Advanced Materials Research Vols. 610-613

Abstract: Methyl orange stimulated wastewater was treated using non-homogeneous Fenton reaction. First the effect of catalyst composition on the treatment was investigated and then further investigation of the impact of reaction conditions on the degradation effect in the catalytic process was carried out. It showed the optimal conditions of treating methyl orange wastewater(100ml) of 10mg/L, The optimal conditions for catalyst preparation through experiments above were: proportion of the elements in the catalyst was Co0.5Fel.0(MgO)2.5, this article examined the impact of reaction conditions on the catalytic properties of the catalytic process. It turned out that on the condition that the amount of catalyst was 0.9g/L hydrogen peroxide concentration was 2.5ml/L, within the scope of application in a wide pH (4~14), catalyst degradation efficiency was significantly superior to conventional homogeneous Fenton system and methyl orange removal efficiency was above 95%.

Abstract: Since the concept of acid rain was come up with time has been for a little more than a hundred years. Many researchers have studied the causes of it formation and obtained some results. But a satisfactory explanation can not be given about some phenomena of acid rain until today. For example in some regions the acid substances in atmosphere before formed acid rain are being reduced year after year but acidity of rainwater and acid rain frequency are being increased year after year. The anions are less than cations in acid rain, and so on. In order to solve these problems we have done simulated tests. Here we show that the cause of unaccountability some acid rains is ignored effect of atmosphere CO₂. Firstly, CO₂ is well-known acid substance, it can make water acid and its amount is ten thousand times as much as other acid substances, for example SO₂ and NO_x, in atmosphere. Then, when CO₂ was not dissolved in solution of simulated acid rain pH of solution was larger than 6 although the ions percentage composition of solution is as same as acid rain, and when CO₂ was done pH of solution was less than or equal 4.6. So, we concluded that CO₂ plays an important role in acid rain forming.

Abstract: More frequently drying-rewetting is likely to be expected for soils this century, with strong effect on nitrogen transformation. Experiments were conducted in semi-disturbed soils which were incubated under 4 different moisture regimes (dry wet\constant wet\constant dry\constant flooded) for 71 d. The results show that the dry soil has a rapid NO₃^--N increase after rewetting. Drying-rewetting increases soil nitrification which shows a "pulse" increasing. The drying and rewetting soil has the highest nitrification intensity when the soil moisture content (g/g) ranging at 15.82% ~ 17.06%. Drying-rewetting contributes to the accumulation of NO₃^--N.

Abstract: The defluoridation capacity of phosphate rock in the presence of oxalic acid was investigated using batch experiments. Defluoridation capacity of phosphate rock was enhanced in the presence of oxalic acid, removing fluoride from 22.46% up to 57.98% with 2.5 mmol/L oxalic acid. The contact time and pH for maximum fluoride uptake were found 2 h and 5, respectively. Maximum adsorption capacity (0.36 mg/g) of fluoride on phosphate rock was observed at 50 mg/L initial fluoride concentration using 2 g adsorbent dose.

Abstract: In this study, the effects of pH and metal cations such as Mn(II) and Ca(II) on the oxidation of As(III) by pyrolusite were investigated. Our results showed that the oxidation of As(III) was significantly dependent on pH values. The oxidation rate increased with a decrease of pH from 4.0 to 6.0 or an increase of pH from 8.0 to 9.0, while be the lowest at pH 7.0. The removal of aqueous As(III) and the release of produced As(V) were inhibited when Mn(II) was simultaneously added into the system, which could be explained that added Mn(II) bounded to pyrolusite and consequently blocked the adsorption and oxidation of As(III). Higher concentration of Mn(II) lowered the oxidation of As(III) at both pH 5.83 and 7.82. The addition of Mn(II) caused a greater decrease in the oxidation rate of As(III) than did the addition of Ca(II). The lower oxidation rate of As(III) was observed with the higher concentration of Ca(II) at pH 5.83, while the trend was opposite at pH 8.72.

Abstract: A PNP -degrading strain was isolated from parathion-methyl contaminated soil sample and identified as Arthrobacter on the basis of its complete 16S rRNA gene sequence analysis. The strain could tolerate concentrations of PNP up to 300 mg/L and degrading completely 200 mg/L PNP within 16 h. To study the applicability of the strain for bioremediation of PNP, The effects of parameters such as pH value ,salinities, glucose concentrations on PNP degradation were investigated.The experimental results showed that biodegradation of PNP occurred quickly at an optimal pH of 8.0 and at 0.1% salt (NaCl) contents and 0.01%(W/V) glucose were the best cosubstrate for the process of PNP biodegradation.

Abstract: A dominant bacterium (LW13) for the degradation of chlorobenzene was selected from maturity sludge in a novel combined bio-filter polluted by chlorobenzene gas. Based on the morphological characteristics observation, physio-biochemical characteristics and 16S rDNA sequence homology analysis, strain LW13 was identified as Lysinibacillus fusiformis. Crude enzyme from the fermentation was extracted and their enzymatic properties were also investigated. Results showed that the degradation enzyme produced by the bacteria belong to extracellular enzymes. The purity of the enzyme was determined by SDS-PAGE gel electrophoresis and the molecular weight was found to be 52 kDa. The optimum pH value was about 8.0 with the optimum temperature of 45° C. Throughout the purification process, 85-fold of enzyme purification was achieved with the recovery of 20.69%.

Abstract: In order to provide a more scientific and healthy reference for the people lived in the northeast of China to eat sour pickled cabbages, in the study, the nitrite content of 11 naturally fermented sour pickled cabbages collected from the Daqing area were detected by the spectrophotometry method according to Chinese National Food Standard (GB5009.33-2010). The results shown that the content level of nitrite in the pickled vegetables were between 0.17 mg/kg and 1.98mg/kg,it was more lower than 20mg/kg, the limit of nitrite described in Chinese National Food Standard (GB2714-2003)．

Abstract: The electrochemical reduction behaviors of nitrobenzene in composite ionic liquids were investigated by cyclic voltammetry. The results showed that the electrochemical reduction characteristics of nitrobenzene in binary composite ionic liquids was improved in comparing with pure ionic liquids BMimBF4 and BMimPF6. The reaction velocity of nitrobenzene in composite ionic liquids was controlled by diffusion. With increasing temperature or the concentration of nitrobenzene, the peak current was increased and the peak potential was varied complicated.

Abstract: Experiment simulates the integrated vertical flow constructed wetland (IVCW) operation of the system, discusses the trend of Dissolved Oxygen (DO) within the system and the relativity of DO and removing nitrogen. The results show that NH4+-N, NO3—-N and DO decrease along the flow direction in the integrated vertical flow constructed wetlands; NO3—-N increased and then decreased along the process; because of the DO of upstream pool is low, so the Total Nitrogen (TN) removing process occurs mainly in the downstream pool.