Removal of Copper from Aqueous Amminecopper(II) Solution by Foam Flotation

Abstract

Copper is removed from aqueous amminecopper(II) solution by adsorbing colloid flotation. Iron(III) hydroxide is used as the adsorbing carrier floc, and an anionic surfactant sodium dodecyl sulfate is used as the collector. Optimal flotations are achieved at the pH of maximum adsorption of copper on the resultant flocs. Adsorption of copper on the flocs enhances their floatability. Rapid and efficient removal of copper can be obtained by a batch operation under controlled dosing of iron(III) for samples in various concentrations of total ammonia. A two-step batch method has the advantages of higher efficiency and lower copper residue when dealing with samples of high copper concentration (>200 ppm) and low total ammonia (<0.15 M).     

Removal of Molybdate and Arsenate from Aqueous Solutions by Flotation

Abstract

Ion flotation and adsorbing colloid flotation have been studied in this paper for the effective removal of molybdenum(VI) and arsenic(V) from dilute aqueous solutions. These different flotation methods were also compared. Ion flotation using a cationic surfactant (dodecylamine) as collector, as well as adsorbing colloid flotation using ferric hydroxide as coprecipitant (or sorbent) and an anionic surfactant (sodium dodecyl sulfate) as collector were examined. Laboratory-scale experiments were conducted in order to assess the effects of the following parameters on the efficiency of the process: pH value, dosages of chemical reagents, initial concentrations of arsenic and molybdenum, and the presence of foreign anions, such as Cl^- and SO² ₄ ^-. In practical applications, ion flotation or adsorbing colloid flotation may be selected according to the concentration of arsenic, molybdenum, and also the initial [Mo]/[As] molar ratios in solution.     

Removal of Cu(II) from Aqueous Solutions by the Foam Separation Techniques of Precipitate and Adsorbing Colloid Flotation

Abstract

Experimental investigations on the removal of Cu(II) from aqueous solution were carried out through two foam separation techniques: precipitate flotation and adsorbing colloid flotation with Fe(III). The optimum pH for good removal was found to be about 9 for the former and about 7 for the latter. The effects of surfactant (sodium lauryl sulfate), foreign ions (Na⁺, Ca²⁺, NO^? ₃, and SO^2- ₄), and Al(III) addition on the efficiency of Cu(II) removal are discussed.     

The Elimination of Channeling and Foam Overturning in Continuous Mode Adsorbing Colloid Flotation with a Sodium Dodecylsulfate/Dodecanoic Acid Mixture

Abstract

The effect of hydraulic loading, surfactant concentration, and air flow rate on the removal of Cr(III), Ni(II), and Zn(II) from chromium stream electroplating wastewater by adsorbing colloid flotation using a sodium dodecylsulfate/dodecanoic acid mixture was investigated. Typically, heavy metal concentrations of 81 ppm Cr(III), 55 ppm Ni(II), and 3.3 ppm Zn(II) were reduced to 1.2 ppm Cr(III), 3.2 ppm Ni(II), and 0.05 ppm Zn(II) at a hydraulic loading of 22.9 m³/m²·h (3 L·min^?1), an air flow rate of 45.8 m³/m²·h (6 L·min^?1), 40 ppm dodecanoic acid, and 80 ppm sodium dodecylsulfate, and using a 10-cm inner diameter column. A novel mode of operation (high liquid carryover) was used whereby a large proportion of the liquid entering the column leaves the column with the foam.     

Studies on the Separation of Cadmium from Solutions by Foam Separation. II. Precipitate Flotation of Cadmium Hydroxide

Abstract

Foam separation of cadmium in relation to pH from solutions of different metal concentrations was carried out by means of lauryl sulfate. The effect of inert salt on the removal of cadmium hydroxide and cadmium cations by adsorbing colloid floation was also studied. The precipitate flotation results reflect the precipitation of the metal in the form of a hydroxide. The precipitation pH values calculated are approximately those at which cadmium removal over 50% is obtained. The presence of electrolyte has a negative effect on the results of precipitate flotation of cadmium hydroxide and adsorbing colloid flotation of cadmium cations with lauryl sulfate.     

Foam Separation of Lead(ll) and Cad mi urn (II) from Waste Water

Abstract

Foam separation techniques are evaluated to determine if they would be feasible for removing lead(II) and cadmium(II) from highly contaminated waste water. Variables such as pH, ionic strength, collector concentration, and interfering ions were studied to determine their effects on ion flotation. Increased ionic strength, calcium(II), and phosphate interference made ion flotation impractical. Precipitate flotation of lead sulfide and cadmium sulfide left approximately 0.20 ppm lead(II) and 0.08 ppm cadmium(II) in the bulk solution under optimum conditions—somewhat above the levels considered safe to release into the environment. Adsorbing colloid flotation gave excellent results; lead sulfide and cadmium sulfide were adsorbed to ferrous sulfide which was then removed by foaming with hexadecyltrimethylam-monium bromide. Lead(II) levels were reduced from 0.80 to 0.025 ppm in 34 min foaming with 15 ppm iron(III) added. Cadmium(II) levels were reduced from 1.0 to 0.008 ppm in 45 min foaming with 25 ppm iron(III) added.     

Removal of Organophosphorus Pesticides from Aqueous Solution by Using Adsorptive Bubble Separation Techniques

Abstract

Two organophosphorus pesticides, ddvp (phosphoric acid 2,2-dichlorovinyl dimethyl ester) and phorate (phosphorodithioic acid o,o-diethyl s-[(ethylthio)methyl] ester) were removed from aqueous solution by three adsorptive bubble separation techniques: air stripping, solvent sublation, and adsorbing colloid flotation. The effects of pH, flow rate, surfactant, ethanol, ionic strength, and coprecipitant concentration on the efficiency of pesticide removal were studied. Over 97% of phorate was removed in 30 min by solvent sublation, and 90% of phorate was removed in 10 min by adsorbing colloid flotation with Fe(OH)₃, floc. The separations of ddvp by these techniques were not effective.     

Adsorbing Colloid Flotation of Pb(II). Feasibility of Utilizing Streaming Current Detector

Abstract

A feasibility study was conducted to assess the application of a streaming current detector (SCD) in the flotation of dissolved heavy metals. The adsorbing colloid flotation of Pb(II) with iron oxide and sodium dodecylsulfate was injvestigated. Both zeta potential and streaming current (SC) readings of each colloidal system were measured. For colloids of goethite or of amorphous iron oxide, the results show SC changed with pH values and can be well correlated to the zeta potential. The removal of Pb(II) increased with increasing pH. Judging from the experimental results, it is proposed that when pH is at 3.0 or lower, Pb(II) is mainly removed by foam fractionation. When pH values are between 4.0 and 7.0, Pb(II) removal can be attributed to both foam fractionation and adsorbing colloid flotation. When pH values are higher than 7.0, Pb(II) is mainly removed by precipitate flotation in the form of Pb(OH)₂(s) or Pb-Fe coprecipitate. Advantages and limits of utilizing SCD in flotation processes are discussed. Preliminary results show it is feasible for SCD to be utilized in the flotation of Pb(II).     

Removal of Cadmium from Aqueous Solution Using Adsorptive Bubble Separation Techniques

Abstract

Cadmium ion was removed from aqueous solutions using adsorptive bubble separation techniques. The effect of pH, coagulant and activator concentrations, and ionic strength on separation efficiency was studied. Adsorbing colloid flotation using ferric hydroxide and aluminum hydroxide as the coprecipitant and sodium lauryl sulfate as the collector and frother was found to be very effective provided that the ionic strength of the solution was no greater than 0.01 M. The residual cadmium concentration was less than 0.02 ppm after foaming for 10 min from a solution containing 20 ppm cadmium initially. Effective separation can be achieved from solutions containing 0.1 M NaNO₃ or 0.05 M Na₂SO₄ when zinc ion is used as the activator. The results of foam flotation were compared with the zeta potential of the floc. It was found that the zeta potential of the floc decreases with increasing ionic strength of the solution. The zeta potential of the floc is more positive when activators (aluminum and zinc ions) were added, which presumably gives the floc a stronger affinity for anionic surfactant adsorption, resulting in better separation efficiency. Adsorbing colloid flotation becomes less effective with increasing inert salt concentration of the solution; this effect can be compensated for to quite a large extent with the aid of activators, and the applicability of foam separation techniques for heavy metal removal from wastewater is thus greatly extended     

Selective Separation of Cu,Zn, and As from Solution by Flotation Techniques

Abstract

The selective precipitation and flotation of copper, zinc, and arsenic ions from dilute aqueous solutions were investigated. Phase separation was accomplished effectively by the dissolved-air technique for the production of fine gas bubbles, and a short-chain xanthate was applied as the collector for copper ions, dialkyldithiocarbamate for zinc, and ferric sulfate for the pentavalent arsenic. The procedures followed were ion flotation for copper and zinc, and adsorbing colloid flotation for arsenic (without a surfactant).     

Electrical Aspects of Adsorbing Colloid Flotation. X. Pretreatments,Multiple Removals,Interferences, and Specific Adsorption

Abstract

The compatibility of the adsorbing colloid flotation of Cu(II) with Fe(OH)₃ and sodium lauryl sulfate with a variety of precipitation pretreatment techniques was studied. Procedures were developed which permitted precipitation pretreatment and effective foam flotation polishing. The interferences of glycerol, ClO₄ ^?, NO₃ ^?, C1^?, CN^?, CNS^?, F^?, SO4₄ ^2?, HPO₄ ^2?, HAsO₄ ^2?, C₂O₄ ^2?, (PO₃)₆ ^6?, and EDTA with the precipitate flotation of ferric hydroxide by sodium lauryl sulfate were studied. The simultaneous adsorbing colloid flotation of Cu(II), Pb(II), and Zn(II) with Fe(OH)₃ and sodium lauryl sulfate was found to be effective in the pH range 6 to 7 at ionic strengths below 0.1 mole/l. A model was analyzed for calculating surface potentials for floe surfaces having the charge distributed at discrete sites in the presence of electrolytes. Plots of surface potential versus adsorbable ion concentration were calculated for various values of the model parameters.     

A Rapid Adsorbing Colloid Flotation Method for the Separation of Molybdenum from Sea water

Abstract

A procedure is described whereby the molybdenum in a 500-ml seawater sample is brought to the surface in 5 min by an adsorbing colloid flotation process which utilizes iron(III) hydroxide, sodium dodecyl sulfate, and air. Statistical studies on a test series for recovery of molybdenum by means of spectrophotometric analysis show a mean recovery of 95.3% and a relative standard deviation of 2.6%.     

Removal of Cu(II) from Aqueous Solution by Oil-Water Interfacial Emulsion Technique with Adsorbing Colloids

Abstract

Experimental investigations on the removal of Cu(II) from an aqueous solution were carried out by an interfacial emulsion technique with an adsorbing colloid (Al(OH)₃, FE(OH)₃), Cu(II) from the aqueous solution was segregated into a compact emulsion between water and a water-immiscible oil phase by an interfacial emulsion technique that uses the adsorptive power of the oil-water interface. Trimethylamine was effective as a surfactant for the removal of Cu(II), and the optimum pH for the removal of Cu(II) was found at 9.0 when using Fe(OH)₃ and at 10.0 when using Al(OH)₃ as an adsorbing colloid, respectively. The effects of pH, mixing time, initial surfactant concentration, initial Fe(III) concentration, and foreign ions (Na⁺, Ca²⁺, CI^?, NO₃ ^?, HPO₄ ^2?) on the removal efficiency were investigated. The adsorption and separation mechanisms for the removal of Cu(II) by the interfacial emulsion technique of adsorbing colloids were observed.     

Effect of Al(III) as an Activator for Adsorbing Colloid Flotation

Abstract

The effect of Al(III) on adsorbing colloid flotation using Fe(OH)₃ as the coprecipitant and sodium lauryl sulfate as the collector was studied, and the results of foam separation were compared with the zeta potential of the floc before and after Al(III) being added to the solution. It was found that when Al(III) is used as an activator, the zeta potential of the floc is more positive, which presumbly gives the floc a stronger affinity for anionic surfactant adsorption, resulting in better separation efficiency. The working range of pH for an effective separation is extended and good separation efficiency can be achieved at pH values closer to neutral with the aid of Al(III). Furthermore, the separation efficiency is significantly improved for solutions containing interfering ions, such as sulfate, by using Al(III) as an activator.     

The Adsorbing Colloid Flotation of Fluoride Ion by Aluminum Hydroxide in Aqueous Media

Abstract

Up to 15.7 ppm fluoride can be removed from solution, pH 7.3 to 7.8, by adsorption onto colloidal aluminum hydroxide at a concentration of 40 ppm Al. This adsorbing colloid-adsorbed ion combination is then removed by foaming with 40 ppm sodium lauryl sulfate. After 30 min the concentration of fluoride is 0.0 ppm. The concentration of aluminum is also 0 ppm. Efficiency of removal slowly decreases with increasing ionic strength. Chloride ion interference is minimal.     

Foam Separation of Mercury(II) and Cadmium(II) from Aqueous Systems

Abstract

Mercury(II) and cadmium(II) were separated from aqueous systems by a number of batch-type precipitate flotation and adsorbing colloid flotation techniques. HgS, CdS, and Cd(OH)₂ were removed by precipitate flotation; Fe(OH)₃, Al(OH)₃, FeS, and CuS were used as adsorbing colloids. Sodium lauryl sulfate and hexadecyltrimethylammonium bromide (HTA) were used as collectors. Dependence of separation efficiency on pH and ionic strength was investigated. Floc foam flotation of both metals with CuS and HTA was found to be quite effective, resulting in residual Hg(II) levels as low as 5 ppb and residual Cd(II) levels as low as 20 ppb. Floc foam flotation of Cd(II) with FeS and HTA yielded residual Cd(II) levels as low as 10 ppb.     

Adsorbing Colloid Flotation of Zn(II) with Fe(OH)(3) and Polyelectrolytes

Abstract

It was found that zinc ion could be removed from aqueous solutions by adsorbing colloid flotation with Fe(OH)³ and sodium lauryl sulfate (SLS) provided that the ionic strength of the solution is low (containing no greater than 0.02 M NaNO³). An excess dose of iron resulted in poor separation. Three types of polyelectrolytes were used as the activators to compensate for the effect of increasing ionic strength of the solutions. Betz 1150 (a weakly cationic acrylamide copolymer) was found to be the most effective activator. The separation was effective from a solution containing NaNO³ as high as 0.7 M when Betz 1150 was used as the activator.     

Electrical Aspects of Adsorbing Colloid Flotation. Y. Nonideal Flocs and Salts

Abstract

Three methods are developed for the calculation of adsorption isotherms in precipitate and adsorbing colloid flotation. The Gouy-Chapman model is used in all three, with corrections for the effective volumes of the ions in the ionic atmosphere and of the floc particles. The theories all predict a weak dependence of adsorption isotherm on temperature and a stronger dependence on ionic strength; increasing either variable decreases the surface adsorption. The effects of film surface potential, floc zeta potential, ion and floc effective volumes, and floc-floc screening are examined.     

Solvent Sublation and Adsorptive Flotation/Sublation of Diphenyl

Abstract

Diphenyl is readily removed from aqueous systems by solvent sublation into mineral oil. The process is slightly enhanced by increasing aeration rate, added salts, and surfactants, and slightly retarded by organic solvent. A new technique, adsorptive flotation/sublation, was found to be more effective in removing diphenyl from aqueous solution than either adsorbing colloid flotation or solvent sublation. Over 99% of diphenyl can be removed from the solution in 30 min by a three-step batch process of adsorptive flotation/sublation.     

Surfactant Recovery in Adsorbing Colloid Flotation

Abstract

The displacement of surfactants from floc–water interfaces by salts is examined by statistical mechanical methods. The effect of added salts on the adsorption isotherm is exhibited, and it is found that surfactant condensed films can readily be displaced. This may markedly improve the economics of adsorbing colloid flotation by facilitating surfactant recovery. Preliminary experimental results supporting the theory are presented; Na₂CO₃ is used to displace sodium lauryl sulfate from Fe(OH)₃. The viscous drag forces on floc particles attached to rising bubbles are calculated for bubbles having diameters in the range 0 to 1 mm. At the upper end of this range these forces appear to be large enough to reduce the efficiency of foam flotation.