首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
《分离科学与技术》2012,47(18):2786-2794
Sorption is a viable treatment technology for copper-rich gold mine tailings wastewater. For continuous application, the sorbent should be regenerated with an appropriate desorbent, and reused. In this study, the sequential sorption/desorption characteristics of Cu(II) on coconut shell (CS) and iron oxide coated sand (IOCS) were determined. In batch assays, CS was found to have a Cu(II) uptake capacity of 0.46 mg g?1 and yielded a 93% removal efficiency, while the IOCS had a Cu(II) uptake capacity and removal efficiency of 0.49 mg g?1 and 98%, respectively. Desorption experiments indicated that HCl (0.05 M) was an efficient desorbent for the recovery of Cu(II) from CS, with an average desorption efficiency of 96% (sustained for eight sorption and desorption cycles). HCl (0.05 M) did not diminish the CS's ability to sorb copper even after eight sorption/desorption cycles, but completely deteriorated the iron oxide structure of the IOCS within six cycles. This study showed that CS and IOCS are both good sorbents for Cu(II); but cyclical sorption/desorption using 0.05 M HCl is only feasible with CS.  相似文献   

2.
《分离科学与技术》2012,47(13):2049-2055
Three kinds of agricultural by-products, wheat stem, corncob, and rice husk, were tested as biosorbents for cadmium removal from aqueous solution. The study was focused on the evaluation and comparison of the potential of the agriculture by-products as biosorbents of cadmium with the sorption isotherms determination. The impact of solution pH and kinetic study was also discussed. The result indicated that cadmium removal was strongly dependent on solution pH and the optimum pH range is 4.5 ~ 6.0. The sorption process was fast, and the sorption equilibrium can be attained within 60 min. The kinetic process fit well with the pseudo-second-order kinetic model. For the three kinds of biosorbents, the initial sorption rate as well as the maximum sorption capacity q max calculated from the Langmuir isotherm equation showed the following tendency: rice husk > wheat stem > corncob. The maximum sorption capacity of the three kinds of biosorbents enhanced after being base treated, especially for wheat stem and corncob. This study indicated that wheat stem, corncob, and rice husk displayed the potential to be used as biosorbents for cadmium removal from aqueous solution.  相似文献   

3.
Chloromethylated polystyrene‐divinylbenzene has been functionalized with dithiooxamide. The resulting chelating resin (DTOA) has been characterized by elemental analyses, infrared spectroscopy, thermogravimetric analysis, and metal ion sorption capacities. It has been used for the preconcentration and separation of Cu(II), Zn(II), Cd(II), and Pb(II) prior to their determination by FAAS. Parameters such as the amount of the resin, effect of pH, equilibration rate, sorption and desorption of metal ions, and effect of diverse ions have been studied. The maximum sorption capacities found are 0.97, 0.12, 0.08, and 0.12 mmol g?1 for Cu(II), Zn(II), Cd(II), and Pb(II) at pH 6.0, 5.5, 1.0, and 5.5, respectively. The preconcentration factors are 100, 100, 50, and 50 for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. Recoveries of the metal ions were 96 ± 5, 97 ± 6, 96 ± 5, and 96 ± 5 at 95% confidence level, whereas the limits of detection are 2.0, 1.3, 2.5, and 25.0 μg L?1 for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The calibration curves were linear up to 12 μg mL?1 (R2 = 1.000), 2 μg mL?1 (R2 = 0.998), 2 μg ml?1 (R2 = 1.000), and 5 μg mL?1 (R2 = 0.979) for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The reliability of the method has been tested by analyzing certified samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2281–2285, 2007  相似文献   

4.
BACKGROUND: The removal of heavy metals using adsorption techniques with low cost biosorbents is being extensively investigated. The improved adsorption is essentially due to the pores present in the adsorbent. One way of improving the porosity of the material is by irradiation of the precursor using microwaves. In the present study, the adsorption characteristics of nickel onto microwave‐irradiated rice husks were studied and the process variables were optimized through response surface methodology (RSM). RESULT: The adsorption of nickel onto microwave‐irradiated rice husk (MIRH) was found to be better than that of the raw rice husk (RRH). The kinetics of the adsorption of Ni(II) from aqueous solution onto MIRH was found to follow a pseudo‐second‐order model. Thermodynamic parameters such as standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were also evaluated. The thermodynamics of Ni(II) adsorption onto MIRH indicates that it is spontaneous and endothermic in nature. The response surface methodology (RSM) was employed to optimize the design parameters for the present process. CONCLUSION: Microwave‐irradiated rice husk was found to be a suitable adsorbent for the removal of nickel(II) ions from aqueous solutions. The adsorption capacity of the rice husk was found to be 1.17 mg g?1. The optimized parameters for the current process were found as follows: adsorbent loading 2.8 g (100 mL)?1; Initial adsorbate concentration 6 mg L?1; adsorption time 210 min.; and adsorption temperature 35 °C. Copyright © 2008 Society of Chemical Industry  相似文献   

5.
Graft copolymerization of acrylamide onto coconut husk (CH), initiated by the ferrous ammonium sulfate/H2O2 redox initiator system, was studied. To determine the optimum conditions of grafting, the effect of the concentrations of ferrous ammonium sulfate, the monomer, and H2O2 and the time and temperature on percentage of the graft yield was studied. A new adsorbent media having a carboxylate functional group was synthesized by the surface modification of polymer‐grafted coconut husk (PGCH COOH). The mechanism of graft polymerization and surface functionalization is proposed. The material exhibits a very high adsorption potential for Hg(II). The sorption of Hg(II) was found to be dependent on the contact time, concentration, pH, and temperature. Maximum removal of 99.4% with 2 g/L of the sorbent was observed at 125 μmol L−1 Hg(II) concentration at pH 6.0. The slow step which determines the rate of exchange of Hg(II) ions is diffusion through the adsorbent particles. The diffusion coefficients, energy of activation, and entropy of activation were calculated and used to determine the theoretical behavior of the sorption process. The applicability of the Langmuir isotherm established the endothermic character of the adsorption. Acid regeneration was tried for several cycles with a view to recover the adsorbed metal ions and also to restore the sorbent to its original state. The adsorbent efficiency toward Hg(II) removal was tested using synthetic and chloralkali industry wastewaters. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1261–1269, 2000  相似文献   

6.
In this paper, the ability of Moringa oleifera seed extract–among other natural coagulants–to remove several different types of dyes has been researched. Moringa oleifera has been demonstrated to have a high removal ability for anionic dyes. This study is particularly focused on testing the removal of an azo dye such as Chicago Sky Blue 6B (CSB). It has taken out the fast kinetic of coagulant action and the high potential of this coagulant agent to treat wastewater from dyestuff. Up to 99% of CSB removal has been achieved with M. oleifera extract dosage of 150, 200 and 250 mg l?1 for 100, 160 and 200 mg l?1 of initial CSB concentration, respectively. Temperature does not affect the coagulant process and a pH level greater than 8 has a negative influence. Lower CSB percentage removal is achieved by increasing the initial dye concentration, but an optimum relationship between dye amount removed and M. oleifera extract amount has been established and it appears to be between 0.7 and 0.9, depending on the initial dye concentration and the bulk of the remaining dye concentration.  相似文献   

7.
The adsorption of Cu (II) from aqueous solutions using coconut shell modified powder was investigated in batch experiments. The surface charge of the adsorbent was determined. The points of zero charge (PZC) of the adsorbents (pHPZC) were 4.5, 2.0, and 2.0 to raw coconut (RC), raw coconut alkalized (RCA), and coconut shell modified with tannic acid (TCA) adsorbent, respectively. Batch experiments were performed under kinetic and equilibrium conditions. The kinetic data were analyzed using a pseudo second‐order, and Elovich equation. Adsorption equilibrium data were investigated using the Langmiur, Freundlich, Temkin, and Dubinin–Raduschevich (D–R) isotherm models. It has been found that chemically modified coconut shell (TAC) affected performance when compared with unmodified coconut shell (RC). Kinetic studies showed that the adsorption followed a pseudo‐second‐order rate model. Biosorption kinetics of Cu(II) on the adsorbent TCA was rapid such that almost 90% of Cu(II) were adsorbed within 80 min. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40744.  相似文献   

8.
This research paper covers the suitability of the coagulation–flocculation process using Moringa oleifera seeds after oil extraction as a natural and environmentally friendly coagulant for palm oil mill effluent treatment. The performance of M. oleifera coagulant was studied along with the flocculant KP 9650 in removal of suspended solids, organic components and in increasing the floc size. The optimum values of the operating parameters obtained from the laboratory jar test were applied in a pilot‐scale treatment plant comprised of coagulation–flocculation and filtration processes. Pilot‐scale pretreatment resulted in 99.7% suspended solids removal, 71.5% COD reduction, 68.2% BOD reduction, 100% oil and grease removal and 91% TKN removal. In pilot plant pretreatment, the percentage recovery of water was 83.3%, and 99.7% sludge was recovered after dewatering in a filter press. Copyright © 2006 Society of Chemical Industry  相似文献   

9.
Functionalised SBA‐15 mesoporous silica with polyamidoamine groups (PAMAM‐SBA‐15) was successfully prepared with the structure characterised by X‐ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectra and thermogravimetric analysis. PAMAM‐SBA‐15 was applied as adsorbent for Cu(II), Pb(II) and Cd(II) ions removal from aqueous solution. The effects of the solution pH, adsorbent dosage and metal ion concentration were studied under the batch mode. The Langmuir model was fitted favourably to the experimental data. The maximum sorptive capacities were determined to be 1.74 mmol g?1 for Cu(II), 1.16 mmol g?1 for Pb(II) and 0.97 mmol g?1 for Cd(II). The overall sorption process was fast and its kinetics was fitted well to a pseudo‐first‐order kinetic model. The mean free energy of sorption, calculated from the Dubinin–Radushkevich isotherm, indicated that the sorption of lead and copper, with E > 16 kJ mol?1, followed the sorption mechanism by particle diffusion. The adsorbent could be regenerated three times without significant varying its sorption capacity. A series of column tests were performed to determine the breakthrough curves with varying bed heights and flow rates. The breakthrough data gave a good fit to the Thomas model. Maximum sorption capacity of 1.6, 1.3 and 1.0 mmol g?1 were found for Cu(II), Pb(II) and Cd(II), respectively, at flow rate of 0.4 mL min?1 and bed height of 8 cm, which corresponds to 83%, 75% and 73% of metallic ion removal, respectively, which very close to the value determined in the batch process. Bed depth service time model could describe the breakthrough data from the column experiments properly. © 2012 Canadian Society for Chemical Engineering  相似文献   

10.
BACKGROUND: Biosorption of heavy metals from aqueous solution by modified activated carbon with Phanerochaete chrysosporium immobilised in Ca‐alginate beads was investigated using a batch system and comparison of linear and nonlinear methods. RESULTS: The amount of Cu(II), Zn(II) and Pb(II) ion sorption by the beads was as follows: activated carbon with P. chrysosporium immobilised in Ca‐alginate beads (ACFCA) (193.4, 181.8, 136.6 mg g?1) > activated carbon immobilised in Ca‐alginate beads (ACCA) (174.8, 162.0, 130.7 mg g?1) > P. chrysosporium (F) (148.8, 125.6, 120.4 mg g?1) > activated carbon (AC) (138.8, 112.3, 109.3 mg g?1) > plain Ca‐alginate beads (PCA) (125.4, 105.2, 98.2 mg g?1). The widely used Langmuir and Freundlich isotherm models were utilised to describe the biosorption equilibrium process. CONCLUSION: The results of this study suggest that the immobilisation of modified activated carbon with P. chrysosporium in Ca‐alginate beads is suitable for a batch system. The isotherm parameters were estimated using linear and nonlinear regression analyses. The surface charge density of the biosorbents varied with the pH of the medium; the maximum biosorption of heavy metal ions on the biosorbents was obtained when the pH was between 5.6 and 7.4. Copyright © 2008 Society of Chemical Industry  相似文献   

11.
Biosorption of Cu(II) onto coconut shell, an agricultural biomaterial, was studied in a fixed-bed column. The Cu(II) biosorption column had the best performance at 10 mg L?1 inlet Cu(II) concentration, 10 mL min?1 flow rate and 20 cm bed depth. The equilibrium uptake of Cu(II) amounted to 7.25 mg g?1. The simulation of the breakthrough curve was successful with the BDST and Yoon–Nelson models, but the entire breakthrough curve was best predicted by the Clark model. The design of a fixed bed column for Cu(II) removal from wastewater by biosorption onto coconut shell can be done based on these models.  相似文献   

12.
Moringa oleifera is grown all over the world as a crop for its nutritious pods, leaves and seeds. The purpose of the present study was to evaluate the oil percentage, density, iodine value, saponification value, acid value and fatty acid profile of Egyptian moringa Seed oils. Moringa seeds were irradiated using 60Co at dose levels of 0.0 (control), 5, 10 and 15 kGy and oil was extracted from unirradiated and irradiated samples. Results showed that the oil percentage and density were almost unaffected. Irradiation reduced the iodine value, whereas the acid and saponification values were increased in all irradiated samples. The oil was found to contain high levels of unsaturated fatty acids, especially an omega‐9‐fatty acid (oleic) (up to 76.29 %) at a dose level of 15 kGy. Also at the same dose level, the dominant saturated acids were palmitic, stearic acid and arachidic (the three up to 12.66 %). GC–MS revealed the presence of different compounds (more than 50) in the moringa oil extract, among them alkaloids, terpenoids steroids, saturated and unsaturated fatty acids, aromatic and aliphatic hydrocarbons and polyphenolic compounds. Phenolic and falvonoid were significantly increased by increasing irradiation dose levels. Also, the antioxidant activity of irradiated seed oil increased by increasing the phenolic and flavonoid contents. Moringa oleifera could be grown by wide scale production as a potentially valuable crop. However, isolation of individual compounds and their biological activities needs to be covered in future to enhance its pharmacological importance and to open new avenues of research.  相似文献   

13.
《分离科学与技术》2012,47(6):875-885
The adsorption of Zn(II) and Cu(II) ions onto two dry macrophytes used as biosorbents was investigated in batch systems. All single and binary metal sorption experiments using Egeria densa and Eicchornia crassipes biomasses as biosorbents were performed under constant shaking, at pH 5, with mixed grain size, and drying and sorption temperatures of 30°C. A 20–45 min equilibrium time range was attained with E. densa, whereas a 30–60 min equilibrium time was achieved with E. crassipes. It was also found that the overall adsorption kinetic data was best described by the pseudo second-order kinetic model, and that the intra-particle diffusion model was involved in the sorption process. An extended-to-multi-component Langmuir-type isotherm model and a parameter identification procedure based on the PSO method have been effectively used for the reproduction of the experimental data and the prediction of the maximum adsorption capacities of Zn(II) and Cu(II) ions in a binary metal ion solution. Finally, E. densa and E. crassipes biomasses exhibited opposite metal adsorption affinity order in the Zn(II)-Cu(II) binary system.  相似文献   

14.
Lignocellulosic coconut wastes such as pith and fiber, which are abundantly available and cheap, have the potential of being used as low-cost biosorbents for heavy metal ion removal. In this study, pristine (CF-Pristine) and NaOH-treated (CF-NaOH) coconut fibers were used as a biosorbent for Hg(II) removal from an aqueous solution. The coconut fiber biosorbent (CFB) was characterized by scanning electron microscopy (SEM) and Fourier transform-infrared (FTIR) spectroscopy. The Hg(II) sorption capacities obtained for CF-Pristine and CF-NaOH were 144.4 and 135.0 mg/g, respectively. Both the equilibrium and kinetic data of Hg(II) sorption onto CFB followed the Langmuir isotherm model and a pseudo-second-order kinetic model, respectively. A further analysis of the kinetic data suggested that the Hg(II) sorption process was governed by both intraparticle and external mass transfer processes, in which film diffusion was the rate-limiting step. These results demonstrated that both pristine- and alkali-treated coconut wastes could be potential low-cost biosorbent alternatives for the removal of Hg(II) from aqueous solutions, such as water containing Hg(II) produced in the oil and gas industry.  相似文献   

15.
BACKGROUND: This paper evaluates the use of several biosorbents for Cu removal from aqueous solutions in the absence and presence of ethylenediaminetetraacetic acid (EDTA). The objective was to determine the applicability of the sorption process after conventional physicochemical wastewater treatment, or as primary treatment, replacing the physicochemical process. RESULTS: Fixed‐bed experiments were performed at Cu influent concentrations of 2 and 20 mg dm?3 and EDTA doses between 0 and 10 mg dm?3. At low Cu concentration without EDTA, Cu uptake capacity followed the order Posidonia oceanica > chitosan > chitin > Scharlau AC > Darco AC, with a maximum, at C/C0 = 0.2, of 23.2 mg g?1. In the presence of EDTA, Cu was detected in the effluent from the beginning of the operation, except for the activated carbons and chitosan at low EDTA doses. At higher EDTA doses, the activated carbons showed the best performance. Uptakes at Cu concentration of 20 mg dm?3 without EDTA were 51.6 (Posidonia oceanica) and 41.4 mg g?1 (chitosan) at C/C0 = 0.2. CONCLUSION: A sequence of one fixed bed with Posidonia oceanica followed by another with Scharlau AC should be an alternative to Cu precipitation, with Cu effluent concentration lower than 0.5 mg dm?3 for more than 350 pore volumes. Copyright © 2007 Society of Chemical Industry  相似文献   

16.
BACKGROUND: Phosphate is one of the main contaminants responsible for the eutrophication of surface waters. In developing countries, algae blooming in lakes have threatened the quality of drinking water due to the lack of proper management of phosphate‐containing wastewaters from mining sites and industry. MAJOR RESULTS: The sorption behaviour of phosphate on loess modified by metals (Zn(II), Cu(II) and Pb(II)) was investigated in this paper. Zn(II) and Cu(II) sorption on the loess was attributed to the constituent silicate minerals while the sorption of Pb(II) was assigned to natural carbonate in the loess. The sorption affinity of phosphate towards the modified sorbent was as follows: Pb(II) (221.3–832.2 L g−1) > Cu(II) (20.26 L g−1) > Zn(II) (0.77–1.90 L g−1) > loess (0.11 L g−1) with regard to the partition coefficient. The sorption isotherms were well fitted by an extended Henry's law with multi‐linearity. Several factors including metal loading, pH, sorbent dosage and temperature were investigated and all were found to correlate positively with phosphate sorption. The enthalpy and entropy changes during phosphate sorption on Pb(II) loaded loess were predicted as 14.32 kJ mol−1 and 128.45 J mol−1 K−1, respectively. The sorption mechanism for phosphate on Pb(II) doped loess was investigated by FT‐IR spectra from which the sorption was attributed to chemical bonding with lead carbonate and physisorption with surface adsorbed phosphate as well as diffusion through micropores into the sorbent. CONCLUSIONS: Pb(II) loaded loess shows the best performance for phosphate removal from aqueous solution. The optimum conditions for sorption were pH = 9.5, lead modified loess sorbent dosage = 10 g L−1, temperature = 35 °C and Pb(II) loading 295 mg g−1. Copyright © 2008 Society of Chemical Industry  相似文献   

17.
The sorption of lead and cadmium ions on hybrid pectin-based biosorbents containing gellan, carob, and xanthan gum has been studied. The rate constant of the metal ions’ sorption on hybrid P + X beads (analyzed with the two kinetic models: pseudo-first-order and pseudo-second–order models) is at least two times higher than obtained on other pectin-based sorbents. The Langmuir equation fits experimental data better than Freundlich model. A greater equilibrium constant B for lead(II) than cadmium(II) indicates a stronger bond between Pb(II) and pectin-based beads. Prepared hybrid materials are promising biosorbents for heavy metals’ removal from waste waters.  相似文献   

18.
The efficiency of indigenous functionalized sorbent (sawdust functionalized with polyaniline) was compared with synthetic functionalized sorbents (Dowex functionalized with 8-hydroxyquinoline (Dowex-8HQ) and α-nitroso-β-naphthol (Dowex-αNβN)) for preconcentration and determination of Cu (II) from aqueous samples. The synthetic functionalized sorbents and indigenous functionalized sorbent were characterized using FTIR. Different parameters like pH, equilibration time and sample volume were investigated for maximum sorption of Cu (II). Isotherm studies showed that the sorption data fitted well into Langmuir isotherm for the sawdust functionalized with polyaniline. Freundlich isotherm was followed for Dowex-8HQ and Dowex-αNβN. Four types of kinetic equations were applied to the data, and it was observed that sorption of Cu (II) followed second-order kinetics. Thermodynamically, the sorption of Cu (II) on these three sorbents was found to be exothermic and spontaneous. For maximum recovery of Cu (II) from loaded sorbents, different parameters like shaking time, eluent type, concentration and volume were investigated, and 89% Cu (II) was recovered from loaded sawdust functionalized with polyaniline and Dowex-8HQ. The interference studies showed the selectivity of sawdust functionalized with polyaniline for Cu (II) in comparison to synthetic functionalized sorbents. Thus, Cu (II) can be easily removed from aqueous samples in the presence of foreign ions.  相似文献   

19.
Natural products are always in demand, especially in the food and water treatment industry, to reduce health hazards caused by the prolonged use of chemicals. Though crude seed extract of Moringa oleifera (MOCE) is used for decolouration, the protein responsible for such activity is not fully known. In this study, in silico analysis of Moringa oleifera coagulant protein (MOCP; a predominant oligomeric protein in MOCE) was undertaken to check its molecular interactions with water and soil pollutants, in order to identify the protein accountable for such activities. The molecular docking studies of MOCP with azo dyes like congo red, tartrazine) and a pesticide (dichlorodiphenyltrichloroethane) revealed a strong binding affinity (?5.66, ?5.33 and ?5.04, respectively, kJ mol?1) between the protein and the pollutants through hydrogen bonding and electrostatic interactions. Further, these results were verified in situ with MOCP, a recombinant form of MOCP (MOCRP) and MOCE against congo red (100 mg L?1) and revealed the dye removal efficiency of 63.8%, 65.7%, and 72.3%, respectively. While the jar test results of synthetic coloured water and industrial textile effluent containing congo red showed 51.6% and 58.3%. Hence, we believe that the MOCP is responsible for multiple activities of MOCE and suggest its prospective use for large‐scale treatment of drinking water and industrial effluents. © 2014 Society of Chemical Industry  相似文献   

20.
Heavy metal removal from wastewater is crucial for the proper management of discharged water from mining operations. This residual water is typically unusable for other purposes such as for human/animal, crop, or industrial consumption. Eco‐friendly adsorption materials are necessary to ensure the sustainable treatment of this wastewater. Therefore, the sorption of Cu(II), Cd(II), Pb(II), and Zn(II) ions onto chitosan–tripolyphosphate (CTPP) beads was investigated using real mining wastewater and prepared ion metal solutions. The effects of pH, contact time, temperature, selectivity, and maximum sorption capacity in successive batches at different concentrations were studied. The optimum sorption of cations, except for copper (pH 3) was found at pH 5. Equilibrium in the adsorption of all metals was reached at 24 h of contact. Studies of the maximum sorption capacity at different concentrations showed that the CTPP beads could adsorb 158, 55, 47, and 47 mg/g of Pb(II), Cu(II), Cd(II), and Zn(II), respectively. Experimental data for the sorption of Pb(II) were optimally correlated with the Langmuir model. The thermodynamic parameters such as the changes in enthalpy (ΔH0), entropy (ΔS0), and free energy (ΔG0) were determined. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45511.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号