Materials For Water Purification Research Articles

Ultrasound-assisted preparation of Fe(OH)3@bacterial cellulose aerogel for efficient removal of organic contamination in water

As an abundant and renewable polymer, bacterial cellulose-based aerogel (BCA) loading with Fe(OH)3 nanoparticles was successfully prepared by ultrasound-assisted treatment and exhibited excellent adsorption efficiency for dye removal from polluted water. Wastewater containing toxic synthetic dyes is causing serious damage to the ecological environment and human health, and more attention has been paid to the nanoscale materials for water purification because of their unique structure and large specific surface area. With the help of ultrasonic waves, iron and hydroxide ions could fully penetrate the complex network of cellulose aerogel and generate the uniformed Fe(OH)3 particles, homogeneously being located all over the adsorbent. The physical adsorption from the multi-scaled pore structure in cellulosic aerogel and the chemical formation of electrostatic interaction and the hydrogen bonds between Fe(OH)3 and Congo red (CR) synergistically acted and significantly improved the absorbability. Finally, the maximum adsorption capacity of CR was achieved to 335 mg/g at natural conditions, which was higher than many reported values. The kinetics of the adsorption under different temperatures, pH, and time were comparatively measured, and the physical and structural characteristics were also investigated in detail using XPS, SEM, EDS, XRD, etc., technologies. Importantly, this approach is expected to provide a simple and operable process for fabricating cellulose-based aerogel and broadening the fields of applications.

Preparation and Real World Applications of Titania Composite Materials for Photocatalytic Surface, Air, and Water Purification: State of the Art

The semiconducting transition metal oxide TiO2 is a rather cheap and non-toxic material with superior photocatalytic properties. TiO2 thin films and nanoparticles are known to have antibacterial, antiviral, antifungal, antialgal, self, water, and air-cleaning properties under UV or sun light irradiation. Based on these excellent qualities, titania holds great promises in various fields of applications. The vast majority of published field and pilot scale studies are dealing with the modification of building materials or generally focus on air purification. Based on the reviewed papers, for the coating of glass, walls, ceilings, streets, tunnels, and other large surfaces, titania is usually applied by spray-coating due to the scalibility and cost-efficiency of this method compared to alternative coating procedures. In contrast, commercialized applications of titania in medical fields or in water purification are rarely found. Moreover, in many realistic test scenarios it becomes evident that the photocatalytic activity is often significantly lower than in laboratory settings. In this review, we will give an overview on the most relevant real world applications and commonly applied preparation methods for these purposes. We will also look at the relevant bottlenecks such as visible light photocatalytic activity and long-term stability and will make suggestions to overcome these hurdles for a widespread usage of titania as photocalyst.

Preparation and Characterization of Chitosan/TiO2 Composite Membranes as Adsorbent Materials for Water Purification.

As it is used in all aspects of human life, water has become more and more polluted. For the past few decades, researchers and scientists have focused on developing innovative composite adsorbent membranes for water purification. The purpose of this research was to synthesize a novel composite adsorbent membrane for the removal of toxic pollutants (namely heavy metals, antibiotics and microorganisms). The as-synthesized chitosan/TiO2 composite membranes were successfully prepared through a simple casting method. The TiO2 nanoparticle concentration from the composite membranes was kept low, at 1% and 5%, in order not to block the functional groups of chitosan, which are responsible for the adsorption of metal ions. Nevertheless, the concentration of TiO2 must be high enough to bestow good photocatalytic and antimicrobial activities. The synthesized composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and swelling capacity. The antibacterial activity was determined against four strains, Escherichia coli, Citrobacter spp., Enterococcus faecalis and Staphylococcus aureus. For the Gram-negative strains, a reduction of more than 5 units log CFU/mL was obtained. The adsorption capacity for heavy metal ions was maximum for the chitosan/TiO2 1% composite membrane, the retention values being 297 mg/g for Pb2+ and 315 mg/g for Cd2+ ions. These values were higher for the chitosan/TiO2 1% than for chitosan/TiO2 5%, indicating that a high content of TiO2 can be one of the reasons for modest results reported previously in the literature. The photocatalytic degradation of a five-antibiotic mixture led to removal efficiencies of over 98% for tetracycline and meropenem, while for vancomycin and erythromycin the efficiencies were 86% and 88%, respectively. These values indicate that the chitosan/TiO2 composite membranes exhibit excellent photocatalytic activity under visible light irradiation. The obtained composite membranes can be used for complex water purification processes (removal of heavy metal ions, antibiotics and microorganisms).

Immobilization of Polyoxometalate-Ionic Liquid on Coconut Shell Nanoporous Carbon Support: An improved material for water purification

Access to clean water by all is one of the UN Sustainable Development Goals. To achieve this, there is need to prepare sustainable materials for efficient water purification. This research aims to immobilize the Polyoxomatelate-Ionic Liquid (POM-IL), {[CH3(CH2)6]4N}7[α-PW11O39] on nanoporous carbon (NC) prepared from coconut shell to form an advanced material (POM-IL@NC) for effective removal of multiple contaminants from polluted water. The POM-IL@NC material was characterized by Fourier Transform-Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) Analysis and Brunauer-Emmett-Teller (BET) method. The material was then tested respectively for the removal of copper and lead using Atomic Absorption Spectroscopy (AAS) and methylene blue using Ultraviolet-Visible (UV-Vis) Spectroscopy from simulated polluted waters via adsorption. The material was further subjected to antimicrobial analysis. The results showed that the POM-IL@NC material performed better than the pristine NC in the removal of copper, lead and methylene blue from the contaminated water. The POM-IL@NC also exhibited significant improvement in antimicrobial activity than NC against Escherichia coli and Staphylococcus aureus. This shows that the new material could effectively be applied for multiple contaminants treatment of polluted water.

Improving Science Learning Outcomes in Water Clearance Material with Science, Technology, Engineering, and Mathematics (Stem) Approaches

This study aims to improve the Learning Outcomes of Science, Technology, Engineering, and Mathematics (STEM) Water Purification Materials for Class IX Junior High School Students. This research is a Classroom Action Research (CAR). The Research Procedure includes two cycles. The instruments used for the assessment of learning outcomes are teacher and student observation sheets. From the analysis of the assessment of student learning outcomes, there is an increase in learning outcomes after using the Science, Technology, Engineering, and Mathematics (STEM) approach to Water Purification material, namely from 21 students there are 4 (19.05%) students have high learning outcomes in the cycle category. 1 while in cycle 2 there were 18 (85.71%) students. From the analysis of teacher observations in cycle 1 of the medium category and cycle 2 of the high category. Meanwhile, from the analysis of student activities in cycle 1 for aspects of interest, attention, participation, and presentation in the moderate category and cycle 2 in all these aspects in the high category Based on the research, it can concluded that there is an increase in science learning outcomes in water purification material with the Science, Technology, Engineering and Mathematical, (STEM) approach in class IX students of SMP.

Architectures of flower-like MoS2 nanosheet coated N-doped carbon sphere electrode materials for enhanced capacitive deionization

The development of promising nanomaterials for capacitive deionization (CDI) is an emerging energy-efficient technology for water recovery and purification. Herein, the nanoarchitecture of deposition of molybdenum disulfide nanosheets onto N-doped carbon sphere (MoS2@NCS) has been successfully developed using hydrothermal processes for CDI applications. The morphological and fine structural analyses clearly indicate that the hexagonal structure of MoS2 nanosheets are homogeneously dispersed onto the 300-nm NCS to form the flower-like MoS2@NCS heterostructure. After calcination for 2 h at 800 °C, the MoS2@NCS exhibits a large specific surface area of 82 m2 g−1 and interconnected meso-macroporous channels for rapid ion and electron transfer, resulting in the superior electrochemical behaviors with the specific capacitance of 340 F g−1 at 5 A g−1 in 1 M Na2SO4 solution. Moreover, the electrosorption performance of MoS2@NCS-800 was investigated under different conditions in terms of initial NaCl concentration and voltage, and the superior specific electrosorption capacity of 59.9 mg g−1 is obtained at 2000 mg L−1 NaCl and applied voltage of 1.4 V. The experimental data is then well-fitted with the modified Donnan model, signifying that the electrosorption performance is highly dependent on the formation of electrical double layers and homogeneous potential distribution throughout the diffuse layer of the porous electrodes. The excellent cyclic durability of MoS2@NCS electrode is also highlighted after 100 electrosorption-desorption cycles. These results elaborate that MoS2@NCS composites are promising electrochemical materials for CDI application, which can open a pathway to design the 2D/3D hybrid nanoarchitectures as a highly potential material for green and sustainable water purification and ion removal in grey and salty waters.

A detailed structural analysis, morphological and optical study of Mg-Zn nano ferrite

Mg-Zn nanoferrite with the composition of Mg0.4Zn0.6Fe2O4 was prepared using the citrate precursor process. Detailed structural analysis was performed on Mg-Zn nanoferrite to calculate crystallite size, lattice constant, X-ray density, bulk density, and porosity using XRD data. Also, the strain on the sample was calculated by plotting Williamson – Hall (W-H) plot. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were performed to study morphological and optical properties. The spinel structure was confirmed by XRD with a crystallite size of 38 nm. SEM micrograph of the sample showed almost spherical-shaped nanoparticles. FTIR spectra disclosed two characteristic bands showing tetrahedral (A) and octahedral (B) site occupancies. Under UV–visible light irradiation, photocatalytic degradation of rhodamine B dye and the degradation efficiency is obtained to be 70 % in 60 min. Therefore, it is concluded that Mg0.4Zn0.6Fe2O4 is a promising material for water purification.

Electrospinning of ZIF-67 Derived Co-C-N Composite Efficiently Activating Peroxymonosulfate to Degrade Dimethyl Phthalate

In this work, an efficient cage-core peroxymonosulfate (PMS) catalyst was synthesized by applying an electrospinning–calcination process to the cobalt–zeolitic imidazole framework (ZIF-67) crystals for the catalytic degradation of dimethyl phthalate (DMP). The morphology and surface properties of the synthesized materials (ZIF-67, Z600 and ZP400/600/800) were well characterized. ZP600 showed great performance for the catalytic degradation of DMP in the initial pH range of 7.5–10.5. The removal rate of DMP could reach 90.4% in 60 min under optimum dosages of reagents (catalyst = 0.1 g/L, PMS = 0.5 mM, DMP = 6 ppm), and the mineralization degree of contaminant could reach 65%. By quenching experiments, it was determined that sulfate radical (SO4−·) and hydroxyl radical (·OH) dominated the degradation process. Moreover, due to the good magnetism, ZP600 could be easily separated from liquid and showed great reusability in five-cycle reaction experiments. Surprisingly, with the cover of cage-like polyacrylonitrile (PAN) fibers, the cobalt leaching amount of ZP600 decreased by about 87%. This study would expand the application of the electrospinning process in the development of functional materials for water purification.

The improved textural properties, thermal stability, and cytocompatibility of mesoporous hydroxyapatite by Mg2+ doping

The paper demonstrated the increase of the surface area and meso- and microporosity volume with the low concentration Mg-substitution introduction during the hydroxyapatite (HA) wet method synthesis, as well as samples phase and structure evolution during the heat treatment up to 1200 °C. The incorporation of 0.1 and 1.0 mol.% Mg2+ were studied by magnetic resonance techniques including electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR), magic angle spinning nuclear magnetic resonance (MAS NMR) depending on Mg2+ content, and thermal treatment temperature. The calculation based on Density Functional Theory (DFT) was conducted and a model of the Mg2+ introduction was proposed, which correlated with the unit cell volume evaluations. Incorporation of 0.1 mol. % Mg2+ resulted in the growth of specific surface area (S) on the 37%, while 1.0 mol. % Mg-HA powders demonstrated a more than three times increase of surface area up to 86.91 m2/g compared to 23.35 m2/g for pure HA. The micro- and mesopores volume also demonstrated the near three time growing up with a total pore volume of 0.2938 mm3/g. The established properties indicated the opportunity to apply these materials for water, air, and soil purification, catalyst, as well as active phase support and bone tissue repair including drugs and proteins delivery systems. The in vitro investigations demonstrated the cytocompatibility of the bioceramic granules and confirmed the positive influence of the Mg2+ on cell viability and proliferation.

Formation and evolution of pectin-derived hydrothermal carbon from pectin

Hydrothermal conversion can convert biomass into carbon materials in catalysis, energy storage, and water purification. Pectin, a polysaccharide widely presented in plant cell walls, is an important component of biomass. However, the formation and evolution of pectin-derived hydrothermal carbon are not clear. In this study, we conducted the hydrothermal treatment of pectin at 100–300 °C to investigate the properties at different hydrothermal stages. With the characterization of the solid products with scanning electron microscopy (SEM), elemental analysis, N2 adsorption/desorption, Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and pyrolysis behavior in thermogravimetric analyzer (TGA), we proposed the formation and evolution pathway of pectin-derived hydrothermal carbon from original pectin. Pectin first underwent a physical change of gelation during the hydrothermal process, and then was hydrolyzed to liquid monomers. Pectin-derived hydrothermal carbon was formed by the polymerization of liquid monomers resulting from the hydrolysis of pectin. Moreover, the hydrothermal carbon was further carbonized, accompanied by dehydration and aromatization. Meanwhile, the originally irregular pectin bulk structure was completely transformed into carbon spheres above 200 °C. This work can provide some fundamental guidance for the sustainable synthesis of carbon materials from the hydrothermal process of pectin.

Cellulose‐Based Materials for Water Purification

AbstractCellulose is a linear syndiotactic homopolymer, made up of glucose units designated as D‐anhydroglucopyranose units (AGU). The glucose units are connected with each other by b‐(l‐4)‐glycosidic linkage to form a dimeric structure known as cellobiose. These units are assembled into microfibils in a heirarchial manner with excellent strength and stiffness. The properties of cellulose can be further enhanced by either surface functionalization or by converting it to nano form. Nanocellulosic materials are non‐toxic, biodegradable, biocompatible and exhibit enhanced surface properties so widely used for purification of water through adsorption process. This review outlined the most recent updates of uses of cellulose and cellulose derived nano material, composite and nanocomposite as a new class of adsorbents for water remediation.

Nanostructured Materials for Water Purification: Adsorption of Heavy Metal Ions and Organic Dyes.

Chemical water pollution poses a threat to human beings and ecological systems. The purification of water to remove toxic organic and inorganic pollutants is essential for a safe society and a clean environment. Adsorption-based water treatment is considered one of the most effective and economic technologies designed to remove toxic substances. In this article, we review the recent progress in the field of nanostructured materials used for water purification, particularly those used for the adsorption of heavy metal ions and organic dyes. This review includes a range of nanostructured materials such as metal-based nanoparticles, polymer-based nanomaterials, carbon nanomaterials, bio-mass materials, and other types of nanostructured materials. Finally, the current challenges in the fields of adsorption of toxic materials using nanostructured materials are briefly discussed.

Manganese Ferrite-Hydroxyapatite Nanocomposite Synthesis: Biogenic Waste Remodeling for Water Decontamination.

Environmental pollution, especially water pollution caused by dyes, heavy metal ions and biological pathogens, is a root cause of various lethal diseases in human-beings and animals. Water purification materials and treatment methods are overpriced. Consequently, there is an imperative outlook observance for cheap materials for the purification of wastewaters. In order to fill up the projected demand for clean water, the present study aimed to make use of cost-effective and environmentally friendly methods to convert bone-waste from animals such as cows into novel composites for the decontamination of water. The bone-waste of slaughtered cows from the Najran region of Saudi Arabia was collected and used for the synthesis of hydroxyapatite based on the thermal method. The synthesized hydroxyapatite (Ca10(PO4)6(OH)2) was utilized to prepare a manganese ferrite/hydroxyapatite composite. The nanocomposite was categorized by diverse sophisticated procedures, for instance XRD, FE-SEM, EDX, TEM, UV, PL and FT-IR. This composite possesses outstanding photocatalytic activity against methylene blue dye, which is a common pollutant from industrial wastes. Moreover, the synthesised composite revealed exceptional bacteriostatic commotion towards E. coli and S. aureus bacteria, which are accountable for acute waterborne infections. The outcome of this study demonstrated that the integration of manganese ferrite into hydroxyapatite significantly intensified both antimicrobial and photocatalytic actions when compared to the virgin hydroxyapatite.

MWCNTs Composites-Based on New Chemically Modified Polysulfone Matrix for Biomedical Applications.

Polyvinyl alcohol (PVA) is a non-toxic biosynthetic polymer. Due to the hydrophilic properties of the PVA, its utilization is an easy tool to modify the properties of materials inducing increased hydrophilicity, which can be noticed in the surface properties of the materials, such as wettability. Based on this motivation, we proposed to obtain high-performance composite materials by a facile synthetic method that involves the cross-linking process of polyvinyl alcohol (PVA) with and aldehyde-functionalized polysulfone(mPSF) precursor, prior to incorporation of modified MWCNTs with hydrophilic groups, thus ensuring a high compatibility between the polymeric and the filler components. Materials prepared in this way have been compared with those based on polyvinyl alcohol and same fillers (mMWCNTs) in order to establish the influence of the polymeric matrix on the composites properties. The amount of mMWCNTs varied in both polymeric matrices between 0.5 and 5 wt%. Fourier transformed infrared with attenuated total reflectance spectroscopy (FTIR-ATR) was employed to confirm the changes noted in the PVA, mPSF and their composites. Hemolysis degree was investigated in correlation with the material structural features. Homogenous distribution of mMWCNTs in all the composite materials has been confirmed by scanning electron microscopy. The hydrophilicity of both composite systems, estimated by the contact angle method, was influenced by the presence of the filler amount mMWCNTs in both matrices (PVA and mPSF). Our work demonstrates that mPSF/mMWCNTs and PVA/mMWCNTs composite could be used as water purification or blood-filtration materials.

Highly efficient sunlight-driven self-cleaning electrospun nanofiber membrane NM88B@HPAN for water treatment

Electrospun membranes show great potential as separation materials for water purification due to their high porosity and three-dimension (3D) configuration. However, membrane fouling has still not been effectively solved. In this work, hydrophilic and visible-light responsive NM88B@HPAN nanofiber membrane was fabricated, via introduced the catalyst of NH2-MIL-88B(Fe) (NM88B) into the 3D matrix of the hydrolyzed polyacrylonitrile (HPAN) membrane. Owning to the partial dissociation of protons in carboxyl functional groups, the surface of HPAN membrane shows a negative charge in water, which is conducive to improve the interaction between HPAN membrane and protonated NM88B, resulting in good dispersion of nanoparticles on the membrane surface and high stability of NM88B@HPAN nanofiber membrane. The nanofiber membrane exhibited excellent separation efficiency (up to 99%) and high permeation flux (946–6014 L/m2/h) towards various oil/water emulsions. Meanwhile, the membrane has high flux recovery rate and dye degradation ability towards Rhodamine B (RhB) (90.04%) owing to the synergistic effect of strong hydrophilicity and photo-Fenton activity. Moreover, good mechanical property was observed of the composite nanofiber membrane, which was beneficial for repeated use in the actual production process.

Water purification from cationic organic dyes using kaolin-based ceramic materials

The development of effective sorbents based on cheap natural raw materials for water purification from synthetic organic dyes is an important environmental problem. It is known that layered silicates are distinguished by mechanical strength, thermal and chemical resistance, high dispersion, ion exchange, availability and low cost. However, the main disadvantage of natural clays is their insufficiently high sorption capacity with respect to organic toxicants. Therefore, to increase it, the surface of clay minerals is modified by various physical and chemical methods. The object of study is kaolin from the Glukhovets deposit (Ukraine), the main rock-forming mineral of which is kaolinite. After its thermal modification followed by acid activation with chloride acid, sorbents with sufficiently high structural-sorption properties and increased sorption capacity with respect to the synthetic organic dye, methylene blue, are obtained. The influence of the conditions for the synthesis of ceramic materials on the physicochemical features of the dye removal from the aqueous medium is studied. The dependence of the values of methylene blue sorption by silicate sorbents on the temperature of kaolin treatment and the concentration of chloride acid, which was used for its acid activation, is studied. It has been established that the specific surface of the obtained samples is significantly affected by both the kaolin treatment temperature and the concentration of perchloric acid. Thus, under certain experimental conditions, sorption materials were obtained with a specific surface area of 140 m2/g, which significantly exceeds that for the original kaolin, which is 9 m2/g. A significant increase in the sorption capacity of acid-activated samples compared to the original clay and heat-treated forms was established. The value of the maximum sorption of methylene blue for acid-activated samples exceeds that for natural kaolin by almost 2 times and reaches 16 mg/g.

Laboratory Investigation on Pollutant Removal Effect of Purification Materials for Porous Asphalt Pavement

Purification materials have been widely applied as filter media in best management measures including wetlands, bioretention systems, and so forth, whereas their application in permeable pavement is limited and needs further research. This paper aims to explore the feasible applications of water purification materials in permeable pavement materials and structures. Based on laboratory rainfall test and static adsorption test, the possible application of three types of water purification materials, including diatomite, quartz sand, and straw biochar, in porous asphalt pavement and their pollutant removal effect were investigated. The results show that the filter layers can effectively increase the total suspended solids removal rate to 60%–80%. And when the purification materials are applied as alternative fillers in porous asphalt mixture (PA), they can enhance the removal effect of dissolved pollutants, especially heavy metals, by their special chemical properties and the positive influence on microscopic pore structures of PA. The adsorption effect of PA on pollutants is closely related to the environment temperature. The PA adsorption of nutrients and Cu increases with the increase of temperature, but the adsorption effect of Cr is better at lower temperatures. The pseudo-first-order model and the pseudo-second-order model can properly describe the adsorption process of heavy metals Cu and Cr by PA, respectively. The purification schemes that present purification effects under different runoff pollution characteristics are recommended as well.

Natural Porous Materials for Interfacial Solar Steam Generation toward Clean Water Production

Solar Steam Generation In article number 2100986, Yuen Hong Tsang and co-workers reviewed the recent breakthroughs in photothermal material design using natural porous materials for water purification and desalination application. Biodegradability, abundance, lower thermal conductivity, low-cost, natural capillary mechanism, hydrophilicity, and higher photothermal conversion efficiency have attracted researchers to design natural porous material-based photothermal evaporators for interfacial solar steam generation.

Laser Interferometry for Precise Measurement of Ultralow Flow Rates from Permeable Materials

Novel observations in nanofluidic systems, such as ultrafast water transport, have directed recent research efforts toward developing new materials for water purification. Characterizing the transport properties of these materials is often restricted to exceptionally small areas and low pressures to avoid damage or defect formation. Consequently, observable flow rates are often limited to a few nL h–1, even for materials with intrinsically high permeability. In this work, we apply laser interferometry to indirectly measure extremely low flow rates from permeable materials. We first demonstrate the principles of interferometry for measuring the rate of a moving mirror. We then validate the technique for nanoscale liquid level displacements by measuring the rate of water evaporation from a cylindrical vessel before (0.40 nm s–1) and after (undetectable) sealing the vessel. When applying interferometry to membrane characterization, we find good agreement with water permeance measured in a conventional pressure-driven cell (mean absolute error, MAE = 8.54%). This proof of concept, and the perspectives given herein, could help expedite investigatory science on the fluid flow properties of novel nanofluidic devices and materials critical to innovation at the water–energy nexus.

Re-generable and re-synthesisable micro-structured MIL-53 Rachig Rings for ibuprofen removal

Water-stable metal–organic frameworks (MOFs) are attractive adsorbent materials for water purification. However, for practical applications, they must be structured into beads, granules, pellets, etc. which would impair their adsorption performances. This study demonstrates the feasibility in developing a water-stable MIL-53 onto a micro-structured alumina Raschig Ring (Al-RR) served not only as an aluminium metal source, but also as a support. Our results showed that a MIL-53 layer covers the entire surface of the Al-RR. The unique structure of the Al-RR allows easy access of water pollutants, hence achieving high adsorption efficiencies with its estimated equilibrium adsorption capacity between 222 and 300 mg g−1. In addition, the synthesised MIL-53 Raschig Ring (MIL-53-RR) can be regenerated or re-synthesised without any significant reduction in the adsorption performances, indicating the potential for possible commercialisation of the MIL-53-RR for water purifications such as ibuprofen removal from water.