Weak Acidic Conditions Research Articles

Aquatic photochemistry of Cu(II) in the presence of As(III): Mechanistic insights from Cu(III) production and As(III) oxidation under neutral pH conditions

Surface complexation between arsenite (As(III)) and colloidal metal hydroxides plays an important role not only in the immobilization and oxidation of As(III) but also in the cycle of the metal and the fate of their ligands. However, the photochemical processes between Cu(II) and As(III) are not sufficiently understood. In this work, the photooxidation of As(III) in the presence of Cu(II) under neutral pH conditions was investigated in water containing 200 μM Cu(II) and 5 μM As(III) under simulated solar irradiation consisting of UVB light. The results confirmed the complexation between As(III) and Cu(II) hydroxides, and the photooxidation of As(III) is attributed to the ligand-to-metal charge transfer (LMCT) process and Cu(III) oxidation. The light-induced LMCT process results in simultaneous As(III) oxidation and Cu(II) reduction, then produced Cu(I) undergoes autooxidation with O2 to produce O2•⁻ and H2O2, and further the Cu(I)-Fenton reaction produces Cu(III) that can oxidize As(III) efficiently (kCu(III)+As(III) = 1.02 × 109 M–1 s–1). The contributions from each pathway (ρrCu(II)-As(III)+hv = 0.62, ρrCu(III)+As(III) = 0.38) were obtained using kinetic analysis and simulation. Sunlight experiments showed that the pH range of As(III) oxidation could be extended to weak acidic conditions in downstream water from acid mine drainage (AMD). This work helps to understand the environmental chemistry of Cu(II) and As(III) regarding their interaction and photo-induced redox reactions.

Effect of hydrophobically associating polymeric aluminum-polymer dual coagulant on coagulation of oily sewage from oilfields

Whether the oilfield sewage index can reach the reinjection specification is a crucial issue that is urgently need to be solved in polymer flooding systems. Thus the coagulability and floc morphology development of dual coagulants was systematically studied in different pH oily wastewaters. Acidification improved the deprotonation ability of coagulant. Hydrophobic associative polyaluminum silicate-poly dimethyl diallyl ammonium chloride (PASSC-PD) resolved the problem of excessive acid addition. The dual coagulants prepared not only preserved the high charge density of polyaluminum silicate (PASS) itself but also made it have the hydrophobic association and strong bridging ability. Besides, PASSC-PD was compared with hydrophobic associative polyaluminum silicate (PASS-C), PASS, and poly dimethyl diallyl ammonium chloride (PDMDAAC) pertaining to the polymer flooding oily sewage of Daqing Oilfield. The coagulation result demonstrated that PASSC-PD exhibited more advantageous turbidity and oil removal efficiencies than PASS-C, PASS, and PDMDAAC. The floc morphology result showed that adding dual coagulant made the petal-like floc of oily sewage larger at the pH value of 6. Furthermore relevant results evidenced that the coagulant had more successful fruits of turbidity removal of 96.5% and oil removal of 96.3% under weak acid conditions. These can satisfy the reinjection condition of oily sewage.

Study on the deterioration trend of the rock mass on the reservoir banks under dry-wet cycles

The deterioration of rock mass under dynamic mechanical state is difficult to determine, especially when evolution trends of micro-fractures are considered. Taking the limestone from Wuxia section of the Three Gorges Reservoir area as studying case, cross-scale tests and theoretical analysis were adopted to study the influence of dry-wet cycles on rock deterioration. The weakly acidic condition (pH = 6) and the dry environment at 105°C were together constituted the two extreme mechanical states of the dry-wet cycles. Meanwhile, the number of dry-wet cycles and soaking time were used as the main variables to analyze the deterioration trend. After introducing the damage mechanics, the quantitative relationship between the mechanical parameters and changing mechanical states was obtained. Combined with the microstructure obtained by scanning electron microscope (SEM), it can be found that with the increase of dry-wet cycles and soaking time, the morphology of mineral particles changed, the number of secondary pores gradually increased, the surface structure became looser, and the microcracks gradually increased, causing the decrease of macro strength. The related method proposed in this paper could provide significant references to determine the mechanical parameters of rocky reservoir bank.

Self-healing, reprocessable, degradable, thermadapt shape memory multifunctional polymers based on dynamic imine bonds and their application in nondestructively recyclable carbon fiber composites

Traditional epoxy thermosets have been extensively used in many fields, including the field of carbon fiber composite materials, which is favored by a large number of researchers. But they usually cannot be recycled under mild conditions. To make matters worse, the material loses its usefulness once it is damaged. Self-healing and degradable thermosetting resins with dynamic covalent bonds offer a potential solution to this conflict. In this paper, a series of epoxy polymers named EPCN based on dynamic imine bonds were easily prepared by a one-pot method using inexpensive industrial materials terephthalaldehyde and common bisphenol A diglycidyl ether as raw materials, which were cured by D230. The results show that the materials exhibit certain self-healing, reprocessability and thermadapt shape memory properties due to the dynamic properties of the imine bonds. Moreover, EPCN epoxy polymers can be degraded due to the hydrolysis of dynamic imine bonds, and their degradation exhibit temperature and acidity dependence. More importantly, the recyclable carbon fiber reinforced polymer composites prepared with EPCN-4 as the resin matrix can be completely degraded under weak acid conditions, leading to the ready and non-destructive recycling of its carbon fiber composite. We envision this reprocessable and degradable carbon fiber-reinforced composite material with cheap raw materials, simple process, and suitable for mass production will make it a potential candidate for sustainable structural material applications.

PH-sensitive alginate hydrogel for synergistic anti-infection

This work designed a pH-sensitive sodium alginate hydrogel for combating bacterial infection caused by tissue damage. The antibacterial hydrogels were prepared using sodium alginate, citric acid, and vancomycin by one-step in situ method. Vancomycin (Van) was loaded into hydrogels via reversible imine bonds for controlled drug delivery. The morphology, swelling properties, and antibacterial activity of hydrogel were characterized. The hydrogel shown strong water absorbent behavior and pH-dependent performance. The result under weak acid conditions, the drug release rate of van-loaded gel was faster than neutral and alkaline conditions and followed zero-order kinetic release model, and the cumulative release amount could reach 86.7 % over 320 min. The van-loaded gel had highly effective antibacterial activity in a weak acid environment, the combination of citric acid and vancomycin had a synergistic therapeutic effect for acute infection. The drug-loaded hydrogel shows good biocompatibility. Compared with gauze, the drug-loaded hydrogel exhibited good coagulation properties, high platelet adhesion, high fluid absorption capacity, and proper balance of fluid on the wound bed. This work proposed this simple alginate-based drug delivery system has potential applications in the field of clinical treatment of infections.

Valence-switchable and biocatalytic vanadium-based MXene nanoplatform with photothermal-enhanced dual enzyme-like activities for anti-infective therapy

Nanocatalytic technology is a promising approach for anti-infective therapy based on artificial nanoscale enzyme mimics (nanozymes). Nevertheless, the complex infective microenvironment and single catalytic mechanism restrict the catalytic activity of nanozyme, making it difficult to achieve the desired therapeutic effect. Herein, we developed vanadium nitride MXene (V2N) by a modified chemical exfoliation approach. Benefiting from the valence-switchable state and large specific surface area of V2N, which possesses superior intrinsic dual enzyme-like (oxidase-like and peroxidase-like) catalytic activities in weak acidic conditions (mimic biofilm microenvironment). Typically, V2N exhibited desirable photothermal conversion efficiency (PCE) in the second near-infrared (NIR-II) window, which can remarkably enhance the dual enzyme-like catalytic activities and avoid local hyperthermia to damage surrounding normal tissue. These integrated merits enable the V2N to generate abundant reactive oxygen species (ROS) to effectively eradicate bacteria in vitro and promote the healing of subcutaneous abscesses with negligible toxicity in vivo. Overall, this work proposed a promising strategy based on photothermal-enhanced dual enzyme-like catalytic activities for effective anti-infective therapy.

Fenton-like reaction of glucose oxidase-glucose@Kaolin coupled with green rust: A framework triggering FeⅣ=O in refractory pollutants degradation

Fenton reaction has been widely applied with fast reaction speed and strong oxidation capacity, but it also has some noticeable defects of acid-alkali reagents over-consumption and strong tendency of H2O2 self-decomposition under high concentration. In order to overcome these shortcomings, this study proposed a green rust/Kaolin fixed glucose oxidase (GR/Glu-Kaolin@GOD) Fenton system. The production of H2O2 from Glu-GOD@Kaolin system was catalyzed by GR to generate oxidizing species and degrade aniline organic wastewater. Results showed that the enzymatic reaction could produce H2O2 at a gradual incremental pace in situ, avoiding active agent quenching and heightening its utilization rate. Furthermore, this system was proved to have an excellent removal effect under neutral and weak-acid conditions, which was superior to the traditional homogeneous Fenton with a narrow pH range. In this study, diversified active substances in the system were detected including hydroxyl radicals, FeIV=O and superoxide radicals, whose real-time degradation contribution changes were calculated and analyzed. On basis of the results, the roles of these active agents and the interactional principles among them were explored. Furthermore, the close correlation between Fe2+ in GR and GlcA and degradation mechanisms upon 3, 4-DMA were set forth in detail. Especially, in the middle and later stage of the reaction, the contribution of FeIV=O, generated through the complexes between Fe(Ⅱ) and GlcA, would continue to increase due to the gradually benign pH environment and FeIV=O gave full play to advantages in decarboxylating those intermediate products containing methyl, etc, which consequently enhanced both the oxidation efficiency and effluent biodegradability. In addition, the optimal operational conditions were determined through response surface data analysis. Moreover, the residual Glu and small molecular acids in the water could be fully exploited as suitable microbial carbon sources, and elevate the efficiency of the subsequent biological treatment.

Simultaneous removal of lead, manganese, and copper released from the copper tailings by a novel magnetic modified biosorbent

Potentially toxic elements including lead (Pb), manganese (Mn), and copper (Cu) released from copper tailings would cause severe long-term environmental risks and potential threats to human health. To prevent these negative effects caused by the release of the metals, a novel magnetic carboxyl groups modified bagasse with high adsorption affinity and strong magnetism was synthesized through an in-situ precipitation method and used to simultaneously remove Pb, Mn, and Cu from the eluate of copper tailings. Results showed that release of Pb, Mn, and Cu from the copper tailings was pH, time, and particle size dependent, and maximum concentrations of them released in the eluate was 1.7, 1.9, and 4.1 mg L−1 under weak acid conditions. Batch adsorption experiment showed that the as-synthesized magnetic modified bagasse could selectively absorb Pb, Mn, and Cu from a complex solution with adsorption capacity of 137.3, 13.1, and 90.0 mg g−1, respectively. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy-mapping (EDS-mapping) demonstrated that Pb, Mn, and Cu interacted with the magnetic modified biosorbent mainly through coordination and ion exchange. Column experiments showed that higher than 99.5% of the released Pb, Mn, and Cu could be simultaneously removed by the magnetic modified bagasse, and the maximum concentrations of them released in the eluate of the copper tailings were all decreased to lower than 0.01 mg L−1, which reached the discharge standards. After recycled by a magnet, the magnetic modified bagasse could be collected easily and used repeatedly. Because of the high efficiency and easy recovery, the used method had great practical application value in removal of potentially toxic elements released from metallic tailings.

Fabrication and Characterization of Polyelectrolyte Coatings by Polymerization and Co-Deposition of Acrylic Acid Using the Dopamine in Weak Acid Solution.

Existing medical materials (such as silicone rubber, glass slides, etc.) fail to meet the functional requirements of biosensing, cell culture, and drug delivery due to their poor wettability. The preparation of polyelectrolyte coatings with excellent wettability and protein adsorption helps broaden the application of medical materials. Poly(acrylic acid) (PAA) is a common polyelectrolyte with stronger protein adsorption, but the existing methods for obtaining PAA coating have certain shortcomings to limit their industrial applications. In this study, dopamine (DA) was used to polymerize and co-deposit acrylic acid (AA) in weak acid solution to functionalize the surface of materials, and the effects of different mass ratios of DA/AA on the wettability and protein adsorption of the coating were deeply investigated. The results demonstrate that PDA/PAA coating is successfully prepared on the surface of four substrates and greatly reduces the water contact angle of these surfaces. Moreover, these coatings show excellent protein adsorption, and the amount of adsorbed protein on the coated QCM chip is increased by 57.74% than the uncoated QCM chip. In addition, the coating has a certain pH responsiveness, and its wettability and protein adsorption are closely related to the pH of the solution. The preparation strategy proposed is simple and substrate-independent, which provides valuable insights into the application of the one-step polymerization and co-deposition strategy under weak acid conditions.

Fabrication, characterization, and in vitro evaluation of doxorubicin-coupled chitosan oligosaccharide nanoparticles

In this study, we developed pH-sensitive chito-oligosaccharide nano-drug-loaded particles with good biocompatibility, biodegradation, and controlled drug delivery. Chitosan oligosaccharides (COS), Doxorubicin (DOX) amino groups, and aromatic aldehydes of benzaldehyde-terminated polyethylene glycol were used to spontaneously form pH-sensitive aniline bonds. We aimed to achieve site targeting under weak acidic tumor conditions, improve the efficacy, and reduce the toxic side effects of the drug. Particle size, drug encapsulation efficiency, loading efficiency, and zeta potential of nanoparticles were optimized by altering the ratios of aldehyde, amino groups, and sodium tripolyphosphate. The drug encapsulation efficiency and loading efficiency of COS-DOX1 were 5.55 ± 0.13% and 88.81 ± 2.00%, respectively, and the in vitro drug release process displayed a specific pH responsiveness. Co-culture of COS-DOX with HCT-116 human colon cancer cells showed that the nanoparticles exhibited dose-dependent cytotoxicity. At a low dose, COS-DOX1 can promote DOX uptake of tumor cells and exhibit higher cytotoxicity than DOX alone.

Effectivity of Multiphase Fenton-like System of Iron Reduction Induced by Bisphenol A Authigenic Photoelectron

In recent years, the Fenton-like (Fe2+-PMS/PS) advanced oxidation technology of persulfate activated by ferrous ions has been increasingly developed, but the difficulty of Fe3+ reduction, which stops the reaction, still restricts its large-scale application. In this study, it was found that when some organic compounds represented by bisphenol A (BPA) were mixed with Fe3+ and pristine TiO2, some surface structures could broaden the light response range of TiO2, capture visible light, and transfer the photoelectrons to Fe3+ through TiO2 for reduction, so as to achieve an infinite cycle of Fe3+/Fe2+. According to the above principle, a BPA-TiO2-Fe3+-PS composite system under visible light was constructed to degrade BPA, and its catalytic performance, catalytic mechanism, and influencing factors were discussed. The results showed that the system had outstanding catalytic performance, the degradation efficiency of BPA (50 mg·L-1) reached 93.1%, and the mineralization efficiency reached 70% within 60 min. At the same time, it verified that the system could reduce Fe3+ by the authigenic photoelectron of bisphenol A, and the steady-state concentration of Fe2+ obtained by 60 min reduction was 3.5 μmol·L-1. The main active oxidizing species in the system were sulfate radicals (SO4-[KG-*2/3]·) and hydroxyl radicals (·OH), of which the contribution rate of·OH was more than 60%. An appropriate increase in TiO2, Fe3+, and PS dosage and light intensity could improve the degradation effect. The system had the best treatment efficiency under weak acid conditions, and the degradation efficiency reached 96.5%. It also had a good effect under neutral conditions. CO32-, H2PO4-, and SO42- had a certain inhibitory effect on the system.

An AIE-Active probe for detection and bioimaging of pH values based on lactone hydrolysis reaction.

Cellular pH homeostasis is essential for many physiological and pathological processes. pH monitoring is helpful for the diagnosis, treatment and prevention of disorders and diseases. Herein, we developed a ratiometric fluorescent pH probe (TCC) based on a coumarin derivative containing a highly active lactone ring. TCC exhibited a typical AIE effect and emitted blue fluorescence under weak acidic condition. When under weak basic condition, the active lactone moiety underwent a hydrolysis reaction to afford a water-soluble product, which gave red-shifted emission. The emission color change from blue through cyan and then to yellow within pH 6.5-9.0 which is approximate to the biological pH range. And the fluorescence color change along with pH value is reversible. Furthermore, TCC was successfully utilized in the detection of the intracellular pH change of live HeLa cells, which indicated that TCC had practical potential in biomedical research.

Coagulation behavior of polyaluminum-titanium chloride composite coagulant with humic acid: A mechanism analysis

The hydrolysate species of metal-based coagulants and the binding sites of humic acid (HA) are highly dependent on the pH conditions. Exploring the binding sites and modes between coagulant hydrolysates and HA molecules is critical to understanding the coagulation mechanism. In this paper, the binding behavior between HA molecules and the hydrolysates of a polyaluminum-titanium chloride composite coagulant (PATC) was investigated under different pH conditions by semi-quantitative FTIR and XPS. It was found that oligomeric and mesopolymeric hydrolysates were the dominant species under acid conditions, which could complex with the hydroxyl and carboxyl groups of HA by forming COAl/Ti coordinate bonds. However, large amounts of H+ could compete with Al3+ and weaken the removal efficiency of HA. With the increase of pH, the hydrolysis process of the PATC and the deprotonation of HA were simultaneously underway. Under weakly acid conditions, the complexation of the aluminum hydrolysates with carboxyl groups was improved due to the gradually diminishing competition of H+ and the enhanced charge neutralization of the further polymerized hydrolysates. Consequently, the maximum UV254 removal by adding PATC was observed at pH 6. Under alkaline conditions, the sweeping effect of amorphous hydroxide dominated the HA removals, which was accompanied by the surface complexation of Al/Ti nuclear with carboxyl groups as well as the hydrogen bonds between hydroxyl and hydroxide. This study provides a new clue for the interaction mechanisms between the hydrolysates of composite coagulants and the dominant functional groups of HA at various pH conditions.

Multi-roles of SO2 to enhance the removal of arsenic from wastewater in sulfidation processes

Sulfidation has been an efficient method for arsenic (As) removal from acid wastewater, yet it is inefficient under neutral and weak acid conditions. The higher pH values resulted in the formation of the unstable As-S precipitates, especially employing Na2S as the vulcanizing agent as it can increase the pH value dramatically. Here, we found that SO2 exhibited excellent multi-roles in As removal when applying H2S-sulfidation method. The acidification effect of SO2 lead to the decreasing of pH values, guaranteed the stable As-S precipitates formation. Through the SO2 pre-treatment method, the results indicated that the pH values decreased from 7 to 2.8, with the increased H2S utilization efficiencies for As(III) removal from 20.9% to 92.0%. Moreover, SO2 post-treatment not only increased the As(III) removal efficiency, but also eliminated the excessive sulfides in solution. The reaction mechanism analysis indicated that the liquid comproportionation reaction between SO2 and excessive sulfides plays a vital role. The generated nascent sulfur (N-S0) can adsorb arsenic species and promote the agglomeration of As(III)-S precipitates. Furthermore, the SO2 and H2S co-treatment exhibited excellent As(V) removal performance. This study provides a new alternative method to improve the H2S-sulfidation process with SO2 for As removal from wastewater.

Chlorophyll encapsulation by complex coacervation and vibration nozzle technology: Characterization and stability study

Soy protein isolate (SPI) and chitosan were used as carriers to encapsulate chlorophyll. Optimization conditions utilizing the Box-Behnken design used 1:7 (wet basis) mass ratio of chitosan to SPI, 1:14.8 (wet basis) mass ratio of chlorophyll to SPI, and pH 6.91. Under this condition, the predicted and experimental encapsulation efficiency was 97.95% and 96.21% respectively. Using complex coacervation and vibration nozzle technology, different chlorophyll-loaded nanoparticles were obtained with acceptable green colour, satisfactory encapsulation efficiency (94.9–96.1%) and loading capacity (3.32–4.22%). Z-average diameter, SEM, and TEM showed nanoparticle sizes were nano-sized (273–373 nm), porous and largely spherical with good dispersibility. FTIR, Raman, and DSC analyses confirmed significant interaction between chlorophyll molecules and carriers. Furthermore, chlorophyll retention of nanoparticles after 21 days of exposure to sunlight at room temperature ranged from 58.3–62.3%. At pH 2.5, chlorophyll retention ranged from 59.4–69.5%. In weak acid condition (pH 4.5 and 6.5), nearly all (97.7–100%) chlorophylls remained. Industrial relevanceThe burgeoning awareness of consumers on the negative health implications of synthetic food colorants has stimulated the need to seek for healthier alternatives. Chlorophyll, a natural pigment found in many green vegetables is highly valued due to its chemo-preventive effects. Despite the huge health benefits, the exposure of chlorophyll to external factors such as heat, light, oxygen, and acid during processing and storage limit the gains associated with this pigment. An optimized encapsulation process has the benefit of minimizing chlorophyll degradation under these conditions while also maintaining product integrity.

Blocking the 2,3-butanediol synthesis pathway of Klebsiella pneumoniae resulted in L-valine production.

Klebsiella pneumoniae is a 2,3-butanediol producing bacterium. Nevertheless, a design and construction of L-valine production strain was studied in this paper. The first step of 2,3-butanediol synthesis and branched-chain amino acid synthesis pathways share the same step of α-acetolactate synthesis from pyruvate. However, the two pathways are existing in parallel and do not interfere with each other in the wild-type strain. A knockout of budA blocked the 2,3-butanediol synthesis pathway and resulted in the L-valine production. The budA coded an α-acetolactate decarboxylase and catalyzed the acetoin formation from α-acetolactate. Furthermore, blocking the lactic acid synthesis by knocking out of ldhA, which is encoding a lactate dehydrogenase, improved the L-valine synthesis. 2-Ketoisovalerate is the precursor of L-valine, it is also an intermediate of the isobutanol synthesis pathway, while indole-3-pyruvate decarboxylase (ipdC) is responsible for isobutyraldehyde formation from 2-ketoisovalerate. Production of L-valine has been improved by knocking out of ipdC. On the other side, the ilvE, encoding a transaminase B, reversibly transfers one amino group from glutamate to α-ketoisovalerate. Overexpression of ilvE exhibited a distinct improvement of L-valine production. The brnQ encodes a branched-chain amino acid transporter, and L-valine production was further improved by disrupting brnQ. It is also revealed that weak acidic and aerobic conditions favor L-valine production. Based on these findings, L-valine production by metabolically engineered K. pneumonia was examined. In fed-batch fermentation, 22.4g/L of L-valine was produced by the engineered K. pneumoniae ΔbudA-ΔldhA-ΔipdC-ΔbrnQ-ilvE after 55h of cultivation, with a substrate conversion ratio of 0.27mol/mol glucose.

Understanding and characteristics of coagulation removal of composite pollution of microplastic and norfloxacin during water treatment

Water composite pollution is still a great challenge in the field of water treatment. Especially for microplastic (MP), as an emerging pollutant, its wide distribution in water and persistent eco-environmental influence have received great concerns in recent years. Nevertheless, the removal characteristics and mechanism of conventional coagulation on MP composite pollution is quite insufficient. In this study, the coagulation removal performance and mechanisms of MP (polyethylene, PE) and norfloxacin (NOR) was investigated by polyaluminium chloride (PAC) and anionic polyacrylamide (APAM). Compared with single system, the removal efficiency of PE was significantly improved (>99.0%) under plateau stage in composite system, while the removal efficiency of NOR was slightly decreased to around 42% regardless of the addition of APAM. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), zeta potential and One-way analysis of variance (ANOVA) of experimental data were used to explore the coagulation mechanisms. The results demonstrated that the removal of individual PE and NOR was mainly controlled by charge neutralization and sweep flocculation by PAC and APAM, and adsorption by formation of Al-NOR complex, respectively. Importantly, in composite system, the removal of PE was enhanced not only by the stronger charge neutralization but also the adsorption via the formation of PE-NOR-Al complex. Furthermore, the removal efficiency of PE and NOR in neutral and weak alkaline conditions was higher than that in weak acidic or strong alkaline conditions. The presence of metal ions and humic acid had obvious inhibition and promoting effects on the removal efficiency of PE and NOR. This study can provide a new perspective on fundamental understanding in characteristics and mechanisms of MP composite pollutants removed by coagulation.

PH-responsive mesoporous Fe2O3–Au nanomedicine delivery system with magnetic targeting for cancer therapy

Chemotherapy is the prime tool for the clinical treatment of cancer. The efficiency of treatment has been greatly improved with the assistance of nanomedicine delivery systems. However, it still meets the challenge of inefficient drug delivery and damage to normal tissues caused by uncontrolled drug release. Considering the various processes of nanomedicine acting on cancer cells, a pH-responsive mesoporous Fe2O3–Au nanomedicine delivery system with magnetic targeting was designed to achieve controlled drug release and improve the safety and efficiency. Fe2O3 particles were constructed with external mesopores and internal hollow structures, while Au nanoparticles were connected on the surface of Fe2O3 particles through pH-responsive valence bonds to encapsulate the drug. The Fe2O3–Au nanomedicine delivery system was equipped with magnetic targeting function, which could be induced by an external magnetic field to increase the drug concentration to kill cancer cells as well as reduce damage to normal cells. Meanwhile, based on the pH-responsive feature, the drug embedded could only be released in the weakly acidic condition of the cancer environment, while the nanomedicine delivery system remained closed in normal tissues. The Fe2O3–Au nanomedicine delivery system possessed the functions of pH responsiveness and magnetic targeting, enhancing safety and efficiency and providing a promising method for cancer therapy.

A triple pH-responsive AIEgen: Synthesis, optical properties and applications

• A novel AIEgen with triple pH-responsiveness is synthesized. • Under strong alkaline conditions, the fluorescence is quenched and the micro-rods become nano-rods. • Under weak acidic conditions, the red fluorescence blue-shifts to yellow-green and the micro-rods transform to nano-spheres. • Under strong acidic conditions, the fluorescence is quenched and the nano-spheres are destroyed. • The AIEgen has been successfully applied in anti-counterfeit and dual encryption, photo-patterning and molecular logic gates. Stimuli-responsive luminogens with aggregation-induced emission (AIE) properties have attracted more and more attention for their intense emission in the aggregated state and tunable physicochemical performances. Nevertheless, it still remains challenging to design multifunctional AIE luminogens (AIEgens) with multi-responsive moieties and tunable fluorescence and morphologies. Here, a novel multifunctional AIEgen (DAS-BA) is elaborately designed based on the synergistic effect of twisted intramolecular charge-transfer (TICT), restriction of intramolecular motions (RIM), and excited-state intramolecular proton transfer (ESIPT). DAS-BA not only possesses triple pH-responsivenesses and long-wavelength emission, but also shows corresponding transition in its fluorescence and self-assembled morphologies. Under strong alkaline conditions, owing to the deprotonation of phenolic hydroxyl group, the red emission of DAS-BA is quenched and the molecular assemblies change from micro-rods to nano-rods. However, under weak acidic conditions, the red fluorescence dramatically shifts to yellow-green and the assemblies strikingly transform from micro-rods to nano-spheres due to the protonation of diethylamino moieties. Further acidification can hydrolyze the Schiff base, resulting in fluorescence quenching and destruction of the nano-spheres. Based on the reversible protonation process of diethylamino moiety, DAS-BA exhibits CO 2 -activated reversible fluorescence switching. Furthermore, DAS-BA has been successfully applied in anti-counterfeit and dual encryption, photo-patterning and molecular logic gates.

Strongly coupled cobalt/oxygen co-doped porous g-C3N4 heterostructure with abundant oxygen vacancies modulated the peroxymonosulfate activation pathway

• Co-O@CN-150 heterostructure was successfully fabricated. • Co-O@CN-150 completely degraded OFX within 20 min. • The synergy of abundant oxygen vacancies and Co-O-C bond accelerated the interfacial electron transfer. • Co-O@CN-150 tuned the PMS activation from radicals to non-radicals in weak acid conditions. • Catalytic membrane system achieved the catalytic self-cleaning performance during continuous filtration. How to resist the influence of inorganic ions and limit metal release for enhanced peroxymonosulfate (PMS) activation have been always plagued by researchers. Herein, highly dispersed cobalt and oxygen co-doped porous g-C 3 N 4 heterostructure (Co-O@CN) from g-C 3 N 4 @ZIF-67 composites was successfully fabricated, which could completely degrade ofloxacin within 20 min. Detailed characterizations reflected that the porous Co-O@CN-150 heterostructure not only endowed more active sites to be exposed but also facilitated the formation of a stable conductive structure. Besides, the synergy of abundant oxygen vacancies and Co-O-C bond accelerated the interfacial electron transfer for promoting the redox of Co 2+ /Co 3+ . Notably, Co-O@CN-150 heterostructure tuned the PMS activation pathway from radicals to non-radicals in weak acid conditions. Besides, the fabricated catalytic membrane system exhibited excellent efficiency for instantaneous degradation of ofloxacin and achieved self-cleaning performance during continuous flow-through filtration. This work could deepen the understand of the role of the covalent bond and oxygen vacancy and provided a novel tactic for practical wastewater treatment.