity damage due to authigenic fines migration, and (iv) feasibility of fines breakage in various geo-energy extraction technologies.

Calcined MgFe layered double hydroxides for magnetic separation and enhanced adsorption performance of methyl orange: Mechanism based on the memory effect

This study successfully synthesized magnetic MgFe-layered double oxides (MgFe-LDO-500 °C) by calcining MgFe-layered double hydroxides (MgFe-LDHs) at 500 °C. Calcination temperature was identified as a critical factor for optimizing adsorption capacity and activating a memory effect, with 500 °C being particularly effective. The adsorption performance of MgFe-LDO-500 °C towards methyl orange (MO) in aqueous solutions was evaluated across varying pH levels (2–12), initial MO concentrations (50–1800 mg/L), contact times (0–1440 min), and temperatures (25–45 °C). The results indicated that MgFe-LDO-500 °C adsorption conforms to the pseudo-second-order kinetic and Langmuir models, achieving a theoretical maximum adsorption capacity of 5087.76 mg/g. Characterization through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Zeta potential analysis revealed that the outstanding adsorption performance of MgFe-LDO-500 °C towards MO involves a combination of electrostatic attraction, memory effect, and surface complexation. Moreover, after four regeneration cycles, the material maintained a 73 % MO removal efficiency and could be efficiently separated using magnetic separation technology. In conclusion, MgFe-LDO-500 °C represents a promising adsorbent for wastewater treatment.

Polyoxometalate coupled polymers induced molybdenum phosphide with large surface area for efficient hydrogen evolution

Developing highly active hydrogen evolution reaction (HER) electrocatalysts possesses great significance for the green renewable energy conversion and storage. Here, through the electrostatic attraction between polyoxometalate (PMo12) and ammonium polyphosphate (APP) and the coordination with polyallylamine hydrochloride (PAH), the precursor was constructed, and then nitrogen-doped graphite carbon layer-coated MoP active particles (MoP@NC) were successfully prepared by high temperature carbonization. For HER, the overpotential of η10 for MoP@NC is 119 and 126 mV in acidic and alkaline electrolyte. Furthermore, in alkaline solution, when the current density reaches a certain degree (≥110 mA cm−2), the hydrogen production activity of the catalysts are the same as that of the industrial Pt/C catalysts, or even have a slight advantage. The synergistic interaction of active particles (MoP) and graphitic carbon layers and high specific surface area ensure the excellent activity of HER. N-doped porous carbon layers also protect MoP@NC working for 24 h. Moreover, the catalysts prepared in the same experimental environment with ammonium molybdate as metal source also showed good HER performance in acidic and alkaline environments. This study opens a general way to develop earth-rich Mo-based phosphide electrocatalysts with high activity for hydrolysis applications.

Construction of durable, multifunctional superhydrophobic wood surface via ɛ-polylysine/PDMS/wax treatment

In addressing the limitations of wood's susceptibility to water and moisture, this study explored the development of a durable, superhydrophobic surface through a novel ɛ-polylysine/polydimethylsiloxane (PDMS)/wax composite system. Leveraging the layer-by-layer (LBL) assembly, the incorporation of cationic ɛ-polylysine not only improved the adherence of PDMS and wax to the wood surface through electrostatic attraction but also facilitated a more uniform distribution, achieving optimal hydrophobicity at a ɛ-polylysine concentration of 2 g/L. The synergistic effect of the wood's natural rough structure and the deposition of these hydrophobic substances endowed the treated wood with superhydrophobic properties, showcasing exceptional self-cleaning capabilities by efficiently repelling a variety of liquid contaminants. Durability assessments through sandpaper abrasion, chemical exposure, and accelerated weathering tests confirmed the enhanced long-term stability of the treated wood surfaces. Furthermore, the incorporation of ε-polylysine provided nice antimicrobial properties, showing a substantial reduction in bacterial adhesion. The ε-polylysine/PDMS/wax composite system represents a significant advancement in the development of multifunctional wood surfaces, promising broader applications in sustainable building materials, furniture, and packaging solutions.

Fabrication of lignosulfonate-derived porous carbon via pH-tunable self-assembly strategy for efficient atrazine removal

Herein, a straightforward protocol was developed for the one-pot synthesis of N-doped lignosulfonate-derived carbons (NLDCs) with a tunable porous structure using natural amino acids-templated self-assembly strategy. Specifically, histidine was employed as a template reagent, leading to the preparation of 10-NLDC-21 with remarkable characteristics, including the large specific surface area (SBET = 1844.5 m2/g), pore volume (Vmes = 1.22 cm3/g) and efficient adsorption for atrazine (ATZ) removal. The adsorption behavior of ATZ by NLDCs followed the Langmuir and pseudo-second-order models, suggesting a monolayer chemisorption nature of ATZ adsorption with the maximum adsorption capacity reached up to 265.77 mg/g. Furthermore, NLDCs exhibited excellent environmental adaptability and recycling performance. The robust affinity could be attributed to multi-interactions including pore filling, electrostatic attraction, hydrogen bonding and π-π stacking between the adsorbents and ATZ molecules. This approach offers a practical method for exploring innovative bio-carbon materials for sewage treatment.

β-Ketoenamine covalent organic frameworks with abundant carboxyl groups for the efficient removal of malachite green in actual water environments

In this study, imine-based COF (TpPa-2COOH) with abundant carboxyl groups is constructed by 1,3,5-triisopropylchloroglucitol (Tp) and 2,5-diaminoterephthalic acid (Pa-2COOH) via “one-step” approach with solvent stability and resistance to acidity and alkalinity. TpPa-2COOH COF achieves highly efficient malachite green (MG) adsorption with a maximum adsorption of 296.56 mg·g−1 at pH = 5, and the adsorption capacity exceeds many reported adsorbents. Meanwhile, TpPa-2COOH COF shows outstanding adsorption performance to MG, such as 97.67 % removal rate in actual water environments, unique selective adsorption of MG in kinds of contaminants and good adsorption capacity in highly concentrated salt solutions. Additionally, TpPa-2COOH COF shows 78.4 % removal rate after six cyclic desorption-adsorption, demonstrating its excellent recyclability. Furthermore, the processes of monolayer adsorption and chemisorption are confirmed by the isotherms and kinetics of adsorption experiments. The adsorption mechanisms of π-π interaction, electrostatic attraction, hydrogen bonding and channel adsorption are further verified by XPS, EDX, Zeta potential and DFT calculations. This work hopes the synthesis and adsorption application of carboxylated COFs provide new ideas for developing novel adsorbents.

Demulsification of W/O emulsions induced by terahertz pulse electric fields-driven hydrogen bond disruption of water molecules

Demulsifying highly stable W/O emulsions, composed of heavy oil and water, is crucial for simplifying crude oil processing, reducing production costs, and mitigating environmental pollution. In these emulsions, aromatic components in the oil phase stack via π-π interactions, while hydrogen bonds stabilize the water phase. This leads to the creation of a strong oil-water interface through electrostatic attraction, ultimately hindering water droplet coalescence and oil-water separation. In this study, a 1.0 THz pulse electric field is introduced to effectively disrupt the hydrogen bond network among water molecules by inducing hydrogen bond resonance. This disruption contributes to increased water mobility in the oil phase, weakened stability of the oil-water interface film, and facilitates efficient water droplet coalescence in the oil phase. The results show that throughout the demulsification process, the average number of hydrogen bonds per water molecule rapidly decreases from 1.41 to 1.08 within 100 ps. The upper and lower limits of hydrogen bond lifetimes decrease by 8.12 ps and 3.24 ps, respectively. This indicates a significant disruption in the stability of hydrogen bonds between water molecules. Concurrently, the terahertz pulse electric field disrupts the initially stable oil-water interface film of the emulsion system, leading to a noteworthy reduction in the oil-water interface tension from 54.3 to 39.2 mN·m−1. The self-diffusion coefficient of water molecules increases from 1.33 to 2.62 Å2·ps−1, signifying that water molecules are more inclined to penetrate the interfacial region between the two phases. Additionally, the terahertz pulse electric field induces alterations in the arrangement of water molecules, resulting in the rearrangement of electrons in the water phase and disrupting the originally stable electrical double layer structure of the oil-water interface. This study provides novel insights into the development of efficient and environmentally friendly electric demulsification technologies, holding significant potential for widespread industrial applications.

ZIF-8-derived N-doped porous carbon electrodes enabled with in situ embedded ZrO2 nanoparticles for phosphorus removal

Excessive phosphorus discharges are not favorable to the normal functioning of water ecosystems. Although some treatments have been implemented to control phosphorus concentrations in sewage, several challenges remain for them. Capacitive deionization technology (CDI) possesses excellent potential for phosphorus removal, and the electrode material is the key to CDI. Herein, a novel ZIF-8-derived N-doped porous carbon electrode enabled with in situ embedded ZrO2 nanoparticles (ZNPC) was fabricated through a simple in-situ growth approach. The experimental results demonstrate that ZrO2 embedded in ZNPC can improve the electrochemical performance and provide suitable affinity sites for phosphorus, thus enhancing the electrode performance in capturing phosphorus. Isothermal and kinetic models were adopted to investigate the phosphorus uptake process. Mechanism analysis reveals that the phosphorus removal behavior is associated with the electric field, ligand exchange, and electrostatic attraction. This study provides a promising approach for facile constructing Zr-based N-doped porous carbon and expands its potential utility for phosphorus removal from aqueous solutions.

STMP and PVPA as Templating Analogs of Noncollagenous Proteins Induce Intrafibrillar Mineralization of Type I Collagen via PCCP Process.

The phosphorylated noncollagenous proteins (NCPs) play a vital role in manipulating biomineralization, while the mechanism of phosphorylation of NCPs in intrafibrillar mineralization of collagen fibril has not been completely deciphered. Poly(vinylphosphonic acid) (PVPA) and sodium trimetaphosphate (STMP) as templating analogs of NCPs induce hierarchical mineralization in cooperation with indispensable sequestration analogs such as polyacrylic acid (PAA) via polymer-induced liquid-like precursor (PILP) process. Herein, STMP-Ca and PVPA-Ca complexes are proposed to achieve rapid intrafibrillar mineralization through polyelectrolyte-Ca complexes pre-precursor (PCCP) process. This strategy is further verified effectively for remineralization of demineralized dentin matrix both in vitro and in vivo. Although STMP micromolecule fails to stabilize amorphous calcium phosphate (ACP) precursor, STMP-Ca complexes facilely permeate into intrafibrillar interstices and trigger phase transition of ACP to hydroxyapatite within collagen. In contrast, PVPA-stabilized ACP precursors lack liquid-like characteristic and crystallize outside collagen due to rigid conformation of PVPA macromolecule, while PVPA-Ca complexes infiltrate into partial intrafibrillar intervals under electrostatic attraction and osmotic pressure as evidenced by intuitionistic 3D stochastic optical reconstruction microscopy (3D-STORM). The study not only extends the variety and size range of polyelectrolyte for PCCP process but also sheds light on the role of phosphorylation for NCPs in biomineralization.

Magnetic field-assisted adsorption of phosphate on biochar loading amorphous Zr–Ce (carbonate) oxide composite

For metal-based phosphate adsorbents, the dispersity and utilization of surface metal active sites are crucial factors in their adsorption performance and synthesis cost. In this study, a biochar material modified with amorphous Zr–Ce (carbonate) oxides (BZCCO-13) was synthesized for the phosphate uptake, and the adsorption process was enhanced by magnetic field. The beside-magnetic field was shown to have a better influence than under-magnetic field on adsorption, with maximum adsorption capacities (123.67 mg P/g) 1.14-fold greater than that without magnetic field. The beside-magnetic field could also accelerate the adsorption rate, and the time to reach 90% maximum adsorption capacity decreased by 83%. BZCCO-13 has a wide range of application pHs from 5.0 to 10.0, with great selectivity and reusability. The results of XPS and ELNES showed that the "magnetophoresis" of Ce3+ under the magnetic field was the main reason for the enhanced adsorption performance. In addition, increased surface roughness, pore size and oxygen vacancies, enhanced mass transfer by Lorentz force under a magnetic field, all beneficially influenced the adsorption process. The mechanism of phosphate adsorption by BZCCO-13 could be attributed to electrostatic attraction and CO32–dominated ligand exchange. This study not only provided an effective strategy for designing highly effective phosphate adsorbents, but also provides a new light on the application of rare earth metal-based adsorbent in magnetic field.