Fluoride Removal Using Nanofiltration-Ranged Polyamide Thin-Film Nanocomposite Membrane Incorporated Titanium Oxide Nanosheets.

Drinking water defluoridation has attracted significant attention in the scientific community, from which membrane technology, by exploring thin film nanocomposite (TFN) membranes, has demonstrated a great potential for treating fluoride-contaminated water. This study investigates the development of a TFN membrane by integrating titanium oxide nanosheets (TiO2 NSs) into the polyamide (PA) layer using interfacial polymerization. The characterization results suggest that successfully incorporating TiO2 NSs into the PA layer of the TFN membrane led to a surface with a high negative charge, hydrophilic properties, and a smooth surface at the nanoscale. The TFN membrane, containing 80 ppm of TiO2 NSs, demonstrated a notably high fluoride rejection rate of 98%. The Donnan-steric-pore-model-dielectric-exclusion model was employed to analyze the effect of embedding TiO2 NSs into the PA layer of TFN on membrane properties, including charge density (Xd), the pore radius (rp), and pore dielectric constant (εp). The results indicated that embedding TiO2 NSs increased Xd and decreased the εp by less than the TFC membrane without significantly affecting the rp. The resulting TFN membrane demonstrates promising potential for application in water treatment systems, providing an effective and sustainable solution for fluoride remediation in drinking water.

Sustainable removal of phenol from wastewater using a biopolymer hydrogel adsorbent comprising crosslinked chitosan and κ-carrageenan.

A biopolymer-based adsorbent comprising chitosan (CS) and κ-carrageenan (κ-Carr) was synthesised and evaluated to treat phenolic-contaminated water. The developed CS/κ-Carr hydrogel demonstrated excellent performance with a phenol adsorption uptake of 80 %. The morphologies of CS/κ-Carr hydrogels with different ratios of CS to κ-Carr ranging from 1:2 to 7:3 were characterised using scanning electron microscopy and atomic force microscopy; their chemical structures were investigated by spectral analyses using Fourier-transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry; their adsorption characteristics were determined using tests for swelling, chemical stability, hygroscopic moisture content, and hydrophilicity. Finally, a batch-type evaluation method demonstrated adsorption performance at 25 °C and pH 6.9. Adsorption isotherms and kinetic data were successfully obtained using the Freundlich and pseudo-second-order models, respectively. The results indicate that one-pot synthesis of an insoluble CS/κ-Carr hydrogel adsorbent exhibits considerable potential for the removal of phenol from aqueous solutions, providing an environmentally friendly technology enhancing the phenol adsorption performance of CS.

Fabrication of different SnO2 nanorods for enhanced photocatalytic degradation and antibacterial activity.

The acid-mediated (oxalic acid [OXA], cinnamic acid [CA], and itaconic acid [IA]) SnO2 nanorods were synthesized by the hydrothermal method. The synthesized SnO2 nanorods, in turn, were analyzed with various physico-chemical techniques such as the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and Raman spectroscopy. Furthermore, the photocatalytic activity of the different SnO2 nanorods was investigated with the malachite green (MG) dye under visible light illumination. The OXA-SnO2 nanorods displayed an excellent degradation performance with observed value at 91% and it was compared to CA and IA-SnO2 nanomaterials. This tetragonal phase was identified and confirmed by XRD studies. In this regards, obtained band gap energy is low then optimally performed to the photocatalytic evolution. The OXA-SnO2 materials were tested for antibacterial and antifungal studies; this was as shown in good biological activities with admire to the different bacterial strains. The Candida albicans (antifungal) and Enterococcus faecalis (Gram-positive) bacteria were not affected in the microbial studies.

Transformation of hazardous sacred incense sticks ash waste into less toxic product by sequential approach prior to their disposal into the water bodies.

Incense sticks ash is one of the most unexplored by-products generated at religious places and houses obtained after the combustion of incense sticks. Every year, tonnes of incense sticks ash is produced at religious places in India which are disposed of into the rivers and water bodies. The presence of heavy metals and high content of alkali metals challenges a potential threat to the living organism after the disposal in the river. The leaching of heavy metals and alkali metals may lead to water pollution. Besides this, incense sticks also have a high amount of calcium, silica, alumina, and ferrous along with traces of rutile and other oxides either in crystalline or amorphous phases. The incense sticks ash, heavy metals, and alkali metals can be extracted by water, mineral acids, and alkali. Ferrous can be extracted by magnetic separation, while calcium by HCl, alumina by sulfuric acid treatment, and silica by strong hydroxides like NaOH. The recovery of such elements by using acids and bases will eliminate their toxic heavy metals at the same time recovering major value-added minerals from it. Here, in the present research work, the effect on the elemental composition, morphology, crystallinity, and size of incense sticks ash particles was observed by extracting ferrous, followed by extraction of calcium by HCl and alumina by H2SO4 at 90-95 °C for 90 min. The final residue was treated with 4 M NaOH, in order to extract leachable silica at 90 °C for 90 min along with continuous stirring. The transformation of various minerals phases and microstructures of incense sticks ash (ISA) and other residues during ferrous, extraction, calcium, and alumina and silica extraction was studied using Fourier transform infrared (FTIR), dynamic light scattering (DLS), X-ray fluorescence (XRF), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and inductively coupled plasma-optical emission spectroscopy (ICP-OES). DLS was used for analyzing the size during the experiments while FTIR helped in the confirmation of the formation of new products during the treatments. From the various instrumental analyses, it was found that the toxic metals present in the initial incense sticks ash got eliminated. Besides this, the major alkali metals, i.e., Ca and Mg, got reduced during these successive treatments. Initially, there were mainly irregular shaped, micron-sized particles that were dominant in the incense sticks ash particles. Besides this, there were plenty of carbon particles left unburned during combustion. In the final residue, nanosized flowers shaped along with cuboidal micron-sized particles were dominant. present in If, such sequential techniques will be applied by the industries based on recycling of incense sticks ash, then not only the solid waste pollution will be reduced but also numerous value-added minerals like ferrous, silica, alumina calcium oxides and carbonates can be recovered from such waste. The value-added minerals could act as an economical and sustainable source of adsorbent for wastewater treatment in future.

Efficient Photocatalytic Degradation of Organic Pollutant in Wastewater by Electrospun Functionally Modified Polyacrylonitrile Nanofibers Membrane Anchoring TiO2 Nanostructured.

In this study, polyacrylonitrile (PAN_P) nanofibers (NFs) were fabricated by electrospinning. The PAN_P NFs membrane was functionalized with diethylenetriamine to prepare a functionalized polyacrylonitrile (PAN_F) NFs membrane. TiO2 nanoparticles (NPs) synthesized in the laboratory were anchored to the surface of the PAN_F NFs membrane by electrospray to prepare a TiO2 NPs coated NFs membrane (PAN_Coa). A second TiO2/PAN_P composite membrane (PAN_Co) was prepared by embedding TiO2 NPs into the PAN_P NFs by electrospinning. The membranes were characterized by microscopic, spectroscopic and X-ray techniques. Scanning electron micrographs (SEM) revealed smooth morphologies for PAN_P and PAN_F NFs membranes and a dense cloud of TiO2 NPs on the surface of PAN_Coa NFs membrane. The attenuated total reflectance in the infrared (ATR-IR) proved the addition of the new amine functionality to the chemical structure of PAN. Transmission electron microscope images (TEM) revealed spherical TiO2 NPs with sizes between 18 and 32 nm. X-ray powder diffraction (XRD) patterns and energy dispersive X-ray spectroscopy (EDX) confirmed the existence of the anatase phase of TiO2. Surface profilometry da-ta showed increased surface roughness for the PAN_F and PAN_Coa NFs membranes. The adsorption-desorption isotherms and hysteresis loops for all NFs membranes followed the IV -isotherm and the H3 -hysteresis loop, corresponding to mesoporous and slit pores, respectively. The photocatalytic activities of PAN_Coa and PAN_Co NFs membranes against methyl orange dye degradation were evaluated and compared with those of bare TiO2 NPs.The higher photocatalytic activity of PAN_Coa membrane (92%, 20 ppm) compared to (PAN_Co) NFs membrane (41.64%, 20 ppm) and bare TiO2 (49.60%, 20 ppm) was attributed to the synergy between adsorption, lower band gap, high surface roughness and surface area.

Thin-Film Nanocomposite Membrane Incorporated with Porous Zn-Based Metal-Organic Frameworks: Toward Enhancement of Desalination Performance and Chlorine Resistance.

Metal-organic framework (MOF) materials have received extensive attention for the design of advanced thin-film nanocomposite (TFN) membranes with excellent permselectivity. However, the relationship between the unique physicochemical properties and performance of engineered MOF-based membranes has yet to be extensively investigated. In this work, we investigate the incorporation of porous zinc-based MOFs (Zn-MOFs) into a polyamide active layer for the fabrication of TFN membranes on porous poly(phenylsulfone) (PPSU) support layers through an interfacial polymerization approach. The actual effects of varying the amount of Zn-MOF added as a nanofiller on the physicochemical properties and desalination performance of TFN membranes are studied. The presence and layout of Zn-MOFs on the top layer of the membranes were confirmed by X-ray photoelectron spectroscopy, scanning electron microscopy, and ζ potential analysis. The characterization results revealed that Zn-MOFs strongly bind with polyamide and significantly change the membrane chemistry and morphology. The results indicate that all four studied TFN membranes with incorporated Zn-MOFs enhanced the water permeability while retaining high salt rejection compared to a thin-film composite membrane. Moreover, the highest-performing membrane (50 mg/L Zn-MOF added nanofiller) not only exhibited a water permeability of 2.46 ± 0.12 LMH/bar but also maintained selectivity to reject NaCl (>90%) and Na2SO4 (>95%), similar to benchmark values. Furthermore, the membranes showed outstanding water stability throughout 72 h filtration and chlorine resistance after a 264 h chlorine-soaking test because of the better compatibility between the polyamide and Zn-MOF nanofiller. Therefore, the developed TFN membrane has potential to solve trade-off difficulties between permeability and selectivity. Our findings indicate that porous Zn-MOFs play a significant role in the development of a TFN membrane with high desalination performance and chlorine resistance.

Removal of Cadmium and Chromium by Mixture of Silver Nanoparticles and Nano-Fibrillated Cellulose Isolated from Waste Peels of Citrus Sinensis.

Nano-fibrillated cellulose (NFC) was extracted by a chemical method involving alkali and acid hydrolysis. The characterisation of the citrus sinensis fruit peel bran and nano-fibrillated cellulose was performed by XRD, FTIR, TEM, and FESEM. XRD confirmed the phase of NFC which showed monoclinic crystal with spherical to rod shape morphology with a size of 44-50 nm. The crystallinity index of treated NFC increased from 39% to 75%. FTIR showed the removal of lignin and hemicellulose from waste peels due to the alkaline treatment. Silver nanoparticles were also synthesised by utilizing extract of citrus sinensis skins as a reducing agent. Pharmaceutical effluent samples from an industrial area were tested by Atomic Absorption Spectrometry. Out of the four metals obtained, cadmium and chromium were remediated by silver nanoparticles with nano-fibrillated cellulose via simulated method in 100 mg/L metal-salt concentrations over a time period of 160 min. The highest removal efficiency was found for cadmium, i.e., 83%, by using silver and NFC together as adsorbents. The second highest was for chromium, i.e., 47%, but by using only NFC. The Langmuir and Freundlich isotherms were well fitted for the sorption of Cd (II) and Cr (II) with suitable high R2 values during kinetic simulation. Thus, the isolation of NFC and synthesis of silver nanoparticles proved efficient for heavy metal sorption by the reuse of waste skins.

A highly permeable zinc-based MOF/polyphenylsulfone composite membrane with elevated antifouling properties.

In this study, for the first time, a highly permeable composite membrane was constructed by incorporating a zinc-based metal-organic framework (Zn-MOF) in a polyphenylsulfone matrix for the elevation of antifouling properties. Owing to the hydrophilic nature and high surface charge, this membrane demonstrated effective bovine serum albumin (a model protein) rejection and antifouling characteristics.

A Novel Approach To Optimize the Fabrication Conditions of Thin Film Composite RO Membranes Using Multi-Objective Genetic Algorithm II.

This work focuses on developing a novel method to optimize the fabrication conditions of polyamide (PA) thin film composite (TFC) membranes using the multi-objective genetic algorithm II (MOGA-II) method. We used different fabrication conditions for formation of polyamide layer-trimesoyl chloride (TMC) concentration, reaction time (t), and curing temperature (Tc)-at different levels, and designed the experiment using the factorial design method. Three functions (polynomial, neural network, and radial basis) were used to generate the response surface model (RSM). The results showed that the radial basis predicted good results (R2 = 1) and was selected to generate the RSM that was used as the solver for MOGA-II. The experimental results indicate that TMC concentration and t have the highest influence on water flux, while NaCl rejection is mainly affected by the TMC concentration, t, and Tc. Moreover, the TMC concentration controls the density of the PA, whereas t confers the PA layer thickness. In the optimization run, MOGA-II was used to determine optimal parametric conditions for maximizing water flux and NaCl rejection with constraints on the maximum acceptable levels of Na2SO4, MgSO4, and MgCl2 rejections. The optimized solutions were obtained for longer t, higher Tc, and different TMC concentration levels.

Dye Separation and Antibacterial Activities of Polyaniline Thin Film-Coated Poly(phenyl sulfone) Membranes.

We fabricated a nanofiltration membrane consisting of a polyaniline (PANI) film on a polyphenylsulfone (PPSU) substrate membrane. The PANI film acted as a potent separation enhancer and antimicrobial coating. The membrane was analyzed via scanning electron microscopy and atomic force microscopy to examine its morphology, topography, contact angle, and zeta potential. We aimed to investigate the impact of the PANI film on the surface properties of the membrane. Membrane performance was then evaluated in terms of water permeation and rejection of methylene blue (MB), an organic dye. Coating the PPSU membrane with a PANI film imparted significant advantages, including finely tuned nanometer-scale membrane pores and tailored surface properties, including increased hydrophilicity and zeta potential. The PANI film also significantly enhanced separation of the MB dye. The PANI-coated membrane rejected over 90% of MB with little compromise in membrane permeability. The PANI film also enhanced the antimicrobial activity of the membrane. The bacteriostasis (B R) values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Escherichia coli were 63.5% and 95.2%, respectively. The B R values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Staphylococcus aureus were 70.6% and 88.0%, respectively.

Antimicrobial and antifouling properties of versatile PPSU/carboxylated GO nanocomposite membrane against Gram-positive and Gram-negative bacteria and protein.

Biofouling is a serious issue in membrane-based water and wastewater treatment as it critically compromises the efficacy of the water treatment processes. This investigation demonstrates the antimicrobial and antifouling properties of a nanocomposite membrane system composed of carboxyl-functionalized graphene oxide (COOH-GO) and polyphenylsulfone (PPSU). The PPSU/COOH-GO nanocomposite membrane exhibited excellent antimicrobial properties, achieving maximum bacteriostasis rates of 74.2% and 81.1% against the representative Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa, respectively) and 41.9% against the representative Gram-positive bacterium (Staphylococcus aureus). The PPSU/COOH-GO nanocomposite membrane inhibited the attachment, colonization, and the biofilm formation of three species. Antifouling was assessed through filtration experiments using a model foulant bovine serum albumin (BSA). The fouling mechanisms were investigated by Hermia's models (complete blocking, intermediate blocking, standard blocking, and cake formation), and the analysis involved fitting the volumetric flux decline experimental data to models. The fouling study revealed a less irreversible fouling and increased flux recovery ratio for the PPSU/COOH-GO nanocomposite membrane. Complete blocking of pores and cake formation were the major fouling mechanisms for the membrane.