The separation efficiencies of aqueous solutions containing nitric salts of Zn, Cu, Fe or Pb at various pH in process of nanofiltration have been investigated experimentally. These results were used to obtain the total volume membrane charge densities, through mathematical modelling based on the Donnan–Steric partitioning Model. The experimentally obtained retention values of individual heavy metal ions varied between 36% (Zn²⁺ at pH = 2), 57% (Pb²⁺ at pH = 2), 80% (Fe³⁺ at pH = 9), and up to 97% (Cu²⁺ at pH = 9). The mathematical modelling allowed for fitting the total volume membrane charge density (X_d), which yielded values ranging from −451.90 to +900.16 mol/m³ for different non-symmetric ions. This study presents the application of nanofiltration (NF) modelling, including a consideration of each ion present in the NF system—even those originating from solutions used to adjust the pH values of the feed.

Only about 30% of coffee bean mass can be transformed into coffee drinks; thus, a larger fraction ends up as spent coffee grounds (SCGs), which have been mainly disposed of as waste. The promising direction of SCG reuse is in the cosmetic industry. The aim of this study was to prepare stable cosmetic emulsion bases to create a coffee scrub using SCGs. As the emulsion base and its stability are crucial for the production of cosmetic scrubs, eco-friendly emulsifiers based on apricot kernel oil, soya lecithin and a natural emulsifier from olive oil were included in the study. Apricot kernel oil proved to be the only stable emulsifier. The prepared bases were subjected to microscopic analysis and visual assessment of stability. Cosmetic emulsions with this emulsifier are a good base for coffee scrubs, both with glycerine and castor oil, as well as with the addition of macadamia oil. In emulsions with apricot kernel oil emulsifier and castor oil, macadamia oil increases the percentage of droplets with the smallest diameters, improving the stability of the system. Based on this study, it can be concluded that SCGs are a promising raw material for the production of scrubs with a pleasant coffee aroma.

The study presents results of rheological tests and measurements of pressure drops occurring during the flow of aqueous solutions of a mixture of drag reducing surfactants: cocamidopropyl betaine (CAPB, zwitterionic surfactant) and cocamide DEA (nonionic surfactant) through straight pipes. Tests were carried out at different CAPB/DEA weight ratios and different total concentrations of surfactants in the solution. Rheological measurements demonstrate the formation of a shear-induced structure (SIS) in the temperature range below 10 °C, which provides evidence for the presence of wormlike micelles in CAPB/DEA solutions. Drag reduction was observed during the flow of CAPB/DEA solutions in the temperature range from 3 to 45 °C, however, above 25 °C the degree of drag reduction was markedly decreased. The lower temperature limit at which drag reduction occurs depends on the CAPB and DEA weight ratio in the solution. In the range of higher temperatures, during the flow of CAPB/DEA solutions (similarly to flexible-chain polymer solutions) the onset of drag reduction is noted above a certain critical value of the Re_c,0 number, whose value depends on the temperature of the solution, diameter of the pipe and the weight ratio of surfactants. At the same time, the critical value of wall shear stress τ_w,c0 corresponding to the critical value of Re_c,0 is approximately independent of pipe diameter. The critical value of the Re_c,0 number has been linked to the clouding of CAPB/DEA solutions.

Membrane separation systems have been used in process industry since decades; however, their designs are based mainly on experienced-based and use of trial-and-error approach, especially in case of membrane selection. This chapter reviews recent advancements in the design of membrane systems used either for separation or creation of mixtures from the perspective of industry 4.0 and data management. Additionally, computer-aided design tools have been reviewed with aim of possible use in the design of membrane separation systems.