Advanced Materials Research Vols. 610-613

Abstract: Study on the effect of Ca²⁺ and Fe³⁺ addition on nitrification-denitrification process in a submerged membrane bioreactor was conducted. The removal rate of total nitrogen and ammonia nitrogen was investigated. The result indicated that the ammonia nitrogen and total nitrogen removal rate increased from 75% to 85% and 55% to 75%, respectively, as the calcium concentration ranging from 0 to 150 mg/L, which indicated that the nitrification and denitrification process were promoted. Ferric ion of 50 mg/L obtained a considerable increase in TN removal from 55% to 70% ,with an increase of ammonia nitrogen removal rate from 75% to 83%. However, ferric ion concentration ranging between 100 mg/L and 150mg/L caused a decrease of both total nitrogen and ammonia nitrogen removal efficiency, indicating that the activity of nitrifying and denitrifying bacteria was inhibited.

Abstract: The barrier for low-level radioactive wastes repositories calls for the use of concrete. In a underground situation, the repository may be subject to intrusion of various elements from the external environment and may cause concrete deterioration and reduces its durability. This study focuses on the effect of leaching of concrete as simulated in the laboratory to assess the durability in long term use of concrete materials. The basic mixture of cement, mortar and concrete were used to produce test specimens that were exposed to different conditions such as pure water and substitute ocean water to simulate calcium loss under different circumstances. The possible mechanism of calcium loss and potential influence on concrete durability were then carefully examined. The results of the extensive laboratory experiments show that : (1) concrete materials has better resistance against calcium leaching as compared to mortar and cement paste based on the SEM-EDS measurements on the Ca/Si ratio; (2) the increase in duration of exposure of cement mortars resulted in increases in the porosity of the specimen as exhibited by the decreases of bulk density; (3) microstructural observation showed that mortar samples in ammonium nitrate solution experience accelerated leaching, resulting in the severe deterioration of the region near the exposed surface.

Abstract: A method for determination of formaldehyde by flow injection spectrophotometry based on the catalytic effects of formaldehyde on the oxidation reaction of Bordeaux R by potassium chlorate in sulfuric acid medium was established. The relationship of the reduced absorbency to the concentration of formaldehyde was good linearity and the maximum absorption peak located at 520nm. The affecting factors on the strength of absorption including acidity, dosage, temperature, coexisting ions and so on, and the optimal conditions of the reaction in the system were investigated. Calibration graphs were linear for ranges of 0 to 3.0 mg l−1 and a detection limit of 2×10-8 g ml−1 formaldehyde was achieved. The proposed method was successfully applied to the analyses of environmental samples, with relative standard deviation of less than 1.6% and the recoveries are 93.6 % to 94.5% for the determination of formaldehyde.

Abstract: The Cladophora genus comprises macro benthic green algae, widely distributed in fresh and salt water around the world. This study employed C. glomerata and C. vagabunda to observe changes in the thickness of the mucilage layer formed by extracellular polymeric substance (EPS) and the number of epiphytic algae on the Cladophora species in different tidal reaches near the mouth of a river. Through a cultivation experiment, we observed the influence of salinity on the thickness of mucilage layers and the number of epiphytes on these two algal species. We discovered that the growth of C. glomerata is extremely sensitive to salinity; when salinity exceeds 1.0‰, a significant increase in EPS is induced, thickening the extracellular mucilage layer and affecting the attachment of epiphytes. Due to the wide distribution of C. glomerata, the sensitivity of this algal species to salinity can be employed as a biological indicator of variations in salinity.

Abstract: Based on the oxidation of neutral red by KIO4 in 3.2×10-4 mol/L sulfuric acid solution, a simple kinetic spectrophotometric method was developed for the determination of trace amounts of Se(IV).The reaction was monitored spectrophotometrically by measuring the decrease in the absorbance of neutral red at 530 nm with a fixed-time method. The decrease in the absorbance of neutral red is proportional to the concentration of Se(IV) in the range 0.0–8.0 µg/L with a fixed time of 4–6 min from the initiation of the reaction. The limit of detection is 0.36 µg/L Se(IV). The influence of the factors such as acidity, concentration of reactants, reaction time, temperature and co-existing ions on the reaction is discussed. The optimum conditions of reaction are established and some kinetic parameters are determined. The apparent activation energy of catalytic reaction is 81.60 kJ/mol. The relative standard deviation for the determination of 0.1 and 0.2 µg/mL Se(IV) was 2.1 and 1.9 %, respectively. The method has been successfully applied to the determination of Se (IV) in tea and human hair samples with the relative standard deviation of 0.33 %–1.5 % and the recovery of 97.5 %–103.5 %.

Abstract: It is a main problem that environment can be polluted by discharge of wastewater containing NH4⁺, Ca²⁺ and Na⁺, when rare earths (REs) are extracted in a saponified system using di-(2-ethylhexyl) phosphoric acid (D2EHPA). Pointing to this problem, the selective separation of Pr(Ⅲ) by liquid–liquid extraction using D2EHPA in the presence of a complexing agent of lactic acid (LA) has been studied. Results are shown that the maximum of separation factor (β) between Pr/Ce is 2.04 and extraction selectivity is also enhanced when compared with that of D2EHPA–HCl system. The thermodynamic function △H is determined as exothermically driven. The cation exchange mechanism is discussed by IR spectra. Thus, the results suggest that highly selective separation and extraction of Pr(Ⅲ) from a Pr/Ce solution is possible, providing a simple and environment-friendly complexing method for extraction-separation rare earths, and promoting the sustainable development in rare earths practices.of Pr(Ⅲ) from a Pr/Ce solution is possible, providing a simple and environment-friendly complexing method for extraction-separation rare earths, and promoting the sustainable development in rare earths practices.

Abstract: In order to determine the nitrogen use efficiency of plantlets in vitro under different nitrogen source, near infrared spectroscopy technique and image analysis technique with multi-references were used to obtain the successive information of nitrogen consumption. The Logistic and nonlinear hyperbolic equations were used for fitting the relationship of biomass of plantlet in vitro and culture time, nitrogen utilization of plantlets and culture time, and nitrogen utilization of plantlets and biomass of plantlet in vitro. The models of growth prediction, nitrogen utilization and nitrogen use efficiency of plantlets in vitro were established. The nitrogen use efficiency of Atractylodes lancea plantlets in vitro sub-cultured in different nitrogen source and levels were measured, which decreased with the increase of culture time. Ammonium (0.096 g L^-1) / nitrate (0.555 g L-1) was the preferred nitrogen sources combination for the growth of Atractylodes lancea plantlets in vitro.

Abstract: Synergistic effect of xylanase and bleaching agent on bleaching properties of KP pulp was investigated. The combination of ClO2 chlorination, alkali extraction and ClO2 bleaching with xylanase was applied. Results showed that X/DED bleaching process could make full use of xylanase, xylan was degraded and the role of bleaching agent was accelerated which enhancing the chemical accessibility of xylanase. The coordination of the two parts improved bleaching effect significantly. But for DX/ED bleaching process, the brightness of bleached pulp treated with different xylanase treating time was very low or a little low, indicating the role of xylanase on pulp was very important for improving bleaching properties, and residual xylanase had little effect on improvement of alkaline extract. Effect of xylanase in ClO2 stage had little effect on bleaching effect of pulp, and brightness are near each other. When xylanase and ClO2 were added together, xylanase almost did not show its role in bleaching, and bleaching result was neat to that of DED process

Abstract: Photosynthetic pigment content and photosynthetic activity, as well as the antioxidant capacity were estimated in barley seedlings after 10 or 20 d supplies of Al and Cd individual or combined in nutrient solution. The results showed that stress exposure strongly decreased photosynthetic pigment content and photosynthetic activity, as well as induced oxidative damage as evidenced by increased the activities of peroxidase (POD) and superoxide dismutase (SOD), and malonaldehyde (MDA) content in barley leaves. The most obvious response was found in plants exposed to higher levels of Cd (10 μmol/L) or Al (90 μmol/L) in the nutrient medium. Binary metal combinations generally aggravated photosynthesis reduction and induced more serious oxidative stress as compared with Al or Cd single treatments, and the most deleterious effects were observed in the combination of 90 μmol/L Al+5 μmol/L Cd.

Abstract: In the presented paper, diethanol amine is employed to plasticize corn starch, and plasticized starch is incorporated into polypropylene to create semibio-based composites with the aid of compatibilizer, maleic anhydride-grafted PP (PPMA). Compared with PP/starch blend, the presence of diethanol amine changes the morphology and increases the plasticity of starch due to the reduction effect of intermolecular hydrogen bonding interactions. Adding PPMA could reduce the dispersed size of starch granules in the polymer matrix due to in situ reactive compatibilization. Addition of 30 wt% PPMA decreases the starch granules size from ~10 μm to ~5 μm, and increases the tensile strength from 16 MPa for PP/plasticized starch to 30 MPa, increased by 87.5%. Thus, as-created bio-composites with improved mechanical properties will find many potential applications such as packaging.