阳(阴)离子复配修饰两性磁性膨润土的表面特征差异及对苯酚吸附的影响

以膨润土(BT)为基质,采用共沉淀法制备负载Fe3O4的磁性膨润土(MBT),在两性表面活性剂十二烷基二甲基甜菜碱(BS-12)修饰(BS-MBT)的基础上,以阳离子表面活性剂十六烷基三甲基溴化铵(CTMAB)/阴离子表面活性剂十二烷基磺酸钠(SDS)为复配修饰剂,通过湿法分别制备2种两性复配修饰磁性膨润土(BS-CT-MBT/BS-SDS-MBT),采用扫描电镜、X-射线衍射、热重、红外光谱对样品进行表征,测定磁性、比表面积和孔容等性质,通过批处理实验法对比两性复配修饰磁性膨润土对苯酚的吸附.结果表明,两性复配修饰膨润土具有良好的磁分离性能.与BS-MBT相比,BS-CT-MBT的C、N质量分数增大,复配修饰剂质量分数增加,孔容和比表面积减小,BS-SDS-MBT的C、N质量分数减小,复配修饰剂质量分数减少,孔容减小,比表面积增大.在pH 6.0的0.1 mol·L~(-1)Na Cl溶液中各修饰剂的解吸率低于9%.各土样对苯酚的等温吸附数据符合Henry模型,以分配吸附为主,吸附量顺序为BS-CT-MBTBS-MBTBS-SDS-MBTBTMBT,修饰剂质量分数是影响苯酚吸附的决定性因素,CTMAB提升土样吸附苯酚能力的效果高于SDS.     

菲在大庆黑钙土有机-矿质复合体上的吸附与解吸

利用超声分散法提取了黑龙江大庆黑钙土中不同粒级有机-矿质复合体,并测定了其基本理化性质.其中粘粒复合体的有机质含量最高,比表面积以及阳离子交换容量最大.研究了多环芳烃菲在不同粒级有机-矿质复合体上的吸附和解吸行为.结果表明,菲在各粒级有机-矿质复合体上的吸附和解吸等温线均符合Freundlich方程,随粒径减小,有机-矿质复合体对菲的吸附容量以及吸附的非线性程度都增加.菲在有机-矿质复合体上的解吸表现出明显的滞后现象.高有机质含量的粘粒有机-矿质复合体对菲的吸附和持留能力均较强.      

改性硅藻土对三种有机染料的吸附作用研究

以天然硅藻土分别负载十六烷基三甲基溴化铵(CTMAB)、四甲基溴化铵(TMAB)和壳聚糖,制得一系列改性硅藻土,研究了改性硅藻土吸附水中的阴离子染料(活性红120)、阳离子染料(亚甲基蓝)、酸性染料(玫瑰红B)的适宜条件及吸附机理.结果表明,天然硅藻土对亚甲基蓝、四甲基溴化铵改性硅藻土对玫瑰红B和壳聚糖改性硅藻土对活性红120的饱和吸附量分别为51.15、49.56、56.64mg.L-1,效果良好,可被直接利用.延长吸附时间、增大吸附剂用量、控制溶液的pH值(<6)都能提高改性硅藻土吸附剂的吸附效果;3种染料在各自吸附剂上的平衡吸附量Qe与平衡浓度Ce之间的关系均符合Freundlich等温吸附方程,表明改性硅藻土吸附染料以分配作用、弱的溶质吸收为主.改性剂的引入可以改变硅藻土的表面电性,从而对不同类型染料的吸附能力产生不同影响.     

天然沸石对溶液中氨氮吸附特性的研究

为了探讨天然沸石对NH4 的吸附规律,以浙江缙云出产的粒径为2~3.2mm的天然斜发沸石为实验材料,进行吸附等温线实验和吸附动力学实验。结果表明,实验沸石对NH4 的吸附等温线符合Langmuir公式,且对氨氮吸附量的极限值为1.624mol·kg-1;实验沸石对NH4 的吸附反应符合一级动力学方程,反应速率常数为0.1882h-1。通过监测溶液中各阳离子浓度的变化,可确定沸石晶体内与NH4 进行交换的主要离子为Ca2 和Na ,二者占交换总量的96%以上;在交换反应初期,出现了由于沸石晶体中的离子在固液两相中的再分配所造成的离子交换的不等量现象。     

Microbial degradation of dissolved organic matter (DOM) and its influence on phenanthrene-DOM interactions

Microbial degradation-induced changes in the characteristics of dissolved organic matter (DOM), and the subsequent effects on phenanthrene-DOM interactions were investigated based on the microbial incubation of DOM collected from four different sources for 28 d. Partially biodegraded DOM presented higher specific UV absorbance (SUVA), lower protein-like fluorescence, higher humic-like fluorescence, lower aliphatic carbon fraction, and higher hydrophobic neutral fractions compared to the original DOM. Microbial changes in DOM led to an increase in the isotherm nonlinearity as well as the extent of phenanthrene binding. A negative relationship between SUVA and the Freundlich n values was established for the original and the biodegraded DOM, suggesting that aromatic condensed structures may play important roles in providing nonlinear strong binding sites irrespective of microbial degradation. In contrast, there were two separate slopes of the correlations between the percentage of hydrophobic acid (HoA) fraction and the n values for the original and the biodegraded DOM with a higher slope exhibited for the latter, implying that the microbial utilization of oxygen-containing structures in the HoA fractions may contribute to enhancing the associated isotherm nonlinearity.     

Adsorption behavior of Azo Dye C. I. Acid Red 14 in aqueous solution on surface soils

Azo dyes have received considerable attention because of their association with various human health problems. The aim of the investigation is to determine the adsorption behavior ofazo dyes in aqueous solution on DG06, GSE17200, and GSE17201 soils using C. I. Acid Red 14 （AR14） as example. The experimental results indicate that the Freundlich model expresses the adsorption isotherm better than the Langmuir model and the pseudo-second-order model achieves adsorption of AR14 on the three soils well. Based on the pseudo-second-order model, the adsorption thermodynamic of AR14 on DG06 soil have been studied and the thermodynamics parameter of AGO is determined and AGO value shows the adsorption process of AR14 on DG06 is mainly physical in nature. Furthermore, the effects of temperature, pH and salinity （NaC1） on adsorption have been investigated. The decrease in pH or the increase in salinity enhances the adsorption of AR14 by DG06, GSE17200, and GSE17201.     

Effects of dissolved organic matter from sewage sludge on sorption of tetrabromobisphenol A by soils

Sorption of tetrabromobisphenol A (TBBPA) by soil influences its fate and transport in the environment. The presence of dissolved organic matter (DOM) may complicate the sorption process in soil. The effects of DOM from sewage sludge on TBBPA sorption by three soils were investigated using batch equilibration experiments in the study. DOM was observed to be sorbed on the soils and the isotherms could be fitted by the Langmuir model. The effects of DOM on TBBPA sorption were dependent on the characteristics ...     

Adsorption of Disperse Blue SBL dye by synthesized poorly crystalline hydroxyapatite

The present study has been undertaken to evaluate the adsorption in batch mode of a disperse dye (Disperse Blue SBL) by poorly crystalline hydroxyapatite synthesized by coprecipitation between Ca(NO_3)_2 and (NH_4)_2HPO4 reagents in aqueous solution at room temperature. The adsorption experiments were carried out to investigate the factors that influence the dye uptake by the adsorbent, such as the contact time under agitation, adsorbent dosage, initial dye concentration, solution temperature, and pH. The e...     

Potential nitrogen enrichment of soil and surface water by atmospheric ammonia sorption in intensive livestock production areas

Elevated atmospheric NH₃ levels near intensive livestock operations can add significant N to local agroecosystems. In this study, the potential atmospheric NH₃ sorbed by soil and water was assessed over a 2-year period starting October 2000 in an intensive livestock production area in southern Alberta, Canada. Fifty-two uneven grid sampling sites were selected in the 53,905 ha study area. The sorption rate of atmospheric NH₃ was estimated weekly by exposing distilled water and air-dried soil samples to the atmosphere at the sampling sites. The increases in NH₄–N content in the samples after 1-week exposure was regarded as an index of the atmospheric NH₃ sorbed for that week. The NH₃ sorption rates were highly variable across the 52 sites, with water ranging from 4 to 125 kg ha⁻¹ year⁻¹ with a mean of 22 kg N ha⁻¹ year⁻¹ and soil from 5 to 84 kg N ha⁻¹ year⁻¹ with a mean of 20 kg N ha⁻¹ year⁻¹. Considerable variation in NH₃–N sorption across the study area reflects the effects of size, direction (upwind or downwind) and proximity of nearby livestock operations or other NH₃ sources and operators’ activities around the sampling sites. The NH₃ sorption rate at each site also varied considerably in response to weather conditions. The high rate of NH₃ input poses a direct risk of surface water eutrophication in intensive livestock operation areas. If fertilizer recommendations are not reduced to account for NH₃ sorption by soil, excess N may also contribute to eutrophication through runoff and leaching.     

表面活性剂对2,4-二氯苯酚在黄土中吸附行为的影响

 研究了用阳离子表面活性剂单独改性和用阴、阳离子表面活性剂共同改性的黄土对水中2,4-二氯苯酚的吸附行为以及环境pH值和离子强度的影响.结果表明,天然黄土对2,4-二氯苯酚的等温吸附曲线满足Freundlich方程;改性后的黄土对2,4-二氯苯酚的吸附能力明显增强,吸附率提高2～9倍,且随着阳离子表面活性剂加入量的增多而增大,等温吸附曲线与天然黄土有所不同,并且阴离子表面活性剂的存在会减小相应阳离子表面活性剂改性黄土对2,4-二氯苯酚的吸附;随着pH值的逐渐增大,2,4-二氯苯酚的离子形态逐渐增多不利于改性黄土对2,4-二氯苯酚的吸附,而离子强度对吸附的影响程度却随着pH值的逐渐增大而增强.