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Colloidal Particle Adsorption

Group /input/model/unit_XXX/particle_type_ZZZ/adsorption – ADSORPTION_MODEL = COLLOIDAL_PARTICLE_ADSORPTION

For information on model equations, refer to Colloidal Particle Adsorption.

IS_KINETIC

Selects kinetic or quasi-stationary adsorption mode: 1 = kinetic, 0 = quasi-stationary. If a single value is given, the mode is set for all bound states. Otherwise, the adsorption mode is set for each bound state separately.

Type: int

Range: {0,1}

Length: 1/NTOTALBND

CPA_TEMPERATURE

Absolute temperature \(T\)

Unit: \(\mathrm{K}\)

Type: double

Range: \(> 0\)

Length: 1

CPA_IONIC_STRENGTH

Ionic strength \(I_m\) of the mobile phase. Required but ignored if CPA_IONIC_VALENCE is set (ionic strength is then computed from the pore-phase concentrations).

Unit: \(\mathrm{mol \, m^{-3}}\)

Type: double

Range: \(> 0\)

Length: 1

CPA_PERMITTIVITY

Relative permittivity \(\varepsilon\) of the solvent

Type: double

Range: \(> 0\)

Length: 1

CPA_LIGAND_DENSITY

Ligand surface density \(\Gamma_L\)

Unit: \(\mathrm{mol \, m^{-2}}\)

Type: double

Range: \(\ge 0\)

Length: 1

CPA_LIGAND_CHARGE_FULL

Charge of the fully protonated ligand \(\zeta_L\)

Type: double

Range: \(\ge 0\)

Length: 1

CPA_LIGAND_PK

Dissociation constant \(\mathrm{p}K_L\) of the ligand

Type: double

Range: \(> 0\)

Length: 1

CPA_PH_REF

Reference pH value \(\mathrm{pH}_{\mathrm{ref}}\) for the protein charge polynomial

Type: double

Range: \(\ge 0\)

Length: 1

CPA_SPECIFIC_SURFACE_AREA

Specific adsorber surface area per skeleton volume \(A_{s,i}\). Entries of non-binding components are not used and may be set to zero.

Unit: \(\mathrm{m^{-1}}\)

Type: double

Range: \(> 0\)

Length: NCOMP

CPA_RADIUS

Hydrodynamic radius \(a_i\) of each protein component. Entries of non-binding components are not used and may be set to zero.

Unit: \(\mathrm{m}\)

Type: double

Range: \(> 0\)

Length: NCOMP

CPA_EFFECTIVE_CHARGE_COEF

Matrix of coefficients \(z_{i,k}\) for the pH-dependent protein net charge. Matrix rows correspond to increasing polynomial powers \(k=0,\ldots,P\), and columns correspond to components. The first row therefore contains the constant charges \(z_{i,0}\) at \(\mathrm{pH}=\mathrm{pH}_{\mathrm{ref}}\). The net charge is

\[Z_i(\mathrm{pH}) = z_{i,0} + \sum_{k=1}^{P} z_{i,k} \left(\mathrm{pH}-\mathrm{pH}_{\mathrm{ref}}\right)^k.\]

The matrix is supplied in polynomial-order-row-major ordering. Every row must contain one value for every component, including non-binding components. Coefficients that do not apply should be set to zero.

Type: double

Range: \(\mathbb{R}\)

Length: NCOMP * (P + 1)

CPA_LAT_CHARGE

Lateral charge \(Z_{\mathrm{lat},i}\) used for computing the pairwise Yukawa coefficient \(\beta_{ij}\) in the lateral protein–protein interaction

Type: double

Range: \(\mathbb{R}\)

Length: NCOMP

CPA_DELTA_REF

Reference interaction layer thickness \(\delta_{i,\mathrm{ref}}\) Entries of non-binding components are not used and may be set to zero.

Type: double

Range: \(\ge 0\)

Length: NCOMP

CPA_DELTA_LIN

Linear coefficient \(\delta_{i,\mathrm{lin}}\) for the logarithmic interaction layer thickness parameterisation

Type: double

Range: \(\ge 0\)

Length: NCOMP

CPA_KKIN

Kinetic prefactor \(k^*_{\mathrm{kin},i}\) used to calculate the kinetic rate constant \(k_{\mathrm{kin},i}\).

Unit: \(\mathrm{s^{-1}}\)

Type: double

Range: \(\ge 0\)

Length: NCOMP

CPA_PROTON_IDX

0-based index of the proton/pH component in the mobile phase (optional, defaults to 0). The corresponding component must be non-binding (NBOUND = 0).

Type: int

Range: \(\ge 0\)

Length: 1

CPA_IONIC_VALENCE

Integer valence charge \(z_i\) for each component (optional). If provided, the ionic strength is computed from the pore-phase concentrations, and the Davies activity correction is applied to the proton component when computing pH. The vector must contain one entry per component (NCOMP values). Components that do not contribute to the ionic strength, should be assigned a charge of zero. Note that a charge of zero also disables the Davies activity correction for that component, so assigning \(z = 0\) to the proton component yields \(\gamma_{\mathrm{H}^+} = 1\).

CPA_MAXITER

Maximum number of Newton iterations for solving the adsorber surface potential \(\psi_{0,A}\) (optional, defaults to 100). If the solver does not converge, a warning is emitted and the last iterate is used.

Type: int

Range: \(\ge 1\)

Length: 1