Hydrophilic Ions Research Articles

Computational engineering of water-soluble human potassium ion channels through QTY transformation.

Transmembrane potassium ion channels are crucial for ion transport, metabolism, and signaling, and serve as promising targets for anti-cancer therapies. However, their hydrophobic transmembrane nature requires detergents, posing a major bottleneck for experimental handling. In this paper, we present a structural bioinformatics study of six experimentally determined and twelve modeled potassium channel structures, in which hydrophobic amino acids (L, I/V, and F) were systematically replaced with neutral hydrophilic ones (Q, T, and Y), making the proteins more water-soluble. QTY (computationally predicted) and native (experimental and repredicted) variants show remarkable structural similarity (RMSD: ~0.50 Å - ~2.14 Å) despite significant sequence differences. QTY variants, both rigid and refined with MD simulations, maintain comparable to native variants stability, solvent-accessible surface area (SASA), and ionic, aromatic, and van der Waals interactions but differ in the grand average of hydropathy (GRAVY), solubility, and hydrophobic contacts. Overall, our study presents a computational approach for designing hydrophilic potassium ion channels while maintaining the native global structure that could potentially simplify their practical use by eliminating the need for detergents.

Synergistic effect of Fe/Zr dual doping endows hydrophilic spinel-structured H4Ti5O12 ion sieves for efficient lithium extraction from liquid resources

The practical application of spinel-structured H4Ti5O12(HTO) lithium-ion sieves (LISs) is hampered by their poor adsorption properties and recyclability. Within this research, the surface properties and internal structure of lithium-ion sieve (LIS) materials were modulated by co-doping Fe and Zr metal ions to enhance their adsorption properties. The results show that Fe and Zr have been successfully introduced to the LIS lattice, increasing Li-O bond length of position 8a and O2− content. The synthesized H4Ti4.77Fe0.2Zr0.03O12 (HTFZO-II) LIS was made up of evenly distributed nanosheets layered on top of one another to create an open laminar structure, which possesses a hydrophilic surface (contact angle: 17.8°), a high surface area (95.89 m2/g), and hierarchical porous structure. Compared with the undoped HTO, the HTFZO-II LISs enjoy a high capacity for Li+ adsorption (28.72 mg/g), a strong cycling stability (Ti4+ dissolving loss: 0.12 %), and a fast reaching of the equilibrium in adsorption (adsorption equilibrium: 4 h). Theoretical calculation of DFT shows that Li(H2O)4+ on HTFZO-II and HTO dehydration were partially dehydrated into Li(H2O)+. The energy required for the dehydration of Li(H2O)4+ on HTFZO-II is lower than that on undoped HTO, indicating that metal ion doping modification was beneficial for the dehydration of hydrated lithium ions on the adsorbent surface, thereby accelerating the exchange reaction between H+ and dehydrated Li+ ions. This study reveals the key role of the synergistic effect of multi-element co-doping in enhancing the adsorption performance and structural stability of LISs.

Generation-fusion strategy in metal-earth ionosome investigation using single-entity electrochemistry at the micro-water/trifluorotoluene interface

Ionosomes are water clusters/droplets formed in an organic phase via the spontaneous assembly of ionic bilayers by hydrated cations or anions. The ionosomes formed by monovalent ions, i.e., Li+, Na+, K+, Cl−, etc., have been thoroughly investigated. Herein, single nanowater clusters (viz. ionosomes) in organic solutions, which are formed by the transfer of metal earth cations (i.e., Mg2+, Ca2+, Ba2+) into organic lipophilic electrolytes, were discovered using single-entity electrochemistry (SEE). The generation-fusion strategy involving two-step potentiostatic chronoamperometry was applied to investigate single Mg2+-ionosomes at the water/α,α,α-trifluorotoluene (w/TFT) interface. After an exciting potential forced the hydrophilic ion into the organic phase, a train of current spikes with information on the integrated charges, frequency, and duration were recorded to gain insight into the ionosomes. Variates were thoroughly investigated, including the exciting potential, exciting time, recording potential, size of the applied w/TFT interface, ion species, and concentration. These results suggest that: (1) the size of a single Mg2+-ionosome was revealed; (2) the fleshly formed ionosomes are mainly located on the organic side of the w/TFT interfacial surface instead of diffusing into the organic bulk; (3) when the interface decreases, fewer ionosomes form, and the size of the ionosomes decreases; (4) the mean charge carried by a single ionosome is positively related to the charge density of a single cation; (5) by alternating the recording potential, the negative zeta potential of Mg2+-ionosomes was revealed; (6) Mg2+-ionosomes can form when the aqueous solution contains only 2 μmol·L−1 Mg2+. This work thoroughly investigated hydrated metal earth ion clusters in the organic phase via SEE and provides insights into the interface electric double layer from the electrochemistry perspective. In addition to promoting the understanding of ionosomes, this strategy can provide potential applications to identify high-purity water.

Preparation of highly hydrophilic cesium ion sieve and its performance in adsorbing Cs+

The unique properties of cesium compounds have garnered increasing attention, among which Cs2Ti6O13 shows great potential for applications. This paper synthesized Cs2Ti6O13(CTO-3) using a template-assisted solvothermal method with cesium carbonate as the cesium source and tetrabutyl titanate as the titanium source. Among them, F127 and hexadecylamine are used as template agents to modulate the surface morphology and hydrophilicity of the precursor. The cesium ion sieve H2Ti6O13 (HTO-3) synthesized after hydrochloric acid pickling has a large specific surface area and good hydrophilicity. This structure is conducive to the ion exchange between Cs+ and H+, resulting in a fast adsorption rate. It is completed within 2 h, and the adsorption capacity reaches 360 mg/g, which is significantly greater than that of the traditional high-temperature solid-phase method. The adsorption process of Cs+ on HTO-3 is more consistent with the pseudo-second-order kinetic equation model, and the adsorption process is chemical adsorption. HTO-3 exhibited good selectivity and cycle stability. At the fifth time of the adsorption-resolution cycle, the adsorption capacity was 87.1 % of the first time.

Enhancing proton exchange membrane water electrolysis by building electron/proton pathways

Proton exchange membrane water electrolysis (PEMWE) plays a critical role in practical hydrogen production. Except for the electrode activities, the widespread deployment of PEMWE is severely obstructed by the poor electron-proton permeability across the catalyst layer (CL) and the inefficient transport structure. In this work, the PEDOT:F (Poly(3,4-ethylenedioxythiophene):perfluorosulfonic acid) ionomers with mixed proton-electron conductor (MPEC) were fabricated, which allows for a homogeneous anodic CL structure and the construction of a highly efficient triple-phase interface. The PEDOT:F exhibits strong perfluorosulfonic acid (PFSA) side chain extensibility, enabling the formation of large hydrophilic ion clusters that form proton-electron transport channels within the CL networks, thus contributing to the surface reactant water adsorption. The PEMWE device employing membrane electrode assembly (MEA) prepared by PEDOT:F-2 demonstrates a competitive voltage of 1.713 ​V under a water-splitting current of 2 ​A ​cm−2 (1.746 ​V at 2A cm−2 for MEA prepared by Nafion D520), along with exceptional long-term stability. Meanwhile, the MEA prepared by PEDOT:F-2 also exhibits lower ohmic resistance, which is reduced by 23.4 ​% and 17.6 ​% at 0.1 ​A ​cm−2 and 1.5 ​A ​cm−2, respectively, as compared to the MEA prepared by D520. The augmentation can be ascribed to the superior proton and electron conductivity inherent in PEDOT:F, coupled with its remarkable structural stability. This characteristic enables expeditious mass transfer during electrolytic reactions, thereby enhancing the performance of PEMWE devices.

New aqueous two-phase system formed by piperazinium-based surface-active ionic liquid for extraction of dyes

Aqueous two-phase systems (ATPSs) as alternatives to traditional liquid–liquid extraction systems have been used intensively in recent years. In this work, a new ATPS composed of a piperazinium-based surface-active ionic liquid (SAIL), 1-(2-hydroxyethyl)piperazinium laurate ([HEP][C11CO2]), and a commercial cationic surfactant, dodecyldimethylbenzylammonium chloride (DDBAC) was prepared. The phase diagram for the ternary system DDBAC + [HEP][C11CO2] + H2O was determined, and the effects of composition and temperature on phase behaviors and properties were investigated. Phase separation was found spontaneous and thermodynamically favored when the mass fraction of water (w3) exceeded 0.60, primarily due to the salting-out of the hydrophilic ions [HEP]+ and Cl− in the bottom phase. Micelles were observed in the top phase where high concentrations of the hydrophobic ions [DDBA]+ and [C11CO2]− were present. Increasing the water content at a fixed surfactant-to-SAIL molar ratio resulted in a decreased top phase volume, while the extraction efficiency (EE) and the distribution coefficient (D) were both increased for extractions of Basic Blue 7 and Allura Red AC. When w3 reached 0.96 and the initial concentration of dye was below 1 × 10−4 mol·L−1, the EE values exceeded 98 % with all the D values surpassing 100, indicating the promising potential for SAIL-ATPS applications.

New ionic mesogens with high ionic conductivity based on a cyanoborate building block and lipophilic or hydrophilic counter ions

Ionic liquid crystals based on immobilised, low nucleophilic cyanoborates are designed forming SmA bilayer phases with the lowest density in ionic sections leading to considerable ion conductivity values. Structural details vary with the cation nature.

Evaluation of Connexin Hemichannel Activity In Vivo.

Connexin hemichannels (Cx HCs) are hexameric structures at the cell plasma membrane, whose function as membrane transport proteins allows for the passive flow of small hydrophilic molecules and ions (≤1kDa) between the cytosol and the extracellular environment. Activation of Cx HCs is highly dependent on pathological conditions. HC activity provokes changes in the microenvironment, inducing the dissemination of signaling molecules in both an autocrine and paracrine manner. Given the elicitation of a variety of signaling pathways, and assortment of Cx species and dispersion throughout the body, Cx HCs have been implicated in a range of processes such as cell proliferation, differentiation, cell death, and tissue modeling and remodeling. While studying the expression and localization of Cx HCs can be done using traditional laboratory techniques, such as immunoblot analysis, measuring the functionality/activity of the HCs requires a more explicit methodology and is essential for determining Cx-mediated physiological changes. The study of Cx HC function/activity has focused mainly on in vitro measurements through electrophysiological characterization or, more commonly, using HC-permeable dye uptake studies. Here, we describe the use of dye uptake to measure Cx HC activity in vivo using mechanically stimulated osteocytic Cx43 HCs with Evans blue dye as our model.

Low hysteresis, water retention, anti-freeze multifunctional hydrogel strain sensor for human-machine interfacing and real-time sign language translation.

Hydrogel strain sensors have received increasing attention due to their potential applications in human-machine interfaces and flexible electronics. However, they usually suffer from both mechanical and electrical hysteresis and poor water retention, which limit their practical applications. To address this challenge, a poly(acrylic acid-co-acrylamide) hydrogel crosslinked by silica nanoparticles is fabricated via photo polymerization and salting-out of hydrophilic ions for the strain sensor. The resulting hydrogel strain sensor possessed low electrical hysteresis (1.6%), low mechanical hysteresis (<7%), high cycle stability (>10 000 cycles), high durability, water retention and anti-freezing ability. Moreover, this strain sensor can be used as a wearable sensor for real-time control of robotic hands and hand gesture recognition. Finally, a sign language translation system has been demonstrated with the aid of machine learning, achieving recognition rates of over 98% for 15 different sign languages. This work offers a promising prospect for human-machine interfaces, smart wearable devices, and the Internet of Things.

Hybrid polyionic complexes as nanoreactors for the synthesis of iron oxide nanoparticles: From size control to modulation of magnetic and catalytic properties

Hybrid polyion complexes (HPICs) obtained from the complexation in aqueous solution of a double hydrophilic block copolymers and metal ions can act as efficient precursors for the controlled synthesis of hybrid nanoparticles. Hence, HPICs based on a mixture of ferrous and ferric ions with poly(ethylene oxide)-block-poly(acrylic acid) were used to initiate, after the addition at 70 °C of a solution of NH4OH, the formation of iron oxide nanoparticles. The careful choice of the molar ratio between polymer and metal ions within HPICs enables to tune the morphology and size of the obtained iron oxide nanoparticles while maintaining the same surface composition. This control of size and composition was further used to highlight the relationship between the size of these particles and their catalytic and magnetic properties.

Improving Gas Diffusion Electrodes for Electrochemical CO2 Reduction: Influence of the Ionomer

Electrochemical CO2 reduction is a promising way of harnessing greenhouse gas as an abundant resource for the production of value-added hydrocarbons. By employing copper as the catalyst, CO2 can be converted to multi-carbon compounds such as ethylene. Highly porous gas diffusion electrodes (GDEs) enable efficient contacting of gaseous CO2 and the electrolyte. Copper-coated GDEs are commonly manufactured by depositing a mixture of copper nanoparticles and ionomer on a gas diffusion layer. The ionomer not only acts as a binder, but also influences the GDE’s wetting behavior and can improve mass transport within the catalyst layer due to the combination of a hydrophobic PTFE-backbone and hydrophilic ion groups. Thus, optimizing the type and content of ionomer in the catalyst layer is of utmost importance.In this study, we investigate how the composition of catalyst layers affects the faradaic efficiency (FE) toward ethylene during electrochemical CO2 reduction. For this purpose, we fabricate different GDEs with constant copper loading but varied ionomer content and type (Nafion, Sustainion). To assess the performance of the GDEs, we conduct electrolysis experiments in a flow cell (Flex-E-Cell) setup with KHCO3 as the catholyte. Preliminary screening experiments at up to 50 mA cm-2 reveal a strong effect of the Nafion/copper mass ratio (NCR) on the FE toward ethylene. Within the investigated range (NCRs of 0.1, 0.2, 0.3, 0.4 and 0.5), we identify a sweet spot at an NCR of approximately 0.4. We hypothesize that at higher NCRs negative effects, such as decreasing porosity and an increasingly acidic pH, outweigh the improved mass transport. To assess the performance of the different GDEs at industrially relevant conditions, we perform constant current experiments at ≥ 100 mA cm-2. Here, we corroborate the previously observed trend and find that increasing the NCR from 0.2 to 0.4 doubles the maximum observed FE toward ethylene. When replacing Nafion with an anion exchange ionomer such as Sustainion, the total FE toward carbon products remains nearly unchanged. However, the selectivity shifts from ethylene toward single-carbon species such as CO and formic acid. These results highlight that ionomers play a decisive role in hydrogen evolution mitigation and tuning of the product spectrum during electrochemical CO2 reduction. Figure 1

Synergistic enhancement of the robustness of multifunctional polyurethane via an ionic noncovalent cross-linking network and aromatic disulfides

The preparation of functional polyurethane materials with high strength, toughness, and excellent self-healing ability is currently challenging. In this study, a multifunctional bi-dynamic supramolecular crosslinked network PU elastomer was successfully prepared by introducing ionic bonds and aromatic disulfide bonds into a PU matrix. The resulting ionic PU elastomers exhibited impressive mechanical properties, including high tensile strength (39.9 ± 4.4 MPa) and excellent elongation at break (1930 ± 345 %). They also demonstrated efficient self-healing capability (94.4 %), recyclability and processability. The distribution of hydrophilic ion bonds within the polymer networks enabled the elastomers to possess water-induced shape memory and antibacterial activity. Additionally, the hydrophilicity of the elastomers provided a self-cleaning ability when used as a coating material. The covalent bonding of the cations with the PU matrix prevented the leaching of bactericidal substances, ensuring good biocompatibility of the ionic PU. Furthermore, a double-layered self-healing composite flexible sensor was developed using the ionic PU as the substrate and carboxylated carbon nanotubes (CNTs-COOH) as the conductive medium to detect human motion. These multifunctional ionic PU elastomers offer great potential for the design and preparation of robust materials with self-healing ability for various applications across multiple fields.

Pickering high internal phase emulsions stabilized by metal-organic framework nanoribbons

Pickering high internal phase emulsions (HIPEs) stabilized by colloidal particles are of great practical significance in the formulation of food, pharmaceutical, cosmetic, paint products and the chemical oil flooding. Herein, we report that a manganese-based metal–organic framework (MOF) (Mn3(BTC)2 (BTC = 1,3,5-benzenetricarboxylate)) nanoribbons synthesized by a simple solution method can stabilize water-in-oil (W/O) high-viscosity Pickering HIPEs with crude oil as oil phase for more than one month at 43 °C. The Mn3(BTC)2 nanoribbons assemble at the oil/water interface of HIPE, owing to its advantageous structural features with the size of several micrometers, thickness of about 100 nm and amphiphilicity originated from the hydrophilic metal ions and hydrophobic organic ligands. The phase behavior and properties of the as-prepared HIPEs strongly depend on the MOF concentration (CMOF) and internal phase volume fraction of water (Fw) of emulsion. The MOF dispersions and crude oil are miscible into stable W/O HIPEs at Fw = 75 % when the CMOF ranges from 50 ppm to 5000 ppm. More interestingly, the viscosity of W/O emulsions greatly increases as the Fw varying from 50 % to 80 % and a viscosity of 4.5 Pa·s is obtained at CMOF = 2000 ppm and Fw = 80 %, which is nearly 400 times higher than that of crude oil. Moreover, the pressure generated by HIPEs flowing in core is about 40 times more than that of water injection and can remain the highest stable value substantially. These results show that the MOF dispersions are favorable to form stable W/O emulsions with high internal phase volume fraction, which has a great potential in improving oil displacement efficiency of chemical flooding.

Poly(aryl ether sulfone ketone) with densely sulfonated structural units facilitate microphase separation to promote proton transport

The development of high-performance and low-cost membrane materials is crucial for proton exchange membrane fuel cells. To improve the proton conductivity, we designed a novel multiple phenyls monomer. Then, we synthesize a series of sulfonated poly(aryl ether sulfone ketone) membranes (SPAESK-x). The hydrophilic groups are densely distributed in units after sulfonation, which can form large hydrophilic ion clusters and provide more connected channels for proton transport. The large hydrophilic ion clusters facilitate the separation of hydrophilic and hydrophobic phases to form wider proton transport channels. The SPAESK-15 membrane achieves a high proton conductivity (181.0 mS cm-1) at 80 °C. The novel monomer and polymers are budget and simple to synthesize, offering the possibility of large-scale preparation. Overall, the novel structure has the potential to develop high-performance electrolyte materials.

Injectable alginate hydrogel promotes antitumor immunity through glucose oxidase and Fe3+ amplified RSL3-induced ferroptosis

Ferroptosis induced by RAS-selective lethal small molecule 3 (RSL3) can trigger anti-tumor immune responses by reversing the immunosuppressive tumor microenvironment (TME). However, it is challenging to achieve sufficient ferroptosis in the tumor via RSL3 alone. Because of the excellent reactive oxygen species (ROS) production capacity of glucose oxidase (GOx) and Fe3+, we hypothesized that GOx and Fe3+ could increase intracellular lipid peroxidation (LPO) accumulation, and strengthen RSL3-induced ferroptosis in tumor cells. Herein we designed an in-situ gelation strategy based on sodium alginate (SA) to realize localized transport and specific retention of GOx, RSL3, and Fe3+ in tumor tissues. We loaded hydrophobic RSL3 with the tannic acid (TA)/Fe3+ complexes to form nanoparticles (RTF NPs). GOx diluted in the SA solution was blended with RTF NPs to obtain a homogeneous solution. The solution could form hydrogels in the tumor site (RTFG@SA) upon injection. The retained GOx and Fe3+ amplified the induction of ferroptosis by RSL3, augmented immunogenic cell death (ICD) and promoted antitumor immunity. The RTFG@SA hydrogel presented a significant restraint of tumor growth and metastasis in the 4T1 tumor model. This hydrogel could offer an effective means of co-delivery of hydrophilic drugs, hydrophobic drugs, and metal ions.

SPEEK-co-PEK-x proton exchange membranes with controllable sulfonation degree for proton exchange membrane fuel cells

Sulfonated poly(ether ether ketone)-poly(ether ketone) (SPEEK-co-PEK-x) copolymers with controlled degree of sulfonation are synthesized by the polycondensation reaction of varying monomer ratios. Compared with the traditional homopolymer sulfonated poly(ether ether ketone) (H-SPEEK), the SPEEK-co-PEK-x copolymer membrane has a high degree of sulfonation and excellent proton conductivity. Meanwhile, it also has favorable mechanical properties and stability. This is attributed to the introduction of the -PEK- segment. The SPEEK-co-PEK-75 membrane exhibits the highest conductivity (0.285 S cm−1) at 80 °C, 100% RH and when tests at 80 °C with 80% RH, the SPEEK-co-PEK-75 membrane reaches 0.0587 S cm−1. In addition, the tensile strength of the SPEEK-co-PEK-75 membrane reaches 47.66 MPa at room temperature. Moreover, the study investigates the impact of key variables on the single-cell performance of SPEEK-co-PEK-x membranes. The measured peak power densities of the SPEEK-co-PEK-75 membrane are 212 mW cm−2 and 495 mW cm−2 at 70% RH and 100% RH, which are 1.3 times and 1.7 times higher than that of the Nafion 117 membrane, respectively. After the 80 h durability test at 80 °C and 80% RH, the voltage of the SPEEK-co-PEK-75 membrane only drops by 4.8%. The presence of the -PEK- segment results in a more compact and connected distribution of hydrophilic ion clusters in the SPEEK-co-PEK-X membrane. This adjustment greatly enhances the performance of the membrane, making it an excellent candidate for proton exchange membrane in H2/air fuel cells.

High-performance anion exchange membranes based on poly(aryl piperidinium): With interpenetrating ion transport channels induced by fluorinated crosslinking and side chains

Currently, the trade-off between mechanical stability and electrical conductivity has become one of the challenges in developing high-performance anion exchange membranes. Here, we propose a fluorinated crosslinking strategy to improve the mechanical properties of the membrane while achieving high conductivity. The introduction of hydrophobic fluorination units provides a further driving force for the aggregation of hydrophilic ion clusters within the membrane, forming continuous ion transfer channels within the membrane. The results show that the crosslinked membranes maintain a low swelling rate as well as a high OH– conductivity at 80 °C. Among them, the FPTBP-TMA-7 membrane showed the most comprehensive performance, with a OH– conductivity of 116.9 mS cm−1 and a swelling rate of only 14.1% at 80 °C. The chemical structure of the membranes maintained high stability after immersion in highly concentrated alkaline solutions (2 M NaOH at 80 °C for 720 h), with a conductivity retention rate of over 91.8%. In addition, the FPTBP-TMA-7 based fuel cell achieves a peak power density of 264.2 mA cm−2 at 80 °C, showing an attractive application prospect in alkaline fuel cells.

Preparation of three structurally similar stationary phases with different ionizable terminal groups and evaluation of their retention performances under multiple modes in high performance liquid chromatography

Three structurally similar silane reagents with different terminal groups were prepared and bonded to silica to obtain three structurally similar stationary phases (Sil-Ph-COOH, Sil-Phe and Sil-Ph-NH2). The prepared stationary phases were characterized through elemental analysis (EA) and Fourier Transform Infrared Spectroscopy (FT-IR). These three stationary phases provided acceptable retention repeatability (relative standard deviations between 0.08% and 0.13%) and high column efficiency (7.3 × 104 plates/m for uridine on Sil-Phe). The retention behavior of the three columns was investigated under different chromatographic conditions including different mobile phase ratio, salt concentration, pH etc. The retention mechanisms were explored by linear solvation energy relationships and Van't Hoff plots. Applications in separation under reversed phase liquid chromatography (RPLC), hydrophilic interaction liquid chromatography (HILIC) and ion exchange chromatography (IEC) mode were investigated. The results showed that the retention capacity of the stationary phases with different terminal groups to the analytes is very different, especially for carboxylic acids, because the surface charges of amino groups and carboxyl groups under weakly acidic conditions produce different electrostatic effects with dissociated carboxylic acids. Finally, the Sil-Phe column was employed to detect ibuprofen extracted from pharmaceutical ibuprofen capsules and vitamins extracted from vitamin tablets.

Biochar pyrolyzed with concentrated solar radiation for enhanced nitrate adsorption

Biochar has been recognized as an effective soil amendment for reducing nitrogen leaching in agriculture, but its large-scale implementation is impeded by the costly production process due to high energy requirements for thermal decomposition of feedstock. This study aimed to develop a novel pyrolysis system utilizing concentrated solar radiation to produce biochar and explore the potential of solar-pyrolyzed biochar for nitrate adsorption. Results showed that the solar-pyrolyzed biochar exhibited a maximum adsorption capacity of 35.59 mg/g for nitrate, significantly higher than two out of the three commercially available biochars in America that are selected for comparison. The Fourier-transform infrared (FTIR) analysis suggested a variety of oxygen-containing polar functional groups present in the solar-pyrolysis biochar, which enhances its affinity for nitrate and other hydrophilic ions. The X-ray diffraction (XRD) analysis revealed that the solar pyrolysis biochar was an amorphous material with a poorly crystalline, carbon-rich phase, indicating a high degree of carbonization and recalcitrance, as confirmed by Raman spectroscopy and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) analysis. The porous structure of the solar-pyrolysis biochar suggested a larger specific surface area, which could benefit adsorption. Although further experiments are required to determine the stability and cost-effectiveness of a scaled-up solar-pyrolysis apparatus, these findings provide hope for a more sustainable and high-performing biochar production process in the future.

Iron-based hybrid polyionic complexes as chemical reservoirs for the pH-triggered synthesis of Prussian blue nanoparticles

HypothesisHybrid polyion complexes (HPICs) obtained from the complexation in aqueous solution of a double hydrophilic block copolymer and metal ions can act as efficient precursors for the controlled synthesis of nanoparticles. In particular, the possibility to control the availability of metal ions by playing on the pH conditions is of special interest to obtain nanoparticles with controlled size and composition. ExperimentsHPICs based on Fe3+ ions were used to initiate the formation of Prussian blue (PB) nanoparticles in presence of potassium ferrocyanide in reaction media with varying pH values. FindingsComplexed Fe3+ ions within HPICs can be easily released by adjusting the pH value either through the addition of a base/acid or by using a merocyanine photoacid. This allows to modulate the reactivity of Fe3+ ions with potassium ferrocyanide present in solution. As a result, PB nanoparticles with different structures (core, core–shell), composition and controlled size are obtained.