Interference of EDTA in the treatment of metal plating wastewater by biosorption

BACKGROUND: The applicability of biosorption for the treatment of metal plating wastewater is adversely affected by the presence of complexing agents. To investigate this limitation on the removal of copper(II) onto peat, batch and column experiments were carried out using EDTA as the model complexing agent. The influence of pH and copper(II):EDTA mass ratios were evaluated for copper(II) concentrations between 5 and 100 mg Cu(II) dm^?3. RESULTS: EDTA negatively affected the copper(II) uptake of peat for pH > 5. Batch and column experiments showed that copper(II)‐EDTA complexes were not sorbed by peat. The leaks of copper(II) detected from the beginning of the column operation matched the copper(II)‐EDTA concentration in the feed solutions. To overcome the interference of EDTA, a novel approach based on the combination of peat + activated carbon was proposed. Nearly complete removal of copper(II) was maintained over 70 h in the treatment of a solution containing 20 mg Cu(II) dm^?3 with 11% of copper(II)‐EDTA complexes. CONCLUSION: A new mass transport model coupling copper(II) speciation in the feed and mass transfer rate‐controlled process simulated the copper(II) breakthrough curves in the presence of EDTA and could be used to successfully predict the breakthrough point. This work demonstrated that biosorption can also be applied for the treatment of wastewater containing complexing agents with the proper combination of sorbent materials. © 2012 Society of Chemical Industry     

Modelling of Cr(VI) removal from polluted groundwaters by ion exchange

This work reports the viability and modelling of the removal of Cr(VI) from polluted groundwaters by means of ion exchange using the resin Lewatit MP‐64. Feed groundwaters that contained Cr(VI) at an average concentration of 2431 mg dm^?3 and 1187 mg dm^?3 of chloride and 1735 mg dm^?3 of sulfate as main anions were acidified to a pH of 2.0 prior to the removal process. Dynamic experiments were carried out in a fixed bed column with feed waters at flow rates in the range of 2.78 × 10^?7 m³ s^?1 to 5.55 × 10^?7 m³ s^?1. Regeneration was achieved with NaOH (2 mol dm^?3). From the experimental results, the equilibrium of the ion exchange reaction was successfully modelled, obtaining an equilibrium constant (K′_AB) = 44.90. Finally, a mass balance that included mass transfer resistances in the liquid and solid phases was developed and from the comparison between simulated and experimental data the value of the effective intraparticle diffusivity (D_s) was determined as 1.43 × 10^?12 m² s^?1. Copyright © 2004 Society of Chemical Industry     

Kinetics of removal of p-toluene sulphonic acid from concentrated solution by granular activated carbon

The removal of p-toluene sulphonic acid (p-TSA) from concentrated solution by granular activated carbon (GAC) was studied in batch experiments. The first order rate constant was found to be 5.5010 × 10^?5 s^?1 for a solution of 1000 mg dm^?3. In order to establish the rate limiting step the pore and film diffusion coefficients were calculated from the half time equations. Film diffusion was found to be rate limiting. The average value of the external mass transport rate constant was 2.91 × 10^?6 cm s^?1. The adsorption isotherm was adequately described by the Langmuir model and belongs to type ‘H’ of Giles' classification.     

Removal of 1,1′-Dimethyl-4,4′bipyridyl Dichloride from Aqueous Solution by Natural and Activated Bentonite

The sorption of 1,1′-dimethyl-4,4′bipyridilium dichloride (paraquat) on bentonite desiccated at 110°C untreated, and acid-treated with H₂SO₄ solutions over a concentration range between 0·25 M and 1·00 M , from aqueous solution at 30°C has been studied by using batch experiments. In addition, column experiments were carried out with the bentonite sample treated with the 1·00 M H₂SO₄ solution [B-A(1·00)] by using two aqueous solutions of paraquat of different concentrations (C = 29·40 mg dm⁻³ and C = 65·38 mg dm⁻³). The experimental data points have been fitted to the Langmuir equation in order to calculate the sorption capacities (X_m) of the samples; X_m values range from 1·35×10⁵ mg kg⁻¹ for the sample acid-treated with 0·375 M H₂SO₄ [B-A(0·375)] up to 1·96×10⁵ mg kg⁻¹ for the untreated bentonite [B-N]. The removal efficiency (R) has also been calculated; R values ranging from 44·61% for the [B-A(0·375)] sample up to 67·23% for B-N. The batch experiments show that the natural bentonite is more effective than the acid-treated bentonite in relation to sorption of paraquat. The column experiments show that the B-A(1·00) sample might be reasonably used in removing paraquat, the column efficiency increasing from 37·55% for the C = 65·38 mg dm⁻³ aqueous solution of paraquat up to 66·58% for the C = 29·40 mg dm⁻³ one. © 1997 SCI.     

Solvent Impregnated Resins containing Quinizarin: Preparation and Application to Batch‐mode Separation of Cd(II), Cu(II), Ni(II), and Zn(II) in Aqueous Media Prior to the Determination by Flame Atomic Absorption Spectrometry

Abstract

Preparation of a high stable solvent impregnated resins (SIR) containing 1,4‐dihydroxyanthraquinone (quinizarin, QNZ) was proposed using Amberlite XAD‐16 beads. The SIR was applied for the separation of Cd(II), Cu(II), Ni(II), and Zn(II) in aqueous media prior to the determination by flame atomic absorption spectrometry (FAAS). The optimum conditions for batch mode extraction of the above metal ions were investigated and it was found that the sorption of these metal ions from a 1000‐ml aliquots of the solution on 1.5 g of the SIR can be carried out quantitatively at pH of 9.5 and an ionic strength of 0.01 mol dm^?3. The sorbed metal ions were subsequently eluted with 10 ml 2 mol dm^?3 HCl and the eluent was subjected to FAAS. Beer's law was obeyed in the range of 9×10^?9 ?1×10^?7 mol dm^?3 for Cd(II) and Zn(II), and 9×10^?8 ?1×10^?6 mol dm^?3 for Cu(II) and Ni(II) contents. Significant interference was not observed due to the various ions, which could be found in natural water samples. The practical applicability of the method was confirmed using a synthetic certificated reference material (CRM) and spiked natural water samples.     

Batch and fixed‐bed column adsorption of Cu(II), Pb(II) and Cd(II) from aqueous solution onto functionalised SBA‐15 mesoporous silica

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     

Impact of the presence of solids on peroxidase‐catalyzed treatment of aqueous phenol

The impact of the presence of solids on the treatment of aqueous solutions of phenol using horseradish peroxidase (HRP) and hydrogen peroxide was investigated. The solids studied were silica gel, kaolin, bentonite, cellulose and peat moss. Kaolin, bentonite, cellulose and peat moss enhanced phenol transformation at pH 5.0 and 7.0 starting at concentrations of 100, 1000 or 10 000 mg dm^?3. At pH 9.0, bentonite and kaolin had negative impacts when present at 10 000 mg dm^?3 and peat moss when present at 1000 mg dm^?3 and 10 000 mg dm^?3. In the case of bentonite and peat moss, the enhancing effects at pH 7.0 were associated with the dissolved or colloidal constituents, while in the case of kaolin, the enhancing effects were due to the solid material. Freshly made bentonite suspensions inactivated the peroxidase enzyme; however aged bentonite suspensions and their supernatants did not affect enzyme stability. H₂O₂ was unstable in solutions containing peat moss constituents. Phenolic solutions treated in the presence of bentonite, kaolin and peat moss were significantly less toxic than the controls, indicating that these materials were able to interact with and partially neutralize precursors of toxic reaction products. Copyright © 2003 Society of Chemical Industry     

Sorption of caesium by complex hexacyanoferrates iv. ion exchange kinetics and mechanism of sorption by potassium copper ferrocyanide

The kinetics of caesium sorption by potassium copper ferrocyanide have been studied. Liquid film diffusion is rate controlling in very dilute solutions of caesium (3.8 × 10^?6m). The average film diffusion coefficient was found to be 1.465 × 10^?9 m² s^?1 at 20°C and the activation energy for the corresponding process was found to be 15.14 kJ mol^?1. Chemical reaction rate controls the caesium-potassium ion exchange process at a higher caesium concentration of 3.8 × 10^?3m. The shell progressive reaction model was found applicable to the sorption process. The activation energy for the caesium-potassium ion exchange reaction was measured to be 74.85 kJ mol^?1. Finally, a comparison between the theoretical and the experimental sorption profile has been made to demonstrate the validity of the theory.     

Photoelectrocatalytic humic acid degradation kinetics and effect of pH,applied potential and inorganic ions

This study addresses the removal of humic acid (HA) dissolved in an aqueous medium by a photoelectrocatalytic process. UV₂₅₄ removal and the degradation of color (Vis₄₀₀) followed pseudo‐first order kinetics. Rate constants were 1.1 × 10^?1 min^?1, 8.3 × 10^?2 min^?1 and 2.49 × 10^?2 min^?1 (R² > 0.97) for UV₂₅₄ degradation and 1.7 × 10^?1 min^?1, 6.5 × 10^?2 min^?1 and 2.0 × 10^?2 min^?1 for color removal from 5 mg dm^?3, 10 mg dm^?3 and 25 mg dm^?3 HA respectively. Following a 2 h irradiation time, 96% of the color, 98% of the humic acid and 85% of the total organic carbon (TOC) was removed from an initial 25 mg dm^?3 HA solution in the photoanode cell. Photocatalytic removal on the same photoanode was also studied in order to compare the two methods of degradation. Results showed that the photoelectrocatalytic method was much more effective than the photocatalytic method especially at high pH values and with respect to UV₂₅₄ removal. The effect of other important reaction variables, eg pH, external potential and electrolyte concentration, on the photoelectrocatalytic HA degradation was also studied. Copyright © 2003 Society of Chemical Industry     

Piperazine Functionalized Resins for Au(III), Pt(IV), and Pd(II) Sorption

The result of synthesis of anion exchangers bearing piperazine functionalities is presented in this paper. A series of new ion exchange resins was synthesized by modification of VBC/DVB copolymer with 1(2-aminoethyl)piperazine (resin 1P), 1-amino-4-methylpiperazine (resin 2P), and 1-methylpiperazine (resin 3P). Adsorption studies of gold, platinum, and palladium were conducted with batch and dynamic method from multicomponent solutions containing AuCl₄^?, PtCl₆^2?, and PdCl₄^2? in the concentration range 10 mg/dm³ to 919 mg/dm³. The resins revealed excellent sorption ability towards these metals. The greatest total sorption capacities were determined as 331 mg/g Au for 2P resin, 405 mg/g Pt for 3P resin, and 150 mg/g Pd for 1P resin. The examined 3P resin showed the best total sorption capacity 796 mg/g. Affinity studies were also conducted. The examined resin 1P revealed the greatest affinity to platinum and palladium (lgK 4.5-5) whereas resin 2P revealed the best affinity to gold where lgK were ca. 4.9.     

Treatment of wastewater containing copper,zinc, nickel and cobalt using Duolite ES‐467

Duolite ES‐467 was used to treat wastewater containing heavy metal ions. Sorption experiments were carried out at varying pH values, agitation speeds, reaction times, and metal ion and sorbent concentrations. Each of the parameters affects the sorption behaviour of individual metal ions. Copper sorption was greater compared with other metal ions such as zinc, nickel and cobalt. The presence of other metal ions affects copper sorption. Equilibrium isotherm curves were developed. These were used to predict that the metal ion concentration would be reduced from 100 to less than 1 mg dm^?3. Fixed bed tests were conducted to investigate the efficiency of Duolite ES‐467 for the selective removal of copper ions from multi‐metal solutions. Breakthrough curves were obtained using Duolite ES‐467 for solutions containing copper, nickel and copper, zinc, nickel and cobalt. Elution studies were also carried out using sulfuric acid. © 2002 Society of Chemical Industry     

Cyanide detoxification by selective ion exchange with protonated poly(4-vinyl pyridine)

In order to explore the possibility of using cross-linked poly(4-vinyl pyridine), PVP, for selective removal of cyanide in waste water by complexation of the cyanide with ferrous ion followed by ion exchange, the sorption behaviour of the anionic ferrocyanide complex (Fe(CN)₆^4-) on the resin operating in an acid salt form has been studied. The results are compared with those obtained on a conventional gel-type weak base resin, Amberlite IRA-68. The ferrocyanide complex is selectively sorbed in preference to other common ions and is readily stripped with dilute sodium hydroxide. PVP has a high sorption capacity, fast sorption kinetics and a rapid rate of regeneration, being much superior to Amberlite IRA-68 in all these respects. The sorption rate is film-diffusion controlled at low solution concentrations (< 0.8 mmol litre^?1) and particle-diffusion controlled at higher concentrations (> 0.8 mmol dm^?3). Lowering pH to ～ 1 increases the sorption of Fe(CN)₆^4? on to protonated PVP by 75% over that at pH 7, a phenomenon explained by the formation of protonated ferrocyanide species, HFe(CN)₆^3- and H₂Fe(CN)₆^2-. From column operations with 156 mg dm^?3 cyanide waste stream a capacity of 73 mg CN^? g^?1 of protonated PVP to 1 mg dm^?3 breakthrough is determined, compared to 60 mg CN^? g^?1 of protonated IRA-68.     

Removal of toxic metal ions from aqueous systems by biosorptive flotation

Biosorptive flotation was used as a combined operation for the simultaneous abstraction of nickel, copper and zinc ions from aqueous streams. Laboratory‐scale batch experiments, as well as pilot‐scale continuous experiments, have been conducted. Grape stalks, a by‐product of the winery industry, were used as sorbent material. The experimental procedure consisted of two consecutive stages: (i) biosorption, and (ii) flotation. The possibility of reusing biomass, after appropriate elution, was also examined. The main parameters examined were biomass concentration, particle size of sorbent, surfactant concentration, pH and flocculation. Flotation removals, following laboratory‐scale experiments, were found to be in the order of 100, 85 and 70% for copper, zinc and nickel, respectively. In pilot‐scale experiments, biomass sorption capacities were determined as 25 for copper, 81 for zinc and 7 µmol dm^?3 for nickel. The order of biomass affinity regarding the studied metals was Cu > Zn > Ni. Short retention time and high effectiveness suggest that biosorptive flotation is a promising treatment process for the removal of toxic metals from contaminated aqueous solutions. © 2002 Society of Chemical Industry     

Removal of linuron from water by natural and activated bentonite

The sorption of linuron on bentonite desiccated at 110°C untreated, and acid‐treated with H₂SO₄ solutions over a concentration range between 0.25 M and 1.00 M from aqueous solution at 25°C has been studied by using batch experiments. In addition, column experiments were carried out with the bentonite sample treated with the 1.00 M H ₂SO₄ solution [B‐A(1.00)] by using two aqueous solutions of linuron of different concentrations (C=4.97 mg dm⁻³ and C=7.63 mg dm⁻³ ). The experimental data points have been fitted to the Langmuir equation in order to calculate the sorption capacities (X_m) of the samples; X_m values range from 0.02 g kg⁻¹ for the untreated bentonite [B‐N] up to 0.20 g kg⁻¹ for the sample acid‐treated with the 1.00 M H₂ SO₄ solution. The removal efficiency (R ) has also been calculated; R values ranging from 15.86% for the [B‐N] sample up to 41.54% for [B‐A(1.00)]. The batch experiments show that the acid‐treated bentonite is more effective than the natural bentonite in relation to sorption of linuron. The column experiments show that the B‐A(1.00) sample might be reasonably used in removing linuron, the column efficiency increasing from 61.8% for the C=7.63 mg dm⁻³ aqueous solution of linuron up to 77.6% for the C=4.97 mg dm⁻³ one. © 1999 Society of Chemical Industry     

Use of three types of magnetic biochar in the removal of copper(II) ions from wastewaters

Three types of magnetic biochars (MBC1, MBC2, and MBC3) were synthesized from biochar using NaBH₄ as a reducing agent of Fe(II) to Fe(0) to remove copper(II) ions from different wastewaters. Based on the research it was found that removal of copper(II) ions by MBC1 occurs with a yield of 99.8% for the concentration 50 mg/dm³ and decreases to 71.7% at 200 mg/dm³. The maximum pH sorption was found at pH 5. The highest correlation coefficient values (65.55 mg/g) were obtained for the Langmuir isotherm model. Application of 0.5 mol/dm³ HNO₃ as a desorbing agent gives the highest desorption percentage 98.92%.     

Treatment of gully pot effluent containing nickel and copper with constructed wetlands in a cold climate

The aim of this study was to assess the treatment efficiencies for gully pot effluent of experimental vertical‐flow constructed wetland filters containing macrophytes and granular media of different adsorption capacities in a cold climate. For approximately 6 months, nickel nitrate and copper nitrate were added to sieved gully pot effluent in order to simulate contaminated primary treated stormwater runoff. The inflow concentrations for nickel, copper and nitrate were approximately 1.0, 1.0 and 3.7 mg dm^?3, respectively. For those filters receiving metals, an obvious breakthrough of nickel was recorded after road gritting (containing salt). Reductions of nickel, copper, biochemical oxygen demand and suspended solids were frequently insufficient compared with international secondary wastewater treatment standards (eg suspended solids <30 mg dm^?3). A further treatment step should be considered. Outflow conductivity and nickel concentrations were high due to the effect of road salting. Microbial activity was likely to be responsible for the overall filtration performance. Copyright © 2003 Society of Chemical Industry     

STUDIES OF THE HYDROUS NIOBIUM(V) OXIDE ION EXCHANGER. VII.RATE OF THE ISOTOPIC EXCHANGE OF CESIUM IONS BETWEEN THE EXCHANGER IN THE Cs+ FORM AND AQUEOUS SOLUTION

ABSTRACT

The isotopic exchange rate of Cs⁺ between hydrous niobium(V) oxide in the Cs⁺ form and aqueous solutions was determined radiochemically. The rate was controlled by the diffusion of Cs⁺ in the exchanger particle at varying pH. The diffusion coefficients at 10°C increased with pH up to pH7; from 3.0x10^?11 m²s^?1 at pH6 to 4.0×10^?11 m²s^?1 at pH7, and became constant above pH8 (5.0x10^?11 m²s^?1). While the diffusion coefficients of Na⁺ monotonously decrease with increasing pH; from 7.9×l0^?11 m²s^?1 at pH6.5 to 2.8×l0^?11 m²s^?1 at pHll. The difference in the dependence of diffusion coefficients on pH between Cs⁺ and Na⁺ was interpreted in terms of strength of interaction between counterions and ion-exchange sites since hydrous niobium(V) oxide has selectivity higher for Cs⁺ than for Na⁺.     

Fixed‐Bed Removal of Free and Complexed Ni from Synthetic and Industrial Aqueous Solutions

Abstract

This paper evaluates the application of several biosorbents for Ni removal from aqueous solutions in the absence and in the presence of EDTA. Fixed bed experiments were performed (Ni influent concentration, 2 mg dm^?3; EDTA doses, 0, 5, and 10 mg dm^?3; pH=7) to study the process feasibility as refining after conventional physicochemical treatment. In absence of EDTA, uptake capacity followed the order peat > Posidonia oceanica > chitosan > chitin ? Scharlau AC. Maximum uptakes of 8.95 mg g^?1 and 5.10 mg g^?1 were found for peat and Posidonia oceanica, respectively. In the presence of EDTA, removal capacity decreased for all biosorbents; Ni was detected in the effluent from the beginning of the operation, indicating low ability to retain Ni EDTA‐complexes. Activated carbon presented the ability to remove complexed Ni. Peat exhibited the best performance for the treatment of an industrial spill from a metal‐finishing facility, with effluent Ni concentration lower than 0.2 mg dm^?3 for more than two weeks of treatment (3500 pore volumes of treated wastewater).     

Adsorption equilibrium,thermodynamics, kinetics,mechanism and process design of zinc(II) ions onto cashew nut shell

Cashew nut shell (CNS) is an agricultural waste was investigated as a new adsorbent for the removal of zinc(II) from aqueous environment. Effects of solution pH, CNS dose, contact time, initial zinc(II) concentration and temperature on removal efficiency were tested and optimum conditions were evaluated. The equilibrium data were fitted well with Langmuir isotherm model and pseudo‐second‐order kinetic model. Langmuir monolayer adsorption capacity of CNS was examined as 24.98 mg/g. Changes in standard Gibbs free energy (?G°), standard enthalpy (?H°) and standard entropy (?S°) showed that the sorption of zinc(II) ions onto CNS are spontaneous and exothermic at 303–333 K. Sorption process was found to be controlled by both surface and pore diffusion. A batch adsorber was designed for different CNS dose to effluent volume ratios using Langmuir equation. Effective diffusivity values were found to be 1.927 × 10^?11 (10 mg/L), 2.135 × 10^?11 (20 mg/L), 2.267 × 10^?11 (30 mg/L), 2.305 × 10^?11 (40 mg/L) and 2.362 × 10^?11 (50 mg/L) m²/s. © 2011 Canadian Society for Chemical Engineering     

Modification of dextran through the grafting of N‐vinyl‐2‐pyrrolidone and studies of physicochemical phenomena in terms of metal‐ion uptake,swelling capacity,and flocculation

The optimum conditions for grafting N‐vinyl‐2‐pyrrolidone onto dextran initiated by a peroxydiphosphate/thiourea redox system were determined through the variation of the concentrations of N‐vinyl‐2‐pyrrolidone, hydrogen ion, potassium peroxydiphosphate, thiourea, and dextran along with the time and temperature. The grafting ratio increased as the concentration of N‐vinyl‐2‐pyrrolidone increased and reached the maximum value at 24 × 10^?2 mol/dm³. Similarly, when the concentration of hydrogen ion increased, the grafting parameters increased from 3 × 10^?3 to 5 × 10^?3 mol/dm³ and attained the maximum value at 5 × 10^?3 mol/dm³. The grafting ratio, add‐on, and efficiency increased continuously with the concentration of peroxydiphosphate increasing from 0.8 × 10^?2 to 2.4 × 10^?2 mol/dm³. When the concentration of thiourea increased from 0.4 × 10^?2 to 2.0 × 10^?2 mol/dm³, the grafting ratio attained the maximum value at 1.2 × 10^?2 mol/dm³. The grafting parameters decreased continuously as the concentration of dextran increased from 0.6 to 1.4 g/dm³. An attempt was made to study some physicochemical properties in terms of metal‐ion sorption, swelling, and flocculation. Dextran‐g‐N‐vinyl‐2‐pyrrolidone was characterized with infrared spectroscopy and thermogravimetric analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008