水滑石除磷的吸附动力学研究

采用共沉淀法制备了Mg/Al水滑石,研究了不同Mg/Al物质的量比、材料用量、不同pH条件下Mg/Al水滑石吸附除磷的动力学特征,从而对吸附速率的控制过程进行分析。结果表明水滑石对磷的吸附能较好地符合准二级动力学方程、Elovich动力学方程和内扩散模型。n(Mg)/n(Al)=3是水滑石最理想配比,水滑石投加量越大,外扩散过程越慢;一定范围内pH的升高能促进水滑石对磷吸附速率和吸附容量的提升。     

不同结构铝氧化物对磷的吸附特征

磷是影响藻类生长的重要营养元素, 它在沉积物界面上的吸附是海洋环境中磷循环的重要环节, 金属氧化物是吸附磷沉积物的重要活性组分之一。采用批量实验法研究不同结构的氧化铝对无机磷的吸附特征, 分别使用二段一级动力学方程和Freundlich等方程对其动力学曲线和平衡吸附等温线进行定量描述, 并对介质盐度、温度等影响因素进行研究。结果发现, 无定型氧化铝结晶弱且比表面积大, 该特点使其吸附容量大于γ-Al₂O₃, 结合表面酸碱滴定的结果, 可知吸附也与铝氧化物的表面酸碱性质相关。分析影响因素可知, 与NaNO₃介质相比, 氧化铝吸附海水中的磷受到阻滞, 且随着介质离子强度增大, 吸附量均呈现降低趋势; pH显著影响磷的吸附量, 在pH=5左右, 两种氧化铝表面对磷酸根的吸附达到最大值; 温度升高, 有利于吸附的进行, 该吸附为吸热、自发、熵增加的过程, 两种结构氧化铝的吸附热力学参数无显著差异。     

SA-g-P(AA-co-AMPS)/KL对罗丹明6G的吸附性能研究

研究了海藻酸钠接枝聚丙烯酸2-丙烯酰胺-2-甲基丙磺酸/高岭土(SA-g-P(AA-co-AMPS)/KL)复合树脂对罗丹明6G染液的吸附性能。探讨了染料初始浓度、吸附时间、pH值对吸附性能的影响,并对吸附结果进行热力学和动力学拟合。结果表明,复合树脂对罗丹明6G在实验条件下的最大吸附量为710 mg/g,吸附过程是自发的,且同时符合Freudlich方程和Redlich-Peterson方程,动力学符合拟二级动力学方程。     

Zr改性磷石膏/粉煤灰复合材料对选矿废水中油酸钠的吸附

选用磷石膏和粉煤灰作为复合吸附剂对油酸钠进行吸附,实验采用化学改性的方式,以氧氯化锆为改性剂。实验证明,在10%的氧氯化锆溶液中,改性磷石膏/粉煤灰对油酸钠的吸附效果最好,吸附率达到86%。采用XRD、红外光谱、SEM对Zr改性磷石膏/粉煤灰复合吸附剂进行表征,并研究了pH值、温度、溶液浓度、吸附时间对其吸附油酸钠的影响。结果表明:最优吸附pH值范围为7～9,吸附平衡时间为30 min,在25℃时对油酸钠饱和吸附量为14. 376 mg/g,吸附等温线符合Langmuir等温吸附模型,吸附动力学符合拟二级吸附动力学模型,吸附过程为放热反应,反应热为-15. 969 J/g。     

磷石膏/粉煤灰复合粉体对铅离子的吸附研究

研究使用磷石膏与粉煤灰进行混合。火焰原子吸收分光光度计测定两者掺比为1∶1的条件下对铅离子的吸附率最好,吸附率达到74.03%。对最佳掺比条件下的混合物进行磨矿、煅烧,吸附率可达93.38%。研究了pH值、温度、吸附剂用量、吸附时间对铅离子吸附的影响。结果表明,最佳吸附pH值为7,吸附平衡时间为30 min,饱和吸附量为15.588 mg/g,125℃以下不会产生不利影响。吸附动力学遵循拟二级动力学模型。     

脲基功能化苯酚印迹聚合物的合成及其对苯酚的吸附研究

以苯酚为模板,γ-脲基丙基三甲氧基硅烷为功能单体采用表面分子印迹聚合法制备了脲基功能化的苯酚表面分子印迹聚合物(苯酚-MIP),并使用红外光谱对苯酚-MIP的结构进行了表征。结果表明:在最佳条件下,初始浓度c0=150mg/L,吸附时间t=20min,pH=7,温度T=30℃下,苯酚-MIP的吸附量是非印迹聚合物(NIP)的2.32倍。动力学数据拟合结果显示:苯酚在苯酚-MIP上的吸附符合伪二级动力学模型和Langmuir等温模型。另外,选择性实验结果显示:苯酚-MIP可以快速和选择性地吸附水中的苯酚。     

涂铁多孔陶瓷吸附去除亚甲基蓝的热动力学

研究了涂铁多孔陶瓷(IOCPC)在20～40℃下对亚甲基蓝(MB)静态吸附的热动力学性质.用液相沉积、多次涂层法对赤泥质多孔陶瓷表面改性制备吸附剂,并通过小试摇床实验考察了IOCPC在不同条件下吸附MB的效果.结果表明:IOCPC的比表面积为4.987m2/g,比改性前增大3.28倍,平均孔径为11.36nm.IOCPC对MB的吸附等温线呈S型,Freundlich等温吸附方程和准二级动力学方程较好地描述了IOCPC对MB的吸附等温线及吸附动力学实验结果,相关系数分别＞0.89和0.97,平衡吸附容量随温度的升高而增加.由标准吉布斯自由能变(莫獹＜0 )、标准反应焓变(莫獺0＞0)和吸附活化能(Ea=16.145kJ/mol＞4.184kJ/mol)的值可判断,IOCPC对MB的吸附是自发的、吸热的化学吸附反应.     

DAAMPV树脂对对硝基苯酚吸附性能的研究

以双丙酮丙烯酰胺改性的胺化聚氯乙烯(DAAMPV)树脂为吸附剂,考察了该树脂对对硝基苯酚的吸附性能。结果表明,DAAMPV树脂对对硝基苯酚有较快的动力学吸附速率,吸附过程符合拟二级动力学方程。随着温度的降低和对硝基苯酚质量浓度的增加,DAAMPV树脂的吸附量增大。在25℃、对硝基苯酚初始质量浓度为500mg/L的条件下,DAAMPV树脂对对硝基苯酚的吸附量为53.2mg/g,吸附过程符合Langmuir等温式。实验条件下,DAAMPV树脂对对硝基苯酚的去除率可达94.26%,吸附的对硝基苯酚可用无水乙醇或4%NaOH洗脱。     

烯丙基胺-细菌纤维素的制备及其动力学研究

基于Ce4+引发自由基接枝共聚机理,制备了新型的烯丙基胺-细菌纤维素(al-BC)吸附剂;考察了细菌纤维素(BC)和烯丙基胺加入量、硝酸铈铵(CAN)浓度等对接枝共聚反应的影响并探讨了其接枝动力学过程;以al-BC为吸附剂,研究其对重金属离子Pb2+的吸附性能。结果表明:在CAN浓度25mmol/L、硝酸浓度0.16mol/L、烯丙基胺及BC加入量分别为24mL/L和8g/L、温度40℃、反应时间4h的最优接枝条件下,al-BC接枝率为18.22%;根据实验结果拟合出了反应初期接枝反应动力学方程;在最优吸附条件下,al-BC对Pb2+的吸附能力比BC提高了37.53%。     

磷石膏/粉煤灰/CaO复合材料对氧化石蜡皂的光催化吸附

利用磷石膏、粉煤灰、氧化钙作为吸附剂原料,CeO 2分析纯作为吸附过程的光催化助剂,试验使用紫外线除菌灯为试验提供光催化环境,试验证明:在磷石膏\粉煤灰\CaO掺比为1∶1∶2的前提条件下,加入10 mg的CeO 2助剂,并在紫外线除菌灯1 h的照射下对氧化石蜡皂的吸附率达到了88.10%。试验使用FT IR、SEM对吸附前后的样品进行表征,并研究了pH值、温度、CeO 2助剂的添加量、吸附质浓度、吸附时间对吸附过程的影响;结果表明:吸附较优的条件为pH在7~12,CeO 2助剂添加量为20 mg;吸附平衡时间为2 h;平衡吸附量为119.51 mg/g;平衡时的吸附率达94%;等温吸附线符合Langmuir等温吸附模型,吸附动力学遵循准二级吸附动力学方程。     

Accelerated solvent extraction followed by on-line solid-phase extraction coupled to ion trap LC/MS/MS for analysis of benzalkonium chlorides in sediment samples

Benzalkonium chlorides (BACs) were successfully extracted from sediment samples using a new methodology based on accelerated solvent extraction (ASE) followed by an on-line cleanup step. The BACs were detected by liquid chromatography/ion trap mass spectrometry (LC/MS) or tandem mass spectrometry (MS/MS) using an electrospray interface operated in the positive ion mode. This methodology combines the high efficiency of extraction provided by a pressurized fluid and the high sensitivity offered by the ion trap MS/MS. The effects of solvent type and ASE operational variables, such as temperature and pressure, were evaluated. After optimization, a mixture of acetonitrile/water (6:4 or 7:3) was found to be most efficient for extracting BACs from the sediment samples. Extraction recoveries ranged from 95 to 105% for C12 and C14 homologues, respectively. Total method recoveries from fortified sediment samples, using a cleanup step followed byASE, were 85% for C12BAC and 79% for C14BAC. The methodology developed in this work provides detection limits in the subnanogram per gram range. Concentrations of BAC homologues ranged from 22 to 206 microg/kg in sediment samples from different river sites downstream from wastewater treatment plants. The high affinity of BACs for soil suggests that BACs preferentially concentrate in sediment rather than in water.     

合金元素磷对铁基烧结减摩材料组织性能的影响

系统地对四元铁基减摩材料Fe-C -Cu -P中合金元素磷的作用进行了研究 .研究表明 ,磷有活化烧结的作用 ,磷对铁基烧结减摩材料的力学性能和摩擦性能有较大的影响 ,同时磷的加入还会消弱铜对烧结合金力学性能的负面影响 .     

Distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) in the soil in a typical area of eastern China

The distribution and concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs, also called co-PCBs) in a typical area of eastern China were evaluated by analysis of 21 soil and 6 sediment samples. The range of WHO-TEQ values for the PCDD/Fs and dioxin-like PCBs in 17 soil samples representing the background investigation in the study area was 0.017-5.04 pg g(-1) (dry weight, dw), with a mean value 0.967(+/-1.361)pg g(-1) and medium value 0.348 pg g(-1), which indicates that the levels of PCDD/Fs and dioxin-like PCBs over the major part of this district were low. However, the WHO-TEQ values (6.52-16.7 pg g(-1) dw) for PCDD/Fs and dioxin-like PCBs in soil samples to the leeward of a known contaminated disassembly industrial park were much higher than that of the background investigation, and the levels of sediment samples downstream of this area were in the range 2.25-34.6 pg g(-1) (dw). The levels of WHO-TEQ in soil and sediment samples decreased with an increase in distance from the researched pollution source. The principal component analysis demonstrated that the PCDD/Fs and dioxin-like PCBs in major part of contaminated sediment and soil samples derived from the correlative matrix. Yet the different distribution patterns of them in part of sediment samples strongly indicate that other potential sources may be exist, further researches should be done to get more information about the sources and the distributions of the PCDD/Fs and PCBs.     

Kinetic study of the degradation of the insecticide pymetrozine in a vegetable-field ecosystem

The disappearance kinetics of pymetrozine was studied in a broccoli-field ecosystem, and an efficient method for the determination of pymetrozine in broccoli and soil was also developed. Pymetrozine residues were extracted from samples using acetonitrile. The extracts were cleaned up by liquid-liquid partitioning with dichloromethane, followed by purification with ethyl acetate, and were then determined by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detector. The average recovery was 87-93% from broccoli, and 84-90% from soil. The relative standard deviation (R.S.D.) was less than 4% in broccoli, and in soil less than 11%. These results are all within the accepted range for residue determination. The limit of detection (LOD) of pymetrozine calculated as a sample concentration (S/N ratio of 3) was 0.005 mg kg(-1). The minimum detectable quantity (MDQ) was 1 x 10(-10)g. The results of the kinetics study of pymetrozine residue showed that pymetrozine degradation in broccoli and soil coincided, with C=1.9826 e(-0.1965t) and C=15.352e(-0.4992t), respectively; the half-lives were 3.5 and 1.4 days, respectively. The final residue level was lower than the new maximum residue limit (MRL) for pymetrozine on vegetables with a harvest interval of 23 days. A dosage of 300 g a.i.hm(-2) was suggested, which is considered to be safe for human beings. These results contribute to establishing the scientific basis of the dosage of pymetrozine for use in vegetable-field ecosystems.     

Adsorption of phosphorus on sediments from the Three-Gorges Reservoir (China) and the relation with sediment compositions

The adsorption of phosphorus (P) on four sediment samples (CunTan, XiaoJiang, DaNing and XiangXi) from the Three-Gorges Reservoir on the Yangtze River in China was studied systematically in batch experiments. A sequential chemical extraction experiment was conducted to clarify the effect of sediment composition on P adsorption. The results showed that P adsorption on four sediment samples mainly occurred within 6 h. P adsorption kinetics can be satisfactorily fitted by both power function and simple Elovich model. A modified Langmuir model may describe well the P adsorption on all the samples in our study. Theoretically, the maximum adsorption amount (Q_max) was 0.402 mg-P/g for XiaoJiang sediment, 0.358 mg-P/g for DaNing sediment, 0.165 mg-P/g for CunTan sediment, and 0.15 mg-P/g for XiangXi sediment. The sediment compositions such as organic matter, metal hydroxides, calcium and clay content showed influences on the P adsorption. Wherein, organic matter and metal hydroxides were the main factors affecting the P adsorption. The maximum P adsorption capacity (Q_max) enhanced with the increase of the content of (Fe + Al + Ca). Compared the zero-equilibrium P concentration (EPC₀) values obtained by the modified Langmuir models with actual P concentrations in water, all the sediments studied in this paper except for XiaoJiang showed a trend of releasing P as a source role, which could enhance the risk of eutrophication occurrence in the Three-Gorges Reservoir.     

Facilitation of phosphorus adsorption onto sediment by aquatic plant debris

Aquatic plant debris in lakes or rivers may affect phosphorus flux in water-sediment systems. In this study, either aquatic plant debris or typical plant components (cellulose or glucose), were added into a system of sediment (50 g) and overlying water (2L) with different initial SRP (soluble reactive phosphorus) concentrations to investigate the impact. After 18 days of treatment with 4 g of plant debris, the SRP in the overlying water for 0.5 and 2 mg L(-1) initial SRP tests at 30°C decreased by 41 and 53%, respectively, compared to the treatments without plant debris. Cellulose and glucose treatments gave similar results as plant debris treatment. When the water-sediment system was sterilized, the cellulose- or glucose-facilitated decrease in SRP vanished. Additionally, in the non-sterilized system, the glucose treatment significantly increased both the microbial biomass carbon and the microbial biomass phosphorous in the sediment. Although total phosphorous in the sediment increased with glucose treatment, its water soluble and iron associated inorganic fractions, two labile phosphorus fractions, were clearly reduced. Our results suggest that the short-term retention of plant debris in water systems facilitates a decrease in overlying water SRP through microbe-mediated mechanisms of phosphorus adsorption and stabilization in sediment.     

Adsorption of tetracycline on soil and sediment: effects of pH and the presence of Cu(II)

Tetracycline (TC) is frequently detected in the environment, however, knowledge on the environmental fate and transport of TC is still limited. Batch adsorption experiments of TC by soil and sediment samples were conducted. The distribution of charge and electrostatic potential of individual atoms of various TC species in the aqueous solution were determined using MOPAC version 0.034 W program in ChemBio3D Ultra software. Most of the adsorption isotherms on the soil, river and marine sediments were well fitted with the Freundlich and Polanyi-Manes (PMM) models. The single point organic carbon (OC)-normalized adsorption distribution coefficients (K(OC)) and PMM saturated adsorption capacity (Q(OC)(0)) values of TC were associated with the mesopore volume and clay content to a greater extent, indicating the mesopore volume of the soil and sediments and their clay content possibly influenced the fate and transport of TC in the natural environment. The adsorption of TC on soil and sediments strongly depended on the pH and presence of Cu(II). The presence of Cu(II) facilitated TC adsorption on soil and sediments at low pH (pH<5), possibly due to the metallic complexation and surface-bridging mechanism by Cu(II) adsorption on soil and sediments. The cation exchange interaction, metallic complexation and Coulombic interaction of mechanisms for adsorption of TC to soils and sediments were further supported by quantum chemical calculation of various TC species in different pH.     

含磷零膨胀LAS透明微晶玻璃的相转变动力学的研究

以零膨胀Li2O-Al2O3-SiO2透明微晶玻璃为研究对象,采用示差扫描量热法(DSC)研究无磷和含磷玻璃的析晶动力学和玻璃转变动力学行为.结果发现,引入少量的磷化物使得玻璃的析晶峰温度和玻璃转变温度降低,玻璃的析晶活化能和玻璃转变活化能增大,晶体生长指数n减小,使玻璃网络结构重排困难.     

Characterisation of phosphorous forms in wastewater treatment plants

The removal of different forms of phosphorous (namely total phosphorous, soluble phosphorous, particulate phosphorous and total phosphate) has been studied in two municipal wastewater treatment plants (WWTP) with different characteristics, but without any specific implemented strategy for phosphorous removal. The results obtained for the different forms of phosphorus can be summarised as follows: (1) complete removal of particulate phosphorous is achieved in either primary or secondary clarifiers; (2) total phosphorous concentration in the effluent is mostly soluble phosphorous and this is mainly phosphate; (3) a small amount of soluble phosphorous is removed by biomass growth and/or biosorption; (4) both WWTPs presented a high-buffered behaviour in response to high inlet loading of phosphorous, showing a constant pattern at the outlet of the WWTP; (5) removal of total phosphorous was approximately 60-70% for both WWTPs; and (6) recirculation streams such as supernatant from centrifuge sludge dehydration operation can have a significant contribution to the inlet amount of phosphorous.The results presented in this paper provide a basis to develop prospects for phosphorous removal, which may be adapted to the particular configurations of the WWTP studied.     

Determination of atmospheric methyl bromide by cryotrapping-gas chromatography and application to soil kinetic studies using a dynamic dilution system

Methyl bromide (CH(3)Br) is considered to be a major source of stratospheric Br, which contributes to the destruction of ozone. It is therefore necessary to understand the natural sinks of this compound and to accurately measure ambient mixing ratios. Methodology is described for the measurement of atmospheric CH(3)Br by cryotrapping-gas chromatography and its application to soil kinetics. A 2-propanol/dry ice cryotrap was used to preconcentrate CH(3)Br in standard and air samples, with subsequent detection using a gas chromatograph equipped with an O(2)-doped electron capture detector (GC-ECD). The GC-ECD cryotrapping method had a detection limit of 0.23 pmol of CH(3)Br. This is equivalent to the amount of CH(3)Br in a 500 mL sample of ambient air at the estimated northern hemisphere atmospheric mixing ratio of 11 parts per trillion by volume (pptv). A dynamic dilution system was developed to produce mixing ratios of CH(3)Br ranging between 4 and 1000 pptv. Calibrated mixing ratios of CH(3)Br produced with the dilution system were used to determine soil uptake kinetics employing a dynamic soil incubation method.