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The application of plant extracts in the green synthesis of silver nanoparticles (AgNPs) has attracted significant attention owing to their eco-friendliness and cost-effective features. However, nanoparticles synthesized from plant materials may also display unique physicochemical properties. This study described an improved synthesis process for silver nanoparticles (AgNPs) from the peel of the Citrus unshiu fruit, an agricultural waste product. In addition to evaluating the produced AgNPs' physico-chemical characteristics, the research also examines their antibacterial and cytotoxic/anticancer capabilities. The color change from yellow to dark brown was observed immediately when 20 ml of Citrus unshiu fruit peel extract was added to 0.5 g of silver nitrate. A surface plasmon resonance band at 424 nm revealed by ultra-violet spectroscopy was used as additional confirmation that AgNP had formed. The scanning electron microscope (SEM), and the transmission electron microscope (TEM), revealed spherical-shaped NPs with a mean size of 23 nm. Furthermore, X-ray diffraction (XRD) confirmed the high crystallinity of the obtained NPs while Fourier transform infrared spectroscopy (FTIR) confirmed the bioreducing capacity of the Citrus unshiu fruit peel extract. The minimum inhibitory concentration (MIC) (31.25 μg/mL) of AgNPs significantly revealed a strong dose-dependent antibacterial effect on Staphylococcus aureus and Bacillus cereus. In contrast, their impact on gram-negative bacteria, such as Escherichia coli and Salmonella typhimurium, displayed an MIC of 250 μg/mL. The assessment of cytotoxicity on human embryonic kidney cells (HEK293) and lung cancer cells (A549) through a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay revealed no detectable cytotoxic effects. The IC50 values were determined as 37.73 ± 0.34 μg/mL for HEK293 and 56.37 ± 0.73 μg/mL for A549, indicating the absence of significant adverse impacts on these cell lines. The anticancer drug doxorubicin was used as a reference standard, and had an IC50 value of 1.22 ± 0.09 and 0.76 ± 0.12 μg/mL against HEK293 and A549 cells, respectively. The results show that AgNPs synthesized from Citrus unshiu fruit peel could serve as antibacterial agents that may in the future be optimized for us in for example nanofiltration systems.

Graphene oxide has attracted many interests in the recent decade due to its unique mechanical and chemical properties. This study focuses on the modification of graphene oxide and preparation proton exchange membrane (PEM) by sulfonated poly ether ether ketone (SPEEK) as base polymer for using in MFC as a modified membrane to remove COD and electricity generation. The scanning electron microscope (SEM) images, Fourier transform infrared (FTIR) and contact angle measurements were used to verify hydrophilic properties of the synthesized membranes. First, preparation procedures and properties of sulfonated reduced graphene oxide are briefly described. Subsequently, modification of proton exchange membrane from SPEEK polymer with prepared nano particle of sulfonated reduced graphene oxide 0.5 wt. % and its operation in MFC was considered. COD removal, power density, current density and coulombic efficiency were monitored during the process operation to evaluate the MFC performance. During the process operation, COD removal, power density, current density, and coulombic efficiency were tracked to assess the MFC performance. The power density and current density, 39.43 mW/m2 and 161 mA/m2 and the columbic efficiency 48.9 % was obtained, respectively. The COD removal of 89.5 % was obtained.

In this study, the polyethersulfone (PES) membranes were established by surface modification using C, N codoped-TiO2/WO3 (LTW) photocatalytic nanocomposite to amelioration of the membrane performance in terms of antifouling and self-cleaning properties. The nanocomposite membranes were characterized by ATR-FTIR, SEM, AFM, and water contact angle (WCA). The photocatalytic membranes' performance was evaluated using assessment of the pure water flux (PWF), antifouling behavior, photoactivity, and long-term filtration. The membrane modification improved morphology and hydrophilicity of the membranes surface, contributing to the enhanced permeability (PWF of 49.65 kg/m2.h), and substantial antifouling property (FRR of 96.96 %) as well as photoactivity (94.36 % dye removal) of the optimal photocatalytic membrane (M3 membrane). The long-term filtration of the optimal membrane represented its high performance and noteworthy antifouling resistance.

FSM-16 mesoporous silica modified with metformin (FSM-16-Met) is known as a suitable additive for membrane modification in order to obtain a modified membrane with anti-fouling capability for highly efficient oily wastewater treatment. In this research, the production of polyether sulfone microfiltration membranes was done using an efficient modification process. The modified membrane with FSM-16-Met nanoparticles showed excellent fouling resistance, while maintaining a high net water transfer efficiency of more than 150 kg/m2.h without significant oil infiltration. The optimal modified membrane PES/FSM-16-Met had a high net water flux of 156.07 kg/m2.h and a low contact angle compared with the unmodified membrane (respectively 79.8 and 46.25 for the unmodified and was the modified optimum). Also, the flux recovery ratio is more than 97% and the ability to resist clogging is Rir = 79.58 and Rir = 2.13%, respectively, for unmodified and modified membranes during filtration at different concentrations of oily feed (300 and 500 mg/l). It was one of the features obtained in this study. Overall, this work provides insight into efficient polymer membrane modifications with very low oil cake layer formation on the membrane surface, which shows great potential for industrial-scale oily wastewater treatment in the future.

Abstract In this study, the FSM-16 and FSM-16 modified by metformin (FSM-16-met) additives were applied as modifiers for polyethersulfone-based membranes. The modified membranes were evaluated in terms of morphology, surface roughness, hydrophilicity, pure water flux, pore size and porosity, and resistance ability. The obtained experimental data indicated promising enhancement in permeated flux and hydrophilicity after introducing the FSM-16-met nanomaterials into the membrane texture. In the case assessment of the fabricated membranes, dye removal capability was performed using the direct red-16 and methyl orange (30 mg/L). The modified membranes showed significantly higher dye rejection ability (> 97% for direct red-16 and 95% for methyl orange) compared to the bare membrane (76% for direct red-16 and 74% for methyl orange). The antifouling evaluations were run for milk powder (1000 mg/L) filtration and the best performance was obtained for the modified membrane with 0.1wt.% FSM-16-met (FRR = 95.55 ± 1.91%, Rir = 4.45 ± 0.089%). Also, the effect of the feed pH and concentration, temperature, and membrane driving force was considered on the membrane behavior. High stability in long-term performance was also observed for the modified membrane after 25 h re-running.

Abstract Recent research proclivity is about supplying water for drinking, urban and industrial applications which is recognized as one of the most significant challenges that threaten humanity. Giving its simplicity and high efficient yield, membrane technology has been preferred compared to other separation technologies for water and wastewater treatment. In the present research, KIT-6 (KIT: Korea Advanced Institute of Science and Technology) was functionalized by H-acid to improve hydrophilic functional groups on KIT-6 surface. Different characterization tests were performed to prove the insertion of H-acid on KIT-6 (H-KIT-6), e.g., FT-IR, XRD, zeta potential and FESEM analysis. Also, the effects of different loading of KIT-6 and H-KIT-6 on the morphology, characteristics and performance of Polysulfone (PSf) nanofiltration (NF) membranes were investigated. The maximum pure water flux (30.2 kg/m2 h), the lowest irreversible fouling ratio (3.96%) and the highest flux recovery ratio (96.04%) were obtained for the membrane embedded with 0.1 wt.% H-KIT-6 (optimum membrane). Also, the performance of the synthesized membranes was evaluated by rejection of four different salts (K2SO4, MgSO4, KCl and NaCl) and heavy metal ions (As3+ and Hg2+). The NF membrane embedded with 0.1 wt.% H-KIT-6 also presented the highest rejection of different salts and heavy metal ions (As3+ = 99.85% and Hg2+ = 99.27%) compared to the others. Finally, the performance of the optimum membrane to treat a real case of Gachsaran brackish water was assessed. As a result, by applying the optimum membrane, 565 mg/l, 28 mg/l and 27 mg/l of Ca2+, SO4 2− and Mg2+ were rejected, respectively.