The Adsorption of Lead and Copper from Aqueous Solution on Modified Peat–Resin Particles

Raw peat was modified with sulfuric acid, then mixed modified with resin to prepare the modified peat–resin particles. Using the batch experimental systems, the removal of heavy metals (copper and lead) on the modified peat–resin particles was investigated. The data of the adsorption isotherm could be fitted by the Langmuir equation well. The adsorption rate of heavy metals on modified peat–resin particles was very swift. The removal processes of heavy metals on modified peat–resin particles could be well described by pseudo-second order model. The adsorption rate of lead was affected by the initial heavy metal concentration, initial pH, particle size, agitation speed and particle mass. In the adsorption of heavy metals (lead and copper) on the modified peat–resin particles, ion exchange was the major reaction mechanism. Desorption data showed that the lead adsorbed by modified peat–resin particle could be desorbed by 0.5 N or 1.0 N HNO₃. The desorption rate was swift. The experiments indicated that the modified peat–resin particles have great potential for the removal of heavy metals from wastewater.     

Heavy metals uptake from aqueous solutions using marine algae (Colpomenia sinuosa): kinetics and isotherms

The adsorption of copper, zinc, cobalt, lead and cadmium ions onto Colpomenia sinuosa was studied as a function of contact time, initial metal ion concentration and initial pH. In addition, desorption studies were performed. Characterisation of this adsorbent was also confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Batch adsorption experimental data were analysed using Langmuir, Freundlich and Dubinin–Raduschkevich (D–R) adsorption isotherms. The results indicated that the biosorption equilibrium was well described by both the Freudlich and D–R isotherms. Moreover, sorption kinetics was performed and it was observed that equilibrium was reached in<60 min, which could be described by the pseudo-second-order kinetic model for all heavy metals. The sorption of heavy metals onto the biomass was largely dependent on the initial solution pH. The elution efficiency for heavy metal ions desorption from C. sinuosa was determined for 0.1 M HCl, 1.0 M HCl and 1.0 M HNO₃. Desorption efficiency and also adsorption capacity were highest for Pb(II). The results indicate that C. sinuosa has great potential for the removal of heavy metals in an ecofriendly process.     

干旱区绿洲灌漠土Cu、Zn和Pb的吸附解吸特征

土壤重金属吸附解吸是影响土壤系统中重金属移动性和归宿的主要过程,影响重金属的生物有效性以及重金属在食物链中的传递等.配制一系列不同浓度的重金属,灌漠土对重金属溶液进行吸附实验24 h以达到平衡,再用硝酸铵和乙酸铵进行解吸实验24 h以达到平衡.利用热力学吸附平衡法,对西北干旱区绿洲灌漠土重金属Cu、Ni和Pb的吸附解吸行为进行序批实验研究.实验结果表明:(1)灰漠土在常温下对铜、锌和铅重金属离子的吸附等温线符合Freundlich型吸附模式,灰漠土对重金属铜、锌和铅的吸附能力由强到弱的顺序为:铅,铜,锌.(2)硝酸铵和乙酸铵解吸重金属的量与灰漠土吸附重金属量呈现出线性正相关,乙酸铵解吸重金属的量比硝酸铵解吸重金属的量大,两种解吸剂对铜、锌和铅重金属离子的解吸能力由大到小的顺序都为:铜,锌,铅,说明了一般外源的铜、锌和铅进入土壤以后,铜和锌可能比铅容易向四周转移.(3)硝酸铵和乙酸铵的解吸率呈谷形曲线,开始时硝酸铵和乙酸铵解吸重金属量的百分比随灰漠土吸附重金属量的增加而减小,在吸附量达到某一特定值时,解吸率随吸附量的增加而增加.灰漠土对铜、锌和铅的吸附作用以专性吸附为主,被灰漠土吸附的铜、锌和铅重金属离子较难解吸.     

花生壳吸附Pb^2＋、Cu^2＋、Cr^3＋、Cd^2＋、Ni^2＋的动力学和热力学研究

以花生壳为生物吸附剂,通过序批式实验研究了吸附剂投量、吸附时间、金属离子初始质量浓度、吸附温度对吸附金属离子的影响,探讨了花生壳吸附的动力学及热力学特性。结果表明,准二级动力学方程能很好地描述花生壳对Pb^2＋、Cu^2＋、Cr^3＋、Cd^2＋、Ni^2＋的吸附过程。Langmuir模型和Freundlich模型均能较好地描述花生壳对5种重金属离子的等温吸附过程,而Langmuir模型拟合的线性更好。Pb2＋、Cu2＋、Cr3＋、Cd2＋、Ni2＋5种金属离子的最大吸附量分别是32.25、7.09、3.82、2.95、2.22 mg.g-1,花生壳可用于处理低质量浓度多种重金属混合的废水。热力学研究表明,花生壳对5种金属离子的吸附具有自发、吸热和熵增的特性。     

利用非活体生物质去除废水中重金属的研究

为了解非活体牛物质去除废水中重金属的效果，选择了玉米芯、水稻谷壳、花生壳、松树树皮和茶叶等5种非活体生物质，州室内模拟方法比较研究了它们对重金属的吸附能力。结果表明，生物质对重金属的吸附是一个快速反应，可在20-30min内达到平衡。pH值对牛物质吸附阳离子型重金属有很大的影响，吸附量随pH值上升而增加，pH值在4．5以上时可达到较高水平。5种生物质对重金属都有较高吸附能力，它们吸附重金属的能力依次为：花生壳〉松树树皮〉玉米芯〉水稻谷壳〉茶叶。生物质去除废水中重金属的效果一般为：Cu、Pb〉Cd〉Zn。用碱、柠檬酸和磷酸对生物质进行改性处理可显著增强其对重金属的去除能力。生物质是一种廉价、有效的吸附剂，可替代商品吸附剂用于废水中重金属的去除，主要重金属的移除率在85％以上。     

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.     

Simultaneous removal of Co,Cu, and Cr from water by electrocoagulation

This study provides an electrocoagulation process for the removal of metals such as cobalt, copper, and chromium from water using magnesium as anode and galvanized iron as cathode. The various parameters like pH, current density, temperature, and inter electrode distance on the removal efficiency of metals were studied. The results showed that maximum removal efficiency was achieved for cobalt, copper, and chromium with magnesium as anode and galvanized iron as cathode at a current density of 0.025?A?dm^?2 at pH 7.0. First- and second-order rate equations were applied to study adsorption kinetics. The adsorption process follows second-order kinetics model with good correlation. The Langmuir and Freundlich adsorption isotherm models were studied using the experimental data. The Langmuir adsorption isotherm favors monolayer coverage of adsorbed molecules for the adsorption of cobalt, copper, and chromium. Temperature studies showed that adsorption was endothermic and spontaneous in nature.     

5种不同晶型的纳米二氧化钛对金属铜生物积累的影响

纳米二氧化钛(nTiO_2)作为一种具有独特物理化学性质的纳米材料被广泛应用。然而,在生产、使用的过程中,nTiO_2会不可避免地进入于水环境中。重金属是水体中常见的污染物之一,nTiO_2进入水体后是否会与水体中的重金属发生相互作用,进而影响重金属的生物积累,目前相关报道还很少。本论文以大型溞为模式生物,考察了5种不同晶型nTiO_2对常见的重金属铜生物积累影响。结果表明,nTiO_2对Cu2+的吸附降低了试验液中Cu2+浓度。但5种不同晶型nTiO_2的吸附能力并不一样,其中锐钛矿晶型(A-S)的吸附能力最高,这可能是由于结构缺陷和表面羟基的存在,为Cu2+提供了更多的结合位点,从而提高了A-S的吸附能力。nTiO_2的存在降低了金属铜在大型溞体内的积累,这可能是由于nTiO_2对金属铜的吸附,降低了自由Cu2+的生物可利用性。由于nTiO_2样品之间比表面积的差异,不同晶型之间单位nTiO_2引起的铜积累有显著性差异性(P0.05),其中锐钛矿和金红石之比为4:1混合晶型(M1)最高,A-S最低。     

Retention characteristics of Cu2+, Pb2+, and Zn2+ from aqueous solutions by two types of low lime fly ashes

The technical feasibility of utilization of fly ash as a low-cost adsorbent for the removal of metals from water has been studied. For two types of fly ashes, the retention capacities of copper, lead, and zinc metal ions have been studied. Contact time, initial concentration, and pH have been varied and their effect on retention mechanism has been studied. The dominant mechanisms responsible for retention are found to be precipitation due to the presence of calcium hydroxide, and adsorption due to the presence of silica and alumina oxide surfaces in the fly ash. First-order kinetic plots have revealed that the rate constant increases with increase in the initial concentration and pH. Langmuir adsorption isotherms have been plotted to study the maximum adsorption capacities for metal ions considered under different conditions. X-ray diffraction studies revealed the formation of new peaks corresponding to respective metal ions precipitates under alkaline conditions.     

城市垃圾焚烧飞灰中重金属的形态及酸浸出性研究

研究了城市垃圾焚烧飞灰中重金属形态在不同粒径上的分布,以及HNO3对飞灰中重金属的浸出性.结果表明:飞灰中重金属主要以残渣态存在,可交换离子态含量很少;易挥发性的重金属在较大粒径上有较高分布,亲石性重金属Cr和Ni的分布与粒径的相关性不大,在各粒径上的分布较均匀;飞灰中以碳酸盐结合态存在的重金属对酸不稳定,易被HNO3浸出,而残渣态部分对酸较稳定,不易被HNO3浸出.     

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。     

不同来源太湖沉积物粒径分布及其对Cu的吸附特征

以不同来源的太湖沉积物为研究对象,利用Mastersizer 2000型激光粒度分析仪测定沉积物的粒度组成,利用筛析法和吸管法对不同来源沉积物进行分级,测定不同粒径沉积物中Cu含量及不同粒径沉积物对Cu2＋的饱和吸附量,研究沉积物对水溶液中Cu（Ⅱ）的吸附特性,从粒径分级和动力学角度探讨了太湖沉积物对Cu的吸附机理。结果表明：太湖沉积物粒径范围在0.002-0.1 mm,其颗粒组成以粉砂级与粘粒级为主,养殖区沉积物小粒径比例较高,小于0.05 mm粒径沉积物的比例为82.45%;吸附实验研究表明,粒径小于0.005 mm和0.005-0.01 mm沉积物中Cu含量较高,且此粒径沉积物对Cu（Ⅱ）的吸附量最大;吸附动力学研究表明,沉积物的吸附过程分为快反应和慢反应两个阶段,且吸附过程以表面吸附为主,伪二级动力学方程对动力学曲线拟合较好,其R2值达0.999以上。吸附热力学的研究结果表明：Freundlich方程比较适合描述沉积物对Cu2＋的吸附等温线,其R2大于0.99,对照区、养殖区和生活污水区沉积物对Cu（Ⅱ）的最大吸附量分别为229.20,249.98,261.20 mg.kg-1,方程式中的强度因子1/n不适合描述沉积物与重金属离子的结合能力。     

Effective removal of Cd2+ and Pb2+ pollutants from wastewater by dielectrophoresis-assisted adsorption

Dielectrophoresis (DEP) process could enhance the removal the Cd²⁺ and Pb²⁺ with less absorbent. The removal rates of both Cd²⁺ and Pb²⁺ increased with the increase of voltage. The overall removal rate of Cd²⁺ and Pb²⁺ in the binary system is higher than that of Cd²⁺ or Pb²⁺ in the single system. DEP could cause considerable changes of the bentonite particles in both surface morphology and microstructure. Dielectrophoresis (DEP) was combined with adsorption (ADS) to simultaneously and effectively remove Cd²⁺ and Pb²⁺ species from aqueous solution. To implement the process, bentonite particles of submicro-meter size were used to first adsorb the heavy metal ions. These particles were subsequently trapped and removed by DEP. The effects of the adsorbent dosage, DEP cell voltage and the capture pool numbers on the removal rate were investigated in batch processes, which allowed us to determine the optimal experimental conditions. The high removal efficiency, 97.3% and 99.9% for Cd²⁺ and Pb²⁺, respectively, were achieved when the ions are coexisting in the system. The microstructure of bentonite particles before and after ADS/DEP was examined by scanning electron microscopy. Our results suggest that the dielectrophoresis-assisted adsorption method has a high capability to remove the heavy metals from wastewater.     

麦饭石对Pb2+离子吸附的动力学研究

本文研究了水溶液中麦饭石对Ｐｂ＾２＋离子去除的反应动力学,考察了ＭＦＳ粒度、溶液ＰＨ值和铅离子的初始浓度对吸附反应的影响。结果表明,ＭＦＳ对Ｐｂ＾２离子具有较强的吸附性能,ＰＨ值是影响吸附的主要因素,Ｐｂ＾２＋离子吸附的最初速率与浓度符合一级反应动力学;吸附过程符合Ｌａｎｇｍｕｉｒ吸附等温式;离子交换和表面络合反应是主要吸附形式。     

鼠李糖脂对沉积物中Cd和Pb的去除作用

用铜绿假单胞菌(Pseudomonas aeruginosa)产生的鼠李糖脂生物表面活性剂对沉积物中重金属的去除作用进行了研究．研究表明,鼠李糖脂对沉积物中的Cd和Pb有明显的去除作用,在鼠李糖脂溶液的pH值为10．0的条件下对重金属的去除效率最好,而且当鼠李糖脂在沉积物上的吸附达到饱和时去除效率达到最大．通过连续萃取对提取前和提取后沉积物样品中重金属的形态进行分析,发现可交换态和有机结合态的重金属较容易去除．通过4次连续的提取,使cd和Pb的去除效率分别达到80．1％和36．5％．     

海泡石黏土矿物对Cu2+的吸附动力学研究

研究分析了海泡石黏土矿物对铜离子的吸附性能和动力学特征,结果表明,海泡石黏土矿物对Cu~(2 )吸附的最佳pH值为6.0左右,随着pH值的增大,吸附作用减弱;在[Cu~(2 )]=100mg·l~(-1),溶液pH值为6,吸附时间为2h时,添加0.1 g海泡石,海泡石对Cu~(2 )的吸附去除率仅为39.5%,当海泡石用量提高至0.4 g时,其对Cu~(2 )的吸附去除率提高到94.8%;实验结果同样显示,18min内有90%的Cu~(2 )被海泡石吸附,随着吸附时间的增加,吸附作用趋于稳定,2h可达到吸附平衡。该吸附过程符合Langmuir和Freundlich等温吸附方程.同时,分别采用拟一级模型和拟二级模型考察了吸附动力学,并计算了这些动力学模型的速率常数.实验数据和拟二级模型计算结果之间有较好的相关性.     

Suitability of various chemically prepared activated carbons for the removal of copper(II) ions

Studies on the suitability of various chemically prepared activated carbons (CPACs) like straw carbon (SC), sawdust carbon (SDC), dates nut carbon (DNC) and commercial activated carbon (CAC) for the removal of copper(II) ions by adsorption from simulated wastewater have been carried out under batch mode at 30?±?1°C and the results are compared. The percentage removal of Cu(II) ions increased with a decrease in initial concentration, particle size and added electrolytes (ionic strength) and increased with an increase in contact time, dose of adsorbent and initial pH of the solution. The adsorption data were fitted with the Langmuir isotherm. The applicability of the first order kinetic equation viz. Lagergren equation was tested by correlation analysis. The adsorption process is concluded to be a spontaneous, first order reaction, occurring with increased randomness at the solid–liquid interface. Studies on the desorption of Cu²⁺-loaded activated carbons (ACs) were carried out with nitric acid (0.2–1?N). The possibility of reuse of the regenerated ACs in cycle (in cue-one after another) was tested. SC was found to be a suitable adsorbent alternative to CAC among CPACs for the removal of metal ions, in general, and Cu²⁺ ions, in particular.     

Sequentielle Schwermetallextraktion aus Staubniederschlägen und Stra\ensedimenten

For the application of our method for the sequential extraction of heavy metals from microsamples presented in part 1 (“Sequentielle Schwermetallextraktion von Mikroproben” — “Sequential Extraction of Heavy Metals from Micro Samples”) an investigation was carried out to evaluate airborne dust fallout and street sediments at two urban sites where different heavy metal immission rates occur due to traffic influence. In the street sediments the total concentrations of zinc, copper and lead was three to fivefold higher in the silt and clay fraction (< 63 μm) than in the particle size fraction (< 1,12 mm), but showed nearly the same mobilisation behaviour. The dust samples showed equal mobilisation behaviour as the street sediments for copper and lead, while zinc was considerably more mobile in the dust samples: In extraction steps I–IV (I: mobile fraction; II: easily deliverable fraction; III: fraction bound to manganese oxides; IV: fraction bound organic to matter) zinc, copper and lead in street sediments, as well as copper and lead in dust samples, were dissolved to 40–70%, whereas about 80% of zinc in the dust samples was already dissolved in extraction step I.     

Ecological risk assessment from the perspective of soil heavy metal accumulations in Xiamen city,China

Contamination of soils by heavy metals is of rising concern in many cities in China undergoing rapid urbanization. Here, we evaluate the severity of soil contamination by four heavy metals (arsenic, chromium, copper, and lead) at 146 urban and suburban sites within the city of Xiamen, Fujian, China. A multivariate regression model was proposed and developed to simulate heavy metals accumulation in urban and suburban soils, to identify the concentration and spatial distribution of heavy metals in soils, and to assess ecological risks by 2020. Results showed that, overall, Xiamen soils should be subject to low ecological risks due to heavy metals contamination by 2020, the ecological risks for urban soils were greater than suburban soils, nearly half of Xiamen soils are at moderate ecological risks, and many suburban soils experience low ecological risks. The methods demonstrate the potential to predict future ecological risks from heavy metals contamination which could inform pollution prevention and control measures.     

Copper(II) ions’ removal from aqueous solution using green horse-chestnut shell as a low-cost adsorbent

The adsorption of copper(II) ions from aqueous solutions by the green horse-chestnut shell was studied in a batch adsorption system. It was determined how the parameters of the adsorption process, such as time, pH, copper(II) ions concentration and sorbent dose, influence the effectiveness of copper(II) ions’ removal. The adsorption process was fast and equilibrium was established about 10?min, and near 95–97% of Cu(II) ions were removed from aqueous solution. Maximum copper(II) ions’ adsorption occurred at around pH 5. The adsorption kinetics are also described, using pseudo-first-order model and pseudo-second-order model of type 1 and 2. A comparison of the kinetics models on the overall adsorption rate showed that the adsorption system was best described by the pseudo-second-order model of type 1 (r²?=?0.999) for all initial concentrations. Another key part of this study was the use of the Freundlich model to determine the adsorption isotherm and the experimental data were in strong correspondence with this model.