人居生活废弃物生物黑炭对水溶液中Cd2+的吸附研究

以人居生活废弃物生物黑炭为材料,探讨生物黑炭对Cd2+的吸附动力学及热力学特性,通过平衡吸附法研究吸附时间、Cd2+初始质量浓度、吸附剂投加量、溶液pH值以及黑炭粒径对Cd2+吸附率的影响.结果表明,吸附时间为2h时基本达到吸附平衡,准二级动力学方程能很好地描述生物黑炭对Cd2+的吸附过程.Langmuir模型能较好地描述生物黑炭对Cd2+的等温吸附过程,根据该模型模拟得到25℃条件下Cd2+最大吸附量为6.22mg·g-1.Cd2+去除率随生物黑炭投加量的增加而增大;生物黑炭对Cd2+吸附量随其粒径减小而增大;溶液初始pH值为4.0～7.5时,pH值变化对Cd2+吸附量的影响不显著.采用人居生活废弃物生物黑炭去除水溶液中Cd2+时,控制溶液Cd2+初始质量浓度30mg·L-1,粒径小于0.25 mm,投加水平8g·L-1,反应温度25℃,反应时间1～2h,Cd2+去除率可达80％.人居生活废弃物生物黑炭可以作为去除污染水体中Cd2+的吸附剂.     

EGTA/TSP联合修复模拟重金属污染黄棕壤及其环境风险评价

针对淋洗可能导致土壤残留重金属活化问题,研究淋洗/钝化联合修复对重金属污染土壤风险的削减作用。以乙二醇双(2-氨基乙基醚)四乙酸[ethylenebis (oxyethylenenitrilo) tetraacetic acid,EGTA]为淋洗剂,以重过磷酸钙(triple super phosphate,TSP)为钝化剂,研究了EGTA投加量、液固比、淋洗时间和TSP投加量等对模拟重金属污染黄棕壤中Cu、Zn、Pb和Cd 4种重金属洗脱率和浸出浓度的影响,通过响应面法设计多因素实验,拟合了土壤重金属环境风险削减率与EGTA投加量、液固比及TSP投加量之间的关系,采用涵盖土壤重金属含量、浸出浓度和毒性的土壤重金属环境风险评价方法对修复效果进行评价。结果表明,EGTA对Cu和Cd的洗脱率较高,可显著降低Zn和Cd浸出浓度。增加淋洗时间有助于提高Cu、Zn和Cd洗脱率并降低其浸出浓度,但提高了Pb浸出浓度。随着液固比的增加,Zn和Pb洗脱率呈上升趋势,Cd洗脱率呈下降趋势,Cu洗脱率先提高后下降;Cu、Zn和Cd浸出浓度呈下降趋势,而Pb浸出浓度呈上升趋势。TSP钝化大幅度削减了Pb浸出浓度。总环境风险削减率(β)与EGTA投加量、液固比及TSP投加量呈二次方关系,当EGTA投加量为1.0 g·L~(-1),液固比为10,TSP投加量w为2%时,β为62.80%,与验证实验结果相近,表明模型具有较好的模拟和预测能力。提高EGTA投加量和液固比可以大幅度降低Cu、Zn和Cd的环境风险,TSP钝化处理对Pb环境风险的削减作用较好,EGTA投加量与液固比以及EGTA投加量与TSP投加量对β表现为协同作用。     

高锰酸钾改性活性炭的制备、表征及其吸附Pb2＋的特性

为提高活性炭对废水中Pb2＋的去除效率,采用不同浓度的KMnO4溶液对颗粒活性炭进行静置氧化/冷凝回流改性;利用BET测定了改性活性炭比表面积,并采用BET、SEM、FTIR和XRD等方法对其进行了表征;考察了吸附时间、投加量、pH值、温度对吸附Pb2＋的影响。结果表明,Pb2＋浓度为40 mg/L,在3 g/L的投加量下,0.01KMnO4-GAC和0.03KMnO4-GAC对Pb2＋的吸附去除率分别达到了92%和94%,是GAC对Pb2＋吸附去除率的1.84和1.88倍;在吸附剂3 g/L的投加量下,180 min基本达到吸附平衡;3种吸附剂对Pb2＋的吸附,随着pH值的降低而减少;而温度对吸附Pb2＋的影响相对较小。     

不同作物原料热裂解生物质炭对溶液中Cd2+和Pb2+的吸附特性

选择由小麦秸秆、玉米秸秆和花生壳经350~500℃热裂解制成的生物质炭,研究生物黑炭对水溶液中Cd2+和Pb2+的吸附特性,分析了pH值、吸附时间、溶液初始质量浓度、生物质炭粒径和投加量对吸附效果的影响。结果表明:生物质炭对Cd2+和Pb2+的吸附约10 min即达平衡;3种生物质炭对Cd2+和Pb2+的等温吸附均可用Langmuir方程和Freundlich方程拟合,玉米秸秆炭对Cd2+和Pb2+的最大吸附量远大于小麦秸秆炭和花生壳炭;在生物黑炭投加量为150 mg(6 g.L-1)时,3种生物黑炭对溶液Cd2+的去除率均在90%以上,玉米秸秆炭对溶液Pb2+的去除率达90.30%,而小麦秸秆炭和花生壳炭的去除率仅为52%和47%,玉米秸秆炭有望成为处理重金属污染废水的新型吸附材料。     

壳聚糖活性污泥复合吸附剂处理铅、镉废水研究

研究了壳聚糖活性污泥复合吸附剂(SCTS)对废水中Pb~(2+)和Cd~(2+)的吸附性能,通过单因素试验分析了温度、SCTS投加量、pH值、搅拌转速和重金属离子浓度对SCTS吸附性能的影响,正交试验确定了影响因素的主次顺序及最优组合水平。结果表明:影响SCTS吸附废水中Pb~(2+)的因素从大到小依次为pH值、SCTS投加量、Pb~(2+)初始浓度和搅拌转速,吸附Pb~(2+)的最优组合为pH值=2、SCTS投加量为10 g· L~(-1)、ρ(Pb~(2+))初始值为50 mg· L~(-1)、搅拌转速130 r·min-1,Pb~(2+)去除率达95.76%。影响SCTS吸附废水中Cd~(2+)的因素作用力大小依次为pH值、Cd~(2+)初始浓度、转速和SCTS投加量,吸附Cd~(2+)的最优组合为pH值2、SCTS投加量2.5 g· L~(-1)、ρ(Cd~(2+))初始值60 mg· L~(-1)、转速130 r·min-1,此时Cd~(2+)的去除率为96.08%。     

人居生活废弃物生物黑炭对水溶液中Cd^2＋的吸附研究

以人居生活废弃物生物黑炭为材料,探讨生物黑炭对Cd^2＋的吸附动力学及热力学特性,通过平衡吸附法研究吸附时间、Cd^2＋初始质量浓度、吸附剂投加量、溶液pH值以及黑炭粒径对Cd^2＋吸附率的影响。结果表明,吸附时间为2h时基本达到吸附平衡,准二级动力学方程能很好地描述生物黑炭对Cd^2＋的吸附过程。Langmuir模型能较好地描述生物黑炭对Cd^2＋的等温吸附过程,根据该模型模拟得到25℃条件下Cd^2＋最大吸附量为6．22 mg·g^-1 Cd^2＋去除率随生物黑炭投加量的增加而增大;生物黑炭对Cd^2＋吸附量随其粒径减小而增大;溶液初始pH值为4．0-7．5时,pH值变化对Cd2’吸附量的影响不显著。采用人居生活废弃物生物黑炭去除水溶液中Cd^2＋时,控制溶液Cd^2＋初始质量浓度30mg·L^-1,粒径小于0．25mm,投加水平8g·L^-1,反应温度25℃,反应时间1-2h,Cd^2＋去除率可达80％。人居生活废弃物生物黑炭可以作为去除污染水体中Cd^2＋的吸附剂。     

间歇反应器内污泥衍生吸附剂去除水溶液中镉、镍离子

利用城市污水厂的污泥化学活化法热解产生的吸附剂 ,在间歇反应器内对水溶液中Cd2 和Ni2 离子进行吸附性能的研究 .考察了溶液的pH值、接触时间、吸附剂的投加量及吸附质初始浓度对吸附效果的影响 ,结果表明 ,Cd2 ,Ni2 离子吸附达到平衡时的接触时间为 60min,pH值为 5 5— 6 0 ,溶液的初始浓度为 40mg·l- 1 和 30mg·l- 1 ,吸附剂的投加量不少于 1 0g·l- 1 和 2 0g·l- 1 .     

不同作物原料热裂解生物质炭对溶液中Cd2＋和Pb2＋的吸附特性

选择由小麦秸秆、玉米秸秆和花生壳经350-500℃热裂解制成的生物质炭,研究生物黑炭对水溶液中Cd2＋和Pb2＋的吸附特性,分析了pH值、吸附时间、溶液初始质量浓度、生物质炭粒径和投加量对吸附效果的影响。结果表明：生物质炭对Cd2＋和Pb2＋的吸附约10 min即达平衡;3种生物质炭对Cd2＋和Pb2＋的等温吸附均可用Langmuir方程和Freundlich方程拟合,玉米秸秆炭对Cd2＋和Pb2＋的最大吸附量远大于小麦秸秆炭和花生壳炭;在生物黑炭投加量为150 mg（6 g.L-1）时,3种生物黑炭对溶液Cd2＋的去除率均在90%以上,玉米秸秆炭对溶液Pb2＋的去除率达90.30%,而小麦秸秆炭和花生壳炭的去除率仅为52%和47%,玉米秸秆炭有望成为处理重金属污染废水的新型吸附材料。     

纳米铁去除水体中镉的反应动力学、吸附平衡和影响因素

镉(Cd)具有致癌、无生物降解性和生物累积性特点,日益严重的镉环境污染问题已引起人们广泛关注。纳米铁是一种能有效去除多种有机和无机污染物的吸附剂。采用批实验方式研究纳米铁(nZVI)吸附镉的动力学和去除效率,可为深入研究纳米铁在重金属Cd污染修复的可行性方面提供理论支撑。利用透射电镜和扫描电镜等对实验室合成的纳米铁颗粒进行了表征,结果表明,纳米铁颗粒平均BET比表面积为49.16 m~2·g~(-1),粒径为20—40 nm。探讨了多种影响因素对纳米铁颗粒吸附镉的影响,如溶液pH、反应时间、初始浓度和纳米铁投加量。同时研究了Cd2+的准一级和二级反应动力学,应用Freundlich、Langmuir和Temkin等温吸附模型进行平衡吸附研究。结果表明,纳米铁对水溶液中镉吸附是化学吸附。颗粒内扩散模型表明粒内扩散不是控制反应速率的唯一步骤。吸附动力学研究表明,nZVI吸附Cd2+过程符合准二级反应动力学模型。平衡吸附数据能够很好地符合Langmuir、Freundlich和Temkin模型(r~20.95)。通过Langmuir模型获得室温下吸附剂单层Cd吸附量为256.4 mg·g~(-1)。在pH 7和(25±1)℃条件下,纳米铁能够有效吸附镉。当nZVI颗粒投加量为1.00 g·L~(-1),Cd~(2+)初始质量浓度为74.51 mg·L~(-1)时,24 h之内,Cd2+去除率达到98.62%。纳米铁可作为一种用于水体镉去除的非常有应用前景的材料。     

硅藻土和膨润土对重金属离子Zn~（2＋）、Pb~（2＋）及Cd~（2＋）的吸附特性

以硅藻土和膨润土作为吸附剂,考察微波加热与否条件下,不同吸附时间、不同吸附剂用量和不同pH值对硅藻土和膨润土分别吸附Zn2＋、Pb2＋、Cd2＋重金属离子的影响.实验结果表明,硅藻土和膨润土对3种重金属离子均有很好的吸附效果,吸附时间对去除率影响不大,数分钟即可达到吸附平衡,微波加热、增加吸附剂用量和提高pH值,都有利于提高3种重金属离子的去除率.     

Removal of chromium(VI) by ZnCl2 activated coir pith carbon

The adsorption of chromium(VI) onto ZnCl₂ activated carbon developed from coir pith was investigated to assess the possible use of this adsorbent. The influence of contact time, adsorbent dose, Cr(VI) concentration, pH and temperature were investigated. The two theoretical adsorption isotherms, namely, Langmuir and Freundlich were used to describe the experimental results. The Langmuir adsorption capacity (Q ₀) was found to be 120.5?mg Cr(VI) per g of the adsorbent. The adsorption followed the second-order kinetics and was found to be maximum at pH 2.0. The pH effect and the desorption studies showed that ion exchange mechanism might be involved in the adsorption process. The effects of foreign ions such as chloride, sulphate, phosphate, selenite, molybdate, nitrate and perchlorate on the removal of Cr(VI) have been investigated. The removal of Cr(VI) from synthetic ground water was also tested. The results show that ZnCl₂ activated coir pith carbon is effective for the removal of Cr(VI) from water.     

Removal of congo red dye from water using carbon slurry waste

A cheaper adsorbent has been prepared from carbon slurry waste obtained from National Fertilizer Limited (NFL), Panipat and investigated for the removal of congo red, an anionic dye. Its adsorption on prepared carbonaceous adsorbent was studied as a function of contact time, concentration and temperature. The results have shown that carbonaceous adsorbent adsorbs dye to a sufficient extent (272 mg g^-1). A comparative study of adsorption results with those obtained on activated charcoal shows that the carbonaceous adsorbent is ~95% efficient as compared to activated charcoal. Thus, it can be fruitfully used for the removal of dyes from wastewaters.This work has been presented at the National Symposium on Biochemical Sciences: Health and Environmental Aspects (BSHEA—2003), Agra, India (2003).     

固液相离子吸附体系中吸附剂浓度效应与Langmuir方程的适用性

以蛭石吸附Zn2 和Cd2 为例,探讨Langmuir方程在固液相离子吸附体系中的适用性,结果表明:传统吸附等温线随吸附剂浓度W0增大而下降,吸附量qe不仅仅由液相平衡浓度Ce所决定,而是Ce和W0两个变量的函数;以Langmuir方程的线性形式对实验数据进行拟合,在给定吸附剂浓度水平下的实验数据与Langmuir方程拟合的相关性很好,但方程中的两个参数随吸附剂浓度增大而降低而且差异显著,表明Langmuir方程仅适用于给定吸附剂浓度的体系,采用单一参数的Langmuir方程难以准确描述试验检测范围内Zn2 和Cd2 的吸附规律.     

Removing carbonyl sulfide with metal-modified activated carbon

A Cu-Co-K/activated carbon (AC) adsorbent has been developed for the removal of carbonyl sulfide (COS). The effects of COS concentration, reaction temperature and relative humidity were closely examined. A breakthrough of 33.23 mg COS·g⁻¹ adsorbent at 60°C, under 30% relative humidity and in presence of 1.0% oxygen was exhibited in the Cu-Co-K/AC adsorbent prepared. Competitive adsorption studies for COS in the presence of CS₂, and H₂S were also conducted. TPD analysis was used to identify sulfur-containing products on the carbon surface, and the results indicated that H₂S, COS and SO₂ were all evident in the effluent gas generated from the exhausted Cu-Co-K/AC. Structure of the activated carbon samples has been characterized using nitrogen adsorption, and their surface chemical structures were also determined with X-ray photoelectron spectroscopy (XPS). It turns out that the modification with Cu(OH)₂CO₃-CoPcS-KOH can significantly improve the COS removal capacity, forming SO42− species simultaneously. Regeneration of the spent activated carbon sorbents by thermal desorption has also been explored.     

Adsorptive removal of a synthetic textile dye using cocoa pod husks

The adsorption of a synthetic textile dye (Remazol Brilliant Black Reactive) on cocoa pod husk-based activated carbon was investigated in batch process. The adsorbent prepared was characterized by gas adsorption surface analysis (Brunauer Emmett Teller, BET), scanning electron microscopy, and Fourier transform infrared spectroscopy. The effects of initial dye concentration, contact time, solution temperature, and solution pH were evaluated. Equilibrium data were fitted to Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models, the first being the best with maximum monolayer coverage of 111?mg?g^?1. Kinetic data were fitted into pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich models; the pseudo second-order model provided the best correlation. Maximum adsorption was observed at pH 7. Standard free energy, standard enthalpy, and standard entropy were also calculated. The adsorption interaction was found to be endothermic and spontaneous. Both the mean free energy of adsorption and the activation energy show that the mechanism is by physisorption.     

Removal of fluoride by thermally activated carbon prepared from neem (Azadirachta indica) and kikar (Acacia arabica) leaves

The present investigation deals with fluoride removal from aqueous solution by thermally activated neem (Azadirachta indica) leaves carbon (ANC) and thermally activated kikar (Acacia arabica) leaves carbon (AKC) adsorbents. In this study neem leaves carbon and kikar leaves carbon prepared by heating the leaves at 400 degrees C in electric furnace was found to be useful for the removal of fluoride. The adsorbents of 0.3 mm and 1.0 mm sizes of neem and kikar leaves carbon was prepared by standard sieve. Batch experiments done to see the fluoride removal properties from synthetic solution of 5 ppm to study the influence of pH, adsorbent dose and contact time on adsorption efficiency The optimum pH was found to be 6 for both adsorbents. The optimum dose was found to be 0.5g/100 ml forANC (activated neem leaves carbon) and 0.7g/100 ml forAKC (activated kikar leaves carbon). The optimum time was found to be one hour for both the adsorbent. It was also found that adsorbent size of 0.3 mm was more efficient than the 1.0 mm size. The adsorption process obeyed Freundlich adsorption isotherm. The straight line of log (qe-q) vs time at ambient temperature indicated the validity of langergren equation consequently first order nature of the process involved in the present study. Results indicate that besides intraparticle diffusion there maybe other processes controlling the rate which may be operating simultaneously. All optimized conditions were applied for removal of fluoride from four natural water samples.     

Removal of elemental mercury by KI-impregnated clay

This study described the use of clay impregnated by KI in gas phase elemental mercury (Hg^o) removal in flue gas. The effects of KI loading, temperature, O₂, SO₂ and H₂O on Hg^o removal were investigated using a fixed bed reactor. The Hg^o removal efficiency of KI-clay with 3% KI loading could maintain at a high level (approximately 80 %) after 3 h. The KI-clay demonstrated to be a potential adsorbent for Hg^o removal when compared with activated carbon based adsorbent. O₂ was found to be an important factor in improving the Hg^o removal. O₂ was demonstrated to assist the transfer of KI to I₂ on the surface of KI-clay, which could react with Hg^o directly. NO and SO₂ could slightly improve Hg^o removal, while H₂O inhibited it greatly. The results indicated that after adsorption, most of the mercury escaped from the surface again. Some of the mercury may have been oxidized as it left the surface. The results demonstrated that the chemical reaction primarily occurred between KI and mercury on the surface of the KI-clay.     

改性活性炭对苯的吸附性能

本文研究了用H_3PO_4,SN (以 NaNO_2为主的复盐) 等改性的活性炭对苯的吸附性能,在不同苯浓度和空述下,经适当改性的活性炭对苯的吸附容量大于活性炭本身,探讨了改性活性炭的表观比表面与其吸附性能的关系。     

活性碳纤维在环境保护的应用

活性碳纤维与普通活性碳相比,具有微孔多、孔径分布窄、比表面积大、吸附和脱附速度快,可制成纱、布、毡等形式,是吸附性、机械性能较好的新型吸附材料.可以广泛用于溶剂回收、脱臭装置、废水、废气处理、防毒面具等.活性碳纤维装置重量轻、占地少,回收溶剂质量高、操作简易,很有发展前途.