Precipitate and adsorbing colloid flotation of dissolved copper, lead and zinc ions (original) (raw)
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Minerals Engineering, 1997
The removal of Zn, Cu and Ni ions, from diluted solutions, by the adsorptive particulate flotation (APF) process, was studied at laboratory scale. Zeolite (Chabazite) fines, in small concentrations, were used as the particulate sorbing for the metal ions and dissolved air flotation was employed for the solid/liquid separation of the loaded "carrier % Results showed almost complete removal (>98 %) of the heavy metal ions using Fe(OH) 3 precipitates to "aggregate" the carrier (coprecipitation). The process efficient: depended on solution and interfacial chemistry and aggregation effectiveness. The potential of APF in the field of effluent treatment is discussed. © 1997 Published by
Processes, 2021
This paper presents the results of investigations concerning the simultaneous removal of Al(III), Cu(II), and Zn(II) from dilute aqueous solutions using ion and precipitate flotation methods. The effects of initial solution pH, surface active substance concentration, and the gas velocity on the flotations’ efficiency and course are studied. Experimental results are discussed in terms of physicochemical aspects related to aqueous solutions of metal salts. The results indicate that satisfying simultaneous flotations of aluminum, copper and zinc species are observed if the pH value ranges between 7.0 and 9.0. It was found that an increase in collector concentration results in a decrease in the flotation rate constants. An increase in the gas velocity results in an increase in the ion and precipitate flotation rates.
Physicochemical Problems of Mineral Processing
Many industries, especially mining and metallurgy, deal with solutions containing ions. In some cases, these metal ions need to be concentrated and recovered from solutions and sometimes removed from wastewater. The ion flotation method has been applied for wastewater and water treatment, recovery of precious and platinum group metals, preconcentrating of rare earth elements, selective separation of multicomponent ions from dilute solutions, and analytical chemistry. It has been employed to separate heavy metals from a liquid phase using bubble attachment, originated in mineral processing. In these cases, ion flotation has an important place among other methods because it is a cheap and practical method. In this study, many ion flotation studies, especially applied at laboratory scale, were reviewed. This method gives very successful and promising results in removing heavy metals with toxic effects from wastewater and selective separation of metal ions from very low concentrated solutions. Ion flotation may take place in industrial scale operations with the new developments in flotation machines and collectors with better selectivity, high efficiency, lower cost, and environmental friendliness.
Modified column flotation of adsorbing iron hydroxide colloidal precipitates
International Journal of Mineral Processing, 2006
A promising technique for the removal of heavy metal ions from wastewater streams involved firstly the ions adsorption on a colloidal precipitate (carrier) and then the separation of the loaded flocs (coagula) by a modified column flotation. Here, the effluent feed and the carrier (ferric hydroxide) enter smoothly by the top of the column through a special diffuser, in counter current with rising bubbles (100-600 μm diameter) generated by using recycled water, surfactant and air suction through a venturi. High separation values of the column flotation of the carrier precipitates were achieved, despite the high superficial flow rate and the high Fe + 3 concentration utilized (N 60 mg L − 1 Fe). No rupture of colloidal carrier aggregates was observed and a low split was ensured by monitoring the concentrate (floated product) flow rate. Results indicated that best separation was attained by controlling the medium pH (for best heavy metal ion adsorption onto the carrier), followed by sodium oleate, used as "collector" and optimizing operating parameters (conditioning, flow rates, etc.). The column throughput reached 43 m h − 1 (m 3 m − 2 h − 1 ), which is about 4 times the normal capacity of DAF-dissolved air flotation unit, the most used floater in wastewater treatment. Various metals (Cu, Ni, Pb, etc.) and molybdate ions present in synthetic and real effluent were successfully removed based on this colloidal adsorbing flotation principle. The process was also applied in a pilot scale to treat an industrial electroplating wastewater. Most of toxic metals (Cu, Ni and Zn) were reduced from initial concentrations of about of 2 to 10 mg L − 1 , to below 0.5 to 1.0 mg L − 1 , meeting local municipal discharge limits (but Cd ions). It is believed that flotation separation using medium-sized bubbles has great potential as a clean water and wastewater treatment technology.
Dissolved-Air Flotation of Metal Ions
Separation Science and Technology, 1992
Metal ions (copper, nickel, zinc, and ferric ions) were separated from dilute aqueous solutions by dissolved-air flotation. The ions were either precipitated as sulfides or floated (as ions) by xanthates. Copper and nickel were selectively separated; promising results were obtained with single, binary, and ternary mixtures.
Removal of cadmium from dilute solutions by flotation
Water Science and Technology, 1995
Cadmium constitutes a priority pollutant existing in waste streams from metal plating and various other industries, The removal of this toxic metal employing the dissolved air flotation technique was investigated in laboratory batch experiments; the mechanism of precipitate flotation as the respective hydroxide was followed. Main examined parameters include: recycle ratio, pH of the solution, concentrations of added surfactant (sodium dodecyl sulphate), frother (ethanol) and cadmium. Promising results have been obtained, at the pH range between 10 and II approximately, showing the significance of flotation as a separation process in water and wastewater treatment for dilute solutions (around 10 mg/l of metal). Under the optimum conditions removal of cadmium was near to 100%, while the remaining concentration in the solution after flotation was less than 0.10 mg/l. A comparison was also attempted between two flotation techniques applying different bubble generation methods, i.e. dissolved air and dispersed air flotation. These experiments run in parallel and under the same conditions.
Removal of heavy metal ions from water using ion flotation
Environmental Technology & Innovation, 2017
The effects of different single-chain surfactants obtained by reacting cysteine with octanoyl (C8), decanoyl (C10) and dodecanoyl (C12) chloride were investigated for their use in ion flotation removal of low levels of arsenic, mercury, lead, cadmium and chromium ions from aqueous solution. Re-crystallized octanoyl-cysteine (octanoyl-cys) surfactant showed the highest removal efficiency at 99.9%, for Hg ions, using pure nitrogen gas. Successful removal results of most other ions was found to be in the range 99.1-99.7%, using either air or nitrogen gas. Characterization of the octanoyl-cys surfactant was also carried out using elemental analysis, 1 H NMR, FT-IR, melting point (MP) and critical micelle concentration (CMC) determination.
Removal of cadmium from a liquid effluent by ion flotation
Minerals Engineering, 1999
The removal of Cd using sodium dodecylsulfate (SDS) as collector was studied by ion flotation at laboratory scale. The effect of frothers (iso-propanol and methyl-&obutyl-carbinol (MIBC) and ionic strength (NaCI and Na2S04) were also studied, as well as characterization of the sublate by scanning electron microscopy (SEM) and the surface tension of the initial solutions. In the presence of SDS, the maximum recovery obtained at a stoichiometric metal to collector ratio of 1:3 was 99.1%, however a large volume of wet foam was produced. The best recovery (89.2%) with a dry foam was obtained at a stoichiometric ratio of 1:2. The introduction of frothers (iso-propanol and MIBC) in the system produced the highest recovery of Cd at a concentration of O.1% v/v, where the flotability was 98.8% and 97.7%for iso-propanol and MIBC respectively. An increase in magnitude of ionic strength from 4.7 x 10 -4 moles.dm -3 to 4.7 x 10 -1 moles.dm -3 significantly decreased Cd removal. Surface tension testwork indicates a decrease in flotability of Cd as surface tension drops. The SEM/EDS studies showed that the morphology of the sublate and the foam depends on the physico-chemical conditions of the system.
Recovery of Metals by Ion Flotation from Dilute Aqueous Solutions
Separation & Purification Reviews, 1991
Flotation, a process originating from l..e minerals in-Jstry, is finding its way as a separation process for dilute aqueous solut ions, with particular interest in metal ions recovery. The present paper reviews the several flotation techniques available in this area, with certain illustrative laboratory examples. Metals investigated are the following : chromium, copper, zinc, arsenic, lead, iron and germanium.