Advanced Materials Research Vols. 955-959

Abstract: High density of PM2.5 that has an insignificant contribution to the increasing dusty weather threats the physicaland mental health of approximate six hundred millions Chinese recently. In this paper, we investigate thediffusion and attenuation of PM2.5 and give a prediction of its density in Xi’an city, which is based on nonstationarytwo-dimensional multi-box model, while considering the effect of seasons and wind direction. Asimulation is conducted with data from thirteen random selected stations. Furthermore, by comparing the realmeasured value and numeric value, we evaluate the validity of our proposed model as well as giving the relativeerror.Keywords: Two-Dimensional Multi-Box model, PM2.5, Diffusion, Attenuation.

Abstract: Ditch pond wetland systems have the capacity to remove and purify non-point pollutants of nitrogen and phosphorus from agricultural drainage. This paper measured the changes of nitrogen and phosphorus content in ditches, ponds of runoff water, aquatic plants and sediment. The results show that ditch, pond has the very good intercept and removing effect for nitrogen and phosphorus. The total removal rate of TN and TP were 61.13% and 63.08% in ditch pond wetlands. Phragmites communis, Zizania latifolia, reed nitrogen absorption per unit area respectively were 2.468 g/m², 1.795 g/m², 2.174 g/m². Phragmites communis, Zizania latifolia, reed absorb phosphorus amount per unit area respectively were 0.643 g/m², 0.351 g/m², 0.338 g/m². The TN content and TP content of sediment is increase from ditches1to ditches3. TN content of sediment at pond import is higher than at pond export. TP content changed little in the pond sediment.

Abstract: Emergency disposal combined technology of sorbent cotton intercept and powdered activated carbon (PAC) adsorption was researched. The removal effects of petroleum pollutants individually treated by sorbent cotton were analyzed. The influencing factors of PAC adsorption to deal with petroleum pollutants, including PAC dosage, oscillation frequency and oscillation time, were investigated. The results showed that removal efficiency increased with increasing PAC dosage. When PAC dosage reached 50mg/L, the remaining concentration of petroleum pollutants met the standards. And after oscillated for 120min, the total removal efficiency increased to more than 99%.

Abstract: V-doped TiO₂ was prepared by the sol-gel method. The different reaction and preparation conditions of TiO₂ and V-doped TiO₂were evaluated through the formaldehyde degradation under the visible light. Results showed that the formaldehyde degradation efficiency reached 70.8% when the doping amount of V was 1%(mol), the calcining temperature was 700 oC and pH was 3.5; It improved to 88.5% with 20g activated carbon as support and the 89W energy-saving lamp as light source; The formaldehyde degradation products were H₂O and CO₂; The specific surface area and pore distribution of TiO₂ were analyzed by BET and its crystalline structure was analyzed by XRD,which indicated that mixture of anatase and rutile have large surface area and strong photocatalytic activity due to the V-doping. These suggested that the photocatalytic reactions of formaldehyde included adsorption and photocatalytic oxidation which was obvious for the V-doped TiO₂.

Abstract: This paper examined the treatment of rural domestic wastewater. Influent and effluent samples were experimented for Chemical oxygen demand (COD), NH₄⁺-N, NO₃^--N and TP in the Taihu Lake Environmental laboratory of Southeast University in Wuxi. Different hydraulic retention time (HRT) and recycle ratios were applied to appraise their influence on removal efficiency. The wastewater temperature was controlled between 20 to 24°C and pH ranges 7.6 – 8.1. The result revealed average COD, NH₄⁺-N, NO₃^- -N and TP removal efficiencies of 77.2, 74.1, 94 and 83% with optimum HRT of 3hrs and recycle ratio of 2 respectively. The obtained results confirmed that, the integrated processes of anoxic/oxic bioreactor and artificial wetland was viable and proficient in domestic wastewater treatment.

Abstract: Membrane distillation-crystallization (MDC) is an appropriate process which can completely recover solutes and solvents from high concentration brine under modest operation conditions, and no emissions from system into the environment. In present article, factors restricting the development of membrane distillation-crystallization such as the performance of membrane material and the mass transfer/transfer efficiency were introduced, the process enhancement and sediment control measures of crystallization were reviewed. To reinforce mass and heat transfer efficiency in the process of hollow fiber membrane distillation-crystallization, bubbles were suggested to be added into feed side to format gas-liquid two-phase flow. The secondary flow generated by the bubble would not only substantially increase the maximum shear stress on membrane surfaces, prevent deposition of pollutants, but also could effectively reduce the boundary layer polarization phenomena at the same time. And most importantly, bubbles would not become nucleus for crystal generation of supersaturated solution, and bubbles are easily detached from the solution.

Abstract: Pomelo peel was esterified with acetic anhydride using 4-dimethyl-amino pyridine as a catalyst under reaction temperature of 60 °C and duration of 3 h. At 0.1 g 4-dimethyl-amino pyridine of the catalyst in 80 ml acetic anhydride, the highest sorption values of 14.95 g/g diesel and 18.39 g/g lubricating oil were achieved, which was found to be much higher than raw pomelo peel. FTIR and SEM studies produced evidence for acetylation. The sorption kinetics and reusability were studied. The kinetic studies show good correlation coefficients for a pseudo-second-order kinetic model. This work demonstrated that pomelo peel modified by acetic anhydride is an efficient and environment-friendly biosorbent for the removal of spilled oil.

Abstract: There are high organic matter and cation exchange capacity (CEC) in paper mill sludge, which can be used efficiently to amend soil properties and promote the growth of crops. The batch method was used to investigate effects of paper sludge on adsorption and desorption of Cd (II) and Pb (II) in two types paddy soil (red soil, purple soil), through adding paper sludge to red soil and purple soil. The results showed that isothermal sorption process of Cd (II) and Pb (II) by soils and paper sludge could be well described by Langmuir equation and Freundlich equation, and all coefficients (r) were higher than 0.9. The purple soil had a higher sorption capacity of Cd (II) and Pb (II) than red soil. The sorption capacities of Cd (II) and Pb (II) in soils increased after added paper sludge, and they reached adsorption equilibrium as the percentages of paper sludge were 10%, 1% in red soil and purple soil, respectively. The desorption capacities of Cd (II) and Pb (II) in soils decreased after added paper sludge, and they reached minimum as the percentages of paper sludge were 5%, 2% in red soil and purple soil, respectively. It was better to immobilize Cd (II) and Pb (II) after added paper sludge, thus paper mill sludge can relieve the migration of heavy metals in soil-crop systems. It can provide a new way for safe using of heavy metal contaminated soil and resource utilization of paper sludge.

Abstract: Na-Bentonite/poly AMPS/AA/AM composite was synthesized by aqueous solution polymerization and characterized by XRD, SEM and FTIR spectroscopy. Na-Bentonite and poly AMPS/AA/AM was a mechanical mixture. The composite was used as an adsorbent for the removal of Pb (II) from aqueous solutions. The adsorption quantity of composite was 7.9mg/g.

Abstract: Magnesium ammonium phosphate (MAP) precipitation has been studied by using magnesium hydroxide and sodium dihydrogen phosphate as precipitators for treating simulation wastewater in which the concentration of ammonia nitrogen is 10.00g/L. The effect of reaction time, pH and precipitator ratio on ammonium nitrogen removal rate has been investigated. The obtained optimum treatment conditions of MAP precipitation for treating ammonia nitrogen wastewater are as follows: reaction time is 4 hours, pH is 8.0, the molar ratio of sodium dihydrogen phosphate and ammonia nitrogen in wastewater, i.e. n (P):n (N), is 1.2, the molar ratio of magnesium hydroxide and sodium dihydrogen phosphate, i.e. n (Mg):n (P), is 1.4. Under these conditions, the ammonium nitrogen removal rate, by using MAP precipitation for treating simulation ammonia nitrogen wastewater, is 90.71%.