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1.
A novel adsorbent for heavy metal remediation in aqueous environments   总被引:9,自引:8,他引:1  
The objective of this study was to investigate the possibility of using maize tassel as an alternative adsorbent for the removal of chromium (VI) and cadmium (II) ions from aqueous solutions. The effect of pH, solution temperature, contact time, initial metal ion concentration and adsorbent dose on the adsorption of chromium (VI) and cadmium (II) by tassel was investigated using batch methods. Adsorption for both chromium (VI) and cadmium (II) was found to be highly pH dependent compared to the other parameters investigated. Obtained results gave an adsorption capacity of 79.1 % for chromium (VI) at pH 2, exposure time of 1h at 25 °C. Maximum capacity of cadmium of 88 % was obtained in the pH range of 5-6 at 25 °C after exposure time of 1 h. The adsorption capacities of tassel for both chromium (VI) and cadmium (II) were found to be comparable to those of other commercial adsorbents currently in use for the removal of heavy metals from aqueous wastes. These results have demonstrated the immense potential of maize tassel as an alternative adsorbent for toxic metal ions remediation in polluted water and wastewater.  相似文献   

2.
The removal of poisonous Pb (II) from wastewater by different low-cost abundant adsorbents was investigated. Rice husks, maize cobs and sawdust, were used at different adsorbent/metal ion ratios. The influence of pH, contact time, metal concentration, adsorbent concentration on the selectivity and sensitivity of the removal process was investigated. The adsorption efficiencies were found to be pH dependent, increasing by increasing the solution pH in the range from 2.5 to 6.5. The equilibrium time was attained after 120 min and the maximum removal percentage was achieved at an adsorbent loading weight of 1.5 gm. The equilibrium adsorption capacity of adsorbents used for lead were measured and extrapolated using linear Freundlich, Langmuir and Temkin isotherms and the experimental data were found to fit the Temkin isotherm model.  相似文献   

3.
Pb and Co removal from paint industries effluent using wood ash   总被引:2,自引:2,他引:0  
The release of heavy metals into the environment is a worldwide major concern. Different studies have demonstrated that natural agents have a high removal capacity for divalent heavy metal ions. Wood ash is a natural adsorbent and, in comparison with others, has a very low price. In this study, the removal of heavy metals (Pb and Co) from Binalood paint industry (Kerman, Iran) effluent was investigated in batch condition. Pb and Co measurement in samples were done with atomic absorption equipment and test methods were adapted from standard methods for the examination of water and wastewater. The effect of pH and the amount of adsorbent was determined and different adsorption isotherms were also obtained. This study shows that the adsorption process follows the adsorption Langmuir isotherm. The amount of wood ash has a great role in the adsorption rate and adsorption rate increased as wood ash increased. In the study, the reactions reached equilibrium in 3 h contact time. The maximum Pb removal efficiency was 96.1 % at pH 2 with a contact time of 3 h and 100 g/L wood ash and the maximum Co removal efficiency was 99 % at pH 2 with a contact time of 3 h and 100 g/L wood ash. According to the results, wood ash is recommended as a low cost and available adsorbent to remove Pb and Co from municipal and industrial wastewaters.  相似文献   

4.
The adsorption of cadmium from simulated mining wastewater by coal waste (CW) and calcination-modified coal waste (MCW) was investigated. Effects of pH, initial concentration, particle size of adsorbent, adsorbent dosage and temperature were studied in batch experiments. The adsorption efficiency for cadmium increased with increasing pH, and the optimum pH for cadmium adsorption onto MCW and CW was 6.0 and 6.5, respectively. Kinetic experiments showed that the adsorption equilibrium was reached within 120 min and followed pseudo-second-order model well. The adsorption isotherm data fit Langmuir and Freundlich models, and the adsorption capacity of cadmium on the two adsorbents increased with increasing temperature from 298 to 318 K. MCW had a higher adsorption capacity of cadmium than CW, because calcination treatment can make CW to have more loose structure and higher specific surface area. Thermodynamic parameters, the Gibbs free energy change (?G0), enthalpy change (?H0) and entropy change (?S0), were calculated and the results showed that the adsorption of cadmium on CW and MCW was spontaneous and endothermic. Fourier transform infrared studies indicated silanol and aluminol groups were responsible for cadmium binding. The desorption results indicated that the two adsorbents could be used repeatedly at least three times without significant decrease in the adsorption capacity for cadmium. The results suggested that modified CW could have high potential as low-cost adsorbent for cadmium removal.  相似文献   

5.
This paper reports the potential of chemically treated wood chips to remove copper (II) ions from aqueous solution a function of pH, adsorbent dose, initial copper (II) concentration and contact time by batch technique. The wood chips were treated with (a) boiling, (b) formaldehyde and (c) concentrated sulphuric acid and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive analysis X-ray. pH 5.0 was optimum with 86.1, 88.5 and 93.9 % copper (II) removal by boiled, formaldehyde-treated and concentrated sulphuric acid-treated wood chips, respectively, for dilute solutions at 20 g L?1 adsorbent dose. The experimental data were analysed using Freundlich, Langmuir, Dubinin–Radushkevich and Temkin isotherm models. It was found that Freundlich and Langmuir models fitted better the equilibrium adsorption data and the adsorption process followed pseudo-second-order reaction kinetics. The results showed that the copper (II) is considerably adsorbed on wood chips and it could be an economical option for the removal of copper from aqueous systems.  相似文献   

6.
In the present study, the retention capacity of carbonaceous material obtained from the diesel engine exhaust mufflers for Cr(VI) removal has been investigated. The physicochemical properties such as density, pH of aqueous slurry, pH at point of zero charge, ash content, moisture content, volatile matter, surface area, scanning electron microscopy and electron dispersive spectroscopy of the carbonaceous material were determined. The capacity of adsorbent for removal of Cr(VI) from aqueous solution was observed under different experimental condition like contact time, initial concentration of metal ions, pH and temperatures on the adsorption capacity of the adsorbent. Maximum adsorption of Cr(VI) ions was found at low pH. The adsorption process was found to follow second-order kinetics. The rate constant was evaluated at different temperatures along with other thermodynamic parameters like activation energy, Gibbs free energy change, enthalpy change and entropy change. Both Langmuir and Freundlich isotherms were used to describe the adsorption equilibrium of carbonaceous material at different temperatures. Langmuir isotherm shows better fit than Freundlich isotherm at given conditions. The result shows that low-cost carbonaceous material from diesel engine exhaust mufflers can be efficiently used for wastewater treatment containing Cr(VI) ions.  相似文献   

7.
Granular activated carbon produced from palm kernel shell was used as adsorbent to remove copper, nickel and lead ions from a synthesized industrial wastewater.Laboratory experimental investigation was carried out to identify the effect of pH and contact time on adsorption of lead, copper and nickel from the mixed metals solution. Equilibrium adsorption experiments at ambient room temperature were carried out and fitted to Langmuir and Freundlich models. Results showed that pH 5 was the most suitable, while the maximum adsorbent capacity was at a dosage of 1 g/L, recording a sorption capacity of 1.337 mg/g for lead, 1.581 mg/g for copper and 0.130 mg/g for nickel. The percentage metal removal approached equilibrium within 30 min for lead, 75 min for copper and nickel, with lead recording 100 %, copper 97 % and nickel 55 % removal, having a trend of Pb2+ > Cu2+ > Ni2+. Langmuir model had higher R2 values of 0.977, 0.817 and 0.978 for copper, nickel and lead respectively, which fitted the equilibrium adsorption process more than Freundlich model for the three metals.  相似文献   

8.
In this study, the feasibility of using a low-cost adsorbent mixture composed of leonardite (L) and clinoptilolite (C) was evaluated by batch adsorption method using different parameters such as mixing ratio, contact time, pH, temperature, and adsorbent amount for the removal of Zn (II) ions from an aqueous solution. The adsorbents were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Additionally, leonardite–clinoptilolite mixture was analyzed by scanning electron microscopy coupled with energy dispersive X-ray. The Zn (II) adsorption along with an unprecedented adsorption capacity of 454.55 mg g?1 for unmodified natural sorbents was obtained by mixing leonardite and clinoptilolite (LC) without any pretreatment at a ratio of 3:1, using 0.1 g of sorbent at a pH 6, for 2 h of contact time. The experimental data showed a good fit for the Langmuir isotherm model. The thermodynamic parameters revealed that the present adsorption process was spontaneous and exothermic in nature (25–50 °C). The kinetic results of the adsorption showed that the Zn (II) adsorption onto the LC follows pseudo-second-order model. The resultant LC mixture has an excellent adsorption capacity of a Zn (II) aqueous solution, and data obtained may form the basis for utilization of LC as an unpretreated low-cost adsorbent for treatment of metalliferous industrial wastewater.  相似文献   

9.
Heavy metals are a threat to human health and ecosystem. These days, great deal of attention is being given to green technologies for purification of water contaminated with heavy metal ions. Biosorption is one among such emerging technologies, which utilizes naturally occurring waste materials to sequester heavy metals from wastewater. Cadmium has hazardous impact on living beings; therefore, its removal through green and economical process is an important task. The aim of the present study was to utilize the locally available Portulaca oleracea plant biomass as an adsorbent for cadmium removal from aqueous solution. The biomass was obtained after drying and grinding the portulaca leaves and stem. No chemical treatment was done on the adsorbent so that it remained green in a true sense. Batch experiments were performed at room temperature. The critical parameters studied were effects of pH, contact time, initial metal ion concentration and adsorbent dose on the adsorption of cadmium. The maximum adsorption was found to be 72 %. The kinetic data were found to best fit the pseudo-second-order equation. High adsorption rates were obtained in the initial 45 min, and adsorption equilibrium was then gradually achieved in about 100 min. Adsorption increased with increase in pH for a range 2 and 6. The equilibrium adsorption results closely followed both the Langmuir and Freundlich isotherms. The values of constants were calculated from isotherms. Results indicated that portulaca plant biomass could be developed as a potential material to be used in green water treatment devices for removal of metal ions.  相似文献   

10.
Peganum harmala seeds were assessed as biosorbent for removing Pb2+, Zn2+and Cd2+ ions from aqueous solutions. The effects of various parameters such as the aqueous solution pH, the contact time, the initial metal concentration and the amount of adsorbent in the process were investigated. The adsorption efficiencies increased with pH. It was found that about 95 % of lead, 75 % of zinc and 90 % of cadmium ions could be removed from 45 ml of aqueous solution containing 20 mg l?1 of each cation with 2 g of adsorbent at pH 4.5 after 15 min. The quantitative desorption of cadmium from adsorbent surface was achieved using 10 ml of a 0.5 M nitric acid solution. This condition was attained for lead and zinc ions with 10 ml of 1 M hydrochloric acid solution. Kinetic investigation of the process was performed by considering a pseudo-second-order model. This model predicts the chemisorption mechanism of the process. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were tested for describing the equilibrium data. It was found that the Freundlich model describes the experimental data resulting from the adsorption of lead ions. However for cadmium and zinc ions, the adsorption equilibria were interpreted with the Langmuir model.  相似文献   

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