Effect Of Anions Research Articles

Ionic Liquid–Graphene Interface: Effect of Anions on the Fermi Level

Since energy conversion and storage processes take place at the electrolyte–electrode interface, it is important to develop experimental and theoretical procedures to understand the interfacial nanostructure in graphene-based electrochemical storage devices where ionic liquids (ILs) are used as electrolytes. In this contribution, the impact of the anions of imidazolium-based ILs on the IL–graphene interface as well as on the electronic structure of graphene is investigated. Raman spectroscopy unveils that 1-butyl-3-methylimidazolium ILs having smaller anions induce n-type doping, while ILs with larger anions have a negligible effect on the doping. Molecular modeling simulations reveal that changes in the electrostatic potential at the IL–graphene interface are responsible for the n-type doping.

Stabilizing Bottom Side of Perovskite via Preburying Cesium Formate toward Efficient and Stable Solar Cells

AbstractThe fragile bottom side of perovskite films is demonstrated to be harmful to the efficiency and stability of perovskite solar cells (PSCs) because the carrier extraction and recombination can be significantly influenced by the easily formed strain, voids, and defects on the bottom side. Nevertheless, the bottom side of perovskite films is usually overlooked because it remains a challenge to directly characterize and modify the bottom side. Herein, a facile and effective strategy is reported to stabilize the bottom side via preburying cesium formate (CsFo) into the SnO2 electron transport layer (ETL). It is found that the synergistic effect of cesium cation (Cs+) and formate anion (HCOO−) causes strain relaxation, void elimination, and defects’ reduction, which further facilitate the charge extraction. Consequently, the champion power conversion efficiency (PCE) of formamidinium (FA)‐based PSCs is increased from 23.34% to 24.50%. Meanwhile, the ultraviolet (UV), thermal, and operational stability are also enhanced. Finally, formamidinium–cesium (FACs)‐based PSCs are investigated to confirm the effectiveness of this preburied CsFo strategy, and the optimal device exhibits a champion PCE of 25.03% and a remarkably high fill factor (FF) of 85.65%.

Understanding the Anion Effect of Basic Cobalt Salts for the Electrocatalytic Oxygen Evolution Reaction

Basic cobalt salts with distinct acidic anion Co(OH)x(A)y are efficient electrocatalysts toward the oxygen evolution reaction (OER). However, plenty of present studies are still in the try-and-wrong stage, while the underlying anion effect remains unclear. Herein, a series of Co(OH)x(A)y (A = F–, Cl–, and CO32–) are synthesized via a hydrothermal strategy, and the order of the OER activity is determined to be Co(OH)(CO3)0.5 > Co2(OH)3Cl > Co(OH)F > Co(OH)2. X-ray photoelectron spectroscopy and soft X-ray absorption spectroscopy studies reveal that these Co(OH)x(A)y materials undergo surface oxidation during the OER process, and the highly active Co(IV) content is the dominant factor in deciding the OER performance. Furthermore, quantitative analysis of anion concentrations in the electrolyte solution reveals that the anion leaching ability in Co(OH)x(A)y directly relates to the Co(IV) content and finally the OER catalytic activity, which is the essence of the anion effect and can be summarized as an “anion leaching─metal oxidation” model. Our work not only provides deep understanding of the anion effect of metal basic salt-based OER catalysts but also profound insights for the activation process of the OER pre-catalysts.

Photocatalytic degradation of metronidazole and oxytetracycline by novel l-Arginine (C, N codoped)-TiO2/g-C3N4: RSM optimization, photodegradation mechanism, biodegradability evaluation

Removal of Metronidazole (MNZ) and Oxytetracycline (OTC) from wastewater by the prepared (C, N codoped)-TiO2/g-C3N4 (Graphitic carbon nitride) was examined. l-Arginine (C, N codoped)-TiO2 and l-Arginine (C, N codoped)-TiO2/g-C3N4 photocatalysts were successfully synthesized through the sol-gel method, and optimal ratio of l-arginine:TiO2, as well as l-arginine/TiO2:g-C3N4, was determined by a kinetic study of photodegradation process. The maximum photocatalytic removal rate (0.062 min−1 for MNZ removal) was observed using 1% l-Arginine-TiO2/g-C3N4 (1:1) under visible light illumination, 2.2 and 12.4 times greater than those of 1% l-Arginine-TiO2 and pure TiO2, respectively. l-Arginine (1%)-TiO2/g-C3N4 (1:1) (co-doped-TCN) was investigated using X-ray diffraction analysis (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-ray (EDX), Photo-luminescence (PL), and Differential Reflectance Spectroscopy (DRS) as the best-performing photocatalyst. Response surface methodology (RSM) was used to study the effect of co-doped-TCN dosage (0.5–1.0 g/L), pH of simulated wastewater (4–10), initial concentration of MNZ and OTC (50–100 mg/L), and irradiation time (30–90 min for MNZ and 20–40 min for OTC) on removal efficiency of the antibiotics. Also, their optimum values were determined by RSM. The treated pharmaceutical wastewater showed high biodegradability features with 5-day biological oxygen demand/chemical oxygen demand (BOD5/COD) of 0.51 and 0.46 after 40 and 100 min reaction for OTC and MNZ, respectively. The order of reactive species responsible for the photodegradation of pollutants was •O2─> •OH > h+>1O2. The effect of inorganic anions showed that all anions decreased the removal efficiency of both antibiotics in order of NO3─> Cl─ >SO42─>HPO42─ >HCO3─ for MNZ and NO3─> SO42─ > Cl─ >HPO42─ >HCO3─ for OTC. Also, introducing different oxidants improved the photocatalytic removal efficiency with the order of H2O2>K2S2O8> KBrO3.

Supercritical fluid chromatography based on reversed-phase/ ion chromatography mixed-mode stationary phase for separation of spirooxindole alkaloids

The present paper illustrates the versatility of the supercritical fluid chromatography (SFC) since, for the first time, four spirooxindole alkaloids (SOAs) including two pairs of isomers were separated by using two types of reversed-phase/ ion chromatography (RP/IC) mixed-mode stationary phases. Two mixed-mode stationary phases (C8SAX and C8SCX) was simultaneously provided dispersive and electrostatic interactions, which were suitable for the separation of such alkaloids. This study tried to provide an in-depth understanding of the SFC separation mechanism of the mixed-mode stationary phase through investigation of the impact of changes in mobile phase composition on alkaloids’ retention behavior. On C8SAX, due to the strong electrostatic repulsion, there was a very narrow elution window of the alkaloids, of which behaviors were hardly affected by adding diethylamine in mobile phase. When adding formic acid or acidic ammonium formate, the prolonged retention time of alkaloids was presented because of the shielded effect of formate anions on the electrostatic repulsion. In particular, better peak shape and improved resolution were obtained by using acidic ammonium formate due to the deactivation of silanol groups by ammonium cations. On the other hand, both formic acid and acidic ammonium formate can strengthen the electrostatic attraction of C8SCX, causing difficult elution of the alkaloids. Ammonium cations from either the protonated diethylamine or the ionized ammonium formate, were considered as counter ions to effectively mask the electrostatic attraction of C8SCX, to significantly reduce the retention of alkaloids, but improve the resolution. Finally, utilizing two developed SFC methods, i.e., C8SAX with EtOH+ 10 mM acidic ammonium formate in CO2, or C8SCX with EtOH+0.1% diethylamine in CO2, the baseline separation of corynoxeine and isocorynoxeine, rhynchophylline and isorhynchophylline was achieved within 5 min.

Anion chemistry in energy storage devices.

Anions serve as an essential component of electrolytes, whose effects have long been ignored. However, since the 2010s, we have seen a considerable increase of anion chemistry research in a range of energy storage devices, and it is now understood that anions can be well tuned to effectively improve the electrochemical performance of such devices in many aspects. In this Review, we discuss the roles of anion chemistry across various energy storage devices and clarify the correlations between anion properties and their performance indexes. We highlight the effects of anions on surface and interface chemistry, mass transfer kinetics and solvation sheath structure. Finally, we conclude with a perspective on the challenges and opportunities of anion chemistry for enhancing specific capacity, output voltage, cycling stability and anti-self-discharge ability of energy storage devices.

Efficient degradation of phenol by MnOOH-rGO composite with high peroxymonosulfate utilization efficiency

A high-performance, durable, low-cost, and environmentally friendly catalyst is highly desired in advanced oxidation processes (AOPs) for water treatment. Considering the activity of Mn(Ⅲ) and the superior catalytic properties of reduced graphene oxide (rGO) in peroxymonosulfate (PMS) activation, rGO-modified MnOOH nanowires (MnOOH-rGO) were fabricated by a hydrothermal method for phenol degradation. The results showed that the composite synthesized at 120 °C with 1 wt% rGO dopant exhibited the best performance for phenol degradation. Nearly 100% of the phenol was removed by MnOOH-rGO within 30 min, which is higher than the removal rate of pure MnOOH (70%). The effects of catalyst dosages, PMS concentration, pH, temperature, and anions (Cl−, NO3−, HPO42−and HCO3−) on phenol degradation were investigated. The removal rate of chemical oxygen demand (COD) reached 26.4%, with a low molar ratio of PMS to phenol at 5:1 and a high PMS utilization efficiency (PUE) of 88.8%. The phenol removal rate remained more than 90% after five recycle with less than 0.1 mg L−1 leakage of manganese ions. Together with the results of radical quenching experiments, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectroscopy (EPR), electron transfer and 1O2 were proved to dominate the activation process. During the direct electrons transfer process, the electrons transfer from the phenol to PMS by using the Mn(Ⅲ) as the mediate with a stoichiometric ratio between PMS and phenol at 1:2, which mainly contributed to the high PUE. This work provides new insight into a high-performance Mn(Ⅲ) based catalyst on PMS activation with high PUE, good reusability, and environmentally friendly for removing organic pollutants.

Coordination-Driven Salamo-Salen-Salamo-Type Multinuclear Transition Metal(II) Complexes: Synthesis, Structure, Luminescence, Transformation of Configuration, and Nuclearity Induced by the Acetylacetone Anion.

A flexible polydentate Salamo-Salen-Salamo hybrid ligand H4L was designed and synthesized, which has rich pockets (salamo and salen pockets) so that it may have fascinating coordination patterns with transition metal(II) ions. Four multinuclear transition metal(II) complexes, novel butterfly-shaped homotetranuclear [Ni4(L)(μ1-OAc)2(μ1,3-OAc)2(H2O)0.5(CH3CH2OH)3.5]·4CH3CH2OH (1), helical homotrinuclear [Zn3(L)(μ1-OAc)2]·2CH3CH2OH (2), double-helical homotrinuclear [Cu2(H2L)2]·2CH3CN (3), and mononuclear [Ni(H2L)]·1.5CH3COCH3 (4), have been synthesized and characterized by single-crystal X-ray diffraction. The effects of different anions [OAc- and (O2C5H7)2-] on the complexation behavior of H4L with transition metal(II) ions were studied by UV-vis spectrophotometry. The fluorescent properties of the four complexes were studied with zebrafish, which are expected to be a potential light-emitting material. Ultimately, interaction region indicator (IRI) valuations, Hirshfeld surface analyses, density functional theory (DFT & TD-DFT), electrostatic potential analyses (ESP), and simulations were carried out to further demonstrate the weak interactions and electronic properties of the free ligand and its four complexes.

Caging the Hofmeister Effect by a Biomimetic Supramolecular Receptor.

The effect of anions on the solubility and function of proteins was recognized in 1888 and is now termed the Hofmeister effect. Numerous synthetic receptors are known that overcome the associated anion recognition bias. However, we are unaware of a synthetic host being used to overcome Hofmeister effect perturbations to natural proteins. Here, we report a protonated small molecule cage complex that acts as an exo-receptor and displays non-Hofmeister solubility behavior, with only the chloride complex remaining soluble in aqueous media. This cage allows for the activity of lysozyme to be retained under conditions where anion-induced precipitation would otherwise cause it to be lost. To our knowledge, this is the first time a synthetic anion receptor is used to overcome the Hofmeister effect in a biological system.

Effects of Secondary Dopant Anions on Emissivity and Related Properties of Poly(3,4-ethylenedioxythiophene).

Smart materials that are energy efficient and take up less space are crucial in the development of new technologies. Electrochromic polymers (ECPs) are one such class of materials that actively change their optical behavior in both visible and infrared parts of the electromagnetic spectrum. They show promise in a wide range of applications, from active camouflage to smart displays/windows. The full capabilities of ECPs are still yet to be explored, for while their electrochromic properties are well established, their IR modulation is less reported on. This study addresses the potential of ECPs in active IR modulating devices by optimization of Vapor Phase Polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) thin films via the substitution of its dopant anion. Dynamic ranges denoting emissivity changes between reduced and oxidized states of PEDOT were found across dopants of tosylate, bromide, sulfate, chloride, perchlorate and nitrate. Relative to the emissivity of reduced (neutral) PEDOT, a range of ±15% was achieved from the doped PEDOT films, and a maximum dynamic range of 0.11 across a 34% change was recorded for PEDOT doped with perchlorate. This article is protected by copyright. All rights reserved.

Spin Crossover in Iron(II) Complexes with Polynitrogen Heterocyclic Ligands and Outer-Sphere Boron Cluster Anions (Review)

The results of synthesis and study of magnetically-active iron(II) complexes with polynitrogen heterocyclic ligands and outer-sphere boron cluster anions have been considered. Derivatives of 1,2,4-triazole, tris(pyrazol-1-yl)methane, and 2,6-bis(imidazol-2-yl)pyridine have been used as ligands, decahydro-closo-decaborate, dodecahydro-closo-dodecaborate, decachloro-closo-decaborate, and 1,5,6,10-tetra(R)-7,8-dicarba-nido-undecaborates (R = H, Cl, Br) have been studied as outer-sphere anions. A number of iron(II) complexes showing spin crossover accompanied by thermochromism in the majority of cases has been obtained. Effect of ligand nature and cluster anion on temperature (Tc) and spin transition character has been considered. In particular, it has been shown that introduction of substituent increasing electron density over the system of conjugated three-centered two-electron bonds in cluster anion leads to increase in the field strength of ligand bound to anion via network of hydrogen bonds.

Effect of Metal-Containing Anions on the Catalytic Properties of Imidazolium Derivatives Immobilized on Silochrome in Oxidative Desulfurization

Effect of Metal-Containing Anions on the Catalytic Properties of Imidazolium Derivatives Immobilized on Silochrome in Oxidative Desulfurization

Stabilization/solidification of Mn-contaminated clay slurry by using CaO-GGBS: Effects of anions

Clay sediment is removed by dredging, resulting in the disposal of enormous waste sediment clay slurries that consumes land space, as well as risks the human health and the environment. Manganese (Mn) is often identified in clay slurries. Quicklime (CaO)-activated ground granulated blast-furnace slag (GGBS) can be used to stabilize/solidify (S/S) contaminated soils; nevertheless, few studies have been published on the S/S of Mn-contaminated clay slurries using CaO-GGBS. Moreover, the anions contained in clay slurries may affect the S/S efficiency of CaO-GGBS in treating Mn-contaminated clay slurries, but this effect has hardly been investigated. Therefore, this study investigated the S/S efficiency of CaO-GGBS in treating MnSO4-bearing and Mn(NO3)2-bearing clay slurries. The effect of anions (i.e. SO42− and NO3−) on the strength, leachability, mineralogy, and microstructure of Mn-contaminated clay slurries treated with CaO-GGBS was explored. Results showed that CaO-GGBS could improve the strength of both Mn-contaminated slurries to meet the strength requirement for landfill waste outlined by United States Environmental Protection Agency (USEPA). The Mn leachabilities of both Mn-contaminated slurries were decreased to be less than the Euro limit for drinking water after cured for 56 days. The MnSO4-bearing slurry generally produced higher UCS while lower Mn leachability than Mn(NO3)2-bearing slurry at the same CaO-GGBS addition. CSH and Mn(OH)2 were formed, thereby enhancing strength and reducing leachability of Mn. Ettringite in CaO-GGBS-treated MnSO4-bearing slurry, which was formed by the supply of SO42− from MnSO4, further contributed to the strength enhancement and the decrease of Mn leachability. Ettringite was the factor leading to the difference in strength and leaching properties between MnSO4-bearing and Mn(NO3)2-bearing clay slurries. Hence, anions contained in Mn-contaminated slurries significantly affected the strength and the Mn leachability, and need to be identified before CaO-GGBS was used to treat such slurries.

Interfacial coupling of 3D nanoflower-like Bi2O2CO3 with PANI for tetracycline photocatalytic degradation and intermediate toxicity analysis

The interface coupling between solid electronic medium and semiconductor with good electrical conductivity can promote the separation of photoinduced electron-hole pair and improve the activity of photocatalyst. Polyaniline/Bi2O2CO3 with different proportions was synthesized by simple hydrothermal method under the strong interfacial coupling between polyaniline and Bi2O2CO3. XRD, XPS and FT-IR techniques were used to confirm the successful synthesis of the composite materials. With the help of SEM and TEM techniques, the morphology and structure of the materials were understood, and the photocatalytic properties of the composite materials were determined by UV–Vis, PL and other techniques. The photocatalytic activity of the synthesized photocatalyst was evaluated by degradation of tetracycline, and the effects of sample dose, pH, anion and other factors on the photocatalytic process were explored. The intermediates during the reaction were determined by liquid chromatography mass spectrometry (LC-MS), and five degradation pathways were deduced. Toxicity Estimation Software Tool and Ecosar software were used to test the toxicity of intermediate products, which further illustrated the green safety of photocatalytic technology. We also propose a possible photocatalytic reaction mechanism based on the band structure of the material and the reactive radicals generated during the reaction.

Stabilization of FAPbI3 with multifunctional alkali-functionalized polymer.

The defects located at the interfaces and grain boundaries (GBs) of perovskite films are detrimental to the photovoltaic performance and stability of perovskite solar cells. Manipulating the perovskite crystallization process and tailoring the interfaces with molecular passivators are mainly effective strategies to mitigate performance loss and instability. Herein we report a new strategy to manipulate the crystallization process of FAPbI3 -rich perovskite by incorporating a small amount of alkali functionalized polymers into the antisolvent solution. The synergic effects of alkali cations and polyacrylic acid anion effectively passivate the defects on the surface and GBs of perovskite films. As a result, the rubidium (Rb)-functionalized polyacrylic acid significantly improves the power conversion efficiency of FAPbI3 perovskite solar cells to approaching 25% and reduces the risk of lead ion (Pb2+ ) leakage via the strong interaction between C = O bond and Pb2+ . In addition, the unencapsulated device shows enhanced operational stability, retaining 80% of its initial efficiency after 500h operation at maximum power point under one-sun illumination. This article is protected by copyright. All rights reserved.

Peroxymonosulfate activation with an α-MnO2/Mn2O3/Mn3O4 hybrid system: parametric optimization and oxidative degradation of organic dye.

The present study proposed the synthesis of low-toxicity and eco-friendly spherically shaped manganese oxides (α-MnO2, Mn2O3, and Mn3O4) by using the chemical precipitation method. The unique variable oxidation states and different structural diversity of manganese-based materials have a strong effect on fast electron transfer reactions. XRD, SEM, and BET analyses were used to confirm the structure morphology, higher surface area, and excellent porosity. The catalytic activity of as-prepared manganese oxides (MnOx) was investigated for the rhodamine B (RhB) organic pollutant with peroxymonosulfate (PMS) activation under the condition of control pH. In acidic conditions (pH = 3), complete RhB degradation and 90% total organic carbon (TOC) reduction were attained in 60 min. The effects of operating parameters such as solution pH, PMS loading, catalyst dosage, and dye concentration on RhB removal reduction were also tested. The different oxidation states of MnOx promote the oxidative-reductive reaction under acidic conditions and enhance the SO4•-/•OH radical formation during the treatment, whereas the higher surface area offers sufficient absorption sites for interaction of the catalyst with pollutants. A scavenger experiment was used to investigate the generation of more reactive species that participate in dye degradation. The effect of inorganic anions on divalent metal ions that genuinely occur in water bodies was also studied. Additionally, separation and mass analysis were used to investigate the RhB dye degradation mechanism at optimum conditions based on the intermediate's identification. Repeatability tests confirmed that MnOx showed superb catalytic performance on its removal trend.

Accurate Layer Spacing Matching of Polyoxometalate (POM) Anion‐based Ionic Liquids (ILs) to Promote PET Alcoholysis

AbstractMatching the active site of the catalyst with the carbonyl reactive site of PET at the nanoscale and achieve precise shearing of the PET reactive site at the molecular level by accurately modulating the catalyst layer spacing is particularly challenging. Herein, a new design strategy for green catalysts is proposed to synthesize a novel class of Polyoxometalate (POM) anion‐based ILs (POM‐ILs) [X]n[WZn3(H2O)2(ZnW9O34)2] (X=PyPs, Py, MIMPs, TEAPs, n=3, 6, 9, 12) with high thermally stable and adjustable layer spacing (1.00–1.63 nm). By adjusting the ratio of organic cations to match the spacing (1.34 nm) between the active sites of the catalyst with the spacing (1.32 nm) of the carbonyl functional groups on both sides of the PET benzene ring, the long PET chains were precisely sheared and rapidly degraded to bis(hydroxyethyl) terephthalate (BHET) in short time with the synergistic catalytic effect of anions and cations. Under the optimal conditions, the catalyst dosage was only 0.8 % of PET mass, and it could degrade 100 % in 30 min with BHET yield up to 85.35 %, and the yield of BHET was still greater than 85 % after 5 cycles. In addition, a possible mechanism of synergistic catalytic PET alcoholysis was proposed by density functional theoretical calculation. Moreover, the strategy of promoting PET alcoholysis by accurately modulating the spacing of the catalytic active site has not been reported.

Enhanced fluoride remediation from aqueous solution by La-modified ZIF-8 hybrids

To ensure water safety, fluoride elimination from aqueous environment is an urgent affair. In this study, a series of La-modified ZIF-8 (denoted as La-ZIF-8) hybrids with different contents of La were fabricated via a solvothermal reaction and used for fluoride recovery from wastewater. The structure and morphology of the fabricated La-ZIF-8 hybrid were confirmed by various techniques (SEM, XRD, BET, FTIR, and XPS). The specific surface area along with the pore volume of La-ZIF-8 hybrid was 121 m2 g−1 and 0.816 cm3 g−1, respectively. The defluoridation performance of La-ZIF-8 under different conditions was assessed by static batch trials. The optimized La-ZIF-8 with a La/Zn molar ratio of 4:1 achieved the supreme defluoridation performance. The fluoride uptake was greatly enhanced from 1.85 mg g−1 for pure ZIF-8–49.5 mg g−1 for La-ZIF-8 at C0 = 10 mg L−1. The results revealed that La-ZIF-8 had a maximal fluoride uptake of 224.72–230.95 mg g−1 at 30–50 °C, pH 4, and C0 = 80 mg L−1. Adsorption of fluoride on La-ZIF-8 obeyed to the Langmuir isotherm (R2 > 0.99) and pseudo-second order model (R2 > 0.999), reflecting a single-layer chemical adsorption process. ΔH0 (36.38 kJ mol−1) > 0, ΔS0 (155.36 J mol−1 K−1) > 0, and ΔG0 < 0 stated that the defluoridation by La-ZIF-8 is an endothermic nature, random state, highly feasible and spontaneous process. The co-existing of cations and anions effect inferred that Mg2+, Ca2+, SO42–, Cl–, and NO3– only had a trivial impact on fluoride removal performance, illustrating the high selectivity for F–. The La-ZIF-8 can be deemed to be a candidate adsorbent for tackling F− pollution.

Elucidating the effect of the Hofmeister effect on formation and rheological properties of soy protein/κ-carrageenan hydrogels

Hydrogels derived from soy protein isolates (SPI) offer numerous advantages such as sustainability, biodegradability, and non-toxicity. However, the weak mechanical properties of SPI-based hydrogels limit their practical applications. To address this issue, a soaking strategy employing the Hofmeister effect was proposed to prepare SPI-based hydrogels. In this work, we looked at the possibilities of enhancing the rheological and mechanical characteristics of SPI-based hydrogels utilizing the Hofmeister series. SPI hydrogels were fabricated by introducing κ-carrageenan (SPIK). The SPIK hydrogels were soaked in different concentrations of Hofmeister salts (SO42−, Cl−, and SCN−). The results showed that the mechanical properties of SPIK hybrid hydrogels soaked with kosmotropic anion (SO42−) were obviously enhanced. The neutral ion (Cl−) soaked SPIK hybrid hydrogels showed no apparent difference in mechanical properties compared to the control, while the mechanical properties of chaotropic anion soaked SPIK hybrid hydrogels were weakened and the SPIK hybrid hydrogels were softened. The rheological test results showed that the order of anion effect on the G′ of the SPIK hybrid hydrogels were SO42− > Cl− > SCN−. Meanwhile, the G′ of the SPIK hybrid hydrogel containing SO42− was remarkably higher than the other samples. Moreover, the effect of different ratios of water, salt, and SPI on the SPIK hybrid hydrogel properties, structure, and microstructure was evaluated using a hybrid design. The results of rheological regression analysis showed a strong interaction between protein and salt. Frequency scan tests, strain scan tests, and texture analyzer measurements revealed that the SPIK hybrid hydrogels exhibited superior rheological and mechanical properties when the salt to SPI concentration ratio was 2:1, for both SO42− and Cl− ions. Overall, our results reveal the influence of the Hofmeister effect on SPI-based hydrogels.

Norfloxacin removal by ultraviolet-activated sodium percarbonate and sodium hypochlorite: process optimization and anion effect.

The efficiency of UV-activated sodium percarbonate (SPC) and sodium hypochlorite (SHC) in Norfloxacin (Norf) removal from an aqueous solution was assessed. Control experiments were conducted and the synergistic effect of the UV-SHC and UV-SPC processes were 0.61 and 2.89, respectively. According to the first-order reaction rate constants, the process rates were ranked as UV-SPC > SPC > UV and UV-SHC > SHC > UV. Central composite design was applied to determine the optimum operating conditions for maximum Norf removal. Under optimum conditions (UV-SPC: 1 mg/L initial Norf, 4 mM SPC, pH 3, 50 min; UV-SHC: 1 mg/L initial Norf, 1 mM SHC, pH 7, 8 min), the removal yields for the UV-SPC and UV-SHC were 71.8 and 72.1%, respectively. HCO3-, Cl-, NO3-, and SO42- negatively affected both processes. UV-SPC and UV-SHC processes were effective for Norf removal from aqueous solution. Similar removal efficiencies were obtained with both processes; however, this removal efficiency was achieved in a much shorter time and more economically with the UV-SHC process.