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Although cellulose hydrogels are one of promising biomaterials for drug release carrier, their passive manner of drug release and the absence of remote stimuli response limit their further applications. Herein, we report a simple one-pot method for the synthesis of magnetic β-cyclodextrin (β-CD)/cellulose hydrogel beads, which exhibited rapid swelling–deswelling properties under an external magnetic field (EMF) to remotely control drug release from passive release to stepwise release. The grafted β-CD endows the hydrogel with high drug loading capacity and, simultaneously, the incorporation of Fe3O4 nanoparticles provide the force for stepwise drug release through EMF induced rapid and reversible deformation of 3D network. We demonstrate that the efficiency of the hydrogel in the stepwise drug release dose and rate can be controlled by switching on–off the EMF and adjusting the content of Fe3O4 nanoparticles. Additionally, results from cytotoxicity tests confirmed the excellent biocompatibility of the developed hydrogel, which is promising to be used in the biomedical field.

The deficiency of available silicon (Si) incurred by year-round agricultural and horticultural practices highlights the significance of Si fertilization for soil replenishment. This study focuses on a novel and economical route for the synthesis of Si fertilizer via the calcination method using talc and calcium carbonate (CaCO3) as starting materials. The molar ratio of talc to CaCO3 of 1:2.0, calcination temperature of 1150 °C and calcination time of 120 min were identified as the optimal conditions to maximize the available Si content of the prepared Si fertilizer. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) characterizations elucidate the principles of the calcination temperature-dependent microstructure evolution of Si fertilizers, and the akermanite Ca2Mg(Si2O7) and merwinite Ca3Mg(SiO4)2 were identified as the primary silicates products. The results of release and solubility experiments suggest the content of available metallic element and slow-release property of the Si fertilizer obtained at the optimum preparation condition (Si-OPC). The surface morphology and properties of Si-OPC were illuminated by the results of scanning electron microscope (SEM), surface area and nitrogen adsorption analysis. The acceleration action of CaCO3 in the decomposition process of talc was demonstrated by the thermogravimetry-differential scanning calorimetry (TG-DSC) test. The pot experiment corroborates that 5 g kg−1 soil Si-OPC application sufficed to facilitate the pakchoi growth by providing nutrient elements. This evidence indicates the prepared Si fertilizer as a promising candidate for Si-deficient soil replenishment.

Membrane fouling remains as a critical issue limiting the widespread applications of membrane-based technologies for water and wastewater treatment. In this work, an electrochemical ceramic membrane reactor (ECMR), in which ceramic membrane with built-in Ti mesh acted as cathode/filter and Ti/SnO2-Sb-Ce as anodes, was developed for mitigating membrane fouling during wastewater treatment. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) of Ti/SnO2-Sb-Ce electrode demonstrated favorable electrochemical properties. Filtration tests with influent wastewater containing 50 mg/L sodium alginate (SA) showed that TMP increase rate for the ECMR was decreased by 23.9–72.7% compared to the control, dependent on the exertion modes of electric field in this reactor. It was found that all the oxidants contributed to the enhanced antifouling performance of the ECMR due to in-situ membrane cleaning effects while the hydrogen peroxide and active chlorine (ClT) played a more important role compared to superoxide anions and hydroxyl radicals. SA was oxidized to a smaller size after reacting with reactive oxygen species (ROS) and ClT, benefiting the mitigation of membrane fouling in ECMR.

An electrochemical ceramic microfiltration membrane with built-in cathode (Ti mesh) and Ti/RuO2 anode, which had dual functions of separation and electrochemical oxidation, was developed for p-chloroaniline (PCA) removal from contaminated waters. Results showed that the degradation of PCA followed the pseudo-first-order kinetics in all conditions. PCA degradation efficiency increased with the increase of applied voltages in the range of 0–3.0 V. The optimum solution pH for PCA decay was 7.0. An initial PCA concentration higher than 30 μM had no significant influence (p > 0.05) on the degradation efficiency of PCA. At an applied voltage of 2.0 V and an electrolysis time/hydraulic retention time of 2 h, the removal efficiency of PCA under flow-through mode was found to be 3.6 times that of flow-by mode, due to the better contact and reaction of contaminants with the oxidants generated in the vicinity of membrane surface. It also showed that OH arisen from anodic water oxidation reaction played a key role in PCA degradation. Benzoquinone, aniline, p-aminophenol, hydroquinone, malonic acid, succinic acid, oxamic acid, maleic acid, oxalic acid, α-ketoglutaric acid and formic acid were identified as the main PCA decay products, leading to a lower biological toxicity of the effluent. The system also demonstrated a favorable performance for contaminant elimination after a long-term operation. These results highlight the potential of this electrochemical microfiltration membrane system for efficient PCA degradation.

Inability to remove low-molecular-weight anthropogenic contaminants is a critical issue in low-pressure membrane filtration processes for water treatment. In this work, a novel electrochemical ceramic membrane filtration (ECMF) system using TiO2@SnO2–Sb anode was developed for removing persistent p-chloroaniline (PCA). Results showed that the ECMF system achieved efficient removal of PCA from contaminated waters. At a charging voltage of 3 V, the PCA removal rate of TiO2@SnO2–Sb ECMF system under flow-through mode was 2.4 times that of flow-by mode. The energy consumption for 50% of PCA removal for TiO2@SnO2–Sb ECMF at 3 V under flow-through mode was 0.38 Wh/L, much lower than that of flow-by operation (1.5 Wh/L), which was attributed to the improved utilization of the surface adsorbed HO· and dissociated HO· driven by the enhanced mass transfer of PCA toward the anode surface. Benefiting from the increased production of reactive oxygen species such as O2•–, H2O2, and HO· arising from excitation of anatas...

Removal of recalcitrant anthropogenic contaminants from water calls for the development of cost-effective treatment technologies. In this work, a novel electrochemical membrane filtration (EMF) process using a conducting microfiltration membrane as the cathode has been developed and the degradation of sulphanilic acid (SA) examined. The electrochemical degradation of SA in flow-by mode followed pseudo-first-order kinetics with the degradation rate enhanced with increase in charging voltage. Hydrogen peroxide as well as oxidants such as HO• and Fe(IV)O2+ were generated electrochemically with HO• found to be the dominant oxidant responsible for SA degradation. In addition to the anodic splitting of water, HO• was formed via a heterogeneous Fenton process with surface-bound Fe(II) resulting from aerobic corrosion of the steel mesh. In flow-through mode, the removal rate of SA was 13.0% greater than obtained in flow-by mode, presumably due to the better contact of the contaminant with the oxidants generated i...

Removal of sulfanilic acid (SA) from water is an urgent but still challenging task. Herein, we developed a low pressure electrochemical membrane filtration (EMF) system for SA decontamination using RuO2-TiO2@Ti/PVDF composite membrane to serve as not only a filter but also an anode. Results showed that efficient removal of SA was achieved in this EMF system. At a charging voltage of 1.5 V and a electrolyte concentration of 15 mM, flow-through operation with a hydraulic retention time (HRT) of 2 h led to a high SA removal efficiency (80.4%), as expected from the improved contact reaction of this compound with ROS present at the anode surface. Cyclic voltammetry (CV) analysis indicated that the direct anodic oxidation played a minor role in SA degradation. Electron spin resonance (ESR) spectra demonstrated the production of •OH in the EMF system. Compared to the cathodic polarization, anodic generated ROS was more likely responsible for SA removal. Scavenging tests suggested that adsorbed •OH on the anode (>•OH) played a dominant role in SA degradation, while O2•- was an important intermediate oxidant which mediated the production of •OH. The calculated mineralization current efficiency (MCE) of the flow-through operated system 29.3% with this value much higher than that of the flow-by mode (5.1%). As a consequence, flow-through operation contributed to efficient oxidation of SA toward CO2 and nontoxic carboxylic acids accounting for 71.2% of initial C. These results demonstrate the potential of the EMF system to be used as an effective technology for water decontamination.

Recovery of nutrients and energy from municipal wastewater has attracted much attention in recent years; however, its efficiency is significantly limited by the low-strength properties of municipal wastewater. Herein, we report a pilot-scale forward osmosis (FO) system using a spiral-wound membrane module to concentrate real municipal wastewater. Under active layer facing feed solution mode, the critical concentration factor (CCF) of this FO system was determined to be 8 with 0.5 M NaCl as draw solution. During long-term operation at a concentration factor of 5, (99.8 ± 0.6)% of chemical oxygen demand and (99.7 ± 0.5)% of total phosphorus rejection rates could be achieved at a flux of 6 L/(m2 h) on average. In comparison, only (48.1 ± 10.5)% and (67.8 ± 7.3)% rejection of ammonium and total nitrogen were observed. Cake enhanced concentration polarization is a major contributor to the decrease of water fluxes. The fouling also led to the occurrence of a cake reduced concentration polarization effect, improving ammonium rejection rate with the increase of operation time in each cycle. This work demonstrates the applicability of using FO process for wastewater concentrating and also limitations in ammonium recovery that need further improvement in future.