Jin-Ku Liu

An efficient photocatalyst for degradation of various organic dyes: Ag@Ag2MoO4-AgBr composite.

The Ag2MoO4-AgBr composite was prepared by a facile in-situ anion-exchange method, then the Ag nanoparticles were coated on this composite through photodeposition route to form a novel Ag@Ag2MoO4-AgBr composite. The in-situ Br(-) replacement in a crystal lattice node position of Ag2MoO4 crystal allows for overcoming the resistance of electron transition effectively. Meanwhile silver nano-particles on the surface of Ag@Ag2MoO4-AgBr composite could act as electron traps to intensify the photogeneration electron-hole separation and the subsequent transfer of the trapped electron to the adsorbed O2 as an electron acceptor. As an efficient visible light catalyst, the Ag@Ag2MoO4-AgBr composite exhibited superior photocatalytic activity for the degradation of various organic dyes. The experimental results demonstrated superior photocatalytic rate of Ag@Ag2MoO4-AgBr composite compared to pure AgBr and Ag2MoO4 crystals (37.6% and 348.4% enhancement respectively). The Ag@Ag2MoO4-AgBr composite cloud degraded Rhodamin B, bromophenol blue, and amino black 10b completed in 7min.

Controlled synthesis of silver phosphate crystals with high photocatalytic activity and bacteriostatic activity

Symmetrical silver phosphate (Ag3PO4) crystals with porous structure were grown by a facile controllable route in aqueous solution. The Ag3PO4 crystals have a cubic-type structure and the morphologies are distinctive under different conditions. The crystals had high purity, were well-crystallized and were free of secondary phases by powder X-ray diffraction, IR, Raman spectra, scan electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). It is interesting that the different crystal faces of the crystals have high physical–chemical–biological activity and large surface areas, so as to act as high activity micro-reactors (HAMs). The HAMs can effectively improve the photocatalytic activity and bacteriostatic activity of the Ag3PO4 crystals. Furthermore, we proposed a possible growth mechanism and detailed morphology transformation process of Ag3PO4 crystals with different properties.

Construction of silver tungstate multilevel sphere clusters by controlling the energy distribution on the crystal surface

Silver tungstate (Ag2WO4) multilevel sphere clusters were synthesized for the first time by a dynamic-template route through controlling the energy distribution on the crystal surface. The polymerization reaction of acrylamide monomers as the dynamic-template on the surface of the Ag2WO4 crystals occurred, with more polymerization causing more high energy spots to appear on the surface of the Ag2WO4 crystals, and the change of energy caused by this affected the formation and growth of the multilevel sphere clusters. The Ag2WO4 multilevel sphere clusters were 2.5–2.8 μm in diameter and constituted several second level spheres which were about 0.8 μm in diameter. The XRD patterns indicated that the Ag2WO4 products were perfectly matched with the hexagonal-phase Ag2WO4 crystal system and the symmetric space type belonged to the P63 symmetric system. In addition, the Ag2WO4 products had good visible light photocatalytic performance and antimicrobial ability.

Thermal perturbation nucleation and growth of silver molybdate nanoclusters by a dynamic template route

Silver molybdate (Ag2MoO4) nanoclusters were first prepared by a dynamic template route under 20 °C. The heat released from the polymerization of the acrylamide (AM) assisted templates induced high active sites to be generated on the surface of the crystal where more attracted nuclei were adsorbed on. The continuously formed nuclei assembled together and the nanoclusters were formed. The paper provided an explanation for the formation of the Ag2MoO4 nanoclusters through the research on reaction conditions; on the other hand, the comparison of photocatalytic performance and antibacterial properties between the Ag2MoO4 nanoclusters and the Ag2MoO4 crystals of other morphologies showed that the Ag2MoO4 nanoclusters had better photocatalytic and antibacterial activities, which was a preliminary perspective for the application of the nanocluster materials.

The biotoxicity of hydroxyapatite nanoparticles to the plant growth

In the present study, hydroxyapatite (HAP) nanoparticles of different particle sizes with high crystallinity and similiar structure were prepared by hydrothermal method. The crystal structure and particle size were characterized by X-ray diffraction pattern (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscopy. Mung bean sprouts were first used as experimental models. Instead of by MTT assay, the cytoxicity of HAP nanoparticles were proved and evaluated by measuring the hypocotyle length of mung bean sprouts in the culture media. The result showed that the inhibition effect to the growth of mung bean sprouts enhanced when HAP nanoparticles existed. Culture media of HAP nanoparticles with different concentrations and particle sizes was prepared to investigate the level of inhibition effect to the growth of mung bean sprouts. The result found that hypocotyl length of mung bean sprouts were the shortest cultured in 5mg/mL culture media in which the HAP nanoparticles were prepared by hydrothermal method for 24h. It was concluded the inhibition effect depended on the amount of intracellular HAP nanoparticles. The nanostructure and Ca(2+) concentration were considered as the main factors to cause cell apoptosis which was the reason of inhibition. The study provided a preliminary perspective about biotoxicity of HAP nanomaterials to the plant growth.

Mass preparation and novel visible light photocatalytic activity of C and Ag Co-modified ZnO nanocrystals

A combustion method was developed to synthesize the C and Ag co-modified ZnO NCs to enhance its photocatalytic efficiency and practicability. The results showed that the doped Ag was significant to promote the photocatalytic activity, and the optimum content was 2% molar ratio of Ag to Zn atom. The degradation rate under visible light increased by 150% compared with C-ZnO NCs, while by more 1233.3% than pure ZnO photocatalyst. There were some new little particles with grain size about 10 nm on the C-ZnO NCs surface, which may state for the existence of Ag atoms. The synergy effect of Ag and carbon elements was proposed to explain the mechanism of enhanced photocatalytic performance under visible light irradiation.

A Study on the Desulfurization Performance of Solvent UDS for Purifying High Sour Natural Gas

Abstract A desulfurization solvent called UDS was designed and developed based on the differences in desulfurization efficiencies of respective solvent components. The desulfurization performance of UDS was investigated in a simulated industrial unit and the thermal stability as well as the regeneration performance was evaluated using thermogravimetric analysis. The results indicated that the organosulfur removal performance of UDS was significantly enhanced by introducing the sulfur-containing heterocyclic compound and the cyclic amine compound. In the industrial pressure condition of 8.3 MPa, UDS showed around 30 percentage points higher organosulfur removal efficiency than methyldiethanolamine (MDEA). The contents of H2S and total sulfur were <0.5 and 81.6 mg · m−3, respectively, in purified gas when adsorption was conducted under gas–liquid volume ratio (Vg/Vl) of 169 and pressure of 1.5 MPa, using UDS. The quality of purified natural gas met first-class standards.

Distribution of Nickel and Vanadium in Venezuela Crude Oil

The distribution of nickel and vanadium in five fractions (saturated hydrocarbons, aromatic hydrocarbons, soft resin, hard resin, and asphaltene) of Venezuelan 380 crude oil was studied. The method of column chromatography separation was used two times. Furthermore, the UV-vis spectroscopy was used to characterize the role of metals in different fractions. Results showed that the content of vanadium in crude oil was much higher than nickel. The metals mainly existed in resins (~20%) and asphaltene (~70%). UV-vis spectroscopy had also confirmed the presence of vanadium porphyrins in resins and asphaltene.

Mosaic structure effect and superior catalytic performance of AgBr/Ag2MoO4 composite materials

AgX (X = Cl, Br, I)-modified Ag2MoO4 crystals with a mosaic style can be produced in quantity through an in situ composite method. Different AgX–Ag2MoO4 composite materials (CMs) exhibited various photocatalytic abilities due to their diverse properties, among which AgBr–Ag2MoO4 CMs performed best. The catalytic efficiency of AgBr–Ag2MoO4 CMs was enhanced 149 times compared to pure Ag2MoO4, degrading organic dyes within just 2 min. We have proposed a brand new theory, “the mosaic structure effect”, to explain the achievement of this high efficiency catalysis. This mosaic structure effect contributed most to the artistic and regular coating, the tight inlay of the AgBr and Ag2MoO4, as well as to the increase in the recombination lifetime of the carrier. This study exhibited a certified record efficiency in degrading organic dyes and antibiotics.

Absorption Selectivities of Solvents for Organosulfurs in High Sour Natural Gas

In order to develop a solvent with satisfied organosulfur removal performance for high sour natural gas, the absorption process using UDS and MDEA as solvents was investigated and the absorption model was established to evaluate the selectivities of the two solvents for organosulfurs. The results indicate that both of the solvents, UDS and MDEA, have excellent absorption performance for H2S and CO2. The solvent, UDS, shows evident advantages when adsorbing high content COS and mercaptans. From the viewpoints of the solubility and the mass transfer performance, COS is the most easily absorbed. The methyl mercaptan and ethyl mercaptan come after. The isopropyl mercaptan and n-propyl mercaptan are hard to be absorbed. Compared with MDEA, the solvent UDS shows lower Henry constants and greater mass transfer factors for the organosulfurs; therefore, it has higher solubility and better mass transfer performance for the organosulfurs.