Xinlin Liu

Microwave-assisted in situ synthesis of reduced graphene oxide-BiVO4 composite photocatalysts and their enhanced photocatalytic performance for the degradation of ciprofloxacin

To improve the photodegradation efficiency for ciprofloxacin (CIP), a new-type microwave-assisted in situ growth method is developed for the preparation of reduced graphene oxide (RGO) -BiVO4 composite photocatalysts. The as-produced RGO-BiVO4 composite photocatalysts show extremely high enhancement of CIP degradation ratio over the pure BiVO4 photocatalyst under visible light. Specially, the 2 wt% RGO-BiVO4 composite photocatalyst exhibits the highest CIP degradation ratio (68.2%) in 60 min, which is over 3 times than that (22.7%) of the pure BiVO4 particles. The enhancement of photocatalytic activities of RGO-BiVO4 photocatalysts can be attributed to the effective separation of electron-hole pairs rather than the improvement of light absorption.

Accelerating the design of multi-component nanocomposite imprinted membranes by integrating a versatile metal–organic methodology with a mussel-inspired secondary reaction platform

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.

Bioinspired synthesis of high-performance nanocomposite imprinted membrane by a polydopamine-assisted metal-organic method

Significant efforts have been focused on the functionalization and simplification of membrane-associated molecularly imprinted materials, which can rapidly recognize and separate specific compound. However, issues such as low permselectivity and unstable composite structures are restricting it from developing stage to a higher level. In this work, with the bioinspired design of polydopamine (pDA)-assisted inorganic film, we present a novel molecular imprinting strategy to integrate multilevel nanocomposites (Ag/pDA) into the porous membrane structure. The molecularly imprinted nanocomposite membranes were then obtained through an in situ photoinitiated ATRP method by using tetracycline (TC) as the template molecule. Importantly, attributing to the formation of the Ag/pDA-based TC-imprinted layers, largely enhance TC-rebinding capacity (35.41mg/g), adsorption selectivity and structural stability (still maintained 92.1% of the maximum adsorption capacity after 10 cycling operations) could been easily achieved. Moreover, largely enhanced permselectivity performance toward template molecule (the permeability factor β values were also more than 5.95) was also obtained. Finally, all synthesis methods were conducted in aqueous solution at ambient temperature, which was environmental friendly for scaling up without causing pollution.

Enhanced photocatalytic degradation of tetracycline antibiotics by reduced graphene oxide–CdS/ZnS heterostructure photocatalysts

In this work, reduced graphene oxide (RGO)–CdS/ZnS heterostructure composites have been successfully synthesized by a hydrothermal method by assembling the CdS/ZnS heterostructure nanoparticles on RGO sheets and the reduction of GO occurs simultaneously. The as-prepared RGO–CdS/ZnS composites with the content of 15% RGO exhibit highly active photodegradation of TC. A possible mechanism for the enhanced photocatalytic activity has been discussed. The CdS/ZnS heterostructure facilitates the transformation of electrons, which is excited by light irradiation in the conduction band of CdS. RGO is supposed to be an electron transfer channel, which is used to reduce the recombination of electron–hole pairs, thus enhancing the photo-conversion efficiency. By profiting from the synergy of RGO and CdS/ZnS heterostructure, the photocatalysts not only show a better photocatalytic activity in tetracycline antibiotics but also prevent pure CdS or ZnS from photocorrosion. At last, RGO–CdS/ZnS shows remarkable stability and cyclic performances.

Preparation and photodegradation properties of transition metal ion–poly-o-phenylenediamine/TiO2/fly-ash cenospheres by ion imprinting technology

Transition metal ions have been immobilized on TiO2/fly-ash cenospheres (TiO2/FACs) with poly-o-phenylenediamine (OPD). The as-prepared ion imprinting photocatalyst (M-POPD/TiO2/FACs) has been characterized by SEM, XRD, FT-IR, UV-vis DRS and ICP-AES. The results demonstrated that the polymer and mental ions existed in the M-POPD/TiO2/FACs. The photocatalytic activity of M-POPD/TiO2/FACs was studied by the degradation of tetracycline, oxytetracycline, ciprofloxacin, tetracycline hydrochloride and chloromycetin in simulated wastewater under visible light irradiation. The results showed that the M-POPD/TiO2/FACs could effectively increase the separation rate of photoelectrons and holes in the cycling system and improve the photocatalytic activity for the degradation of antibiotics in solution. Experimental data showed that the as-prepared M-POPD/TiO2/FACs were more suitable for degradation of tetracycline (5 mg L−1), and the photodegradation rate could reach 71.7%. In addition, possible formation and photocatalytic mechanisms were proposed.

Hydrothermal synthesis and enhanced visible-light photocatalytic activity of octahedral Bi2WO6 modified with CdSe quantum dots

In this paper, octahedral Bi2WO6 modified with CdSe quantum dots was synthesized by a hydrothermal method. This as-prepared CdSe–Bi2WO6 photocatalyst exhibited a higher photocatalytic activity for the degradation of tetracycline (TC) than octahedral Bi2WO6. Moreover, 15%-CdSe–85%-Bi2WO6 showed the best Dr of 65.38%, which is over 5 times that of the pure Bi2WO6. Furthermore, the as-synthesized CdSe–Bi2WO6 composite photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (UV-vis) and photoluminescence spectroscopy (PL).

Fabrication and evaluation of artemisinin-imprinted composite membranes by developing a surface functional monomer-directing prepolymerization system.

Inspired by a surface functional monomer-directing prepolymerization system, a straightforward and effective synthesis method was first developed to prepare highly regenerate and perm-selective molecularly imprinted composite membranes of artemisinin (Ars) molecules. Attributing to the formation of the prepolymerization system, Ars molecules are attracted and bound to the membrane surface, hence promoting the growth of homogeneous and high-density molecular recognition sites on the surface of membrane materials. Afterward, a two-step-temperature imprinting procedure was carried out to prepare the novel surface functional monomer capping molecularly imprinted membranes (FMIMs). The as-prepared FMIMs not only exhibited highly adsorption capacity (11.91 mg g(-1)) but also showed an outstanding specific selectivity (imprinting factor α is 4.50) and excellent perm-selectivity ability (separation factor β is 10.60) toward Ars molecules, which is promising for Ars separation and purification.

Construction of stable core–shell imprinted Ag-(poly-o-phenylenediamine)/CoFe2O4 photocatalyst endowed with the specific recognition capability for selective photodegradation of ciprofloxacin

A stable core–shell imprinted Ag-(poly-o-phenylenediamine)/CoFe2O4 (imprinted Ag-POPD/CoFe2O4) was synthesized via the surface imprinting technique. Ag-POPD was introduced into an imprinted layer, which significantly enhanced the photocatalytic activity. Meanwhile, due to the existence of imprinted cavities in the imprinted layer, the imprinted Ag-POPD/CoFe2O4 exhibited the superior specific recognition capability for selective photodegradation of ciprofloxacin (CIP). This work puts forward a novel design idea for synthesizing imprinted photocatalysts.

One-step hydrothermal synthesis of cobalt and potassium codoped CdSe quantum dots with high visible light photocatalytic activity

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.

Synthesis of thermal-responsive photocatalysts by surface molecular imprinting for selective degradation of tetracycline

A novel thermal-responsive surface molecular imprinted photocatalyst of poly(N-isopropylacrylamide) (PNIPAm) modified CdS/halloysite nanotubes (HNTs) was prepared using surface molecular imprinting technology and evaluated as a potential effective photocatalyst for selectively remove tetracycline (TC) existing in aquatic environments. Free radical polymerization of TC, NIPAm, N,N′-methylenebisacrylamide (MBA) and 2,2′-azobisisobutyronitrile (AIBN) was used as a molecular template, functional monomer, cross-linking agent and initiator, respectively. The imprinted photocatalysts were further characterized by SEM, EDS, TEM, UV-vis DRS, FT-IR, BET and TG, which showed that the CdS/HNTs were successfully imprinted with PNIPAm. In addition, benefiting from the common effect of the specific binding of imprinted polymers, thermo-responsiveness of PNIPAm shells, and high photocatalytic activity of CdS/HNTs cores, the obtained material showed high photocatalytic activity and excellent selectivity to remove molecular template TC and the photocatalytic activity could be tuned by changing the environmental temperature. According to our experimental and characterized results, the mechanism of the preparation of imprinted photocatalyst and its use in photocatalytic degradation was further discussed, respectively.