Study of basic red 12 transport through a liquid membrane cell using polypropylene nonwoven membranes in aqueous solution

This is the authors' abstract. We don't add key points for this paper.

• Polypropylene nonwoven (PP-nw) membranes facilitate dual-phase diffusion of BR12 dye. • Initial transport is rapid due to steep concentration gradients and large pores. • Secondary transport phase is slower, constrained by saturation and tortuosity. • Optimal extraction and reextraction achieved at low concentrations and neutral pH. • Time-dependent kinetic and diffusion models accurately predict BR12 behavior. This study systematically examined the transport dynamics, extraction kinetics, and reextraction behaviour of Basic Red 12 (BR12) dye using polypropylene nonwoven (PP-nw) membranes in aqueous liquid membrane (LM) systems. A dual-phase diffusion mechanism was observed in the source compartment, with an initial rapid phase (A source = 0.058 µmol L⁻¹, k₁ = 0.233 h⁻¹) at 5 mg L⁻¹, followed by a slower equilibrium-limited phase (k₁ = 0.066 h⁻¹) at 50 mg L⁻¹ due to pore saturation. Accumulation in the receiving phase followed a pseudo-first-order model, where extraction efficiency peaked at 48.70 % at 5 mg L⁻¹ with near-instantaneous initiation ( t l a g E , k i n e t i c = 8.62 × 10⁻⁸ h). Reextraction also displayed a dual-phase pattern, dominated by rapid desorption (R₁ = 77.16 %, k R₁ = 0.014 h⁻¹) and minimal slow-phase contribution (R₂ = 2.68 %) at 50 mg L⁻¹. The transport properties of BR12 are significantly influenced by pH, as reflected by clear variations in extraction efficiency and kinetic behaviour. Maximum extraction efficiency (E max = 56.58 %) was achieved at neutral pH (pH 7), where electrostatic interactions and molecular aggregation were optimally balanced. This dual-phase behaviour is especially important for real wastewater treatment, as it accounts for both rapid dye transport and the delayed release of strongly bound species, thus reflecting the complexities of industrial effluent systems.