冬季菹草对悬浮泥沙的影响

利用冬季沉水植物菹草构建由浅水到深水的串联系统,含沙水依次流经浅水区和深水区,测定各级菹草对水体悬浮泥沙含量和沉降量的影响.结果显示,菹草系统可以降低水体中悬浮泥沙含量,并随水力停留时间延长而降低程度加大.各运行条件下,菹草系统悬浮泥沙平均沉降量65.7 g·m-2,比对照组高39.4%.菹草表面泥沙的吸附是一个"吸附-沉降-再吸附" 的动态过程,吸附量为3.26～5.69 g·kg-1.菹草对冬季水生态系统的自净功能起着十分重要的作用.     

Adsorption thermodynamics and kinetic investigation of aromatic amphoteric compounds onto different polymeric adsorbents

The adsorption behavior of p-aminobenzoic acid and o-aminobenzoic acid onto the different polymeric adsorbents was systematically investigated as a function of the solution concentration and temperature.Experimental results indicated that the equilibrium adsorption data of the four polymeric adsorbents fitted well in the Freundlich isotherm.The adsorption capacity of multi-functional polymeric adsorbent NJ-99 was the highest,which might be attributed to the strong hydrogen-bonding interaction between the amino groups on the resin and the carboxyl group of aminobenzoic acid.The adsorption capacity of o-aminobenzoic acid onto any adsorbent was higher than p-aminobenzoic acid.Thermodynamic studies suggested the exothermic,spontaneous physical adsorption process.Adsorption kinetics results showed that the adsorption followed the pseudo-second-order kinetics model and the intraparticle mass transfer process was the rate-controlling step.     

Thermodynamics and kinetics of cadmium adsorption onto oxidized granular activated carbon

Cadmium sorption behavior of granular activated carbon oxidized with nitric acid was systematically studied by sets of the equilibrium and time-based experiments under various conditions.The cadmium adsorption capacity of oxidized granular activated carbon enlarged with an increase in pH,and reduced with an increase in ionic strength.Experimental data were evaluated to find out kinetic characteristics.Adsorption processes were found to follow pseudo-second order rate equation.Adsorption isotherms correlate well with the Langmuir isotherm model and the maximum sorption capacity of cadmium evaluated is 51.02μmol/g.Thermodynamic parameters were calculated based on Van't Hoff equation.Equilibrium constant Kd was evaluated from Freundlich isotherm model constants,Langmnir isotherm model constants,and isotherms,respectively.The average change of standard adsorption heatΔH~0 was -25.29 kJ/mol.NegativeΔH~0 andΔG~0 values indicate the adsorption process for cadmium onto the studied activated carbon is exothermic and spontaneous.The standard entropyΔS~0 was also negative,which suggests a decrease in the freedom of the system.     

Improvement of the antifouling characteristics in a bioreactor of polypropylene microporous membrane by the adsorption of Tween 20

Surface modification by physical adsorption of Tween 20 was accomplished on polypropylene microporous membranes (PPMMs). Attenuated total reflection-Fourier transform infrared spectroscopy (ATR/FT-IR) and scanning electron microscope (SEM) were used to characterize the chemical and morphological changes on the membrane surfaces. Water contact angles and relative pure water fluxes were measured. The data showed that the hydrophilic performance for the modified membranes increased with the increase in the adsorption amount of Tween 20 onto the surface or into the pores of polypropylene microporous membranes. To test the antifouling property of the membranes by the adsorption of Tween 20 in a membrane bioreactor (MBR), filtration for active sludge was performed using synthetic wastewater. With the help of the data of water fluxes and the FE-SEM photos of the modified PPMMs before or after operating in a MBR for about 12 d, the PPMMs with monolayer adsorption of Tween 20 showed higher remained flux and stronger antifouling ability than unmodified membrane and other modification membranes studied.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

旅游地的类生命特征研究

把旅游地视为一个特殊生命体和特殊的生态系统．旅游地与生物体存在非常类似的机理。具有旅游地生命周期、旅游地生态系统、旅游地之间存在诸如共生、竞争、寄生、捕食生态空间关系等明显的类生命特征。研究旅游地的类生命特征．为运用生态学理论研究旅游发展问题提供了可靠依据和切实可行性,为更好地解释和透视旅游发展问题实质提供了崭新的途径与思路,生态学理论在旅游中的应用和解决旅游问题具有现实的可能性和潜在的应用价值,在丰富旅游学与生态学理论的同时,指导并促进旅游业的可持续发展。     

活性炭纤维处理甲苯废气试验研究

采用动态吸附试验,研究了进气温度、废气浓度对粘胶基活性炭纤维吸附甲苯过程的影响,分析了活性炭纤维(ACF)的穿透时间、平衡饱和吸附量的变化情况,并用Y-N模型对穿透曲线进行拟合.研究了吸附饱和ACF采用氮气热再生法,确定了温度、流量、再生时间等最佳操作参数,并进行了相关机理的探讨.     

近海沉积物对粪固醇的等温吸附和热力学研究

采用大连湾近海表层沉积物为吸附剂,粪固醇为吸附质,通过批量平衡法,研究了近海沉积物对12种粪固醇的吸附行为.结果表明,12种粪固醇在24 h吸附达到平衡后,5种粪固醇的指纹值变化趋于稳定;用Henry、Freundlich、Langumir、Dubinin-Radushkevich(D-R模型)、Temkin这5种等温吸附模型来拟合,其中Langumir模型不适合拟合沉积物对粪固醇的吸附数据,其他4种模型均能较好地拟合.D-R模型拟合效果表明,12种粪固醇的吸附平均自由能在7 071.1～9 128.7 J.mol-1之间,12种粪固醇的吸附过程主要是物理吸附的作用.Temkin模型拟合效果表明,加氢胆固酮(Kf=8.89×106)的Kf值最大,说明沉积物吸附加氢胆固酮之间的作用最大,加氢胆固酮更容易被吸附.热力学参数吸附焓ΔH0<0,熵变ΔS0<0,ΔG0<0呈现出放热反应,自发过程的特征.     

无定型纳米TiO2吸附去除饮用水中的低浓度As(Ⅲ)

研究了纳米无定型TiO2颗粒对饮用水中低浓度的三价砷As(Ⅲ)吸附行为。纳米TiO2颗粒吸附剂的BET表面积为205 m2/g,计算的BJH吸附平均孔径为4.02 nm(4 V/A)。对起始As(Ⅲ)浓度为150μg/L的模拟含砷水,经过5h的吸附处理后残余浓度不足4μg/L,As(Ⅲ)去除率达到97%。反应起始阶段吸附速率较快,84%的As(Ⅲ)能够在20min内去除。As(Ⅲ)吸附动力学较好地符合拟二级动力学模式。最佳As(Ⅲ)吸附pH为9.3,低于此值,随酸性增加吸附速率有所降低;而高于此值的强碱性pH对吸附有强烈抑制作用。在平衡浓度较低的情形下(10～220μg/L),Lang-muir,Freundlich和Dubinin-Radushkevich(D-R)吸附等温式均可较好拟合吸附行为,但中性和弱碱性条件下更符合Fre-undlich吸附等温式;平衡浓度大于220μg/L,吸附容量随平衡浓度增加而迅速增加,最大吸附容量在低浓度下达到4.79 mg/g。     

粉煤灰多孔陶粒在水处理中的应用研究

研究采用电厂的粉煤灰为主要原料制备多孔陶粒,分别将其用作水处理中的微生物载体和吸附剂。挂膜结果表明:COD、氨氮这两项指标的出水基本稳定,去除率高。用多孔陶粒作吸附剂处理含铬废水时,等温吸附实验表明,多孔陶粒吸附水中的铬的等温方程基本符合Langmiur等温方程式,在pH值为酸性时对铬的去除率较高。用HCl和NaOH溶液再生多孔陶粒,酸的效果更好。