Advanced Materials Research Vols. 233-235

Abstract: This paper focused on the effluent chroma which is a long-term puzzle about the aerobic treatment for pulping midcourse wastewater. The organic in the influent and effluent was tested by GC-MS. The analysis indicates that the macromolecular lignin-type substances are partly degraded using aerobic technique. Some micromolecular substances are produced accordingly, which leads to the auxochrome groups and chromophore groups increasing. There are two organic coloration compositions in influent but three in effluent, which account for 22.98% of the organic substances in influent but 33.12% of the organic substances in effluent.

Abstract: Using four types of calixarene derivatives (RCT, PCT, MRCT, TBCA) as coating materials, quartz crystal microbalance (QCM) sensors have been examined for detection of toxic formaldehyde gas indoors. The results showed that PCT was the most efficient adsorption coating material for host-guest recognition of formaldehyde molecule, when the coating mass was 43.93 μg. The PCT based QCM sensor possessed a linear response range of 109 ~ 2721 ppm formaldehyde gas. In comparison with gas chromatography method, the QCM sensor had a recovery of 97.98~104.59 % with a good reversibility, stability and reproducibility, showing that the PCT based QCM sensor can be well used for the determination of trace formaldehyde in the living environment.

Abstract: The factors that influence the performance of Bi₂₀TiO₃₂ were discussed, and the removal of TOC in the analogue waste water was also examined. The shorter the light wavelength or the more the intensity, the more efficient the photocatalytic process. Different substance has different optimum pH for being photodegraded by photocatalyst Bi₂₀TiO₃₂, which may be related with its surface charge. Aeration have little benefit for decomposing the organics. Some organics like methyl orange and phenol can be photodegraded by Bi₂₀TiO₃₂ completely. Bi₂₀TiO₃₂ has visible-light activity for the degradation of organics.

Abstract: Taking high concentration livestock wastewater as research object, The results showed that the constructed rapid infiltration system operated at the largest hydraulic loading of 0.26m/d, and during the period of the flooding for ond day and drying for two days, the main efficiency of pollutants occurred in filter height of 0.65m, with the maximum removal efficiency of COD and ammonia nitrogen as 80%; TF and MLVSS also reached maximum.

Abstract: A lab-scale study was conducted to precipitate the ammonia from high NH₃-N concentration wastewater in the form of magnesium ammonium phosphate(MAP) by applying such chemicals such as MgCl₂·6H₂O and KH₂PO₄.The influences of pH value, reactive time and removal rate of ammonia nitrogen were tested.The results shows that the feasible pH values of crystallization and precipitation were between 8 and 10. The structure of struvite crystallization was destroyed under high pH value condition that resulted in ammonia nitrogen dissociating from MAP, which reduced the removal rate of ammonia nitrogen. Results also demonstrated that ammonia nitrogen was effectively reduced from initia1981mg/L to final 5 mg/L, which removal efficiency reached 99% with crystallization and precipitation method when the optimal pH, precipitation time mole ratio of Mg²⁺, NH₄⁺, PO₄^3- were 8.0, 20 min and 1.4∶1∶1.4 respectively.

Abstract: The degradation of rhodamine B (RB) in aqueous solution by Fenton’s reagent was studied. After 30 min, the 96.2% removal of RB in water (pH = 3.0, T = 25 °C) was achieved when the initial concentrations of Fe²⁺, H₂O₂ and RB were 0.5 mM, 5 mM and 10 mg/L, respectively. A higher initial concentration of Fe²⁺ and H₂O₂ resulted in a higher efficiency in RB discolorization. The removal of RB was dependent strongly on the pH value of solution. Increasing the reaction temperature was beneficial for the RB degradation. Based on the Arrhenius equation, the activation energy (Ea) was calculated to be 16.78 kJ/mol from rate constants at different temperatures. The degradation of RB by Fenton’s reagent was inhibited by the presence of oxalic acid.

Abstract: The graft copolymer, chitosan-g-AM-AA, was prepared through graft polymerization of acryamide and acryl acid onto chitosan by K₂S₂O₈ initiation under homogeneous conditions in 2 wt% acetic acid. The product was characterized by infrared spectrometry (IR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The adsorption capacities and removal ratioes of the copolymer for heavy metal ions were studied by using medium concentration (about 50mg/L) of Cu²⁺ ,Zn ²⁺and Pb²⁺ at pH 6. The results indicated the copolymer exhibited higher adsorbability than chitosan.

Abstract: Researches on precipitation of calcium from seawater have been carried out using CO₂. The effect of pH value on calcium removals from seawater was investigated. It was found that it is easier to remove calcium from seawater at a higher pH value, and the removal rate of calcium can reach 60% to 90% when the pH value is from pH 8.0 to pH 9.0. The precipitated solids were characterized using X-ray diffraction (XRD) analysis. The results show that they consist of CaCO₃·H₂O at pH 8.0 to pH 8.7, of CaCO₃·H₂O and MgCO₃·3H₂O at more than pH 9.0.

Abstract: The paigeite resources are abundant in China, but most of them are difficult to be utilized efficiently because of the current technical problems on industrial practice. It is necessary to perfected and innovated for comprehensive utilization of paigeite. The new process of gas-based shaft furnace direct reduction-electric furnace smelting separation provides a new way to efficient and clean comprehensive utilization of paigeite resources. In this paper, the pellets are prepared from boron-bearing iron concentrate. The mechanisms of roasting, the rules of reduction, and the properties of reduction swelling are also investigated. And then the pellets after reduction are smelted and separated in electric furnace to study the properties of products and analyze the feasibility and superiority of new technique. The results showed that boron-bearing iron concentrate is a kind of good raw material for pelletizing process. The properties of boron-bearing pellets after roasting for 20 min at 1200°C could meet to the requirements of gas-based shaft furnace direct reduction process, which exhibited fast reaction rate, good reduction swelling properties and high compressive strength both before and after reduction. With the new process, the efficient separation of boron and iron can be realized. The high boron grade and high activity of boron-rich slag obtained from new process can be used directly in boric acid manufacture. The new process shows excellent tech-economy feasibility to achieve efficiency and clean comprehensive utilization of paigeite resources.

Abstract: A laboratory-scale biotrickling filter was evaluated for its effectiveness in treating waste gases containing ammonia at different inlet loading rates. The inlet concentration of ammonia varied from 20～300mg/m³, and the air flow rates were 0.61m³/h, 0.85m³/h and 1.06m³/h, equivalent to empty bed residence time of 35s, 25s and 20s, respectively. The experimental results showed that the inlet ammonia can be efficiently removed in the biotrickling filter. The removal efficiency was nearly 100% when inlet ammonia loading rate was below 28.33g/m³·h, and the maximum elimination capacity for the biotrickling filter was determined to be about 33.99 g/m³·h. The results in microbial analyses had proven that the ammonia oxidizing bacteria and nitrite oxidizing bacteria were dominant in the biotrickling filter. These results show that the treatment system studied can be considered as a viable alternative for the treatment of gaseous emissions containing different concentrations of ammonia.