• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.41-53
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• 2013

The study is to propose the optimal separation technique of heavy metals (Pb and Zn) contaminated in soil for improving the removal efficiency by various applicable techniques. The heavy metal contaminated soil samples near abandoned mine X-1 and X-2 were used for the study. Firstly, the wet classification process was shown more than 80% of removal efficiency for lead and zinc. Meanwhile, the magnetic separation process was shown low removal efficiency for lead and zincs because those heavy metals were non-magnetic materials. For the next step, the flotation separation process was shown approximately 24.4% of removal efficiency for zinc, while the gravity concentration process was shown approximately 57% of removal efficiency for lead, and 19.9% of removal efficiency for zinc, respectively. Therefore, zinc contaminated in soil would be effectively treated by the combination technique of the wet classification and the flotation technique. Meanwhile, lead contaminated in soil would be effectively treated by the combination technique of the wet classification process and the flotation process. Furthermore, the extraction of organic matter was shown more effective with aeration, 3% of hydrogen peroxide and 3% of lime such as calcium hydroxide.

• Environmental Engineering Research
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• v.24 no.3
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• pp.363-375
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• 2019

Micellar-enhanced ultrafiltration (MEUF) is a surfactant-based separation technique and has been investigated for the removal of heavy metals from wastewater. The performance of heavy metals removal from wastewater through MEUF relies on membrane characteristics, surfactant properties, various operational parameters including operating pressure, surfactant and heavy metal concentration, pH of the solution, temperature, and presence of dissolved solutes and salts. This study presents an overview of literature related to MEUF with respect to the all significant parameters including membranes, surfactants, operating conditions and MEUF hybrid processes. Moreover, this study illustrates that MEUF is an adaptable technique in various applications. Nowadays water contamination caused by heavy metals has become a serious concern around the globe. MEUF is a significant separation technique in wastewater treatment that should be acknowledged, for the reason that removal of heavy metals contamination even at lower concentrations becomes achievable, which is evidently made known in the presented review. Hybrid processes presented the better results as compared to MEUF. Future studies are required to continue the experimental work with various combinations of surfactant and heavy metals, and to investigate for the treatment of concentrated solutions, as well as for real industrial wastewater.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.107-112
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• 2001

This work reports the application of a hollow fiber module(HFM) for Cr(VI) extraction from heavy metal salts mixed solution by using microporous hydrophobic hollow fiber module. In HFM configuration, the organic extraction used for the extraction of Cr(VI) was di-(2-ethyl hexyl) phosphoric acid(D2EHPA) diluted with n-heptane. The study of HFM includes the influence of hydrodynamic and chemical condition, i.e., the flow rate of feed solution, the time of reactive extraction, the concentration of feed solution, and the pH of aqueous phase solutions. Several experiments with synthetic solution of different mixed components system of Cr(VI) solutions established optimum condition to achieve a clean separation of Cr(VI). It was possible to separate Cr(VI) in the presence of metal salts mixed solution, such as Zn(II), Ni(II), Cu(II), and Cd(II) using the HFM technique.

• Nuclear Engineering and Technology
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• v.41 no.8
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• pp.1101-1108
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• 2009

The ocean contains around eighty elements of the periodic table and uranium is also one among them, with a uniform concentration of 3.3 ppb and a relative abundance factor of 23. With a large coastline, India has a large stake in exploiting the 4 billion tonnes of uranium locked in seawater. The development of radiation grafting techniques, which are useful in incorporating the required functional groups, has led to more efficient adsorbent preparations in various geometrical configurations. Separation based on a polymeric adsorbent is becoming an increasingly popular technique for the extraction of trace heavy metals from seawater. Radiation grafting has provided definite advantages over chemical grafting. Studies related to thermally bonded non woven porous polypropylene fiber sheet substrate characterization and parameters to incorporate specific groups such as acrylonitrile (AN) into polymer back bones have been investigated. The grafted polyacrylonitrile chains were chemically modified to convert acrylonitrile group into an amidoxime group, a chelating group responsible for heavy metal uptake from seawater/brine. The present work has been undertaken to concentrate heavy metal ions from lean solutions from constant potential sources only. A scheme was designed and developed for investigation of the recovery of heavy metal ions such as uranium and vanadium from seawater.

• Membrane and Water Treatment
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• v.15 no.3
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• pp.139-152
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• 2024

Mixed matrix membranes have gained significant recognition in the wastewater treatment industry for their effectiveness in removing dyes, proteins, and heavy metals from water sources. Researchers have developed an innovative technique to enhance properties of these membranes by incorporating amine-functionalized carbon nanotubes into the polymer matrix. This approach introduces amine functional groups onto the membrane surface, which are then modified with trimesoyl chloride and cyanuric chloride. The modified membranes are characterized by XPS to confirm successful bonding of amines with the trimesoyl chloride and cyanuric chloride. The surface charge of the modified membrane also plays a role in the modification process; the membrane modified with trimesoyl chloride has a negative surface charge, while the one modified with cyanuric chloride has a more positive charge. At the same acidic pH, the positive or negative charge of the mixed matrix membranes assists in enhancing the rejection of heavy metals. This results in improved antifouling properties for both modified membranes. The heavy metal rejection for all modified membranes is higher than for unmodified membranes, due to both adsorption and complexation abilities of the functional groups on the membrane surface with heavy metal ions. As the membrane surface functionalities increase through modification, the separation due to complexation also increases. The bulk morphology of the membrane remains unchanged, while roughness slightly increases due to the surface treatment.

• Membrane and Water Treatment
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• v.13 no.4
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• pp.201-208
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• 2022

Emulsion Liquid Membrane (ELM) is a prominent technique for the separation of heavy metal ions from wastewater due to the fast extraction and is a single-stage operation of stripping-extraction. The selection of the components (Surfactant and Carrier) of ELM is a very significant step for its preparation. In the ELM technique, the primary water- in-oil (W/O) emulsion is emulsified in water to produce water-in-oil-in-water (W/O/W) emulsion. The water in oil emulsion was prepared by mixing the membrane phase and internal phase. To prepare the membrane phase, the extractant D2EHPA (di-2-ethylhexylphosphoric acid) was used as a mobile carrier, Span-80 as a surfactant, and Paraffin as a diluent. Moreover, the internal (receiving) phase was prepared by dissolving sulphuric acid in water. Di-(2- ethylhexyl) phosphoric acid such as surfactant concentration, carrier concentration, sulphuric acid concentration in the receiving (internal) phase, agitation time (emulsion phase and feed phase), the volume ratio of the membrane phase to the receiving phase, the volume ratio of the external feed phase to the primary water-in-oil emulsion and pH of feed were studied on the percentage extraction of metal ions at 20℃. The results show that it is possible to remove 78% for As(V), 98% for Cd(II), and 99% for Pb(II). Emulsion Liquid Membrane (ELM) is a well-known technique for separating heavy metal ions from wastewater due to the fast extraction and is a single-stage operation of stripping-extraction. The selection of ELM components (Surfactant and Carrier) is a very significant step in its preparation. In the ELM technique, the primary water-in-oil (W/O) emulsion is emulsified to produce water-in-oil-in-water (W/O/W) emulsion. The water in the oil emulsion was prepared by mixing the membrane and internal phases. The extractant D2EHPA (di-2-ethylhexylphosphoric acid) was used as a mobile carrier, Span-80 as a surfactant, and Paraffin as a diluent. Moreover, the internal (receiving) phase was prepared by dissolving sulphuric acid in water. Di-(2-ethylhexyl) phosphoric acid such as surfactant concentration, carrier concentration, sulphuric acid concentration in the receiving (internal) phase, agitation time (emulsion phase and feed phase), the volume ratio of the membrane phase to the receiving phase, the volume ratio of the external feed phase to the primary water-in-oil emulsion and pH of feed were studied on the percentage extraction of metal ions at 20℃. The results show that it is possible to remove 78% for As(V), 98% for Cd(II), and 99% for Pb(II).

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.109-117
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• 1996

Removal of metal ions on the ultrafiltration membrane with micellar-enhanced with anion surfactants is a recently developed technique which can remove heavy metals and small molecular weight ions from wastewater with simple separation process and without a phase change. Above a certain concentration, so called the critical micelle con binding cationic cobalt ions and anionic surfactants, were removed by ultrafiltration membrane. The transmembrane pressure difference had a relatively small effect on the rejection coefficient of metal ions on the ultrafiltration membrane whereas the level of anionic surfactant-to-metal ratio (S/M) had a substantial effect.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.527-532
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• 2009

In this paper simulations for the impact into ceramics and/or metal materials have been discussed. To model discrete nature for fracture and damage of brittle materials, we implemented cohesive-law fracture model with a node separation algorithm for the tensile failure and Mohr-Coulomb model for the compressive loading. The drawback of this scheme is that it requires a heavy computational time. This is because new nodes are generated continuously whenever a new crack surface is created. In order to reduce the amount of calculation, parallelization with MPI library has been implemented. For the high-speed impact problems, the mesh configuration and contact calculation changes continuously as time step advances and it causes unbalance of computational load of each processor. Dynamic load balancing technique which re-allocates the loading dynamically is used to achieve good parallel performance. Some impact problems have been simulated and the parallel performance and accuracy of the solutions are discussed.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.52-57
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• 2010

Although chemical sedimentation and ion exchange are usually applied to the treatment of heavy metal ions and radioactive cations, they have some serious disadvantages like a great consumption of chemicals, the disposal of valuable metals, and the secondary pollution of soil by the solid-waste. The advanced countries recently have studied the electrochemical ion exchange, combined electrochemical reduction and ion exchange, for the development of the alternative technique. This study has been performed to investigate the optimum condition for the preparation of the nickel hexacyanoferrate (NiHCNFe) which is an electrochemical ion exchanger. NiHCNFe film was deposited on the surface of nickel plate by chemical method or electrochemical method. The morphology and composition of NiHCNFe were observed by SEM and EDS, respectively. The peak current density of NiHCNFe was measured from the cyclic voltammograms of the continuous oxidation-reduction reaction in a parallel plane ion exchange electrode reactor. It was found that the chemical preparation method was better than the electrochemical method. The concentrated NiHCNFe was apparently deposited on nickel plate when dipping in the preparing solution for 118 h, especially. It also had a best durable performance as an ion exchange electrode.