Cryogel Retention Capacity for Antibiotic Modeling

The prepared cryogel samples (P1-K ÷ P9-K) were tested for their capacity to retain PG as the model antibiotic. In this respect, 0.02 mol/L PG solution was prepared by the dissolution of 0.356 g of PG into 50 mL of H₂O under magnetic stirring (200 rpm), while ensuring light protection. Each cryogel sample (approximately 0.02 g) was contacted with a volume of 10 mL of PG solution. At different time intervals (5, 15, 30, 60, 120, 180, 1440 min), the liquid phase (supernatant) was tested by UV–Vis spectroscopy at λ = 322 nm (specific wavelength of PG) [62 (link)] in order to evaluate the retention capacity of cryogels for PG (q, mmol PG/g cryogel) as given in Equation (2), where Ci (mmol/L) and Cf (mmol/L) are the initial and final concentrations of PG in the supernatant, Vs (L) and Mcryogel (g) represent the volume of the PG solution and the weight of the dried cryogel taken into account. The UV–Vis spectra were recorded using a UV–Vis ThermoScientific EVOLUTION 260 BioSpectrophotometer.
$$q=\left(Ci-Cf\right)\ast Vs/Mcryogel$$
The adsorption mechanism was analyzed using a pseudo-second-order kinetic model, described by Ho and McKay [66 (link)], as presented in Equation (3).
$$\frac{1}{q_t}=\frac{t}{q_e}+\frac{1}{k_2{q}_e^2}$$
where q_e and q_t are the adsorption capacity (mg/g) at equilibrium and at time t (min), respectively, and k₂ (g mg⁻¹ min⁻¹) is the pseudo-second-order adsorption rate constant.