Sorption and desorption of cadmium and lead on pectin-based biosorbents – batch and column studies

ABSTRACT

The hybrid pectin-based beads containing carob, gellan and xanthan gum were studied to be suitable for removing the Cd(II) and Pb(II) from aqueous solution in column system. Desorption of the ions from studied materials was also determined in batch and continuous studies. It was possible to remove the Cd(II) and Pb(II) ions from solution of concentration ca. 130 and 250 mg/L, respectively, to the level permissible by law. Both ions may be completely removed from our biosorbents using mineral acid solutions (confirmed by mass balance). The minimal lifetime of sorbent was also determined to be at least 10 cycles.     

Sorption of cadmium and lead ions on modified groundnut (Arachis hypogea) husks

The removal of cadmium and lead ions from aqueous solutions by groundnut husks modified by reaction with EDTA (% N = 12.05) was examined by equilibrium sorption studies at 29°C. The maximum metal ion binding capacity of the EDTA-modified husk determined from the sorption isotherm from solutions of pH 6.8 was found to be 0.36 mmol g^?1 and 0.19 mmol g^?1 for Cd(II) and Pb(II) ions, respectively. It was found that the rate of sorption was particle-diffusion controlled, and the particle-diffusion control rate coefficient was determined to be of the order of 10^?2 min^?1.     

Sorption studies of heavy metal ions on pectin-nano-titanium dioxide composite adsorbent

The Cu(II), Cd(II), Zn(II), and Pb(II) sorption kinetics and equilibrium on hybrid material, composed of pectin and titanium dioxide nanopowder, were examined. Parameters, such as pH and adsorbent dose, were also investigated. The experimental data were better described by the Langmuir model. The maximum adsorption capacities were 1.37, 0.68, 0.51, and 0.83 mmol/g for Cu(II), Cd(II), Zn(II), and Pb(II), respectively. The introduction of nano-TiO₂ improved the kinetics of the metal ion sorption. The titanium dioxide, despite its small content (6%), contributes to the removal of the examined metal ions and eventually to the adsorption capacity of hybrid beads.     

Waste spider crab shell and derived chitin as low‐cost materials for cadmium and lead removal

Crab shell and inexpensive chitin obtained from it have been studied to determine their capability to remove cadmium and lead from aqueous solutions. Factors affecting the process such as pH, metal concentration, time and temperature have been critically analysed. Results show that only cadmium uptake on crab shell is strongly influenced by the pH of the solution. The crab shell was also found to be more efficient. Equilibrium data analysis using the Langmuir isotherm indicates that crab shell can remove at least 1.4 mmol of metal per gram of sorbent at optimum pH. Temperature studies for metal sorption on chitin showed that the effect of temperature is very small for both the kinetic constant of the sorption process and for maximum uptake. Copyright © 2006 Society of Chemical Industry     

二甲酚橙浸渍树脂对铅和镉的吸附性能研究

用2g·L~(-1)二甲酚橙水溶液处理201×7阴离子交换树脂,制取得到二甲酚橙浸渍树脂。经过最佳条件选择,在同一水样中可以同时进行吸附、洗脱铅和镉。结果表明：二甲酚橙浸渍树脂在pH值为3～7时,对Pb~(2 )、Cd~(2 )具有较好的吸附性能。温度低有利于铅的吸附,而温度高则有利于镉的吸附。二甲酚橙树脂对Pb~(2 )和Cd~(2 )的平衡时吸附容量分别达到95和85mg·g~(-1)树脂,达到最大吸附容量平衡时仅需要50min。50mL 0．1mol·L~(-1)HCl就可以同时将铅、镉同时洗脱完全。二甲酚橙浸渍树脂吸附Pb~(2 )、Cd~(2 ),具有交换速度快、易于洗脱、富集倍数大、选择性好等优点。     

Removal of lead and cadmium ions by single and binary systems using phytogenic magnetic nanoparticles functionalized by 3-marcaptopropanic acid

The present research study is focused on green fabrication of superparamagnetic Phytogenic Magnetic Nanoparticles(PMNPs), and then its surface functionalization with 3-Mercaptopropionic acid(3-MPA). The resulting material(i.e. 3-MPA@PMNPs) characterized by FTIR, powder XRD, SEM, TEM, EDX, VSM, BET and TGA techniques and then further employed for the investigation of the adsorptive removal of lead(Pb~(2+)) and cadmium(Cd~(2+)) ions from aqueous solutions in single and binary systems. The material showed fastest adsorptive rate(98.23%) for Pb~(2+) and(96.5%) Cd~(2+)within the contact time of 60 min at pH 6.5 in the single system. The experimental data were fitted well to Langmuir isotherm, indicated monolayer adsorption of both metal ions onto 3-MPA@PMNPs and an estimated comparable adsorptive capacity of 68.41 mg·g~(-1)(Pb~(2+)) and 79.8 mg·g~(-1)(Cd~(2+)) at p H 6.5. However, kinetic data agreed well with pseudo-second-order model, and indicated that the removal mainly supported chemisorption and/or ion-exchange mechanism. Thermodynamic parameters such asΔGo, ΔHo, and ΔSo, were-3259.20, 119.35 and 20.73 for Pb2+, and-1491.10, 45.441 and 7.87 for Cd~(2+) at temperature 298.15 K, confirmed that adsorption was endothermic, spontaneous and favorable. The material demonstrated higher selectivity of Pb~(2+) and its removal efficiency was(98.20 ± 0.3)% in binary system experiments. The material persisted performance up-to seven(07) consecutive treatment cycles without losing their stability and offered comparable fastest magnetic separation(35 s) from aqueous solutions. Therefore, it is recommended that the prepared material can be employed to remove toxic heavy metal ions from water/wastewaters and this "green" method can easily be implemented at large scale in low economy countries.     

Removal of cadmium and lead from soil using aescin as a biosurfactant

Remediation of a soil contaminated with cadmium or lead was performed by a soil washing process using aescin as a biosurfactant. The removal of cadmium and lead from the soil was evaluated as a function of aescin concentration and pH in a batch process. A 30-mM aescin solution was most effective in the removal of cadmium and lead at pH 6.8. Cadmium and lead migrated from the soil to the aescin-containing aqueous phase, depending on the pH value. We found that 41% of cadmium (pH 7.8) and 25% of lead (pH 2.8) in the soil matrix migrated into a 30-mM aescin solution. Also, the complexation of aescin with cadmium and lead ions was confirmed by Fourier transform infrared spectroscopy and electrical conductivity measurements. As a result, the maximal complexation capacity of aescin with metal ions was approximately aescin/cadmium=2∶1 and aescin/lead=3∶1 on a molar basis. It was suggested that aescin may sequester cadmium and lead ions by the carboxylic and saccharide moieties. Then, the complex of aescin with cadmium or lead may migrate to the aqueous phase as the result of dispersion.     

纺织品中铅和镉的含量测定方法研究进展

介绍了纺织品中的重金属铅、镉元素的来源及毒性;综述了纺织品中铅和镉的含量测定方法研究进展;纺织品中铅和镉含量的传统测定方法有原子吸收光谱法、电感耦合等离子体原子发射光谱法、电感耦合等离子体质谱法、高效液相色谱法、电化学分析方法、X射线荧光光谱法、基于显色剂的分光光度法,快速检测方法有固体直接进样技术、基于金纳米颗粒目视比色法、胶体金层析试纸条、生物条形码检测技术;对传统检测方法存在的问题及快速检测技术的发展瓶颈进行了阐述;指出研制试样用量少、耗时短、成本低、简单便捷可靠、便于实现现场快速、准确检测纺织品试样的前处理方法是纺织品重金属铅镉元素安全快检技术的关键点;建议将高效便携仪器及车载仪器,溶剂提取、微波技术等试样快速前处理技术与纺织品快速检测技术联用,以便实现现场快速便捷、灵敏、准确地检测纺织品中重金属铅、镉含量。     

电感耦合等离子体质谱法测定仿真饰品用塑料珠中可萃取的铅和镉含量

为了解仿真饰品用塑料珠对人体的安全性,讨论了用不同萃取方法(模拟人工汗液、0.07 mol/L的盐酸溶液、4%的乙酸溶液)处理塑料珠后,通过ICP-MS法测定塑料珠中可萃取的铅和镉的含量。实验结果表明,在弱酸性溶液条件下,塑料珠中的铅和镉对人体有潜在的健康危害。本方法操作简便,灵敏度高,准确性好,可以在高盐的情况下直接测定铅和镉的含量。在选定的实验条件下,铅和镉的浓度在0~20μg/L范围内线性关系良好,铅和镉的检出限分别为0.71μg/L和0.01μg/L,相对标准偏差(RSD)<1%。     

阳极溶出伏安法测定硫酸锌中的铅和镉

采用玻碳电极为工作电极，以醋酸钠－醋酸－氯化钾溶液为底液，用二次导数阳极溶出伏安法测定了硫酸锌中的微量铅和镉，峰电位分别为－0．43V（Vs,SCF)和－0．62V（Vs,SCE)，线性范围分别为0－2．0μg/925mL)和0－0．8μg/(25mL)，方法准确，快速、简便。     

Polymer‐grafted banana (Musa paradisiaca) stalk as an adsorbent for the removal of lead(II) and cadmium(II) ions from aqueous solutions: kinetic and equilibrium studies

This study examined the effectiveness of a new adsorbent prepared from banana (Musa paradisiaca) stalk, one of the abundantly available lignocellulosic agrowastes, in removing Pb(II) and Cd(II) ions from aqueous solutions. The adsorbent (PGBS‐COOH) having a carboxylate functional group at its chain end was synthesized by graft copolymerization of acrylamide on to banana stalk, followed by functionalization. Batch adsorption experiments were carried out as a function of solution pH, ionic strength, contact time, metal concentration, adsorbent dose and temperature. A pH range of 5.5–8.0 was found to be effective for the maximum removal for both Pb(II) and Cd(II). Metal uptake was found to decrease with increase in ionic strength due to the expansion of the diffuse double layer and, more importantly, the formation of some chloro complexes (since NaCl was used in the adjustment of ionic strength), which do not appear to be adsorbed to the same extent as cations [M²⁺ and M(OH)⁺]. The kinetic studies showed that an equilibrium time of 3 h was needed for the adsorption of Pb(II) and Cd(II) on PGBS‐COOH and adsorption processes followed a pseudo‐second‐order equation. The Langmuir isotherm model fitted the experimental equilibrium data well. The maximum sorption capacity for Pb(II) and Cd(II) ions was 185.34 and 65.88 mg g^?1, respectively, at 30 °C. The thermodynamic parameters such as changes in free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were derived to predict the nature of adsorption. The isosteric heat of adsorption was found to be independent of surface coverage. Adsorption experiments were also conducted using a commercial cation exchanger, Ceralite IRC‐50, for comparison. Synthetic wastewater samples were treated with the adsorbent to demonstrate its efficiency in removing Pb(II) and Cd(II) ions from industrial wastewaters. Acid regeneration was tried for several cycles with a view to recovering the sorbed metal ions and also restoring the sorbent to its original state. Copyright © 2005 Society of Chemical Industry     

悬浮进样—石墨炉原子吸收法测定鸡全蛋粉中的铜、铅和镉的研究

直接悬浮进样石墨炉原子吸收法测定铜、铅和隔,样品不用消化,极大地简化了步骤,避免了样品的污染和损失。优化了悬浮液的配方,使鸡全蛋粉的水悬浮液均匀稳定。该法快速、简便、准确,结果满意。     

直接进样-火焰原子吸收光谱法测定矿区水样中的铅和镉

采集某一矿区附近3km内的排放污水、河水,用火焰原子吸收分光光度法直接测定水体中铅、镉的含量,对区域水体污染的调查有着重要的作用。在最佳仪器条件下,铅在1.0~8.0μg·m L-1范围内,相关系数为0.9992;镉在0.1~0.8μg·m L-1范围内,相关系数为0.9992。铅、镉最低检出限分别为0.043和0.004μg·m L-1,相对标准偏差均不大于2.0%,铅、镉加标回收率分别为98.4%、102.3%。该方法简便、快速、准确,具有一定的实用价值。     

Hydrogenation of 2,5-dimethyl-2,4-hexadiene and cis-2-heptene on palladium black modified by lead,thallium and cadmium

The competitive hydrogenation of 2,5-dimethyl-2,4-hexadiene and cis-2-heptene catalysed by palladium black modified by lead, thallium and cadmium to various degrees of surface coverage, was investigated. An electrochemical method was used to determine the amounts of hydrogen dissolved and adsorbed on the catalyst. The effect of ad-atoms of lead, thallium and cadmium on the kinetics of the competitive hydrogenation is discussed in terms of measured values of the reaction selectivity.     

Preparation of Pectin-Based Biosorbents for Cadmium and Lead Ions Removal

The optimal formation conditions of pectin-based, as well as new hybrid pectin-guar gum, biosorbents were found. The lead affinity for obtained biosorbents was very strong even in solution of pH = 1, in opposite to cadmium, which was adsorbed from solutions of pH ≥ 2. The sorption capacities in the studied conditions were about 0.6 and 0.8 mmol/g for cadmium and lead, respectively. The cadmium removal could be fast and it is almost quantitatively desorbed using 0.25 M HNO₃, while desorption of lead required 1 M HNO₃ to achieve a removal efficiency of ca. 75% from pectin-based beads. The possibility of biosorbents’ reuse was also proved. Addition of guar gum to pectin biosorbent did not change its sorption properties significantly.     

混酸分解-电感耦合等离子体质谱法测定土壤中铬镉铅

本文采用HNO3-HF-HCl O4分解-电感耦合等离子体质谱法(ICP-MS)测定土壤样品中Cr、Cd、Pb,对样品预处理方法,条件等进行了改进和优化,同时给出了方法的检出限、线性范围、精密度、准确度、加标回收率等方法参数。经国家标准土壤样品验证,方法的精密度符合分析要求,结果令人满意。研究表明,该方法适用于土壤样品中Cr、Cd、Pb的分析测定。     

高铁酸钾混凝去除矿井水中的铅、镉、铁、锰

采用烧杯试验考察了投加高铁酸钾强化混凝去除矿井水中铅、镉、铁、锰的效果.结果表明,高铁酸钾为30 mg/L时,混凝沉淀对低浓度矿井水中铅、镉、铁、锰的去除率分别约为55%、28%、93%、54%;高铁酸钾对模拟高浓度矿井水中铅、镉、铁、锰的去除率随pH的升高而提高,pH 8～10范围内对铅、镉、铁、锰有较好的去除效果,去除率可分别达到约95%、61%、97%和92%.处理后的矿井水中重金属含量可以达到饮用水标准,这给矿井水提供了很好的利用前景.     

磁性生物炭对铅镉离子的吸附动力学

采用水热合成法制备磁性生物炭,利用XRD、FTIR和BET分析磁性生物炭的结构、官能团种类和比表面积,并研究磁性生物炭对Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾的吸附机理。结果表明,磁性生物炭含有丰富的含氧官能团和芳香结构,磁性物质为Fe_3O_4颗粒。Pb(2+)的吸附机理。结果表明,磁性生物炭含有丰富的含氧官能团和芳香结构,磁性物质为Fe_3O_4颗粒。Pb⁽²⁺⁾、Cd(2+)、Cd⁽²⁺⁾在磁性生物炭上的吸附是一个高温自发、吸热且熵增的过程,其吸附过程符合准二级动力学方程,表明化学吸附占据优势,吸附过程是由液膜扩散和颗粒内扩散共同控制。Pb(2+)在磁性生物炭上的吸附是一个高温自发、吸热且熵增的过程,其吸附过程符合准二级动力学方程,表明化学吸附占据优势,吸附过程是由液膜扩散和颗粒内扩散共同控制。Pb⁽²⁺⁾在磁性生物炭的吸附机制,主要与含氧官能团(—COOH、—OH、C—O—C)的络合作用和π电子的配位作用有关,还存在氧化还原反应。磁性生物炭吸附Cd(2+)在磁性生物炭的吸附机制,主要与含氧官能团(—COOH、—OH、C—O—C)的络合作用和π电子的配位作用有关,还存在氧化还原反应。磁性生物炭吸附Cd⁽²⁺⁾的机制,主要与—COOH、—OH和π电子的络合作用有关,C—O—C和氧化还原反应不参与磁性生物炭对Cd(2+)的机制,主要与—COOH、—OH和π电子的络合作用有关,C—O—C和氧化还原反应不参与磁性生物炭对Cd⁽²⁺⁾的吸附。     

强化混凝沉淀去除水中三种二价重金属离子的试验研究

本研究模拟水源水分别受到5倍超标的铅、镍、镉3种重金属的污染,考察了常规混凝工艺的去除效果,温度对于混凝-沉淀工艺去除3种重金属污染的效果影响,并本文重点研究了pH值对于去除3种重金属效果的影响.结果表明,常规混凝沉淀工艺无法将该污染水处理达标,混凝剂聚合氯化铝(PAC)投量为90mg·L-1时,可以取得相对较好的混凝...