共查询到20条相似文献,搜索用时 15 毫秒
1.
Hassan Rezaei Satish D. Kulkarni Praveen G. Saptarshi 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(8):1332-1339
Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Biosorption of heavy metals by metabolically inactive biomass of microbial organisms is an innovative and alternative technology for removal of these pollutants from aqueous solution. Presence of heavy metals in the aquatic system is posing serious problems. Zinc has been used in many industries and removal of Zn ions from waste water is significant. Biosorption is one of the economic methods used for removal of heavy metals. In the present study, the biomass obtained from the dried Chlorella pyrenoidosa was used for evaluating the biosorption characteristics of Zn ions in aqueous solutions. Batch adsorption experiments were performed with this material and it was found that the amount of metal ions adsorbed increased with the increase in the initial metal ion concentration. In this study effect of agitation time, initial metal ion concentration, temperature, pH and biomass dosage were studied. Maximum metal uptake (q max) observed at pH 5 was 101.11 mg/g. The biosorption followed both Langmuir and Freundlich isotherm model. The adsorption equilibrium was reached in about 1 h. The kinetic of biosorption followed the second-border rate. The biomass could be regenerated using 0.1 M HNO3. A positive value of ΔH° indicated the endothermic nature of the process. A negative value of the free energy (ΔG°) indicated the spontaneous nature of the adsorption process. A positive value of ΔS° showed increased randomness at solid-liquid interface during the adsorption of heavy metals, it also suggests some structural changes in the adsorbate and the adsorbent. FTIR Spectrums of Chlorella pyrenoidosa revealed the presence of hydroxyl, amino, carboxylic and carbonyl groups. The scanning electron micrograph clearly revealed the surface texture and morphology of the biosorbent. 相似文献
2.
Study of a heavy metal biosorption onto raw and chemically modified Sargassum sp. via spectroscopic and modeling analysis 总被引:1,自引:0,他引:1
In this study, raw and formaldehyde-modified Sargassum sp. are used for heavy metal removal. A series of experiments shows that the chemical modification by formaldehyde improves biosorption capacity by approximately 20%. Solution pH plays an important role in the metal uptake. According to X-ray photoelectron spectroscopic and Fourier transform infrared spectroscopic analysis, the possible organic functional groups in the metal binding include carboxyl, ether, alcoholic, hydroxyl, and amino functional groups. A new model that includes a series of coordination reactions among a generalized functional group, alkaline earth metal ions and heavy metal ions, is developed for simulation of biosorption process. The model well describes the single- and multiple-species metal biosorption process under different conditions such as pH. The biosorption of heavy metals is due to the ion exchange between the heavy metals and alkaline earth metals and their adsorption onto the free sites of the seaweeds. Slightly more than half of the metal uptake is due to ion exchange. The metal affinity for the functional groups follows a descending order of lead > copper > alkaline earth metal. 相似文献
3.
Extensive research has been conducted for removal and recovery of heavy metals from wastewater and industrial wastewater in
recent years. Due to its low cost and high sorption efficiency, alginate was extensively investigated as a biosorbent. It
is known that the sorption of metals to alginate is rate limited. However, the sampling in the beginning of experiments, from
30 seconds to few minutes, is very difficult, if not impossible. In this study, a nontraditional experimental method was used
to determine the removal kinetics of metals for short time periods. A relationship among pH, conductivity, and metal concentration
was established. It was shown that the sorption mechanism was ion exchange for all metals investigated in this study. A series
of experiments was conducted to determine the ion exchange kinetics of different metals at varying pH conditions. Second order
pseudo rate kinetics was shown to define the experimental findings well. Results also showed that the extent of exchange significantly
reduced as the pH decreased. The selectivity of metal exchange to alginate beads was determined. It was observed that the
extent of the ion exchange was greatest for Cu2 + and lowest for Mn2 + and Fe2 +, following the order of Cu2 + > Zn2+≅ Co2 +≅ Ni2+ > Mn2+≅ Fe2+. 相似文献
4.
《Analytica chimica acta》2002,458(1):95-102
An easy, fast and reliable analytical method is proposed to determine the concentration of volatile phenols (ethyl- and vinylphenols) in fino sherry wines. The technique employed is a single stage sample treatment by solid-phase extraction (SPE) following a simple, fast procedure that enables 12 samples to be extracted simultaneously and requires a small volume sample and little time. Subsequently, the extracts are analyzed by gas chromatography (GC) with flame ionization detection. The method proposed has been applied to the study of fino sherry wines affected by microbial contamination with yeasts of the Brettanomyces genus, and the relationship of these yeasts with the concentrations of volatile phenols present in this wine. 相似文献
5.
Clarification of the musts is carried out to remove particles that cause turbidity, oxidizable polyphenols, and eliminate excess of proteins. However, an excessive clarification of the musts can lead to the reduction of volatile compound concentrations and, as a consequence, modify the sensorial properties of the wines. Therefore, in this study, the influence of two pre-fermentation clarification techniques (static settling and flotation) on the concentrations of volatile compounds has been assessed in Albariño and Treixadura wines. Fermentations were performed at an industrial scale. Volatile compounds have been identified and quantified by gas chromatography (FID and mass spectrometry detection) and expert panelists assessed the sensory properties of the final wines. The results showed effects of the clarification techniques on the volatile composition of wines from both varieties. Flotation significantly increased the concentrations of benzyl alcohol in Treixadura wines, whereas this technique increased the concentration of 1-hexanol, octanoic acid, and furfural in Albariño wines, but without exceeding the corresponding perception thresholds. Panelists tended to score higher the wines coming from flotation, which, together with the shorter application time, makes this technique suitable for clarifying the musts of these two white varieties. 相似文献
6.
Industrial wastes as low-cost potential adsorbents for the treatment of wastewater laden with heavy metals 总被引:2,自引:0,他引:2
Ahmaruzzaman M 《Advances in colloid and interface science》2011,166(1-2):36-59
Industrial wastes, such as, fly ash, blast furnace slag and sludge, black liquor lignin, red mud, and waste slurry, etc. are currently being investigated as potential adsorbents for the removal of the heavy metals from wastewater. It was found that modified industrial wastes showed higher adsorption capacity. The application of low-cost adsorbents obtained from the industrial wastes as a replacement for costly conventional methods of removing heavy metal ions from wastewater has been reviewed. The adsorption mechanism, influencing factors, favorable conditions, and competitive ions etc. on the adsorption of heavy metals have also been discussed in this article. From the review, it is evident that certain industrial waste materials have demonstrated high removal capacities for the heavy metals laden with wastewater. However, it is to be mentioned that adsorption capacities of the adsorbents vary depending on the characteristics of the adsorbents, the extent of chemical modification and the concentration of adsorbates. There are also few issues and drawbacks on the utilization of industrial wastes as low-cost adsorbents that have been addressed. In order to find out the practical utilization of industrial waste as low-cost adsorbents on the commercial scale, more research should be conducted in this direction. 相似文献
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9.
R. S. Lokhande P. U. Singare T. S. Prabhavalkar 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(9):1589-1595
In the present investigation, the 82Br radioactive isotope was used as a tracer to study the kinetics and mechanism of the exchange reaction between an ion exchange
resin and an external solution of bromide ions. In an attempt to study the reversible bromide isotope exchange reaction kinetics,
it was expected that whether the initial step was the exchange of radioactive bromide ions from the solution to the ion exchange
resin (forward reaction) or from the ion exchange resin to the solution (reverse reaction), the two ion-isotope exchange reactions
should occur simultaneously, which was further confirmed by the experimental values of specific reaction rates, 0.142 and
0.141 min−1, respectively. The results will be useful to standardize the process parameters so as to achieve optimum use of ion exchange
resins in various industrial applications.
The text was submitted by the authors in English. 相似文献
10.
Farzaneh Afshariazar Prof. Ali Morsali Dr. Jun Wang Prof. Peter C. Junk 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(6):1355-1362
To overcome the challenge of developing a multipurpose adsorbent for effective removal of toxic and carcinogenic PbII ions from aqueous solutions, a made-for-purpose functional group (N1,N2-di(pyridine-4-yl)oxalamide) was rationally designed and incorporated into the cavities of a Zn metal–organic framework (MOF), namely, TMU-56. Large enough pore size along with high densities of strong metal chelating sites lead not only to the highest uptake capacity for PbII ions, but also the fastest removal rate that has ever been reported for functionalized MOFs, occurring in just 20 s. Moreover, high concentrations of lead ions favor the ion exchange reaction, resulting in a high degree of metal exchange. In addition, TMU-56 can be a practical adsorbent because of its notable performance in the simultaneous removal of several toxic and carcinogenic heavy metals from wastewater, which has rare precedence. 相似文献
11.
In this work, composite cation‐exchange membrane was prepared by chemical polymerization of pyrrole on the surface of the poly(vinylidene fluoride) (PVDF) membrane using ferric ions. The changes in the surface morphologies of non‐modified and polymer‐modified PVDF membrane were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. The ion‐exchange capacity, water uptake, and fixed group concentration of the composite membrane were investigated. The polypyrrole/PVDF composite membrane was used for the removal of copper (II), chromium (III), iron (III), and aluminum (III) ions from aqueous solution with Donnan dialysis experiments. The flux values (J) and recovery factors (RF) of Cu(II), Cr(III), Fe(III), and Al(III) were obtained. Because of the smaller ion charge and hydration volume, the transport of the Cu(II) ion is higher than that of the other metals. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
12.
微囊化海藻酸离子移变凝胶的制备、结构与性能 总被引:6,自引:0,他引:6
通过静电脉冲技术制备了海藻酸-壳聚糖-海藻酸(Alginate-Chitosan-Alginate,ACA)微胶囊,红外光谱分析表明,ACA是一种以聚电解质配合物为囊膜,以海藻酸钠离子吸附剂为囊心物的微胶囊型离子吸附体系.扫描电镜测试表明,ACA吸附重金属离子的过程是微胶囊囊内海藻酸凝胶化的过程,其解吸附过程是海藻酸凝胶转变成海藻酸溶液的过程.与传统离子交换树脂相比,ACA对Pb2+的吸附具有较高的去除率、很强的富集能力和较低的极限吸附浓度,并且能够被多次重复使用.ACA的离子交换速率比传统离子交换树脂快得多,离子交换过程中,交换离子和吸附剂海藻酸分子的相互扩散大大提高了离子交换速率. 相似文献
13.
R. S. Lokhande P. U. Singare P. Karthikeyan 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(11):1768-1773
In the present investigation, 82Br radioactive isotope was used as a tracer to study the kinetics and mechanism of exchange reaction between an ion exchange
resin and an external bromide ion solution. In an attempt to study the reversible bromide ion isotopic exchange reaction kinetics,
it was expected that whether the initial step was the exchange of radioactive bromide ions from the solution into the ion
exchange resin (forward reaction) or from the ion exchange resin into the solution (reverse reaction), two ion isotopic exchange
reactions should occur simultaneously, which was further confirmed by the experimental specific reaction rates of 0.130 and
0.131 min−1, respectively. The results can be used to standardize process parameters so as to optimize the utilization of ion exchange
resins in various industrial applications.
The text was submitted by the authors in English. 相似文献
14.
《Journal of membrane science》1998,145(1):27-44
In ligand-modified micellar-enhanced ultrafiltration (LM-MEUF), a surfactant and a ligand are added to an aqueous solution containing ions of like charge. The ligand forms a complex with the target ion of interest and becomes incorporated in the micelle. This solution is then treated by an ultrafiltration process with membrane pore sizes small enough to reject the micelles and their solubilized metal–ligand complex. Previous studies have demonstrated the technical feasibility of LM-MEUF with copper rejection exceeding 99% with no removal of calcium using several different ligands. The ability to regenerate the surfactant/ligand for reuse has also been shown. In this study, an economic analysis of LM-MEUF (with regeneration) for a 1×105 gal/day unit is reported. The effects of important parameters are investigated; including feed surfactant, ligand, and copper concentrations. The results from the sensitivity analysis are used to compare the cost of LM-MEUF for copper removal and recovery to the conventional copper solvent extraction process. The comparative economic analysis indicates a 17% higher capital and a 43% higher operating cost for LM-MEUF process compared to the solvent extraction process. 相似文献
15.
Adsorption of fluoride, phosphate, and arsenate ions on a new type of ion exchange fiber 总被引:11,自引:0,他引:11
A new type of ion exchange fiber for the removal of fluoride, phosphate, and arsenate ions has been developed. A batch adsorption technique for investigating adsorption kinetic and equilibrium parameters and determining pH adsorption edges is applied. It is shown that the adsorption properties of the ion exchange fiber for fluoride, phosphate, and arsenate ions depend on the pH value and anion concentration. The adsorption of arsenate on the sorbent reaches a maximum of 97.9% in the pH value range of 3.5 to 7.0. The adsorption percentage of phosphate is more than 99% in the pH range of 3.0 to 5.5. The adsorption of fluoride on the ion exchange fiber is found to be 90.4% at pH 3.0. The Freundlich model can describe the adsorption equilibrium data of fluoride, arsenate, and phosphate anions. The sorption of the three anions on the ion exchange fiber is a rapid process, and the adsorption kinetic data can be simulated very well by the pseudo-second-order rate equation. The column performance is carried out to assess the applicability of the ion exchange fiber for the removal of fluoride, phosphate, and arsenate ions from synthetic wastewaters with satisfactory removal efficiency. The desorption experiment shows that fluoride ion sorbed by the fiber column can be quantitatively desorbed with 5 mL of 0.50 mol/L NaOH at elution rate of 1 mL/min, and 30 mL of NaOH is necessary for the quantitative recovery of phosphate and arsenate ions. 相似文献
16.
建立了毛细管离子色谱测定酒、饮料等样品中阳离子的分析方法。使用毛细管离子色谱柱IonPac CS12A(250 mm×0.4 mm, 8 μm),以甲基磺酸淋洗液发生器(EGC-MSA)产生18 mmol/L的甲基磺酸为流动相,进样量0.4 μL,在流速0.01 mL/min的条件下,采用自循环抑制电导检测的方法对啤酒、葡萄酒、白酒、果汁及奶茶等样品中的阳离子含量进行检测。结果表明,毛细管离子色谱法能满足阳离子含量的测定要求,系统稳定不易堵,在灵敏度方面优于常规离子色谱系统。该方法能够快速、准确地测定酒、饮料等样品中的5种阳离子(钠、铵、钾、镁和钙),回归方程的相关系数在0.9997以上,实际样品的加标回收率为95.2%~103.3%。该方法具有灵敏度高,操作简单,环境友好的特点。 相似文献
17.
Li Xiaofan Shi Shaoyuan Cao Hongbin Li Yuping Xu Dongyao 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(6):1229-1236
Russian Journal of Physical Chemistry A - Ion exchange process is an alternative technique for removal of heavy metal ions from industrial wastewater. The main aim of this paper is to evaluate the... 相似文献
18.
Kim Bang Mo 《Journal of membrane science》1984,21(1):5-19
A membrane-based solvent extraction process was developed for selective removal and recovery of metals from aqueous solutions. The process utilizes microporous membranes as an interface between an aqueous solution and organic solvents containing liquid ion exchangers. Metal ions are transported from the aqueous solution to the organic phase at the interface created in the pores of membrane. The organic solvent, which is loaded with metal ions in the extraction module, is regenerated in contact with the stripping solution in the stripping module. One important feature of this process is the stability of the membrane system, which results from using an aqueous—organic separator to remove aqueous solution from the organic circulating line. This process was evaluated for enrichment of copper using solvents containing LIX 64N. The process is applicable to selective recovery of metals from ore leachates or metal-containing wastewater. 相似文献
19.
Ram Niwas A. A. Khan K. G. Varshney 《Colloids and surfaces. A, Physicochemical and engineering aspects》1999,150(1-3):7-14
Incorporation of a polymer material into an inorganic ion exchanger provides a class of hybrid ion exchangers with a good ion exchange capacity, high stability, reproducibility and selectivity for heavy metals. Such a type of ion exchanger ‘polyaniline Sn(IV) arsenophosphate’ has been synthesized by mixing polyaniline into inorganic material. This material is characterized using X-ray, IR, TGA studies in addition to ion exchange capacity, pH-titration, elution and distribution behaviour. On the basis of distribution studies, the material has been found to be highly selective for Pb(II). Kinetic study of exchange for the metal ions has been performed and some physical parameters such as self diffusion coefficient D0, energy Ea and entropy ΔS* of activation have been determined. 相似文献
20.
Adsorption of cadmium ions from aqueous solutions using nano-montmorillonite: kinetics,isotherm and mechanism evaluations 总被引:1,自引:0,他引:1
Wei Liu Chenchen Zhao Shutao Wang Lin Niu Yunli Wang Shuxuan Liang Zhe Cui 《Research on Chemical Intermediates》2018,44(3):1441-1458
With increasing industrial development, heavy metal pollution, e.g., cadmium (Cd) pollution, is increasingly serious in soil and water environments. This study investigated the sorption performance of nano-montmorillonite (NMMT) for Cd ions. Adsorption experiments were carried out to examine the effects of the initial metal ion concentration (22.4–224 mg/L), pH (2.5–7.5), contact time (2–180 min) and temperature (15–40 °C). A simulated acid rain solution was prepared to study the desorption of Cd adsorbed on NMMT. After the adsorption or desorption process, the supernatant was analyzed using a flame atomic absorption spectrometry method. The Cd removal rate increased as the pH and contact time increased but decreased as the initial metal ion concentration increased. The maximum adsorption capacity was estimated to be 17.61 mg/g at a Cd2+ concentration of 22.4 mg/L. The sorption process can be described by both the Langmuir and Freundlich models, and the kinetic studies revealed that the pseudo-second-order model fit the experimental data. The Cd desorption rate when exposed to simulated acid rain was less than 1%. NMMT possesses a good adsorption capacity for Cd ions. Additionally, ion exchange was the main adsorption mechanism, but some precipitation or surface adsorption also occurred. 相似文献