有机污染土壤修复表面活性剂淋洗液的回收处理方法

本文介绍了表面活性剂及其在有机污染土壤化学淋洗吸附技术中的应用,具体阐述了从表面活性剂淋洗废水中回收表面活性剂淋洗液的常用方法,并对主要方法进行了评价和比较,显示有机膨润土吸附法为经济有效的回收表面活性剂的方法,并简述了膨润土吸附表面活性剂的机理。     

脱水污泥中聚合物的碱提取及其镉吸附效能研究

市政污水处理厂产生的脱水剩余污泥中含有大量的细菌胞外聚合物、胞内聚合物等大分子有机物,是一种良好的生物吸附剂制备原料。以脱水污泥为原料,采用碱提取的方法,对污泥中胞外聚合物与胞内聚合物进行提取,提取得到聚合物吸附剂,分析了聚合物吸附剂中聚合物浓度、核酸浓度随提取剂中NaOH浓度的变化,考察了聚合物吸附剂对水中镉的等温吸附性能。研究结果表明,当NaOH浓度小于0.5 mol/L时,随着提取剂NaOH浓度的升高,得到的提取液中聚合物浓度、核酸浓度逐渐升高。最佳的提取剂中NaOH浓度为0.3 mol/L,该条件下能够充分实现污泥中聚合物的提取。当NaOH浓度高于0.5 mol/L,聚合物中核酸存在一定程度的分解。聚合物吸附剂对水中Cd2+的吸附符合Langmuir模型,NaOH浓度为0.3 mol/L条件下提取得到的聚合物吸附剂的镉饱和吸附容量最大,达1.022 mmol/g。     

改性小麦秸秆的制备及其对水中亚甲基蓝的吸附性能

用碳酸钾(K2CO3)溶液活化法成功地制备改性小麦秸秆。采用傅里叶红外光谱仪(FT-IR)、扫描电子显微镜(SEM)和静态吸附试验对改性前后样品的组成、形貌和吸附性能进行表征和测定,对比了秸秆改性前后的结构和组成变化。结果表明:改性后小麦秸秆半纤维素被部分溶解,出现了多孔疏松的结构。改性小麦秸秆用量、溶液p H和亚甲基蓝的浓度在一定范围内增大有助于改性小麦秸秆对亚甲基蓝吸附速率的提高,吸附类型符合Langmuir吸附等温方程模型且属于拟二级动力学吸附过程。     

铁锰复合氧化物吸附活性黑染料的性能研究

采用高锰酸钾和硫酸亚铁反应制备铁锰复合氧化物,考察其吸附活性黑染料过程中的影响因素,并比较原位生成的和提前制备的铁锰复合氧化物的吸附性能。结果表明:铁锰复合氧化物对活性黑有较强的吸附能力,吸附过滤之后的去除率较高;染料废水中的硫酸根离子会降低去除率,而氯离子则无明显影响;染料废水的pH值对去除效果的影响较小;原位生成的铁锰复合氧化物的吸附容量大于预制的铁锰复合氧化物固体。通过傅里叶—红外光谱(FTIR)表征分析,推测出铁锰复合氧化物中丰富的表面羟基(Mn-OH、FeOOH官能团等)在吸附过程中起到了重要作用。     

壳聚糖对Cu~(2+)的吸附与解吸

研究了溶液pH值、Cu2+初始浓度、吸附剂投加量、吸附时间及温度对壳聚糖吸附Cu2+的影响,并对达到吸附平衡的壳聚糖进行了解吸研究。结果表明,壳聚糖对Cu2+的吸附量随pH值的升高而增大,在pH值为4.7时,基本达到吸附平衡;吸附过程同时符合Langmuir模型和Freundlich模型,最大吸附量为142.9 mg/g;与拟一级动力学模型相比,拟二级动力学模型可以更好地描述吸附过程;吸附剂最佳投加量为1 g/L。用0.03 mol/L H2SO4溶液做脱附液,搅拌10 min,脱附率为73.4%;经过4次脱附-吸附循环,壳聚糖平衡吸附量变化不大,具有良好的重复使用性。     

Comparison of quartz sand, anthracite, shale and biological ceramsite for adsorptive removal of phosphorus from aqueous solution

The choice of substrates with high phosphorus adsorption capacity is vital for sustainable phosphorus removal from waste water in constructed wetlands. In this study, four substrates were used： quartz sand, anthracite, shale and biological ceramsite. These substrate samples were characterized by X- ray diffractometry and scanning electron microscopy studies for their mineral components （chemical components） and surface characteristics. The dynamic experimental results revealed the following ranking order for total phosphorus （TP） removal efficiency： anthracite 〉 biological ceramsite 〉 shale 〉 quartz sand. The adsorptive removal capacities for TP using anthracite, biological ceramsite, shale and quartz sand were 85.87, 81.44, 59.65, and 55.98 mg/kg, respectively. Phosphorus desorption was also studied to analyze the substrates＇ adsorption efficiency in wastewater treatment as well as the substrates＇ ability to be reused for treatment. It was noted that the removal performance for the different forms of phosphorus was dependent on the nature of the substrate and the adsorption mechanism. A comparative analysis showed that the removal of particulate phosphorus was much easier using shale. Whereas anthracite had the highest soluble reactive phosphorus （SRP） adsorptive capacity, biological ceramsite had the highest dissolved organic phosphorus （DOP） removal capacity. Phosphorus removal by shale and biological ceramsite was mainly through chemical adsorption, precipitation or biological adsorption. On the other hand, phosphorus removal through physical adsorption （electrostatic attraction or ion exchange） was dominant in anthracite and quartz sand.     

Biosorption mechanisms involved in immobilization of soil Pb by Bacillus subtilis DBM in a multimetal-contaminated soil

Mechanisms of soil Pb immobilization by Bacillus subtilis DBM, a bacterial strain isolated from a heavy-metal-contaminated soil, were investigated. Adsorption and desorption experiments with living bacterial cells as well as dead cells revealed that both extracellular adsorption and intracellular accumulation were involved in the Pb2＋removal from the liquid phase. Of the sequestered Pb（II）, 8.5% was held by physical entrapment within the cell wall, 43.3% was held by ion-exchange, 9.7% was complexed with cell surface functional groups or precipitated on the cell surface, and 38.5% was intracellularly accumulated.Complexation of Pb2＋with carboxyl, hydroxyl, carbonyl, amido, and phosphate groups was demonstrated by Fourier transform infrared spectroscopic analysis. Precipitates of Pb5（PO4）3OH, Pb5（PO4）3Cl and Pb10（PO4）6（OH）2that formed on the cell surface during the biosorption process were identified by X-ray diffraction analysis. Transmission electron microscopy–energy dispersive spectroscopic analysis confirmed the presence of the Pb（II）precipitates and that Pb（II） could be sequestered both extracellularly and intracellularly.Incubation with B. subtilis DBM significantly decreased the amount of the weak-acid-soluble Pb fraction in a heavy-metal-contaminated soil, resulting in a reduction in Pb bioavailability, but increased the amount of its organic-matter-bound fraction by 71%. The ability of B.subtilis DBM to reduce the bioavailability of soil Pb makes it potentially useful for bacteria-assisted phytostabilization of multi-heavy-metal-contaminated soil.     

Removal of phosphate from wastewater using alkaline residue

Alkaline residue(AR) was found to be an efficient adsorbent for phosphate removal from wastewater. The kinetic and equilibrium of phosphate removal were investigated to evaluate the performance of modified alkaline residue. After treatment by NaOH(AR-NaOH), removal performance was significantly improved, while removal performance was almost completely lost after treatment by HCl(AR-HCl). The kinetics of the removal process by all adsorbents was well characterized by the pseudo second-order model. The Langmuir model exhibited the best correlation for AR-HCl, while AR was effectively described by Freundlich model. Both models were well fitted to AR-NaOH. The maximum adsorption capacities calculated from Langmuir equation were in following manner: AR-NaOH AR AR-HCl. Phosphate removal by alkaline residue was pH dependent process. Mechanisms for phosphate removal mainly involved adsorption and precipitation, varied with equilibrium pH of solution. For AR-HCl, the acid equilibrium pH( 6.0) was unfavorable for the formation of Ca-P precipitate, with adsorption as the key mechanism for phosphate removal. In contrast, for AR and ARNaOH, precipitation was the dominant mechanism for phosphate removal, due to the incrase on pH( 8.0) after phosphate removal. The results of both XRD and SEM analysis confirmed CaHPO4·2H2O formation after phosphate removal by AR and AR-NaOH.     

有机氯农药在农田土壤中的吸附解吸特征

选取3种不同深度的农田土壤作为吸附剂,采用批量实验方法,研究了有机氯农药p,p’-DDD和γ-HCH在等温条件下的吸附解吸行为。结果表明,p,p’-DDD和γ-HCH的吸附解吸曲线均可用Freundlich模型较好拟合,并且在表层土壤中表现为线性,而在深部土壤中表现为非线性,表明深部土壤的组成可能更加复杂和不均匀。3种土壤对p,p’-DDD的吸附容量参数Kf值与总有机碳(TOC)含量大小关系一致,而γ-HCH的吸附Kf值却与DOM含量显著正相关。p,p’-DDD和γ-HCH在所有样品中的解吸均有不同程度的滞后现象,其中p,p’-DDD的解吸主要受土壤中有机质含量的影响,TOC含量越低滞后性越不明显,而γ-HCH的解吸滞后性比较复杂。     

凹凸棒石纤维复合气凝胶吸附水体中TPH吸附特性

以水体中总石油烃(total petroleum hydrocarbons,TPH)为目标污染物,采用凹凸棒石复合二氧化硅气凝胶进行净化石油类污染水体研究,主要考察复合气凝胶使用量及环境要素对去除水体中TPH的影响。研究结果表明:凹凸棒石纤维复合气凝胶与污染水体的质量比为1:60,对TPH的去除率随温度的升高而降低,受pH变化影响较小;当NaCl浓度在0~100 g/L,MgCl2浓度在0~2.5 g/L时,复合气凝胶对水体中TPH的去除率几乎不受盐度的影响;Fe3+、Mn2+、NH4+、NO3-均能促进复合气凝胶对TPH的去除,但受其浓度变化影响较小,同时,凹凸棒石纤维复合气凝胶对上述离子也有微弱的去除作用。研究成果为凹凸棒石复合气凝胶在实际石油类污染水体中的应用提供了科学可靠的数据支撑。