Advanced Materials Research Vols. 864-867

Abstract: Phosphoric acid /graphene composites were synthesized by a facile one-pot method in the oil-phase. The composites produced in this study have more active groups than reduced graphene oxide. Adsorption data indicated that active groups of the material had far greater influence on the adsorption capacity than inert functional groups of reduced graphene oxide.

Abstract: The absorption performance of CO₂ from the simulated flue gas using fresh MDEA-PZ-TETA absorbent and the desorption behavior of CO₂ from the CO₂-saturated absorbent were investigated. In the process of CO₂ absorption, the absorption temperature and the inlet flow rate of CO₂ played important effects on the absorption performance. The experimental results showed that the suitable absorption condition of CO₂ using fresh absorbent was the absorption temperature of 20 oC for 18 min and the inlet flow rate of CO₂ of 50 mL/min. In the process of CO₂ desorption from the used absorbent, the desorption temperature played an important role and the regeneration time had little effect on the desorption behavior. The suitable desorption condition was the desorption temperature of 105 oC for 1.0 h and the regeneration time of 1.

Abstract: With the clear emission reduction target of China for 2020, the refining industry as a large emission source inevitably plays a significant role. The paper confirmed and assessed three commercially available CO₂ separation technologies for refineries, vacuum swing adsorption (VSA), monoethanolamine (MEA) and membrane absorption (MA). The economic results indicate that the capital cost of constructing a CO₂ capture unit is 35.996 M¥, 34.418 M¥, 37.502 M¥, respectively. And the corresponding cost of avoided is 379.8 ¥/tCO₂, 249.6 ¥/tCO₂ and 376.5 ¥/tCO₂. Sensitivity analyses are also performed examining the effect of CO₂ price on economic feasibility, as well as improvements of regeneration energy demand and CO₂ capture system on the CO₂ avoided cost. The regeneration energy demand impacts the avoided cost significantly, whereas CO₂ capture system demonstrates insensitivity. Though the CO₂ avoided cost for MEA case is highest, MEA has been commercially the most available processe so far for existing refineries. However, MA will be the most promising alternative to chemical absorption in the future, provided that membrane performance is further improved. In addition, the CO₂ avoided cost of VSA is close to that of MEA, but other economic indicators are optimal due to a large amount of H₂ recovered. Currently, without any incentive and a major technological break-through, CO₂ capture from the source of hydrogen production units at Chinese refineries is the most attractive opportunity.

Abstract: Cobalt ions, which are commonly found in low concentrations in industrial wastewater, are toxic, biocumulative, and hard to degrade. Therefore, the removal of these heavy metal ions from wastewater is highly important. The removal of Co (II) from aqueous solutions using untreated and alkali-modified coal fly ash was studied. The results for untreated fly ash show that the pseudo-second-order kinetic equation better fits the observed adsorption progress. The Langmuir and Freundlich isotherms could describe the reaction efficiently, and the maximum adsorption capacity for Co (II) was 237 mg·g^-1 at 20°C. Pretreating the fly ash with an alkali solution decreases the adsorption capability, possibly by destroying the zeolite structure. When the ratio of the fly ash dose and Co (II) concentration is between 40 and 60, the removal rate of Co (II) at a concentration of 20 mg·L^-1 reaches 99.95%.

Abstract: In the paper methyl violet degradation by bamboo charcoal-microwave irradiation method was researched. The main parameters which were studied including the amount of bamboo charcoal, H₂O₂ dosage, FeSO₄·7H₂O dosage and time of microwave irradiation were investigated. The UV-visible spectra of methyl violet were determined. The results show that: under bamboo charcoal, H₂O₂ and FeSO₄·7H₂O microwave condition the degeneration rate of methyl violet was almost 100%. The increase of bamboo charcoal dosage can accelerate the reaction process, speeding up the degradation of methyl violet. The increase of H₂O₂ may provide more ·OH and speed up the reaction process, but when up to a certain amount, the influence is weakened. The lengthening of microwave time may enhance the reaction temperature, and urge the methyl violet to degrade completely. For 0.2 g·L^-1 methyl violet 4:9 diluted, by adding 0.5g bamboo charcoal, 1 mL 36% H₂O₂, 1 mL FeSO₄·7H₂O of 1mol·L^-1 and under mesotherm microwave for 30s, the methyl violet can be all degradated.

Abstract: Variations of heavy metals in sludge during microwave pyrolysis and muffle pyrolysis were analyzed by means of scanning electron microscope (SEM) and inductively coupled plasma atomic emission spectrometer (ICP-AES). Increased basicity of residues from the sludge is found. Leaching percentages of heavy metals ranging from 0.031% to 5.364% after microwave treatment are lower. Releases of cadmium, lead, zinc and copper from the residues obtained in microwave pyrolysis reduce by 92.68% compared with muffle pyrolysis. Alkaline intermediates formed in the pyrolysis residues bring about improved immobilization of heavy metals. Transformation in morphology of heavy metals and strong alkaline of the residues, lead to the immobilization of heavy metals during microwave pyrolysis.

Abstract: This paper presents a method combined of HPLC and DAD in detecting the total nitrogen index in urban waste water and studies the digestion condition of the sample pretreatment. The result shows that after pressurized digestion and adjusting pH to around 7.0 with phosphoric acid buffer solution, the sample can be applied chromatographic analysis. The chromatographic analysis is conducted with phosphoric acid buffer solution-acetonitrile as the mobile phase, flow velocity 0.8mL.min^-1, column temperature 30 °C, intake-sample volume 10 μL,with ODS as the stationary phase, and the sample is detected with wavelength of 208nm. The linearly dependent coefficient of standard curve is 0.9971, the linearity range is 0.10-30.0mg·L^-1, relative standard deviation (RSD) is less than 12%, the recycle rate is 107-159%,detection limit (S/N=2.4) reaches 0.05ng.

Abstract: Metals distribution (Cu, Zn, Pb, Mn and Ni) in campus wastewater was examined by nonparametric tests (Kolmogorov-Smirnov (K S) and Friedman One-Way ANOVA). Based on the K-S test, all metals except zinc followed normal distribution. Based on the Friedman One-Way ANOVA test, nickel concentration posed substantial difference between three sampling stations under study (p < 0.05). All metals posed under the critical values on the basis of Environmental Quality (Sewage and Industrial Effluents) Regulations (1979). The water parameters (BOD, COD, TSS, pH and temperature) were also implicated to inform the chemical background of wastewater under study in relation to metals distribution.

Abstract: The objective of this study was to investigate the removal of phenol from aqueous solution by using activated and non-activated red mud in adsorption experiments. The study was carried out as function of red mud dosage and initial phenol concentration. It was found that the maximum removal was obtained at dosage of 0.5 g of red mud and initial concentration of phenol 40 mg/l. Activation has no positive effect on adsorption effectiveness.

Abstract: The characteristics of biological aerated filter (BAF) backwashing sludge and the combined coagulation efficiency of chemical coagulant and biological sludge, and the properties of the settled sludge produced in the utilization process were investigated. The results showed that the backwashing sludge had preferable biological flocculation ability. A promising treatment performance, which sufficed the influent requirement of BAF was observed whether by using the backwashing sludge or combined using chemical coagulant and biological sludge in the enhanced domestic wastewater pretreatment process. The removal efficiency of COD, SS and TP were up to 74.6%、81.9% and 84.2% respectively where as backwashing sludge dosage was 38~76mg and FeCl3 dosage was 30mg per liter domestic wastewater.