Removal of Cadmium, Copper

1
Removal of Cadmium, Copper Lead Ions from
Aqueous Solutions Using Waste Tire Crumb Rubber
as Sorbent

• Dr. Félix R. Román, and
• Diana Sánchez-Rivera
• Chemistry Deparment
• Dr. Oscar Perales-Pérez
• Engineering Science and Materials

2
Agenda

• Objectives
• Introduction
• Experimental Results
• Conclusions
• Acknowledgments
• References

3
Objectives

• The present study pretends to remove toxic metals
  (Cu, Cd, and Pb) below the EPA drinking water
  regulations using waste tire crumb rubber (WTCR)
  as sorbent.

4
Introduction

• Annually around the world 6.5 millions tons of
  tires are disposed as waste.
• By 2003, U.S.A. disposed around 290 millions of
  tires, and 80.4 have been recycled.
• The recycling activities includes uses as solid
  fuel, civil engineering projects, as ground
  rubber, for exportation, and as additive to
  modified asphalt.

5
Tire Rubber Composition
6
Why Remove Heavy Metals?
LT- long term, ST- short term, A-adults, I-Infants
7
Metal Contamination Sources

• Erosion of natural rock deposits, mine
  activities, refineries waste water, waste from
  industries of electroplating, other sewage
  producers industries, corrosion of pipes, paints,
  and from the deficient disposal of rechargeable
  batteries.

8
Experimental Design
Metals solutions range from 0,1, 5,10, to 20 mg/L
Dried rubber (10-15g/L) in contact with metals
solutions
Wash the crumb rubber 200g/L
Samples (2.5 mL) were taken at 0, 8, 24, 48, 72,
and 96 hours
Samples were acidified with nitric acid trace
metal grade
Samples are Ready for ICP-OES or ICP-MS Analysis
9
Experimental Parameters/Experiments

• Optimum pH of solution
• Rubber particle size mesh 30 (0.67mm) and mesh
  14-20 (1.5-4.0mm)
• Addition of alkaline metals such as Ca and Mg to
  simulate water hardness
• Cd, Cd and Pb mixtures

10
Cadmium Results
11
Calibration Curve for Cadmium from ICP-OES
Studies
LOD 2 ppb LOQ 5 ppb
12
Sorption Behavior of Cd(II) Ions on Mesh 30 at a
Sorbent Concentration of 10g per Liter of
Solution
Legend C/Ci Concentration of the Metal/
Initial Metal Concentration h hours ppm parts
per million Cd Cadmium
Lines are only visual guides and do not
represent a theoric model
13
Sorption Behavior of Cd(II) Ions on Mesh 30 at a
Sorbent Concentration of 15g per Liter of
Solution
14
Sorption Behavior of Cd(II) Ions on Mesh 30 at
15g/L, different pH, and Initial Metal
Concentration of 1ppm
15
Sorption Behavior of Cd(II) Ions on Mesh 14-20,
15g/L, and pH 6.0
16
Sorption Behavior of Cd(II) Ions on Mesh 30,
15g/L, and pH 6.0
17
Effect of the WTCR Size on the Removal of Cadmium
Ions from Solution
18
Effect of Calcium (50 ppm) presence during
Cadmium Sorption at Optimized Conditions
19
Calcium Remain in Solution During the Sorption
Experiments of Cadmium onto WTCR
20
Effect of the Alkaline Metals Addition on the
Removal of Cadmium Ions from Solution
21
The Effect of Ca and Mg Metals Ions on Cadmium
Sorption Behavior

• During the sorption process Cd by the WTCR the
  Ca and Mg seems not to be involved because
  experimental results show its presence mostly in
  the solutions.
• The addition of anions such Carbonate ,chloride
  and sulphate, which have the tendency to form
  ionic pairs with cadmium seems responsible for
  the significant decrese in Cd removal effeciency
  by the WTCR

22
Desorption Test of Cd(II) Ions by Acidic Contact
with 10v/v Nitric Acid with WTCR-mesh 30
23
Desorption Test Data for Cadmium Release to
Solution
24
Discussion of Cadmium Desorption Studies

• Because the difficulty of the cadmium removal at
  extreme acidic conditions a disposal of the tire
  rubber as waste is recommended when the Cd is
  sorbed only at trace levels.
• EPA regulations for solid is 85mg Cd/kg of solid.

25
Copper Results
26
Calibration Curve from ICP-OES Analysis
LOD 23 ppb LOQ 70 ppb
27
Sorption Behavior of Cu(II) Ions on Mesh 30 at
10g/L, different pH, and Initial Metal
Concentration of 1ppm
28
Sorption Behavior of Cu(II) Ions on Mesh 14-20 at
10g/L, and pH 6.0
29
Sorption Behavior of Cu(II) Ions on Mesh 30 at
10g/L, and pH 6.0
30
Effect of the WTCR Size on the Removal of Copper
Ions from Solution
31
Effect of Calcium (50 ppm) presence during
Copper Sorption at Optimize Conditions
32
Effect of the Addition of Alkaline Metals on the
Removal of Copper Ions from Solution
33
Desorption Test of Cu(II) Ions by Acidic Contact
of 10v/v Nitric Acid with WTCR-mesh 30
34
Desorption Studies Data for Copper
35
Copper Desorptions Results

• At pH 3.0 to 9.0 Cu was not realeased from the
  WTCR.
• Liberation of copper was measured from the WTCR,
  at a solution pH of 1.5 (0.105 ppm) and 10
  nitric acid sol. (1.23 ppm), all under the EPA
  drinking water regulations of 1.3 ppm.
• Our results are consistent with San Miguel et al.
  (2002) studies that determine a tire copper
  content of 68.5 ppm
• EPA regulations for Cu on solids is 4,300mg/kg.
• This study recommend the desorption process for
  the Cu removal

36
Lead Results
37
Lead Calibration Curve from ICP-MS (207m/z)
LOD 0.28 ppb LOQ 0.84 ppb
38
Sorption Behavior of Pb(II) Ions on Mesh 30 at
10g/L, different pH, and Initial Metal
Concentration of 1ppm
39
Sorption Behavior of Pb(II) Ions on Mesh 14-20 at
10g/L, and pH 6.0
40
Sorption Behavior of Pb(II) Ions on Mesh 30 at
10g/L, and pH 6.0
41
Effect of the WTCR Size on the Removal of Lead
Ions from Solution
42
Effect of Calcium (50 ppm) Presence During Lead
Sorption at Optimized Conditions
43
Effect of the Addition of Alkaline Metals on the
Removal of Lead Ions from Solution
44
Desorption Test of Pb(II) Ions by Acidic Contact
of 10v/v Nitric Acid with WTCR-mesh 30
45
Desorption Test Data for Lead Release to Solution
46
Lead Desorption Results Discussion

• At pH 3 - 9 no lead was released from the rubber.
• At pH 1.5 lead was liberated at 0.074 ppm and
  0.305 ppm when subjected to 10v/v nitric acid.
• According San Miguel et al., lead was found at 59
  ppm on the tire rubber.
• The EPA regulations for lead in solid waste is
  840 mg/kg.
• This study recommends the desorption process for
  the lead recovered.

47
LINEAR ISOTHERM

• Cs Kd Cf
• Cs concentration of solute in solid phase at
  equilibrium (mg/g)
• Cf concentration of solute on fluid phase at
  equilibrium (mg/L)
• Kd distribution equilibrium coefficient (L/g)

48
Linear Isotherm for Copper on Mesh 30 at pH 6.0,
and 298 K
49
Linear Isotherm Parameters
50
Freundlich Isotherm

• qe mg of solute per gram of adsorbent at
  equilibrium (mg/g)
• Ce concentration of adsorbate in the solution
  at equilibrium (mg/L)
• k Freundlich Isotherm Parameter
  ((mg/g)(L/mg)n ) that represents the relative
  adsorption capacity of the sorbent
• n Freundlich Parameter (g/L), the reciprocal
  number value (1/n), indicates the intensity of
  the adsorption between the adsorbate and the
  sorbent studied

51
Freundlich Isotherm for Copper on Mesh 14-20, pH
6.0, and 298K
52
Freundlich Isotherms Parameters

• Copper
• 
  
• 
  Cadmium
• Lead

53
Langmuir Isotherm

• Ce concentration of solute in solution at
  equilibrium (mg/L)
• qe mg of solute adsorbate per gram of adsorbent
  at equilibrium (mg/g)
• Qo maximum adsorption capacity for a monolayer
  up to saturation (mg/g)
• B constant related to the free energy of
  adsorption Langmuir bonding (L/mg)

54
Langmuir Isotherm for Copper on Mesh 30, at pH
6.0, and 298 K
55
Langmuir Isotherms Parameters
56
Isotherms Conclusions

• The adsorption capacity of the rubber is greater
  on terms of mg/g for PbgtCugtCd. Instead in terms
  of mol/g the order changes to CugtPbgtCd, which
  consist in their descendant order of
  electronegativities Cu (1.8), Pb (1.6), and Cd
  (1.5). Indicating that the electrostatic
  attraction between the metal and the rubber
  surface is an important part for the sorption
  process.

57
Isotherms Conclussions

• The adsorption between the rubber-metal is
  stronger for Cd than for Pb, than for Cu.
• The process is more favorable for copper, than
  for lead, than for cadmium as the parameter B
  explains.

58
Mixed Solutions of CuCd on Mesh 30, pH 6.0,
298K, and Combination Ratios of 11, 15, and 51
59
Mixed Solutions of PbCd on Mesh 30, pH 6.0,
298K, and Combination Ratios of 11, 15, and 51
60
Mixed Solutions of PbCu on mesh 30, pH 6.0,
298K, and combinations ratios of 11, 15, and 51
61
Mixed Solutions

• The sorption behavior of the metal ions are not
  significantly affected in the presence of others
  cations.
• Instead, in the presence of other anions at a
  concentration greater than 5 ppm, the formation
  of ionic pairs affected the sorption behavior of
  cadmium due to increase the radius and the
  decrease of the charge.

62
General Conclusions

• The WTCR is an excellent cheap sorbent for the
  removal of Cu, Cd, and Pb in order to comply with
  the EPA drinking water regulation at low
  concentrations.
• The addition of alkaline metals do not affected
  the removal efficiency of Pb and Cu ions.
• The sorption efficiency of Cd by WTCR is
  affected by presence of high concentrations of
  anions such as chloride and carbonate which tend
  to form ion pairs in solution.

63
Conclusions Cont.

• The recovery by desorption of lead and copper
  ions is possible up to 100 at acidic conditions
  and can be used for other purposes such as
  chemical reagents or metal industries.
• Due to its difficulty of removal, the WTCR
  contaminated with Cd could be disposed as solid
  waste if the metal content is less than solid EPA
  regulations.

64
Acknowledgments
We are grateful to Rubber Recycling and
Manufacturing Company (REMA), Puerto Rico Water
Resources and Environmental Research Institute
and US Geological Survey, Puerto Rico Solid Waste
Authority, USDA HSI Grant Program, and Toyota
Foundation for their financial support to this
research.
65
References

• Christphi, C. Axe, P. J. Environ. Eng. 2000, 1,
  66-74.
• Entezari, M.H. Ghows, N. Chamsaz, M. J.
  Hazardous Mat. 2006, B131, 84-89.
• Kaikake, K Hoaki, K. Sunada, H. Prasad, R.
  Baba, Y. Bioresearch Thecnol. 2007, 98,
  2787-2791.
• Budinova, T. Petrov, N. Razvigorova, M. Parra,
  J. Galiatsatou, P. Ind. Eng. Chem. Res. 2006,
  45, 1896-1901.
• Sekar, M. Sakthi, V. Rengaraj, S. J. of Colloid
  Interfase Science 2004, 279, 307-313.
• Gunasekara, A. S. Donovan, J. A. Xing, B.
  Chemosphere 2000, 41, 1155-1160.
• Navia, R. Fuentes, B. Diez, M. Lorber, K.
  Waste Manage. Res. 2005, 23, 260-269.
• EPA website. www.epa.gov (accessed June 2007)

66
Questions
67
Ionic Pairs Logarithm Constant Table
68
Comparison with the Literature Copper
69
Lead
70
Cadmium