Purification, Volume 1, Issue 1 (June 2025) – 5 articles

In this study, the adsorption of a textile dye from water onto activated carbon is considered and the results of our own experimental studies on adsorption equilibrium and kinetics are presented. The adsorption isotherm and kinetic curves were found to reflect the possibility of removing the dye from water by adsorption onto activated carbon. Kinetic studies were conducted using a fixed bed of adsorbent grains. The water and dye solution flowed through the column with the adsorbent. The main aim of this study was to determine diffusion coefficients and mass transfer coefficients. The values of the external mass transfer coefficient and external diffusion coefficient of the dye in water were calculated for different flow rates of the solution, i.e., for different external resistance values. The external diffusion coefficient was D_AB = 2.21·10⁻¹⁰ m²/s and the external mass transfer coefficient was between k_c = 4.813·10⁻⁸ m/s for the lowest solution velocity in the adsorber equal to 0.0693 m/s and k_c = 5.623·10⁻⁸ m/s for the highest velocity equal to 0.185 m/s. The internal diffusion coefficient and internal mass transfer coefficient, i.e., the coefficients of the transfer from the external surface of a grain to its interior, were determined with the use of the analytical solution of the diffusion and adsorption equation For the apparent solution velocity of 0.0693 m/s the internal diffusion coefficient was D_s = 0.57·10⁻¹⁰ m²/s and the internal mass transfer coefficient was k_s = 1.89·10⁻¹⁰ m/s. For the velocity of 0.163 m/s, the internal diffusion coefficient was D_s = 0.84·10⁻¹⁰ m²/s and the internal mass transfer coefficient was k_s = 9.00·10⁻¹⁰ m/s. The results of the calculations presented are a measure of the efficiency of a given adsorbent in a given system. The values obtained for the mass transfer coefficients can be used as data for further calculations of this process. Full article

Indoor air quality (IAQ) has emerged as a critical area of research, reflecting growing concerns regarding occupant health, well-being, and comfort in enclosed environments. The increasing complexity of modern indoor spaces, coupled with rapid advancements in sensing technologies and data analysis methodologies, has intensified scientific interest in effective IAQ assessment and management. This review aims to examine current technologies and methodologies for monitoring key indoor air quality indicators. Furthermore, it offers practical recommendations for enhancing IAQ in diverse built environments and explores the integration of artificial intelligence (AI) into monitoring systems. The findings underscore the potential of AI-enhanced approaches to optimize indoor environmental conditions and support proactive air quality management strategies. Full article

Crossflow membrane separation was used as a scalable downstream process for the up concentrate of low-molecular-weight peptides and for the removal of salt (NaCl) from Calanus finmarchicus hydrolysate. Membrane processes are increasingly used for various applications in both upstream and downstream processing. The C. finmarchicus hydrolysate was prepared by enzymatic hydrolysis, followed by crossflow separation. The stepwise membrane nanofiltration of hydrolysate contributed to a progressive reduction in salt in the hydrolysate. The salt concentration in the concentrates decreased by 34%, 53%, and 75%, highlighting the efficiency of the filtration process in separating NaCl from peptides. This gradual reduction in salt concentration suggests that the membrane effectively facilitated NaCl removal while retaining peptides. Briefly, 75% NaCl removal was achieved, with peptide recovery reaching 57% using an NFX membrane in crossflow filtration. Full article

This study investigates the relationship between surface properties and microstructural characteristics of photocatalytic composites and their impact on air purification efficiency. High-resolution energy-dispersive X-ray spectroscopy (EDS) mapping and mercury intrusion porosimetry (MIP) were employed to analyze photocatalyst distribution and pore structure quantitatively. The findings demonstrated a strong correlation between TiO₂ coverage on the photoactive surface and NO removal rates and between pore structure characteristics and NO₂ generation rates. Two predictive models were developed to link NOx removal rates with photocatalytic cementitious mortars’ surface and structural properties. A stepwise regression approach produced a second-degree polynomial model with an adjusted R² of 0.98 and a Mean Absolute Percentage Error (MAPE) of 8.34%, indicating high predictive accuracy. The results underscore the critical role of uniform photocatalyst distribution and optimized pore structure in enhancing NOx removal efficiency while promoting the generation of desirable products (NO₃⁻) and minimizing the formation of undesirable byproducts (NO₂). Full article