Advanced Materials Research Vols. 233-235

Abstract: To study the formation mechanism and the chemical component of biofouling, the biofouling formation was simulated by the dynamic simulation device of circulating cooling water under the constant condition of 30°C and 0.4 m/s. The slime-forming bacteria and Iron Bacteria were selected as the research subject. Adsorption theory of bacteria in the solid/liquid interface was analyzed by colloidal stability theory. The two kinds of bacteria on heat transfer and the relationship between the total number of bacteria and fouling resistance were studied. The main component of biofouling was characterized using XPS. The results show that Iron Bacteria on the negative effects of heat transfer is greater than the slime-forming bacteria. The total number of bacteria is the maximum in the end of the induction period. The main component of biofouling of the slime-forming bacteria of iron bacteria is C, O, N, Fe, Ca, Mg, etc. The major elements of the ratio in different strains exists diversity in the stainless steel heat exchanger, but the most important elements is carbon and oxygen.

Abstract: In this paper, a rigorous mathematical model of multistage flash system (MSF) is presented based on a detailed physicochemical representation of the process, including all the fundamental elementary phenomena. In particular, Comparison to the mathematical model of reference, two integer variables, which are the number of recovery stage (NR) and the number of rejection stage (NJ), are introduced to the model. Additionally, two special variables, which are the ratio of recirculation brine water flow rate and distillation flow rate and the ratio of make-up flow rate and the distillation flow rate, are introduced to the model as the continuous variables too. Then, the MSF system is described as a mixed-integer nonlinear programming (MINLP). The objective is to minimize the total annual cost (TAC), which is mainly composed of the operating costs and investment cost. Here the modified genetic algorithm (MGA), which is characterized as mixing coding way, is adopted for the system optimization. A case study and a discussion of the results are presented.

Abstract: The carrying capacity of 2m-caliber microwave antenna was analyzed by ANSYS software under the action of the wind load, the antenna’s reliability was analyzed and calculated from the different wind load directions which in the case of the working wind speed ensure accuracy and the limit wind speed ensure intensity, and the results of the analysis and the reliability of resisting the wind were tested and verified through simulating the test about wind load. The test proved that the analysis and results of the test were equivalent.

Abstract: Magnetite was prepared to remove poisonous hexavalent chromium [Cr(VI)] from aqueous solution. Batch experiments were conducted to measure the effects on removal of Cr(VI) of different parameters such as ionic strength, pH, and initial concentration. Results demonstrated that the removal of Cr(VI) on magnetite was decreased with the increase of pH in the range of 3.4-5.0, but independent of ionic strength. The removal percentage of Cr(VI) also decreased with the increase of Cr(VI) concentration in the range of 50-200 mg/L. At pH 3.5 and 5.0, the presence of SO₄²⁻ retarded the removal of Cr(VI) via electrostatic interactions and/or competition for surfaces sites on magnetite. The pH of the medium and presence of anion species were critical factors in the removal of Cr(VI) from aqueous solution.

Abstract: Ni-P-PTFE composite coating was prepared by electroless plating based on the Ni-P coating technology. The effects of surfactant and PTFE content on the binding force, hardness, friction coefficient, wear rate and content of PTFE particles of the composite coating was investigated. In addition, the tribological behaviors of composite coating were discussed. The surface morphology and microstructures of composite coating were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the wear mechanism of composite coating was analyzed by using the MRH-3 friction and wear tester. The results indicated that the Ni-P-PTFE composite coating prepared under the optimum process condition exhibited excellent friction properties, and the wear mechanism is manifested as adhesion and slight grain-abrasion during the abrasion.

Abstract: Two kinds of oil tank steels were fabricated by added B(B-steel) and Cu(Cu-steel) , and their microstructures, tensile and Charpy impact properties, undercooled austenite transformation were investigated. In this work,0.0016%B can improve hardenability distinctly. The B-steel was mainly composed of bainite at the cooling rate of 3°Cs^-1, but the Cu-steel completely consisted of bainite when the cooling rate exceed 20°Cs^-1. The steels manufactured by thermo-mechanical controlled process , test results indicated that the B-steel had the higher yield and tensile strength than the Cu-steel ,because their volume fractions and morphologies of bainite. The Cu-steel had the higher impact energy than the B-steel because of their higher effective grain size. Majority of the precipitation particles which were compounded of Nb and Ti existed as（Nb_x,Ti_(1-x)) (C_yN_(1-y)).

Abstract: A novel technique of Spent FCC equilibrium catalyst utilization is presented and mullite are prepared from it. The chemical composition, structure and thermal stability of the spent FCC equilibrium catalyst from oil refinery are characterized by XRD, FT-IR, DTA-TG, Fully chemical analysis technique, SEM. Mullite specimens are prepared by reaction sintering the spent FCC equilibrium catalyst at different temperatures. The result indicates that at 1300-1350°C, the spent FCC equilibrium catalyst could be used to prepare high purity mullite.

Abstract: Solid superacids SO₄^2- /γ-Al₂O₃ were prepared with wetness impregnation method in different concentrations of sulphuric acid and calcination temperatures. Polyethylene terephthalate (PET, grains) depolymerizations were catalyzed by SO₄^2- /γ-Al₂O₃ superacids in pure water under microwave irradiation with a reaction time of 150min, a temperature of 190°C and a pressure of 200psi. The results indicated that the catalytic activity of SO₄^2- /γ-Al₂O₃ superacids was influenced by the calcination temperature, concentration of sulphuric acid and the catalyst dosage. When the superacid SO₄^2- /γ-Al₂O₃ catalyst was calcined at 600°C, soaked in 2.5 mol·L^-1 sulfuric acid solution and the catalyst dosage was 1%, a good catalytic activity appeared.

Abstract: In this paper, the PET depolymerization catalyzed by metal oxides (MgO, CdO, Cu₂O, Sb₂O₃, MnO₂, V₂O₅, SiO₂, MoO₃) under microwave irradiation were investigated, and the effects of acid-base on PET depolymerization was studied by acid-base scale method. The results indicated that the stronger the acidity or basicity of metal oxide was, the better the effects of catalytic depolymerization of PET appeared. Compared with alkali metal oxide, the catalytic effect of acid metal oxide to PET depolymerization was better.

Abstract: Slag is the main by-product of iron and steelmaking process. Ladle slag, melted fully after secondary refining, usually contains rich CaO, Al₂O₃ and 2CaO·SiO₂ phase, which has a potential value to recycle into steelmaking process as the substitution of lime. However, reuse of ladle slag is easy to induce an accumulation effect of sulphur or phosphorus. In this present work, CaS powder was used to replace the sulphur containing phase in ladle slag to investigate the roasting process under different atmosphere conditions. The influence of temperature and oxygen pressure on sulphur removal mechanism and products composition has been discussed. By adding solid sulfur into molten ladle slag, the results of SEM has showed that sulphur element in ladle slag existed as independent CaS phase. Roasting experiments showed that lower oxygen pressure and higher reaction temperature were beneficial for CaS changing into CaO, it was very important to design the optimum roasting route for sulphur removal from the ladle slag.