Freundlich Isotherm
Environmental Engineering · FE Reference Handbook section
Core formulas for this FE topic
Definitions, applicability, units, assumptions and worked examples for each relation.
Worked exam-style examples
The four ways this section is written on the real exam — thoughts first, then equations, then substitution.
Freundlich isotherm for activated carbon adsorption of an organic compound Given Freundlich capacity coefficient (K_f) = 92.5000; equilibrium concentration (C_e) = 10.2000 mg/L; Freundlich intensity constant (n) = 4.3500, determine the adsorption capacity (x/m) (x_m) in mg/g.
Given
Find
adsorption capacity (x/m) (x_m), in mg/g
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except x_m is given, so isolate x_m symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 1 — schematic for Freundlich Isotherm — solve for adsorption capacity (x/m) — Freundlich Isotherm
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for x_m:
Step 3 — List the givens: Freundlich capacity coefficient (K_f) = 92.5000, equilibrium concentration (C_e) = 10.2000 mg/L, Freundlich intensity constant (n) = 4.3500.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning x_m = 157.8 mg/g to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 315.5 — kept a factor of two that cancels in the correct rearrangement.
- 78.8813 — dropped that same factor in the other direction.
- 173.5 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm
Freundlich isotherm linearized form fit to laboratory adsorption data Given equilibrium concentration (C_e) = 21.2000 mg/L; Freundlich intensity constant (n) = 2.1500; adsorption capacity (x/m) (x_m) = 72.6000 mg/g, determine the Freundlich capacity coefficient (K_f).
Given
Find
Freundlich capacity coefficient (K_f)
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except K_f is given, so isolate K_f symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 2 — schematic for Freundlich Isotherm — solve for Freundlich capacity coefficient — Freundlich Isotherm (2)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for K_f:
Step 3 — List the givens: equilibrium concentration (C_e) = 21.2000 mg/L, Freundlich intensity constant (n) = 2.1500, adsorption capacity (x/m) (x_m) = 72.6000 mg/g.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning K_f = 17.5403 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 35.0805 — kept a factor of two that cancels in the correct rearrangement.
- 8.7701 — dropped that same factor in the other direction.
- 19.2943 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm
Freundlich isotherm used to design a granular activated carbon column Given Freundlich capacity coefficient (K_f) = 14.0000; Freundlich intensity constant (n) = 4.8500; adsorption capacity (x/m) (x_m) = 24.1000 mg/g, determine the equilibrium concentration (C_e) in mg/L.
Given
Find
equilibrium concentration (C_e), in mg/L
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except C_e is given, so isolate C_e symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 3 — schematic for Freundlich Isotherm — solve for equilibrium concentration — Freundlich Isotherm (3)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for C_e:
Step 3 — List the givens: Freundlich capacity coefficient (K_f) = 14.0000, Freundlich intensity constant (n) = 4.8500, adsorption capacity (x/m) (x_m) = 24.1000 mg/g.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning C_e = 13.9335 mg/L to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 27.8671 — kept a factor of two that cancels in the correct rearrangement.
- 6.9668 — dropped that same factor in the other direction.
- 15.3269 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm
Freundlich isotherm for activated carbon adsorption of an organic compound Given Freundlich capacity coefficient (K_f) = 9.0000; equilibrium concentration (C_e) = 29.5000 mg/L; Freundlich intensity constant (n) = 2.9500, determine the adsorption capacity (x/m) (x_m) in mg/g.
Given
Find
adsorption capacity (x/m) (x_m), in mg/g
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except x_m is given, so isolate x_m symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 4 — schematic for Freundlich Isotherm — solve for adsorption capacity (x/m) (case 2) — Freundlich Isotherm (4)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for x_m:
Step 3 — List the givens: Freundlich capacity coefficient (K_f) = 9.0000, equilibrium concentration (C_e) = 29.5000 mg/L, Freundlich intensity constant (n) = 2.9500.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning x_m = 28.3457 mg/g to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 56.6914 — kept a factor of two that cancels in the correct rearrangement.
- 14.1729 — dropped that same factor in the other direction.
- 31.1803 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm
Freundlich isotherm linearized form fit to laboratory adsorption data Given equilibrium concentration (C_e) = 32.5000 mg/L; Freundlich intensity constant (n) = 1.2000; adsorption capacity (x/m) (x_m) = 40.9000 mg/g, determine the Freundlich capacity coefficient (K_f).
Given
Find
Freundlich capacity coefficient (K_f)
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except K_f is given, so isolate K_f symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 5 — schematic for Freundlich Isotherm — solve for Freundlich capacity coefficient (case 2) — Freundlich Isotherm (5)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for K_f:
Step 3 — List the givens: equilibrium concentration (C_e) = 32.5000 mg/L, Freundlich intensity constant (n) = 1.2000, adsorption capacity (x/m) (x_m) = 40.9000 mg/g.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning K_f = 2.2481 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 4.4963 — kept a factor of two that cancels in the correct rearrangement.
- 1.1241 — dropped that same factor in the other direction.
- 2.4729 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm
Freundlich isotherm used to design a granular activated carbon column Given Freundlich capacity coefficient (K_f) = 73.0000; Freundlich intensity constant (n) = 1.2000; adsorption capacity (x/m) (x_m) = 62.9000 mg/g, determine the equilibrium concentration (C_e) in mg/L.
Given
Find
equilibrium concentration (C_e), in mg/L
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except C_e is given, so isolate C_e symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 6 — schematic for Freundlich Isotherm — solve for equilibrium concentration (case 2) — Freundlich Isotherm (6)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for C_e:
Step 3 — List the givens: Freundlich capacity coefficient (K_f) = 73.0000, Freundlich intensity constant (n) = 1.2000, adsorption capacity (x/m) (x_m) = 62.9000 mg/g.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning C_e = 0.8364 mg/L to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1.6727 — kept a factor of two that cancels in the correct rearrangement.
- 0.4182 — dropped that same factor in the other direction.
- 0.9200 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm
Freundlich isotherm for activated carbon adsorption of an organic compound Given Freundlich capacity coefficient (K_f) = 96.0000; equilibrium concentration (C_e) = 19.9000 mg/L; Freundlich intensity constant (n) = 3.9500, determine the adsorption capacity (x/m) (x_m) in mg/g.
Given
Find
adsorption capacity (x/m) (x_m), in mg/g
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except x_m is given, so isolate x_m symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 7 — schematic for Freundlich Isotherm — solve for adsorption capacity (x/m) (case 3) — Freundlich Isotherm (7)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for x_m:
Step 3 — List the givens: Freundlich capacity coefficient (K_f) = 96.0000, equilibrium concentration (C_e) = 19.9000 mg/L, Freundlich intensity constant (n) = 3.9500.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning x_m = 204.7 mg/g to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 409.4 — kept a factor of two that cancels in the correct rearrangement.
- 102.3 — dropped that same factor in the other direction.
- 225.2 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm
Freundlich isotherm linearized form fit to laboratory adsorption data Given equilibrium concentration (C_e) = 21.4000 mg/L; Freundlich intensity constant (n) = 4.0500; adsorption capacity (x/m) (x_m) = 159.0 mg/g, determine the Freundlich capacity coefficient (K_f).
Given
Find
Freundlich capacity coefficient (K_f)
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except K_f is given, so isolate K_f symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 8 — schematic for Freundlich Isotherm — solve for Freundlich capacity coefficient (case 3) — Freundlich Isotherm (8)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for K_f:
Step 3 — List the givens: equilibrium concentration (C_e) = 21.4000 mg/L, Freundlich intensity constant (n) = 4.0500, adsorption capacity (x/m) (x_m) = 159.0 mg/g.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning K_f = 74.6277 to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 149.3 — kept a factor of two that cancels in the correct rearrangement.
- 37.3138 — dropped that same factor in the other direction.
- 82.0904 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm
Freundlich isotherm used to design a granular activated carbon column Given Freundlich capacity coefficient (K_f) = 58.5000; Freundlich intensity constant (n) = 4.7000; adsorption capacity (x/m) (x_m) = 153.1 mg/g, determine the equilibrium concentration (C_e) in mg/L.
Given
Find
equilibrium concentration (C_e), in mg/L
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except C_e is given, so isolate C_e symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 9 — schematic for Freundlich Isotherm — solve for equilibrium concentration (case 3) — Freundlich Isotherm (9)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for C_e:
Step 3 — List the givens: Freundlich capacity coefficient (K_f) = 58.5000, Freundlich intensity constant (n) = 4.7000, adsorption capacity (x/m) (x_m) = 153.1 mg/g.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning C_e = 91.9922 mg/L to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 184.0 — kept a factor of two that cancels in the correct rearrangement.
- 45.9961 — dropped that same factor in the other direction.
- 101.2 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm
Freundlich isotherm for activated carbon adsorption of an organic compound Given Freundlich capacity coefficient (K_f) = 61.5000; equilibrium concentration (C_e) = 8.4000 mg/L; Freundlich intensity constant (n) = 4.3000, determine the adsorption capacity (x/m) (x_m) in mg/g.
Given
Find
adsorption capacity (x/m) (x_m), in mg/g
Start with the thinking
- The governing relation printed in this handbook section is Freundlich Isotherm.
- Everything except x_m is given, so isolate x_m symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- The Freundlich isotherm relates adsorption capacity to equilibrium concentration for activated carbon adsorption in a linearized form.
Figure 10 — schematic for Freundlich Isotherm — solve for adsorption capacity (x/m) (case 4) — Freundlich Isotherm (10)
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange symbolically for x_m:
Step 3 — List the givens: Freundlich capacity coefficient (K_f) = 61.5000, equilibrium concentration (C_e) = 8.4000 mg/L, Freundlich intensity constant (n) = 4.3000.
Step 4 — Substitute the given values:
Step 5 — Evaluate:
Step 6 — Check: returning x_m = 100.9 mg/g to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 201.8 — kept a factor of two that cancels in the correct rearrangement.
- 50.4422 — dropped that same factor in the other direction.
- 111.0 — rounded an intermediate value before the final step.
Reference: FE Handbook — Freundlich Isotherm