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Colloids and organics in shale gas fracturing flowback water (SGFFW) during shale gas extraction are of primary concerns. Coagulation combined with oxidation might be a promising process for SGFFW treatment. In this study, a novel electrocoagulation-peroxone (ECP) process was developed for SGFFW treatment by simultaneous coagulation and oxidation process with a Al plate as the anode and a carbon-PTFE gas diffusion electrode as the cathode, realizing the simultaneous processes of coagulation, H2O2 generation and activation by O3 at the cathode. Compared with electrocoagulation (EC) and peroxi-electrocoagulation (PEC), COD removal efficiency mainly followed the declining order of ECP, PEC and EC under the optimal current density of 50 mA cm−2. The appearance of medium MW fraction (1919 Da) during ozonation and PEC but disappearance in ECP indicated that these intermediate products couldn't be degraded by ozonation and PEC but could be further oxidized and mineralized by the hydroxyl radical produced by the cathode in ECP, demonstrating the hydroxyl radical might be responsible for the significant enhancement of COD removal. The pseudo-first order kinetic model can well fit ozonation and EC process but not the PEC and ECP process due to the synthetic effect of coagulation and oxidation. However, the proposed mechanism based model can generally fit ECP satisfactorily. The average current efficiency for PEC was 35.4% and 12% higher than that of ozonation and EC, respectively. This study demonstrated the feasibility of establishing a high efficiency and space-saving electrochemical system with integrated anodic coagulation and cathodic electro-peroxone for SGFFW treatment.

Shale gas fracturing flowback water (SGFFW) generated during shale gas extraction is of great concern due to its high salinity and complicated components. In this study, the feasibility of nanofiltration (NF) and reverse osmosis (RO) for SGFFW desalination in assisting SGFFW reuse and discharge were systematically evaluated after the pretreatment of coagulation-ultrafiltration (UF) process. Under the same initial water flux of 1.27 × 10 −6 m/s, the water flux decreased tremendously within 800–1000 min for both NF(NF90) and low pressure RO(ESPA1) membranes. The stable water flux was only 38.2% and 15.8% of the initial water flux for NF90 and ESPA1 membrane, respectively. The removal efficiency of the Na + was 81.2% for NF90 membrane and 88.1% for ESPA1 membrane, while the rejection ratios of Cl − were 83.3% and 87.3% for NF90 and ESPA1 membrane, respectively. The rejection ratios for multivalent ions (i.e., Fe 3+ , Ca 2+ and Ba 2+ ) were typically very high (>90%). According to fluorescence regional integration (FRI) under the Excitation—Emission—Matrix Spectra (EEM) within each region volume, the dissolved organics removed by NF in different region decreased in the order of VI (86.0%), I (47.2%), III (31.8%), II (20.8%), V (6.2%), IV(0.2%), while the overall rejection ratio of RO decreased in the order of VI (100.0%), I (88.3%), II (70.7%), III (66.8%), V (58.9%), IV(0.3%). The difference in molecular weight(MW) distribution between the feed and permeate of NF/RO samples showed that the organics with MW of 20 kDa were greatly removed, indicating the NF/RO mainly intercepted this portion of organics such as guar gum, polyacrylamide and various surfactants. However, the effluent of the NF/RO still contained a large portion of biopolymers, which was plausible that small portion of polyacrylamide passed through the membrane. The elemental analysis by scanning electron microscope (SEM)-energy dispersive spectrometer (EDS) demonstrated the fouling layer was mainly composed of organics (i.e., polyacrylamide and aromatic protein). It seemed that developing new-type anti-fouling membrane was a feasible approach to decelerate the membrane fouling.

Polyamide (PA) nanofiltration (NF) membranes were fabricated via interfacial polymerization (IP) with graphene oxide (GO)/aminated GO (NGO)-incorporated substrate and then compared for petrochemical wastewater and shale gas produced water desalination. Crosslinking degree of PA layer with GO-incorporated substrate and NGO-incorporated substrate was higher than pristine membrane. Water flux of TFCGO-0.05 (with GO addition mass of 0.05 wt%) and TFCNGO-0.075 (with NGO addition mass of 0.075 wt%) membrane substantially increased by 15.6% and 26.9% with the highest flux of 44.93 and 49.30 L m-2 h-1, respectively, while slight difference was observed for Na2SO4, MgSO4, NaCl rejection. The better performance of TFCNGO than TFCGO was attributed to much thinner PA layer due to relatively larger pore size, higher hydrophilicity, and possible reaction of amino group of NGOs with TMC, which resulted in lower PA layer thickness of TFCNGO membranes. Substantial enhancement of water flux (higher than 24.8%) and similar divalent ion rejections can be observed for petrochemical wastewater, as consistent with the single salt test. However, better performance in permeability and divalent ion rejections (approximately 6% higher than pristine membrane) was observed for shale gas produced water. These results also demonstrated that it is feasible to incorporate NGO into substrate for NF fabrication to improve performance for industrial water desalination.

Graphene oxide (GO)-based membranes were fabricated by first immobilizing GO nanosheet using polydopamine (PDA) on the polyvinylidene fluoride (PVDF) substrate and then tuning the interlaminar spacing and properties by the different crosslinkers (i.e., ethylenediamine (EDA) or β-cyclodextrin functionalized EDA (β-CD-EDA)) to investigate rejection performance and mechanism of three pharmaceuticals. The d-spacings of EDA crosslinked membrane (PDA-GO/EDA) and β-CD-EDA crosslinked membrane (PDA-GO/β-CD-EDA) were determined to be 1.13 and 0.97 nm, respectively, which were much higher than that of PDA coated GO membrane (PDA-GO) of 0.78 nm. The moderate and even relatively low rejection ratio of the pharmaceuticals demonstrated that molecular sieving didn't contribute significantly to the pharmaceutical rejection as expected. In addition to molecular sieving, the electrostatic and chemical interactions from the active sites GO might play the significant and noticeable role on pharmaceutical rejection. When adsorption was not much higher in some scenarios (i.e., carbamazepine at all pH, sulfadiazine @ pH = 11 and propranolol @ pH = 3), it was plausible that conformation of GO nanosheets dramatically changed, which resulted in decrease of d-spacing and thus much higher rejection ratio. In contrast, when adsorption was much higher in some scenarios (sulfadiazine @ pH = 3, 7 and propranolol @ pH = 7, 11), the solubility in the membrane matrix increased and therefore the rejection ratio decreased. The disagreement demonstrated that more attention should be paid on the interactions between pharmaceutical and GO membranes, although the stability of the membrane was enhanced by crosslinking.

Polysulfone ultrafiltration (UF) and polypiperazine-amide nanofiltration (NF) membranes were first fabricated by phase inversion and interfacial polymerization, and then modified by the commonly used TiO2 on the membrane surface, respectively. Compared with the pristine UF and NF membranes, pure water flux decreased by 40.66% for modified UF membrane and 12.92% for modified NF membrane, while the contact angle of the modified membranes decreased from 66.5° to 35.3° for UF membrane and from 48.2° to37.7° for NF membrane. However, the membrane modified by TiO2 nanoparticles for both UF and NF membranes exhibited much better anti-fouling and separation performance for two types of oil-in-water emulsions with different droplet size (i.e., prepared oil-in-water emulsion with low salinity and oil produced water in Shengli oilfield, China). It was obvious that water flux of modified UF only slightly decreased and the stable water flux was 2.2 times and 15.6% higher than that of pristine membranes for the prepared oil-in-water emulsion and produced water, respectively. According to the five fouling models for UF, the TiO2 modified UF membrane could alleviate the fouling on membrane surface and greatly increase water flux by reducing the adsorption, deposition, blockage of membrane pores and formation of cake layer for two types of oil-in-water emulsion. For NF, water flux of the modified membrane increased by 66.1% and 22.8% for prepared oil-in-water emulsion and produced water, respectively. TiO2 coating effectively alleviated the oil adhesion and cake layer formation on the membrane surface.

Cognitive impairments have been proposed as a core feature of schizophrenia. Studies have shown that chronic or subchronic treatment with N-methyl-d-aspartate (NMDA) antagonists could induce cognitive deficits that resemble the symptoms of schizophrenia, yet few studies have investigated the effects of repeated NMDA blockade during adolescence on cognition. In the current study, adolescent, male rats were treated with an intraperitoneal injection of MK-801 (0.05, 0.1, and 0.2mg/kg) once daily for 14days. They were then tested 24h and 14days after drug cessation, respectively, in a series of behavioural tasks, including the object recognition task, the object-in-context recognition task and the working memory task of the Morris water maze (MWM). Results showed that object-in-context recognition and spatial working memory in the MWM were significantly impaired by repeated MK-801 treatment when animals were tested 24h after drug cessation, but object recognition was left intact. In particular, such deficits were observed 14days after drug cessation in the 0.2mg/kg group. The cognition-impairing effect of MK-801 could not be attributed to malnutrition or alterations in motor functions. Taken together, this study may provide support for establishing an animal model of cognitive deficits of schizophrenia based on low-dose, repeated treatment of MK-801 during adolescence.

A simplified reflection-mode optical resonator for high-sensitivity biodetection is presented. Sensing is based on interaction between the optical micro-resonator and a nano-particle taggant attached to the analyte molecule, which causes scattering between resonator modes and a resultant change in broadband output power. The design of the resonator eliminates the need for evanescent coupling between the resonator cavity and bus waveguides, relying instead on direct core coupling, thus simplifying the device fabrication process and facilitating low-cost manufacture. Performance of the resonator sensor has been simulated via Finite Difference Time Domain (FDTD) calculations. Prototype resonator devices have been fabricated and characterized using an Atomic Force Microscope (AFM) probe to simulate a nano-particle; these experiments demonstrate the feasibility of detection using a low-cost broadband optical source and detector. Sensor subsystems incorporating the resonator chip, aminosilane surface functionalization, and microfluidic flow channels have been used to detect gold nano-particles suspended in a buffer solution; these experiments demonstrate the potential of detecting the occurrence of fewer than three particles attached to the active region of the micro-resonator.