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Here, a novel transformed CdO with low coordination and N doping environment was simply synthesized through the involvement of the target molecule tetracycline (TC). The results showed that the shedding of surface hydroxyl groups led to a low coordination environment, and N doping formed a new doping energy level, which increased the charge density and promoted the migration and separation of photo-generated carriers. Its photocatalytic performance was 4.32 times higher than that of hydroxy-rich CdO and the selectivity coefficient was 4.8. Combined with theoretical calculation and in situ Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) analysis, the significant improvement of selectivity was due to the interaction of the doped N atom with the methyl carbon in TC. This work provided a new idea for the simultaneous construction of low coordination environment and N-doped materials for efficient selective photocatalysis. [ABSTRACT FROM AUTHOR]

The development of molecularly imprinted membranes (MIMs) has promoted applications of membrane-based separation technology, which has shown considerable advantages in water treatment, chemical separation and drug purification. Herein, imitated core–shell PEI@SiO2-based enoxacin-imprinted nanocomposite membranes (SPEIMs) were developed by mixing polyethylenimene-modified silica nanoparticles with polyvinylidene fluoride powder under freezing operation. As a typical and hazardous water pollutant, enoxacin was selected as the template molecule. Morphology and chemical characterizations were explored for an insightful analysis of the obtained membranes. Based on the organic–inorganic hybrid strategy, the as-prepared SPEIMs exhibited superior selectivity towards the target (enoxacin). Satisfactory adsorption performance (55.94 mg g−1), permeability (3.22 for norfloxacin/enoxacin and 7.07 for ciprofloxacin/enoxacin) and regeneration performance (90.31%) were achieved onto SPEIMs. The products and methods obtained in this work would potentially enrich the applications of MIMs in pollution control and biochemical separation. [ABSTRACT FROM AUTHOR]

A novel biomass carbon quantum dots@Bi2WO6 (BC-QDs@Bi2WO6) photocatalyst with uniform dispersivity was prepared via a dialysis-assisted hydrothermal process. Multiple techniques including HR-TEM, XPS, UV-Vis, PL, photocurrent analysis, and electrochemical impedance spectroscopy were employed to investigate the morphology and structures as well as the optical and electronic properties of the as-prepared samples. The photocatalytic activity of BC-QDs@Bi2WO6 was assessed by the degradation of antibiotics (tetracycline, ciprofloxacin, and gatifloxacin). The improved photocatalytic activity was attributed to the quantum effect of BC-QDs, which acted as the light harvesting center, electron reservoir, and reaction center for degrading the pollutants. Furthermore, a plausible mechanism for photocatalysis was put forward according to the ESR and quenching experiments. The present work can have significant advantages in the construction of biomass carbon-based photocatalysts in pollutant degradation and improved light utilization. [ABSTRACT FROM AUTHOR]

By combining the photopolymerization method with surface imprinting techniques, a magnetic photocatalyst modified with a POPD–CdS heterojunction embedded imprinted layer (a POPD–CdS heterojunction embedded magnetic imprinted photocatalyst) was successfully prepared. And ciprofloxacin (CIP) can be recognized and degraded by the POPD–CdS heterojunction embedded magnetic imprinted photocatalyst. The coefficient of selectivity of the POPD–CdS heterojunction embedded magnetic imprinted photocatalyst relative to CdS, POPD–CdS and a non-imprinted photocatalyst were 1.88, 1.98 and 2.12, respectively. Moreover, the secondary pollution resulting from CdS photo-corrosion can also be effectively suppressed by the surface imprinted layer. More importantly, the POPD–CdS heterojunction, as a functional monomer, was embedded into the surface imprinted layer. This method not only ensured sufficient contact between POPD and CdS, but also effectively solved the problem that the photocatalytic activity decreased drastically because of coverage by the surface imprinted layer. Therefore, this work offers an innovative concept and technical approach for the application of the selective removal of specific target pollutants in complex water environments. [ABSTRACT FROM AUTHOR]

A novel Z-scheme CdS/Ag/g-C3N4 nanosheets photocatalyst was synthesized by combining the hydrothermal and photo-deposition techniques, where Ag nanoparticles as carrier transport channels significantly improve the separation efficiency of electron–hole pairs. Outstanding photocatalytic activity was observed, which indicates that the constructed Z-scheme can retain the oxidizing ability of the CdS valence band and reducing ability of the g-C3N4 conduction band. In addition, trapping experiments and ESR measurement reveal that the superoxide radical (ṖO2−) and holes (h+) are the predominant active species. This study provides a new approach to perfect the Z-scheme photocatalytic system for application in the efficient treatment of persistent pollutants in wastewater. [ABSTRACT FROM AUTHOR]

Inspired by the biomimetic membrane modification technique of polydopamine (pDA), SiO2/pDA-based nanocomposite-imprinted membranes (SpIMs) with high selectivity and stability have been successfully synthesized. Herein, tetracycline (TC) was used as a template molecule and instead of constructing imprinted polymers onto pristine membrane surfaces, a versatile pDA-modified strategy was initially conducted on the membrane surfaces followed by the reformative sol–gel imprinting technique. Moreover, largely enhanced TC-rebinding capacity (45.95 mg g−1), permselectivity of TC (separation factors more than 11.5) and structural stability (maintained 93% of the maximum adsorption capacity after 11 cycling operations) could be easily achieved because of the construction of membrane-based multilevel nanocomposite surfaces. These results strongly illustrated that the incorporation of pDA-based sol–gel imprinted polymers into molecularly imprinted membranes could result in both high rebinding capacity and excellent permselectivity. All synthesis processes were carried out at low temperatures and ordinary pressures, which is energy-efficient and environmentally friendly for large-scale applications. [ABSTRACT FROM AUTHOR]

Efforts to engineer novel membrane materials with enhanced anti-fouling and comprehensive properties as well as highly selective separation abilities are hampered by the lack of effective imprinted cavities and structure stability. In this work, a novel multi-component metal–organic nanocomposite imprinted membrane (MMO-MIM) has been prepared by integrating a bioinspired metal–organic methodology with the secondary surface sol–gel imprinting technique. The synthesis pathway of MMO-MIM involves two steps: initially, a self-polymerized polydopamine process followed by hydrolysis with ammonium fluotitanate on the surface of the PVDF membrane, a surface-initiated sol–gel imprinted procedure is then conducted on the obtained bio-adhesive nano-sized TiO2 surface system for the fabrication of MMO-MIM. Attributed to the formation of the multilayered membrane structure, stronger fouling resistance and largely enhanced adsorption capacities have been obtained in this case. Meanwhile, the as-prepared MMO-MIM not only exhibits rapid adsorption dynamics, but also possesses excellent separation performance (βMMO-MIM/MMO-NIM and βm-cresol/2,4-DP are higher than 2.6 and 4.0, respectively) of templates. In addition, all synthesis procedures were conducted in aqueous or ethanol solution at ambient temperature, which was environmental friendly for scaling up without causing pollution. [ABSTRACT FROM AUTHOR]

The effect of metal ion doping on the electronic structure and optical properties of CdSe quantum dots has been investigated by various characterization techniques and experiments. Various cation codoped CdSe quantum dot photocatalysts were synthesized via a hydrothermal method. The prepared quantum dots were examined using X-ray diffraction, fluorescence spectroscopy, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy. The activities of the photocatalysts were evaluated with respect to the photodegradation of tetracycline hydrochloride solutions under simulated sunlight irradiation. 3%Co–4%K/CdSe quantum dots showed a higher photocatalytic activity than others within 30 min of visible light irradiation. Furthermore, there was hardly any decrease in the catalytic efficiency after the fourth experimental cycle. Identification data illustrate that Co and K codoping may cause improvement in the photocatalytic performance of CdSe quantum dots, which is crucial for tetracycline hydrochloride degradation under simulated sunlight irradiation. Therefore, this study demonstrates a promising strategy for the design of highly efficient photocatalysts for the remediation of aqueous pollutants. [ABSTRACT FROM AUTHOR]

Inspired by the biomimetic membrane modification technique of polydopamine (pDA), SiO2/pDA-based nanocomposite-imprinted membranes (SpIMs) with high selectivity and stability have been successfully synthesized. Herein, tetracycline (TC) was used as a template molecule and instead of constructing imprinted polymers onto pristine membrane surfaces, a versatile pDA-modified strategy was initially conducted on the membrane surfaces followed by the reformative sol-gel imprinting technique. Moreover, largely enhanced TC-rebinding capacity (45.95 mg g-1), permselectivity of TC (separation factors more than 11.5) and structural stability (maintained 93% of the maximum adsorption capacity after 11 cycling operations) could be easily achieved because of the construction of membrane-based multilevel nanocomposite surfaces. These results strongly illustrated that the incorporation of pDA-based sol-gel imprinted polymers into molecularly imprinted membranes could result in both high rebinding capacity and excellent permselectivity. All synthesis processes were carried out at low temperatures and ordinary pressures, which is energy-efficient and environmentally friendly for large-scale applications.