Lasâad Dammak

Metformin, a widely prescribed antidiabetic drug, is a representative small (≈0.5–0.6 nm), hydrophilic (log P ≈ −1.43), and positively charged (pKₐ ≈ 12.4) emerging contaminant. Because its molecular size is well below the pore size of ultrafiltration membranes (>2 nm), it cannot be efficiently removed by size exclusion alone, and its high solubility and poor biodegradability further complicate conventional treatment. In this context, hybrid ceramic membranes incorporating adsorptive functionalities offer a promising alternative. However, the fouling behavior of such hybrid systems remains quantitatively uncharacterized. This study provides a quantitative assessment of flux decline and fouling reversibility in kaolin-based membranes containing 0, 5, and 10 wt.% activated carbon, evaluated for metformin removal under dead-end filtration at 4 bars, using a synthetic feed concentration of 20 mg L⁻¹ at neutral pH (≈6.8) over 60 min. Increasing AC content raises open porosity from 29.1% (M0%) to 34.2% (M5%) and 39.1% (M10%), and water permeability from 3.3 to 10.9 and 28.4 L m⁻² h⁻¹ bar⁻¹, respectively, without significantly compromising mechanical integrity (>20 MPa). The porosity enhancement is accompanied by a systematic improvement in apparent metformin removal, consistent with a contribution from carbon- and phosphorus-containing phases detected after thermal treatment (which provides abundant surface functional groups for electrostatic and π–π interactions) and is consistent with the observed improvement in permeability and apparent metformin removal. Consequently, metformin apparent removal after 60 min increases from 56.1% (M0%) to 76.2% (M5%) and 91.1% (M10%), while total fouling decreases from 38.5% to 20.5% and 11.0%, and irreversible fouling from 23.1% to 13.6% and 6.0%, respectively.

The widespread presence of stable and hazardous organic contaminants, such as synthetic dyes, in industrial effluents necessitates the development of resilient treatment strategies capable of achieving efficient degradation and decolorization of dye pollutants. Conventional treatment processes often fail to remove such recalcitrant compounds, prompting growing interest in integrated advanced systems. Photocatalytic membranes represent a promising solution due to the synergistic combination of physical separation and catalytic degradation. In this study, zinc oxide (ZnO) thin films were deposited by spin coating onto smectite–zeolite ceramic membranes (MS10/Z90), applying one (M1), two (M2), and three (M3) successive coating layers to control catalyst thickness. SEM analysis confirmed that increasing the number of layers resulted in a thicker and more homogeneous ZnO coating, while XRD revealed enhanced crystallinity and larger crystallite size. Water permeability decreased progressively from 623 L·h⁻¹·m⁻²·bar⁻¹ for the uncoated membrane to 506, 439, and 350 L·h⁻¹·m⁻²·bar⁻¹ for M1, M2, and M3, respectively. Photocatalytic performance was evaluated using Rhodamine B (RhB) (10 mg·L⁻¹) under UV irradiation (365 nm, 18 W) for 180 min, achieving degradation efficiencies of 83.0%, 94.6%, and 99.1% for M1, M2, and M3, respectively. The degradation kinetics followed a pseudo-first-order model, with rate constants increasing with catalyst layer thickness. Free radical scavenging assays confirmed that hydroxyl radicals (•OH) were the primary reactive species responsible for RhB degradation. These findings highlight the critical influence of ZnO layer thickness and mass transfer on photocatalytic performance, demonstrating the potential of ZnO-coated ceramic membranes for efficient pollutant degradation and in situ photocatalytic regeneration. Permeability measurements after photocatalytic treatment confirmed effective flux recovery, supporting the operational durability of the developed membranes.

The increasing occurrence of persistent and bio-recalcitrant organic pollutants in aquatic environments necessitates the development of more resilient and efficient water treatment technologies. Conventional treatment processes often fail to remove such stable contaminants, prompting growing interest in integrated advanced systems. Photocatalytic membranes represent a promising solution due to the synergistic combination of separation and catalytic degradation. In this study, ZnO thin films were deposited by spin coating onto smectite–zeolite ceramic membranes (MS10/Z90), with one to three layers applied to control catalyst thickness (M1–M3). SEM analysis showed that increasing the number of layers led to a thicker, more homogeneous ZnO coating, while XRD confirmed enhanced crystallinity and larger crystallite size. Water permeability decreased from 623 L.h-1.m-2.bar-1 for the uncoated MS10/Z90 membrane to 506, 439, and 350 L.h-1.m-2.bar-1 respectively for M1, M2, and M3 after coating. Photocatalytic performance was assessed using Rhodamine B (RhB) as a model dye, achieving degradation efficiencies of 83.0%, 94.6%, and 99.1% for M1, M2, and M3, respectively, following pseudo-first-order kinetics. The free radical scavenging assays confirmed that hydroxyl radicals (•OH) were responsible for the RhB conversion.These results highlight the key influence of ZnO layer thickness and mass transfer on photocatalytic performance, de-monstrating the multifunctionality of ZnO-coated membranes, including efficient pollu-tant degradation and self-cleaning capability.

This study investigates the influence of sintering temperature (850–950 °C) and almond shell content (2–10 wt.%) on the structural, mechanical, and functional properties of natural-clay-based ceramic membranes. Several membranes were prepared by incorporating different proportions of almond shell powder and 2 wt.% lime as additives and sintered under controlled thermal conditions to optimize their performance. The results demonstrate that both sintering temperature and almond shell content significantly affect membrane porosity, mechanical strength, and water permeability. Among all of the tested samples, the membrane designated MP2-900, composed of natural clay, 2 wt.% almond shell powder, and 2 wt.% lime, sintered at 900 °C, exhibited the most balanced performance. It showed high mechanical strength (≈28 MPa), low shrinkage (−1·m⁻²·bar⁻¹). When tested for the removal of crystal violet (CV) dye and paracetamol (PCT) from synthetic wastewater, the MP2-900 membrane achieved a removal efficiency of 87% for both pollutants. Overall, the MP2-900 membrane represents the optimal configuration, providing an excellent balance between mechanical robustness, porosity, and separation performance. These findings highlight the potential of sustainable clay-based ceramic membranes derived from agricultural by-products for the efficient removal of recalcitrant pollutants from wastewater.

This study investigates the simultaneous removal of copper and nickel ions from aqueous solutions using Donnan dialysis (DD), with process optimization performed through Response Surface Methodology (RSM). An initial screening identified the most effective counter-ion, guiding the experimental design toward optimal ion removal. Comparative experiments using Fujifilm Type 1 and Type 2 cation-exchange membranes revealed the superior performance of Type 1 for both metals, as confirmed by FTIR-ATR spectroscopic analysis of membrane morphology. A comprehensive experimental campaign based on a Central Composite Design (CCD) evaluated the effects of copper, nickel, and sodium ion concentrations on removal efficiency. Under optimized conditions—80 mg/L Cu²⁺, 100 mg/L Ni²⁺, and 0.06 mol/L Na⁺—the Fujifilm Type 1 membrane achieved remarkable removal rates of 99.67 ± 0.21% for copper and 98.85 ± 0.34% for nickel. These values were experimentally validated (99.45 ± 0.18% and 98.71 ± 0.27%, n = 3), showing excellent agreement between predicted and observed data and confirming the robustness of the optimized Donnan dialysis process. Overall, the results highlight Donnan dialysis as a highly efficient and environmentally sustainable approach for the removal and recovery of heavy metals from aqueous solutions using Fujifilm cation-exchange membranes.

Due to industrialization and globalization, water sources are increasingly contaminated with drugs. Among the various methods available, adsorption remains one of the most widely used techniques for drug removal. This work was to develop polysulfone (PSF) membranes integrated with montmorillonite (MMT) clay. The fabricated membranes were subsequently evaluated for their performance in removing diclofenac (DCF) from aqueous solutions. The membranes were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), contact angle measurements, as well as chemical and mechanical tests. Adding MMT at 1.5 and 2 wt% improved both hydrophilicity and mechanical strength. The natural hydrophilicity of MMT also accelerates the non-solvent/solvent exchange during phase inversion, resulting in higher porosity. These structural and surface modifications increased water permeability (16.36 L·m⁻²·h⁻¹·bar⁻¹), achieved 79% DCF removal, and enhanced antifouling properties. However, increasing the MMT clay content to 2.5 wt% caused particle aggregation, which reduced membrane performance. Fouling resistance tests with bovine serum albumin (BSA) as a model foulant showed a rejection rate of 89% and a flux recovery ratio (FRR) above 82% using an optimized membrane. These findings demonstrate that PSF/MMT membranes can serve as promising candidates for sustainable pharmaceutical wastewater treatment.

Due to industrialization and globalization, water sources are increasingly contaminated with drugs. Among the various methods available, adsorption remains one of the most widely used techniques for drug removal. This work was to develop polysulfone (PSF) membranes integrated with montmorillonite (MMT) clay. The fabricated membranes were subsequently evaluated for their performance in removing diclofenac (DCF) from aqueous solutions. The membranes were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), contact angle measurements, as well as chemical and mechanical tests. Adding MMT at 1.5 and 2 wt% improved both hydrophilicity and mechanical strength. The natural hydrophilicity of MMT also accelerates the non-solvent/solvent exchange during phase inversion, resulting in higher porosity. These structural and surface modifications increased water permeability (7.5 L.m⁻².h⁻¹.bar⁻¹), achieved 79% DCF removal, and enhanced antifouling properties. However, increasing the MMT clay content to 2.5 wt% caused particle aggregation, which reduced membrane performance. Fouling resistance tests with bovine serum albumin (BSA) as a model foulant showed a rejection rate of 89% and a flux recovery ratio (FRR) above 82% using an optimized membrane. These findings demonstrate that PSF/MMT membranes can serve as promising candidates for sustainable pharmaceutical wastewater treatment.

Ceramic membrane technology plays an important role in water and wastewater treatment. Strategic sourcing of various natural mineral resources has contributed to developing low-cost ceramic membranes. The combination with calcination of inorganic and organic wastes from domestic and agricultural activities results in fully sustainable ceramic membrane materials. In this work, ceramic membranes were developed using 96% clay, 2% almond shells and 2% lime. Sintering at 900, 950, and 1000 °C enabled the production of membranes (MK-900, MK-950, and MK-1000) in a clean, simple, and cost-effective manner. The average pore diameter and porosity decreased slightly from 44 to 42 nm and from about 30% to 26% with increasing sintering temperature, while the flexural strength increased from 25 to 40 MPa. The pure water permeability was 68 and 59 L·m⁻²·h⁻¹·bar⁻¹ for MK-900 and MK-950, respectively. Effective color (as Indigo blue) removal of 78% and 92% was observed for MK-900 and MK-950, respectively. More than 90% of the initial permeability was recovered after three cycles of dye filtration using water backwashing at each stage, indicating good fouling resistance of the prepared membranes.