抗生素在沉积物中的吸附机制及其影响因素

抗生素作为医疗业和农业使用量最大的药物之一,由于其本身的特性,很容易进入沉积物一水环境中。抗生素在沉积物中的吸附过程是影响抗生素的反应活性、可移动性、持久性及生物可利用性的关键过程。本文选择四环素类、喹诺酮类、磺胺类和大环内酯类4类常用抗生素,在总结了这4类抗生素在湖泊沉积物中污染状况的基础上,分析了抗生素在沉积物中的吸附机制,并归纳论述了pH值、盐度、重金属离子、表面活性剂以及水动力条件对其在沉积物上吸附的影响机制。     

土壤和沉积物对多环芳烃吸附作用的研究进展

多环芳烃在土壤和沉积物上的吸附作用是影响其持留、分布、迁移转化及最终归趋的关键过程。本文阐述了土壤和沉积物对多环芳烃的吸附作用机理,分析了其影响因素及吸附作用对其他降解过程的影响,并探讨了所存在的主要问题及发展趋势。土壤/沉积物是一个复杂的多介质多界面体系,具有复杂的吸附活性中心,多环芳烃在其上的吸附是矿物成分和有机物质共同作用的结果而非单一的表面吸附过程或分配过程,因此形成了各式各样的吸附等温线。在吸附过程中,土壤和沉积物的粒度、有机质含量与组成、温度、pH以及被吸附多环芳烃的性质均是重要的影响因素。在多环芳烃吸附过程中,如何结合其定量结构性质、有机无机复合体的界面结构以及环境化学特征认识吸附机理是今后研究的一个趋势。     

乌鲁木齐东道海子湖岸表层沉积物对氨氮的等温吸附特征研究

乌鲁木齐东道海子是乌鲁木齐河与头屯河下游的尾闾湖泊,东道海子水体氮素主要受放牧和采樵对荒漠植被破坏和农业排碱影响。而湖泊沉积物是湖泊水体污染物源汇关系中的重要介质,这些沉积物可能成为污染物运移转化的载体。本文通过野外采样与实验室模拟的方法,研究东道海子湖岸沉积物对氨氮的吸附特征。在吸附动力学特征中,准二级反应动力学达到极显著水平,沉积物Q_(max)变化范围在179~450mg/kg之间,平均值为238mg/kg,沉积物对氨氮的最终平衡时间在2h,均遵循先快后慢的规律,在前30min的吸附量基本已经与最终的吸附平衡浓度差别不大。在吸附热力学特征中,在低浓度条件下,对吸附浓度与吸附量进行拟合,Henry模型的拟合效果基本达到了显著水平,东道海子沉积物对氨氮吸附规律适用于低浓度吸附氨氮,在低浓度下Langmuir和Freundlich模型对数据没有达到显著水平,拟合效果不如Henry模型。     

干旱半干旱地区湖泊沉积物对Cu2+的吸附-解吸研究

吸附-解吸是重金属在沉积物中迁移转化的重要过程。本文研究干旱半干旱地区湖泊———乌梁素海不同区域沉积物对Cu2+的吸附-解吸过程。结果表明,吸附过程中,pH值逐渐降低;沉积物TOC含量越高,其对Cu2+的吸附能力也越强;生活污水和工业废水影响的S1样点及受农田退水影响的S2样点对Cu2+的吸附量相对较低,而相对较洁净的S3和S4样点具有较高的Cu2+吸附量。4个样点吸附量能力大小为S3>S4>S2>S1。解吸实验显示,沉积物吸附的Cu2+大部分都不能被解吸。试验结果符合Langmuir和Freundlich等温吸附方程,Langmuir方程的拟合效果要好于Freundlich方程,Langmuir方程拟合的饱和吸附量分别为3.31 mg/g、4.84 mg/g、8.39 mg/g和7.75 mg/g。     

调理吸附稳定法处理低含油沉积物

通过吸附、分散、固定等协同作用,可将沉积物中的有机物、重金属等污染物转化为不易溶解、不易迁移的状态。针对含油量5%、含水量60%的低含油、低含水污水池沉积物,调理吸附稳定技术可实现大规模、快速的处理。应用该技术处理孤岛某污水池底沉积物约8×103 m3,药剂投加量为沉积物质量的10%,强化养护时间≥3d,处理后沉积物含油量2%,浸出液的氨氮、pH值及石油类达到GB 8978—1996《污水综合排放标准》一级标准,COD去除率约80%。     

有机质在水体富营养化过程中的作用及其对有机农业管理的启示意义

富营养化是指一种过程，在这一过程中，植物营养元素磷的增加与氧的锐减将导致湖泊生态系统发生一系列剧变。富营养化亦可被定义为生态系统中有机质输入速率增加的过程。从上述两方面的意义上讲，有机质的分解必然伴随生物可利用性磷的再生，从而对富营养化过程产生有效的反馈。本文扼要概述了上述反馈途径及其生态风险，即水体沉积物磷释放的原始驱动力来自有机质的分解，其主要途径包括自身的矿化与厌氧状态促成之后磷酸盐的解吸附。微生物群落将依有机质的数量和性质在分解过程的不同阶段发生明显变化，从而形成因时因地而异的分解速率与还原力，二者共同促进沉积物磷的释放，因高分解速率伴随高缺氧程度，且源于沉积物之长期库存，磷酸盐的解吸附量并非简单正比于有机质含量，而可能远大于此，换言之，有机质的大量输入与沉积可能导致生物有效性磷的净增，水体富营养化程度将因此而以正反馈的形式加剧。在倡导和推行有机农业的过程中，应充分注意并严格控制土壤有机质的流失。     

黄河河口磷酸盐的缓冲作用探讨

河口区,磷酸盐浓度在很宽的盐度范围变化很小,甚至不变,对此提出悬浮物和沉积物对磷有缓冲作用。我们认为解吸吸附反应是其缓冲机制,从而进行了大量的模拟实验,并加以系统的分析。     

静态条件下持续时间对底泥中有机氯农药释放的影响

有机氯农药是广泛存在于环境中一类有机污染物,溶解度低,疏水性强,容易被颗粒物吸附,并随其在沉积物中积累,蓄积在沉积物中的有机氯农药在沉积物的再悬浮过程中会重新释放进入水体,造成二次污染。为了考察悬浮持续时间对沉积物中有机氟农药的释放的影响,采用沉积物释放模拟装置在60天内对微山湖沉积物中有机氯农药释放进行研究。结果表明,随着扰动时间的延长,上覆水中有机氯农药的含量在0—20天内增长很快,在60天左右含量趋于到稳定。不同的有机氟农药在扰动条件下,释放的速率和浓度是不一样的,其中水溶性大的农药更易向水体再次释放。     

自然水体多相体系中重金属离子在生物膜上的竞争吸附

在实验室中模拟松花江水体,研究了在表层沉积物和悬浮颗粒物存在的条件下,铅、镉和铜3种重金属离子在生物膜上竞争吸附的热力学规律。对重金属在自然水体多相体系中的迁移规律进行了探究,以期为重金属污染的治理提供理论依据。     

针铁矿吸附去除水中锑特性研究

针铁矿是土壤和沉积物中的重要成分,能够有效地影响环境中有毒物质的迁移和转化。实验以水中Sb(V)为目标污染物,以针铁矿为吸附剂,分析吸附的影响因素和吸附动力学,探讨在不同p H、离子强度、磷酸根浓度条件下针铁矿对Sb(V)的吸附特性。结果表明,准二级动力学方程和Elovich模型能够较好地描述Sb(V)在针铁矿上的吸附动力学特性;针铁矿对Sb(V)吸附性能随p H值的增大而减小,随离子强度的升高而降低;磷酸根与Sb(V)在针铁矿表面发生竞争吸附,加速Sb(V)向水体中的迁移。实验结果表明,针铁矿吸附去除水中锑(Ⅴ)领域有实际应用的潜力。     

磁性活性炭吸附苯酚的初步研究

本文研究了磁性活性炭对苯酚的吸附性能;探讨了Cd2＋对苯酚在磁性活性炭上吸附的影响。目的是对磁性活性炭进行研究,以及为在实际废水中吸附处理苯酚提供参考。结果表明,磁性活性炭对苯酚的吸附过程符合拟二级动力学模型,R2为0.9935;与Freundlich吸附模型相比,Langmuir吸附模型能更好地描述磁性活性炭对苯酚的吸附行为;在不影响去除率的情况下,Cd2＋的存在使苯酚吸附处理最佳浓度由30 mg/L增大至50 mg/L;同时,Cd2＋对磁性活性炭和活性炭吸附苯酚分别具有促进和抑制作用。针对苯酚的吸附去除率,当无Cd2＋时,磁性活性炭的比活性炭的低10.65%～20.2%;当有Cd2＋时,磁性活性炭的比活性炭的高0.3%～7.71%。     

壳聚糖吸附处理废水的研究进展

壳聚糖吸附处理废水的研究包括其对废水吸附性能和吸附机理的研究两个方面。壳聚糖表现出了良好的吸附废水中重金属离子、染料分子和其它易引起变异物质的能力;壳聚糖对金属离子和染料的吸附机理模型研究理论意义重大,它将进一步推动壳聚糖的实际工程应用。     

Removal of phenol from aqueous solutions by adsorption

Experiments have been conducted to examine the liquid-phase adsorption of phenol from water by silica gel, HiSiv 3000, activated alumina, activated carbon, Filtrasorb-400, and HiSiv 1000. Experiments were carried out for the analysis of adsorption equilibrium capacities and kinetics. The adsorption isotherm model of the Langmuir-Freundlich type was the best to describe adsorption equilibrium data for phenol for the adsorbents studied. Results of kinetic experiments indicated that HiSiv 1000 had the highest rate of adsorption among the adsorbents studied and therefore more detailed studies were carried out with this adsorbent. The influence of particle size, temperature, and thermal regeneration on adsorption of phenol by HiSiv 1000 was evaluated. From particle size experiments it appeared that adsorption capacity of HiSiv 1000 did not change by changing the particle size, but the rate of adsorption decreased considerably by increasing the particle size. The effect of temperature on adsorption was studied by determining equilibrium isotherms for HiSiv 1000 at 25, 40, and 55 degrees C. The results showed that adsorption capacity decreased with increasing temperature. Thermal regeneration of HiSiv 1000 was performed at 360 degrees C. It was observed that adsorption capacity of HiSiv 1000 did not change after 14 regeneration cycles. Equilibrium experiments showed that the adsorption capacities of activated carbon and Filtrasorb-400 were several times higher than that of HiSiv 1000.     

树脂固定床吸附含酚废水预测模型研究

针对应用于实际工业化的树脂固定床吸附研究较少,而与之相关的固定床吸附穿透曲线可以用来确定固定床吸附操作参数,为固定床的设计和实际操作提供指导。通过对恒定波振荡理论和吸附等温方程的联合,来预测固定床吸附穿透曲线;并研究了不同操作条件对大孔弱碱树脂吸附对硝基酚穿透曲线预测模型的影响。以期望为树脂固定床的设计和实际工业应用产生指导意义。     

分子印迹硅纳米改性氧化石墨烯复合材料的制备及其对双酚A的吸附研究

制备了分子印迹硅纳米-氧化石墨烯复合吸附材料,并研究了复合材料对双酚A(Bisphenol A,BPA)的吸附性能.实验结果表明:复合吸附材料对BPA的吸附在35min内达到吸附平衡,Langmuir等温线模型得出最大吸附容量约为338.3mg/g;相对于BPA的结构类似物,对BPA具有良好的选择吸附性能;在溶液pH接...     

LDO处理垃圾渗滤液中氮的实验研究

研究了复合金属氧化物（LDO）用于处理垃圾渗滤液中氮的可行性,并与传统吸附剂粉末活性炭（PAC）进行了比较,考察了投加量、振荡速度、吸附时间、吸附温度、pH等因素对处理效果的影响。结果表明,当垃圾渗滤液中总氮浓度为561mg/L、LDO投加量为6g/L、振荡速度为170r/min、吸附时间为60min、温度为25℃、pH值为11时,LDO对总氮的吸附量最高,达到41mg/g。在相同条件下,LDO对总氮的吸附量是PAC的2.5—3.5倍。     

Adsorption of arsenate and arsenite on ferrihydrite in the presence and absence of dissolved organic carbon

The adsorption of As(V) and As(III) on synthetic two-line ferrihydrite in the presence and absence of a peat humic acid (HAp), Suwannee River fulvic acid (FA), or citric acid (CA) was investigated. Previous work with goethite has demonstrated the ability of dissolved organic carbon (DOC) to decrease As(V) and As(III) adsorption. The results obtained demonstrate that As(V) adsorption on ferrihydrite was decreased only in the presence of CA. Arsenate decreased the adsorption of all organic acids except HAp. Both FA and CA reduced As(III) adsorption on ferrihydrite, while HAp had no effect. Fulvic and citric acid adsorption on ferrihydrite was decreased in the presence of As(III); however, FA and CA adsorption increased at lower pH, which was consistent with decreased As(III) adsorption. Peat humic acid did not decrease As(III) adsorption, and we believe that the adsorption process of HAp and As(III) and As(V) on ferrihydrite are independent of each other. Previously, we observed that As(V) adsorption on goethite decreased in the presence of HAp > FA > CA, while As(III) adsorption on goethite was decreased similarly to that on ferrihydrite in the presence of CA > FA approximately HAp, yet As(III) adsorption on ferrihydrite was greater than on goethite. The observed differences between this study and the earlier study on goethite are believed to be an intricate function of ferrihydrite's surface characteristics, which affect the mechanisms of adsorption and hence the affinity of organic acids such as HAp, FA, and CA for the ferrihydrite surface. As such, the adsorption of DOCs to ferrihydrite are assumed to be less favorable and to occur with a fewer number of ligands, resulting in lower surface coverage of weaker bond strength.     

Comparison and application of different component municipal solid wastes based carbon on adsorption of carbon dioxide

The prepared different components municipal solid wastes based carbons were used to investigate the adsorption of CO₂. The optimum conditions for CO₂ adsorption were investigated firstly. And then, the CO₂ adsorption performance of different components based carbon adsorbents were compared with each other under the optimum parameters. The results illustrated that the triple components (pinewood, acrylic textile, and tire) based carbon exhibited the best adsorption performance, which is 1.522 mmol/g and its physical prosperity was also conducted to interpret the adsorption mechanism. Besides, to further approach to the actual gas, the influence of additional O₂ and SO₂ on CO₂ adsorption properties of ternary-component-based carbon was investigated. The results illustrate that O₂ concentration exerts little effect on adsorption capacity. SO₂ plays the dominated role in the competitive adsorption effect.     

环境因子对长江宜宾段底泥吸附磷的影响

本文主要研究模拟长江底泥对富营养化水体磷的吸附,分析环境因子对底泥吸附磷的影响。结果显示：（1）在25℃时,底泥对磷的吸附在碱性条件时的吸附速率小于酸性和中性条件,中性条件下的吸附速率最大;（2）在控制上覆水温度时,温度越高底泥对磷的吸附量越小,20℃时底泥的吸附量是30℃吸附量的1.5倍;（3）上覆水中溶解氧的浓度越高,吸附速率越高。     

Adsorption of carbon dioxide on alkali-modified zeolite 13X adsorbents

Shaped zeolite 13X adsorbent with kaolin as binder was hydrothermally modified in sodium hydroxide solution to improve its adsorption performance. The characterization of the product by XRD, N₂ adsorption–desorption and water vapour adsorption displayed that kaolin component in zeolite adsorbent can be converted into zeolite during the alkali treatment, resulting in the modified adsorbent consisting entirely of effectual adsorption composition. Compared with the unmodified adsorbent, the modified adsorbent exhibited higher adsorption capacity and uptake rate for carbon dioxide, because of the increase of effective adsorption surface and the decrease of diffusion resistance owing to conversion of kaolin binder into zeolite. The model parameters of isotherms and the isosteric heats calculated by the Clausius–Clapeyron equation for CO₂ adsorption showed the stronger interaction of adsorbate–adsorbent and the higher degree of heterogeneity of adsorption centers in modified than unmodified adsorbents.