Zhilan Cai

Facile fabrication of a mpg-C3N4/TiO2 heterojunction photocatalyst with enhanced visible light photoactivity toward organic pollutant degradation

A facile hard template approach has been developed to prepare mpg-C3N4/TiO2 composites using SiO2 nanoparticles as a hard template and cyanamide as a precursor. The samples have been well characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The results demonstrate that TiO2 nanoparticles sized 5–10 nm were distributed on the surface of mpg-C3N4 to form the mpg-C3N4/TiO2 heterojunction photocatalyst. In this way, the mpg-C3N4/TiO2 heterojunction catalyst has a porous structure and large surface area, which increases the contact area for pollutants. Rhodamine B (RhB) was used as a representative organic pollutant to evaluate the photocatalytic activity of the samples under visible light irradiation. The results show that the as-prepared mpg-C3N4/TiO2 heterojunction catalyst has a significantly enhanced visible light photocatalytic activity compared to pure mpg-C3N4 and that the degradation rate was 1.6 times higher than that of pure mpg-C3N4. The increased photocatalytic activity of the mpg-C3N4/TiO2 heterojunction catalyst can be attributed to the formation of the heterojunction between mpg-C3N4 and TiO2, which suppresses the recombination of photoinduced electron–hole pairs. Furthermore, based on systematic characterization and discussion, a possible photocatalytic mechanism for the excellent photocatalytic performance was proposed.

Template-Assisted Hydrothermal Growth of One-Dimensional Zinc Oxide Nanowires for Photocatalytic Application

One-dimensional (1D) semiconductor ZnO nanowires have been successfully synthesized by a novel soft-chemical hydrothermal method with allylpolyethoxy amino carboxylate (AA-APEA) at low temperature. Their structure and properties have been characterized by a series of techniques, including X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). It was found that ZnO nanowires with diameters around 50 nm and lengths up to about several micrometers are well-distributed. The photocatalytic activity toward degradation of methylene blue (MB) aqueous solution under ultraviolet (UV) was investigated and the results showed that the ZnO nanowires exhibit a markedly higher photoactivity compared to the ZnO nanoparticles which were obtained without AA-APEA polymer assistant, and it can be ascribed to the special 1D morphology of the ZnO nanowires. In particular, the rate of degradation of the ZnO nanowires was 11 times faster than that of ZnO nanoparticles. In addition, the ZnO nanowires could be easily recycled in UV photocatalytic activity. These observations could promote new applications of photocatalyst for wastewater treatment utilizing oxide semiconductor nanostructures.

Enhanced mechanical properties of silica nanoparticle-covered cross-linking graphene oxide filled thermoplastic polyurethane composite

In this work, silica nanoparticle-covered cross-linking graphene oxide (GOES) was successfully synthesized in a stacking graphene oxide (GOE) solution where ethylenediamine (EDA) was used for simultaneous reduction and functionalization of the graphene oxide (GO). The GOES-filled thermoplastic polyurethane (TPU) composites were prepared through solution mixing and the mechanical properties of GOES/TPU were systematically investigated. The results revealed that the properties of composites filled with the cross-linked (GOE, GOES) filler are better than those of un-cross-linked (GO, GOS) filler. Furthermore, with a loading of 2 wt%, the tensile strengths and the tensile strains of GOES/TPU composites were significantly enhanced (48.9 MPa, 2140%), as compared to pure TPU (30.6 MPa, 1370%). The improvement in mechanical properties of GOES/TPU is attributed to the homogeneous dispersion of GOES in the TPU matrix and the strong interfacial interactions between them.

Development of a Novel Terpolymer as a Green and Efficient Decalcifying Agent for Crude Petroleum

A novel environmental decalcifying agent was prepared with allylpolyethoxy amino carboxylate (APEAA), hydroxyethyl acrylate (HEA), and maleic anhydride (MA) by means of free-radical polymerization in an aqueous solution. The morphology and structure of the samples were characterized through scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, and 1H nuclear magnetic resonance (1H NMR) spectra. The molecular-weight distribution of APEAA–HEA–MA was determined by the gel permeation chromatography method. APEAA–HEA–MA was used as a green decalcifying agent to remove calcium from crude petroleum, and the impact of factors such as monomer ratio, copolymerization time, dosages, and desalination temperature was analyzed. It is found that the decalcification rate of APEAA–HEA–MA could reach to its maximum, and the calcium removal efficiency was approximately 97.88% when the monomer molar ratio of APEAA–HEA–MA was 1:2:5, the reaction time of copolymerization was 2 h, the dosage was 100 ppm, and the desalination temperature was 100 °C. This research work can promote the exploration on facile synthesis of a novel terpolymer and its potential application in refinery desalting processes.

Double-Hydrophilic Block Copolymer as an Environmentally Friendly Inhibitor for Calcium Sulfate Dehydrate (Gypsum) Scale in Cooling Water Systems

Abstract In this study, a novel environmentally friendly copolymer acrylic acid-itaconic acid-allylpolyethoxy maleic carboxylate was synthesized and used for inhibiting the calcium sulfate dehydrate (gypsum) scale. The properties of the synthesized copolymer were characterized by Fourier-transform infrared, nuclear magnetic resonance spectroscopy and thermal gravity analysis. Also, the structure and morphology changes of scale crystals were studied by scanning electronic microscopy, transmission electron microscopy and X-ray powder diffraction analysis. The copolymer inhibition ability was evaluated by means of static scale inhibition experiments. Results show that the copolymer was effective in inhibiting the scales by changing the size and morphology of the crystals. The maximum inhibition efficiency was 99.8% at a concentration of 2 mg · L–1, far more efficient than most commercial inhibitors.

Preparation of a phosphorous-free terpolymer as a decalcifying agent for removing calcium from crude oil

A novel phosphorous-free terpolymer, used as a decalcifying agent for removing calcium from crude oil, was prepared through a free-radical polymerization reaction of acrylic acid (AA), allylpolyethoxy amino carboxylate (APEA), and 2-hydroxyethyl acrylate (HEA) in water with ammonium persulfate as initiator. The structure of the synthesized AA–APEA–HEA terpolymer was characterized by Fourier transform infrared spectrometry and 1H nuclear magnetic resonance (1H-NMR). AA–APEA–HEA was used to remove calcium from Luning pipeline crude oil. The effects of several factors, such as molar ratio, dosage, and reaction temperature on calcium removal efficiencies from crude oil were evaluated. The results indicated that the removal of calcium from crude oil using AA–APEA–HEA was far more efficient than that using AA–APEA, PAA, HPMA, and PESA under the same conditions. The optimum conditions for calcium removal from crude oils were as follows: (a) molar ratio of AA–APEA–HEA, 2 : 1 : 0.5; (b) dosage of AA–APEA–HEA, 100 ppm; (c) reaction temperature, 100 °C. Under these conditions, the removal efficiency of calcium from Luning pipeline crude oils was approximately 98.63%. Furthermore, the proposed decalcification mechanism suggests surface complexation and chelation between the carboxylic (–COO−) and amino (–NH2) functional groups and Ca2+, with the polyethylene glycol segments increasing its solubility in water and the lipophilic ester groups increasing its affinity to oil.

Synthesis of acrylic acid-allylpolyethoxy amino carboxylate copolymer and its application for removing calcium from crude oil

A novel environmentally friendly type of decalcifying agent acid, allylpolyethoxy amino carboxylate (AA–APEA), was synthesized and characterized by Fourier transform infrared spectrometry (FT-IR) and 1H-NMR. AA–APEA was used to remove calcium from Luning pipeline crude oil. The effects of several factors, such as molar ratio, dosage and reaction temperature on calcium removal efficiencies from crude oil were evaluated. The optimum conditions for calcium removal from crude oil were as follows: (a) molar ratio of AA–APEA was 2 : 1, (b) dosage of AA–APEA was 150 ppm, and (c) reaction temperature was 120 °C. Under these conditions, the removal efficiency of calcium from Luning pipeline crude oils was approximately 98.78%.