Hybrid conditioning of ionic liquid coupling with H2SO4 to improve the dewatering performance of municipal sludge.

Municipal sludge generated from wastewater treatment plants can cause a serious environmental and economic burden. A novel hybrid conditioning strategy was developed to enhance the dewatering performance of sludge, employing 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4mim][CF3SO3]) treatment combined with H2SO4 acidification. Following conditioning, the capillary suction time ( CST normalized ), the specific resistance of filtration (SRF), and moisture content of the treated sludge were decreased to 1.99 ± 0.24 (s·L/g TSS), 1.33 ± 0.05 (1012 m/kg), and 72.01 ± 0.94%, respectively. The results were superior to those achieved with sludge treated solely by H2SO4 acidification or [C4mim][CF3SO3] alone. The biomacromolecules within the sludge flocs were dissolved by [C4mim][CF3SO3], while simultaneously, the microorganisms were inactivated. Consequently, the colloidal-like structures of the sludge flocs were destroyed. Additionally, the ionizable functional groups of the biomacromolecules were instantly protonated by the introduced H+ ions, and their negative charges were neutralized during the H2SO4 acidification process. The presence of H+ ions promoted the weakening of electrostatic repulsion between the sludge flocs. As a result, an enhancement of sludge dewaterability was obtained after treatment with [C4mim][CF3SO3] and H2SO4 acidification. The finding of the intensification mechanism of sludge dewaterability brought by hybrid treatment of acidification and [C4mim][CF3SO3] provides novel insights into the field of sludge disposal.

Degradation of micropollutants in secondary wastewater effluent using nonthermal plasma-based AOPs: The roles of free radicals and molecular oxidants.

Emerging micropollutants (µPs) appearing in water bodies endanger aquatic animals, plants, microorganisms and humans. The nonthermal plasma-based advanced oxidation process is a promising technology for eliminating µPs in wastewater but still needs further development in view of full-scale industrial application. A novel cascade reactor design which consists of an ozonation chamber preceding a dielectric barrier discharge (DBD) plasma reactor with a falling water film on an activated carbon textile (Zorflex®) was used to remove a selection of µPs from secondary municipal wastewater effluent. Compare to previous plasma reactor, molecular oxidants degraded micropollutants again in an ozonation chamber in this study, and the utilization of different reactive oxygen species (ROS) was improved. A gas flow rate of 0.4 standard liter per minute (SLM), a water flow rate of 100 mL min-1, and a discharge power of 25 W are identified as the optimal plasma reactor parameters, and the µP degradation efficiency and electrical energy per order value (EE/O) are 84-98% and 2.4-5.3 kW/m³, respectively. The presence of ROS during plasma treatment was determined in view of the µPs removal mechanisms. The degradation of diuron (DIU), bisphenol A (BPA) and 2-n-octyl-4-isothiazolin-3-one (OIT) was mainly performed in ozonation chamber, while the degradation of atrazine (ATZ), alachlor (ALA) and primidone (PRD) occurred in entire cascade system. The ROS not only degrade the µPs, but also remove nitrite (90.5%), nitrate (69.6%), ammonium (39.6%) and bulk organics (11.4%). This study provides insights and optimal settings for an energy-efficient removal of µPs from secondary effluent using both free radicals and molecular oxidants generated by the plasma in view of full-scale application.

A novel insight on the intensification mechanism of sludge dewaterability by ionic liquids.

The huge output of sewage sludge has caused a remarkable environmental burden. Sludge dewatering is considered as an important way to reduce the sludge volume. Five imidazole-based ionic liquids were used to improve the dewaterability of sewage sludge. 1-ethyl-3-methylimidazolium dihydrogen phosphate ([Emim][H2PO4]) was screened out as a potential conditioner of sludge due to its excellent dewatering performance and reusability. The solid content of sludge filter cake after treatment with [Emim][H2PO4] was about 10% higher than that of sludge treated by cationic polyacrylamides (CPAM). The intensification mechanism of ionic liquids to the improvement of sludge dewatering performance was studied. The presence of acidic ionic liquids [Emim][H2PO4] resulted the increase of zeta potential from -14.57 ± 0.81 mV to -5.60 ± 0.30 mV and led to the protonation of biopolymers. Acidic ionic liquids [Emim][H2PO4] inactivated the microorganism and led to a porous and unconsolidated structure of the solid sludge particles. All these effects were conducive to destroy the microstructure of sludge and release water. However, [Emim]Cl, [Bmim][OTf] and [Hmim][OTf] showed little effect on the protonation of ionizable functional groups at near-neutral environment. The dissolution of biopolymer decreased the zeta potential and strengthened the electrostatic repulsion. So, they showed weaker intensification effects than CPAM.

Novel functional separator with self-assembled MnO2 layer via a simple and fast method in lithium-sulfur battery.

Modifying separator with metal oxides has been considered as a strong strategy to inhibit the shuttling of soluble polysulfide in the lithium-sulfur battery (Li-S battery). Manganesedioxide (MnO2), one kind of transition metal oxide, is widely applied to decorate the PP (Polypropylene) separator. However, the fabrication by physical coating is always multistep and complicated. Here, we design a simple and fast method to chemically decorate separator. Based on the oxidizing property of acidic KMnO4 solution, the PP separator was oxidized and an ultrathin self-assembled MnO2 layer was directly constructed on one side of separator, by immersing in acidic KMnO4 solution for only 1 h. The self-assembled MnO2 layer has the synergistic effect of adsorption and catalytic conversion on polysulfides, which can effectively inhibit the shuttle effect. It can also help battery to maintain excellent electrochemical kinetics in the electrochemical cycle and maintain the effective recycling of active substances. As a result, the shuttling of polysulfide is greatly prohibited by this novel functional separator, and cycling stability is outstandingly improved, with a low-capacity decaying of 0.058% after 500 cycles at 0.5C. The rapid and simple modification method proposed in this study has a certain reference value for the future large-scale application of lithium-sulfur battery.

Destroying the structure of extracellular polymeric substance to improve the dewatering performance of waste activated sludge by ionic liquid.

The disposal and resource utilization of waste activated sludge (WAS) is a big challenge for its high moisture content. Ionic liquid (IL), 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][OTf]), was innovatively used as a conditioner to improve the dewatering performance of WAS. The WAS was characterized by flocs size, three-dimensional excitation-emission matrix (3D-EEM), zeta potential, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) for the investigation of intensification mechanism. The results showed that the dewatering performance of WAS conditioned by [EMIM][OTf] was significantly improved. The moisture content was successfully decreased to 64.99±0.92 %, and the intensification mechanism was investigated. The results showed that the structures of extracellular polymeric substance (EPS) were destroyed by [EMIM][OTf]. It brought a sharp decrease of the contents of polysaccharides (PS), proteins (PN), humic acid (HA) and fulvic acid (FA) in tightly bound extracellular polymeric substance (TB-EPS) structure. The inactivation of microbial cells promoted the disintegration of flocs. Large flocs were converted into unstable small particles and biopolymers. In addition, the negative charges of WAS were also neutralized for dissolution of biopolymers in [EMIM][OTf], and the electrostatic repulsion between flocs was weakened. [EMIM][OTf] was easily recycled five times. The research results indicate that specific IL, such as [EMIM][OTf], is a potential conditioner to improve the dewatering performance of WAS.

Novel Bifunctional Separator with a Self-Assembled FeOOH/Coated g-C3N4/KB Bilayer in Lithium-Sulfur Batteries.

Separator modification with metal oxide and carbon composite recently has become a potential and competitive way to confine polysulfide diffusion and mitigate the shuttling effect. However, other modification methods also have an impact on the stability of the modified layer and the enhancement of electrochemical performance. Herein, we first design a novel bifunctional separator combined with one self-assembled FeOOH layer via a chemical way and one conductive g-C3N4/KB layer by physical coating. Different from directly coating the metal oxide and carbon composite on the separator, the self-assembled FeOOH layer is firmly formed on the PP separator, which enables the chemical capture of the soluble polysulfide and prohibit the shuttling effect. Then, the coated g-C3N4/KB layer is further introduced to greatly enhance the transportation of lithium ions and physically confine the migration of intermediates. As a result, the battery with this bifunctional separator (G-SFO) achieves outstanding rate capacities (1000, 901, and 802 mA h/g at 0.5, 1, and 2 C). After 900 cycles at 1 C, it also shows excellent long cycle performance, with relatively low fading (0.055%). This original fabrication will present a new and feasible strategy for fabricating a bifunctional separator with metal oxide and carbon material.

One-step fabrication of integrated disposable biosensor based on ADH/NAD+/meldola's blue/graphitized mesoporous carbons/chitosan nanobiocomposite for ethanol detection.

A novel strategy to simplify the dehydrogenase-based electrochemical biosensor fabrication through one-step drop-coating nanobiocomposite on a screen printed electrode (SPE) was developed. The nanobiocomposite was prepared by successively adding graphitized mesoporous carbons (GMCs), meldola's blue (MDB), alcohol dehydrogenase (ADH) and cofactor nicotinamide adenine dinucleotide (NAD(+)) in chitosan (CS) solution. MDB/GMCs/CS film was prepared. Cyclic voltammetry measurements demonstrated that MDB was strongly adsorbed on GMCs. After optimizing the concentration of MDB and the working potential, the MDB/GMCs/CS film presented a fast amperometric response (5s), excellent sensitivity (10.36 nA µM(-1)), wide linear range (10-410 µM) toward NADH and without any other interference signals (such as AA, UA, DA, H2O2 and metal ions). Furthermore, concentrations of ADH and NAD(+) in nanobiocomposite and the detection conditions (temperature and pH) were also optimized. The constructed disposable ethanol biosensor showed an excellent linear response ranged from 0.5 to 15 mM with high sensitivity (67.28 nA mM(-1)) and a low limit of detection (80 µM) and a remarkable long-term stability (40 days). The intra-batch and inter-batch variation coefficients were both less than 5% (n=5). The ethanol recovery test demonstrated that the proposed biosensor offered a remarkable and accurate method for ethanol detection in the real blood samples.