Abstract
Water scarcity is a critical global issue, especially in arid and semi-arid regions. This study focuses on optimizing Reverse Osmosis (RO) technology for brackish water desalination in Algeria, utilizing three water sources and various configurations. An experimental system was developed to evaluate the performance of advanced thin-film composite (TFC) membranes, specifically the TW30-2540 RO membrane, by systematically varying key parameters such as pressure, temperature, and salinity to assess their impact on efficiency. The experimental data was validated using regression analysis and TRNSYS software, ensuring robust modeling of the desalination process. Results indicate that closed-circuit RO systems achieved salt rejection rates of up to 98%, despite higher energy demands, and moderate pressure settings enhanced both efficiency and short-term operational stability. Water flux increased significantly from 4.577 L/h·m2 at 360 KPa to 18.571 L/h·m2 at 960 KPa, with TDS rejection rates of 95%, 97%, and 98% for water samples 1, 2, and 3, respectively, and recovery rates reaching 9.381%. Additionally, energy consumption was minimized to 1.293 kWh/m3, underscoring the study's contribution to enhancing desalination efficiency and sustainability.
Key Words
closed-circuit configuration; desalination; reverse osmosis (RO); thin-film composite membranes; total dissolved solids (TDS)
Address
Abdelfatah Marni Sandid: Center of Research in Mechanics (CRM), BP N73B, Freres Ferrad, Ain El Bey, 25021, Constantine, Algeria
Maya Kebaili: Unit of Research in Nanosciences and Nanotechnologies (URNN), Center for Development of Advanced Technologies (CDTA), University of Ferhat Abbas Setif 1, 19000 Setif, Algeria
Abderrezak Bouchareb: Department of Materials Science, Abbes Laghrour University, PO152, 40004, Khenchela, Algeria
Abderrahmane Elmeriah: Department of Mechanical Engineering, Faculty of Sciences and Technology, University of Mustapha Stambouli Mascara, BP 305 Route de Mamounia, Mascara 29000, Mascara, Algeria
Abstract
Polyaniline (PANI)/polyethyleneimine (PEI)/graphene hydroxyl (G-OH) hybrid adsorptive membranes were fabricated through a solvent evaporation process. The membranes were used for the adsorption of chromium (Cr) and cadmium (Cd) ions from aqueous media. RSM (response surface methodology) with a Box-Behnken design matrix was used for modeling, optimization, and minimizing the number of experiments. Three crucial parameters examined in determining the optimal membrane were the concentrations of PANI, PEI, and G-OH, which were selected as independent variables. The fabricated membranes' performance was investigated using static adsorption experiments. Based on the analysis of variance (ANOVA), both models for the adsorption capacity of membrane for Cd(II) and Cr(VI) removal were statistically significant with p-values less than 0.0001.
Key Words
adsorption capacity; adsorptive membrane; heavy metals; polyaniline; response surface methodology; polyethyleneimine
Address
Elham Ghorbani, Amir Hesam Hassani: Department of Natural Resources and Environment, SR.C., Islamic Azad University, Tehran, Iran
Lobat Taghavi: Department of Natural Resources and Environment, SR.C., Islamic Azad University, P. O. Box 14515-775, Tehran, Iran
Seyed Mahmoud Mousavi: Department of Chemical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Homayon Ahmad Panahi: Department of Chemistry, CT.C., Islamic Azad University, Tehran, Iran
Abstract
This study assessed wood ash (WA), a byproduct of wood combustion, as a waste-derived adsorbent for Cd removal from synthetic solutions and real zinc smelter wastewater. Cd adsorption onto WA reached equilibrium within 3 h and was well described by the pseudo-second-order kinetic model (R2 = 0.995). The equilibrium data were more accurately described by the Langmuir model than by the Freundlich model, with a maximum adsorption capacity of 401.70 mg/g, exceeding those of many previously reported biochar and waste-derived adsorbents. Mechanistic analyses showed that Cd removal was primarily governed by ion exchange, precipitation, and surface complexation. XRF and stoichiometric analyses revealed that Ca release accounted for 31.2% of the removed Cd equivalents. XRD, FT–IR, and XPS analyses confirmed the formation of CdCO3 and Cd(OH)2, while changes in oxygen-containing functional groups indicated an additional contribution of surface complexation. Using response surface methodology on real zinc smelter wastewater containing 77.99 mg/L Cd, the study identified reaction time and WA dose as the dominant factors influencing Cd removal. Under optimized conditions of pH 3.84, 2.97 h, 9.42 g/L WA, and 133.84 rpm, the predicted Cd removal efficiency reached 100%. Regeneration tests showed limited recovery of adsorption capacity, while TCLP analysis indicated that spent Cd–WA requires appropriate post-treatment or disposal due to Cd leaching above the US EPA regulatory level. These findings demonstrate the effectiveness of WA for Cd removal from complex industrial wastewater while highlighting the importance of appropriate management of spent WA.
Key Words
box–behnken design; ion exchange; surface complexation; surface precipitation; zinc smelter wastewater
Address
Woon-Deok Seo: Department of Bioresources and Rural System Engineering, Hankyong National University, Anseong 17579, Republic of Korea
Jae-In Lee: Institute of Agricultural Environmental Science, Hankyong National University, Anseong 17579, Republic of Korea
Heejin Yang: Department of Environmental Research Institute, Ajou University, Suwon 16499, Republic of Korea/ Department of Environmental and Safety Engineering, Ajou University, Suwon, 16499, Republic of Korea
Chang-Gu Lee: Department of Environmental and Safety Engineering, Ajou University, Suwon, 16499, Republic of Korea
Young-Man Yoon: Department of Plant Life & Environmental Science, Hankyong National University, Anseong 17579,
Republic of Korea
Seong-Jik Park: Department of Bioresources and Rural System Engineering, Hankyong National University, Anseong 17579, Republic of Korea/ Institute of Agricultural Environmental Science, Hankyong National University, Anseong 17579, Republic of Korea
Abstract
The increasing amounts of synthetic dyes discharged into aquatic systems by industries pose severe environmental and health risks, and methyl orange (MO) is a particularly persistent pollutant. This study investigates biochar derived from pomegranate peel waste via pyrolysis at 650–680°C as an eco-friendly adsorbent to remove MO from aqueous solutions. The structural and surface properties of the biochar were characterized using scanning electron microscopy, Brunauer–Emmett–Teller surface area analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy coupled with energy dispersive spectroscopy. Batch adsorption experiments evaluated the influence of pH, initial dye concentration, adsorbent dosage, and temperature on MO removal efficiency. Kinetic modeling showed that the pseudo-second order model best fitted the data, while Bangham and Elovich models indicated that intraparticle diffusion and time-dependent adsorption on heterogeneous surface sites also contribute. Isotherm analysis showed good agreement with both the Langmuir and Freundlich models, and the Temkin model suggested a gradual decrease in adsorption energy with increasing surface coverage. The maximum adsorption capacity was 6.62 mg g-1. Overall, the results demonstrate that pomegranate peel-derived biochar combines surface heterogeneity, porosity, and moderate adsorption affinity, making it a promising and environmentally friendly adsorbent for dye-contaminated wastewater treatment.
Abstract
In this study, membrane filtration method was used to separate crude oil from water. The stainless steel meshes (300 and 600) were coated with reduced graphene oxide (rGO) and rGO/ZnO nanocomposites with different concentrations of 4, 8, 16, 32 and 64 mg/ml. Structural and morphological characterization of the samples was performed using X-ray diffraction pattern (XRD) and field emission scanning electron microscopy (FESEM). In order to investigate the performance of the meshes in separating crude oil from water, UV-visible spectroscopy was used. The results showed that with increasing the rGO concentration from 4 to 32 mg/ml, the intensity of the UV-vis spectrum peak decreases, which means an increase in the separation of crude oil from water. But with a further increase in the rGO concentration to 64 mg/ml, no improvement in the separation of crude oil was observed. The highest crude oil separation was obtained 32% and 56% for 300 and 600 meshes coated with 32 mg/ml rGO, respectively. In addition, the performance of membranes coated with rGO/ZnO nanocomposites at different concentrations was investigated, and the highest crude oil separation was observed at the concentration of 32 mg/ml. The highest crude oil separation for rGO/ZnO nanocomposites with ratios of 1:1, 4:1, and 8:1 coated on 300 mesh were 15%, 26%, and 32%, and for 600 mesh were 18%, 33%, and 45%, respectively. The possibility of reusing the membranes was also investigated and it was observed that it is possible to use the coated membranes several times, however with reusing the membranes, their performance in separating crude oil decreases.
