Preparation and characterization of clay based ceramic porous membranes and their use for the removal of lead ions from synthetic wastewater with an insight into the removal mechanism.

The present study explores the use of local clay from the United Arab Emirates (UAE) to prepare porous ceramic membranes (flat disk shape) for the purpose of removing toxic heavy metals from contaminated water. Four distinct ceramic membranes, crafted from locally sourced clay and incorporated with activated carbon and graphite, underwent careful and thorough preparation. The initial set of membranes was subjected to open-air sintering, resulting in the creation of mACA and mGrA membranes. Concurrently, a second set of meticulously prepared membranes underwent sintering under inert nitrogen conditions, yielding the formation of mACI and mGrI membranes, respectively. Prior to making the membranes, the clay material was characterized by thermogravimetric analysis (TGA), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD). The clay presented the lowest weight loss compared to AC and Gr, implying that these two materials could be used as porogen agents. The X-ray fluorescence results indicated that the natural clay contained 65.5 wt% of silicon dioxide (SiO2), aluminium oxide (Al2O3), and iron (III) oxide (Fe2O3) falling within the class C category of clays according to ASTM. The FTIR analysis showed different clay regions allocated to various stretching and deformation vibrations of hydroxide, organic fraction, and (Si, Al, Fe)-O groups. The XRD analysis revealed the presence of kaolinite, illite, smectite and calcite phyllite phases in the clay mineral. The membranes were characterized using FESEM, with those containing AC (used as porogen) exhibiting large pores clearly visible on the surface, and were tested for the removal of lead (Pb2+) ions from synthetic wastewater. The removal efficiencies of the membranes were 33 %, 75.2 %, 100 % and 100 % for mACA, mACI, mGrA and mGrI respectively after 100 min operation. The wettability of the membranes was found to follow the order mACI < mACA < mGrI < mGrA, which corroborated well with water fluxes of 7, 8, 112 and 214 L h-1 m-2 recorded after 60 min duration and 1.0 bar applied pressure. The mechanisms of filtration of Pb2+ ions were adsorption for the AC-based membranes (mACA, mACI) and a combination of adsorption and size exclusion for the Gr-based membranes (mGrA, mGrI).

Novel composites of activated carbon and layered double oxide for the removal of sulfate from synthetic and brackish groundwater.

Sulfate (SO42-) is a major water and environmental concern that causes severe diarrhea, death of invertebrates and plant species, and clogging of industrial pipes. In the current work, treatment of SO42- from synthetic and real groundwater having 3901 mg(SO42-)/L was investigated for the first time using Zn-Al and Mg-Al layered double oxides doped granular activated carbon (GAC/Mg-Al LDO and GAC/Zn-Al LDO). The co-precipitation method was followed to synthesize the GAC/LDO composites using an Mg or Zn to Al molar ratio of 3:1. The GAC/Mg-Al LDO possessed a higher specific surface area (323.9 m2/g) compared to GAC/Zn-Al LDO (195.1 m2/g). The GAC/Mg-Al LDO demonstrated more than 99% removal of SO42- from synthetic water, while it was 50.9% for GAC/Zn-Al LDO and less than 1% for raw GAC at an initial concentration of 50 mg/L. The GAC/Mg-Al LDO was selected for further batch experiments and modeling investigation. The equilibrium data followed the Redlich-Peterson and Langmuir models with determination coefficients of 0.943 and 0.935, respectively. The maximum Langmuir adsorption capacity was 143.5 mg/g. In the real groundwater adsorption study, the screening experiment revealed high selectivity towards SO42- with 62% removal efficiency. The optimum dosage was found to be 50 g/L with an uptake capacity of 61.5 mg/g. The kinetic data of SO42- removal from synthetic and brackish water were in excellent agreement with the pseudo-second order model, and the equilibrium was attained in 5 h. Accordingly, it can be concluded that the GAC/Mg-Al LDO is an efficient material for treating SO42- from real groundwater and can be utilized as a pretreatment unit for high sulfate water resources.

Oxidized carbide-derived carbon as a novel filler for improved antifouling characteristics and permeate flux of hybrid polyethersulfone ultrafiltration membranes.

Polyethersulfone (PES) is a widely used polymer for ultrafiltration (UF) membrane fabrication. In the current study, carbide-derived carbon (CDC) oxidized by acid treatment was utilized as a filler to fabricate a novel PES composites UF membranes. The successful oxidation of CDC was validated from presence of oxygen containing functional groups and improved oxygen content, from 5.08 at.% for CDC to 26.22 at.% for oxidized CDC (OCDC). The OCDC PES UF membranes were prepared at different loadings of OCDC between 0.5 and 3.0 wt%. The membrane porosity, pore size and surface free energy found to be improved while a noticeable reduction in water contact angle was observed with OCDC loading implying the improved hydrophilicity of PES membranes. Consequently, the pure water flux found to improve from 151.6 to 569.6 (L/(m2. h)) for the 3.0 wt% modified OCDC membrane (M-3) which is 3.8 folds of the bare PES membrane. The antifouling characteristics were evaluated by humic acid (HA) filtration. The results revealed a significant enhancement in HA rejection with OCDC loading, the highest rejection was 96.8% for M-3 membrane. Additionally, the adsorption capacity of OCDC modified membranes found to decrease with OCDC loading indicating improved rejection of HA from the membrane surface. Moreover, M-3 demonstrated the maximum flux recovery ratio (FRR) of 92.3%. Reusability of the fabricated membranes was evaluated by deionized water/humic acid cycling filtration. The FRR was higher than 86.7% over three cycles of pure water/HA filtration for 140 min, indicated the excellent stability and reusability of the membranes. Overall, the OCDC was an effective filler for enhancing the PES UF membranes antifouling and permeability properties.

Facile Coaxial Electrospinning Synthesis of Polyacrylonitrile/Cellulose Acetate Nanofiber Membrane for Oil-Water Separations.

Oil-contaminated water and industrial oily wastewater discharges have adversely affected aquatic ecosystems and human safety. Membrane separation technology offers a promising solution for effective oil-water separation. Thus, a membrane with high surface area, hydrophilic-oleophobic properties, and stability is a promising candidate. Electrospinning, a straightforward and efficient process, produces highly porous polymer-based membranes with a vast surface area and stability. The main objective of this study is to produce hydrophilic-oleophobic polyacrylonitrile (PAN) and cellulose acetate (CA) nanofibers using core-shell electrospinning. Incorporating CA into the shell of the nanofibers enhances the wettability. The core PAN polymer improves the electrospinning process and contributes to the hydrophilicity-oleophobicity of the produced nanofibers. The PAN/CA nanofibers were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, and surface-wetting behavior. The resulting PAN/cellulose nanofibers exhibited significantly improved surface-wetting properties, demonstrating super-hydrophilicity and underwater superoleophobicity, making them a promising choice for oil-water separation. Various oils, including gasoline, diesel, toluene, xylene, and benzene, were employed in the preparation of oil-water mixture solutions. The utilization of PAN/CA nanofibers as a substrate proved to be highly efficient, confirming exceptional separation efficiency, remarkable stability, and prolonged durability. The current work introduces an innovative single-step fabrication method of composite nanofibers, specially designed for efficient oil-water separation. This technology exhibits significant promise for deployment in challenging situations, offering excellent reusability and a remarkable separation efficiency of nearly 99.9%.

A Comparative Analysis of the Effect of Carbonaceous Nanoparticles on the Physicochemical Properties of Hybrid Polyethersulfone Ultrafiltration Membranes.

Numerous studies have been previously reported on the use of nanoscale carbonaceous fillers, such as multi-walled carbon nanotubes (MWCNTs) and graphene oxide (GO), in polymeric ultrafiltration (UF) membranes; however, no insight has been clearly reported on which material provides the best enhancements in membrane performance. In this study, a comparative analysis was carried out to establish a comprehensible understanding of the physicochemical properties of hybrid polyethersulfone (PES) UF membranes incorporated with MWCNTs and GO nanoparticles at various concentrations. The hybrid membranes were prepared via the non-solvent-induced phase separation process and further characterized by field emission scanning electron microscopy and atomic force microscope (AFM). The AFM images showed homogeneous membrane surfaces with a reduction in the membrane surface roughness from 2.62 nm for bare PES to 2.39 nm for PES/MWCNTs and to 1.68 nm for PES/GO membranes due to improved hydrophilicity of the membranes. Physicochemical properties of the hybrid PES membranes were assessed, and the outcomes showed an enhancement in the porosity, pore size, water contact angle, and water permeability with respect to nanoparticle concentration. GO-incorporated PES membranes exhibited the highest porosity, pore size, and lowest contact angle as compared to PES/MWCNTs, indicating the homogeneous distribution of nanoparticles within the membrane structure. PES/MWCNTs (0.5 wt.%) and PES/GO (1.0 wt.%) hybrid membranes exhibited the highest water flux of 450.0 and 554.8 L m-2 h-1, respectively, at an applied operating pressure of 1 bar. The filtration and antifouling performance of the PES hybrid membranes were evaluated using 50 mg L-1 of humic acid (HA) as a foulant at pH = 7. Compared to the bare PES membrane, the MWCNTs and GO-incorporated PES hybrid membranes exhibited enhanced permeability and HA removal. Moreover, PES/MWCNTs (0.5 wt.%) and PES/GO (1 wt.%) hybrid membranes reported HA rejection of 90.8% and 94.8%, respectively. The abundant oxygen-containing functional groups in GO-incorporated PES membranes resulted in more hydrophilic membranes, leading to enhanced permeability and fouling resistance. The antifouling properties and flux recovery ratio were improved by the addition of both nanoparticles. Given these findings, although both MWCNTs and GO nanoparticles are seen to notably improve the membrane performance, PES membranes with 1 wt.% GO loading provided the highest removal of natural organic matter, such as HA, under the same experimental conditions.

Carbide-derived carbon as an extraordinary material for the removal of chromium from an aqueous solution.

In the present work, the adsorptive removal of chromium (Cr) from water by carbide-derived carbon (CDC) was investigated. The morphology and structure of the CDC were characterized by using FTIR, SEM, TEM, XRD, and N2 adsorption-desorption measurements. The effect of adsorption parameters including contact time, initial Cr concentration, temperature, initial solution pH, and CDC dosage was examined on the removal of Cr ions. The kinetic analysis revealed that the experimental data on the removal of Cr ions on CDC is well correlated with the pseudo-second order kinetic model (with R2 > 0.999), while the equilibrium data were fitted by the Redlich-Peterson isotherm model (with R2 > 0.992). The Langmuir and Sips models were also in good compliance with the equilibrium data, indicating a monolayer coverage of Cr ions onto the CDC surface with some heterogeneous active adsorption sites. The CDC revealed a notable Langmuir adsorption capacity of 159.1 mg/g for Cr ions at pH 6 and room temperature. The thermodynamic analysis illustrated that the Cr ions elimination by CDC is a feasible adsorption process and endothermic in nature. After five adsorption/desorption cycles, less than 18% reduction in the adsorption capacity was obtained indicating the stability and reusability of the CDC. Moreover, the CDC demonstrated an excellent potential in removing the Cr ions from real brackish water. According to the adsorption data, both physical and chemical adsorption processes occurred, and the adsorption was mainly controlled by electrostatic interactions with a possible reduction of hexavalent Cr to trivalent Cr at acidic conditions.

Kinetic and thermodynamic investigations of surfactants adsorption from water by carbide-derived carbon.

The objective of the study is to investigate the potential of carbide-derived carbon (CDC) for the adsorptive removal of nonionic t-octylphenoxy poly ethoxy ethanol (TX-100), anionic sodium dodecylbenzene sulfonate (SDBS) and cationic 1-hexadecylpyridinium bromide (HDPB) surfactants from water. The CDC was characterized using TEM, SEM, FTIR, BET, EDS, XPS methods and zeta potential measurements. The effects of adsorption parameters included initial surfactant concentration, contact time, temperature, and pH of the feed solution were evaluated. The adsorption capacity and mechanism were determined by modeling the isotherm, kinetic and thermodynamic data. The kinetics results demonstrated that the adsorption of the surfactant by CDC obeys the pseudo 2nd order model. The thermodynamic results have shown that surfactants adsorption by CDC is an endothermic and spontaneous process. The Sips model agreed with the adsorption isotherm data of SDBS with R2 of 0.987, while both Freundlich and Redlich-Peterson models comply well with adsorption data for TX-100 and HDPB. The hydrophobic and electrostatic interactions were found the dominant mechanisms of the adsorption of the surfactant by CDC. The adsorption capacities of CDC were found to be 442.4, 462.0 and 578.4 mg/g for SDBS, HDPB and TX-100, respectively.

Faradic capacitive deionization (FCDI) for desalination and ion removal from wastewater.

Capacitive deionization (CDI) is one of the emerging desalination technologies that attracted much attention in the last years as a low-cost, energy-efficient, and environmentally-friendly alternative to other desalination technologies, such as multi-stage flash desalination (MSF) and multiple effect distillation (MED). The implementation of faradaic electrode materials is a promising method for enhancing CDI systems' performance by achieving higher salt removal characteristics, lower energy consumption, and better ion selectivity. Therefore, a novel CDI technology named Faradaic CDI (FCDI) that implements faradaic electrode materials arose as a high-performance CDI cell design. In this work, the application of FCDI cells in desalination and wastewater treatment systems is reviewed. First, the progress done on using various FCDI systems for saline water desalination is summarized and discussed. Next, the application of FCDI in wastewater treatment applications and selective ion removal is presented. A thorough comparison between FCDI and conventional carbon-based CDI is carried out in terms of working principle, electrode material's cost, salt removal performance, energy consumption, advantages, and disadvantages. Finally, future research consideration regarding FCDI technology is included to drive this technology closer towards practical application.

Review of phosphate removal from water by carbonaceous sorbents.

In the last decades, phosphate is considered the main cause of eutrophication and has received substantial attention from the scientific community. Phosphate is a major pollutant that deteriorates water quality, which has been increasing in water resources, primarily due to the increasing global population and corresponding activities. Adsorption technology is amongst the different technologies used to decrease the phosphate levels in water, and has been found to be highly effective even at low phosphate concentrations. Carbonaceous materials and their composites have been widely used for phosphate removal due to their exceptional surface properties and high phosphate sorption capacity. Considering the importance of the topic, this study reviews the reported literature in the field of adsorptive removal of phosphate over various carbon-based adsorbents such as activated carbon, charcoal, graphene, graphene oxide, graphite and carbon nanotubes. Moreover, insights into the adsorption behaviour, experimental parameters, mechanisms, thermodynamics, effect of coexisting ions and the possible desorption processes of phosphate onto modified and unmodified carbonaceous adsorbents are also considered. Finally, research challenges and gaps have been highlighted.

Monolayer Graphene Transfer onto Hydrophilic Substrates: A New Protocol Using Electrostatic Charging.

In the present work, we developed a novel method for transferring monolayer graphene onto four different commercial hydrophilic micro/ultra-filtration substrates. The developed method used electrostatic charging to maintain the contact between the graphene and the target substrate intact during the etching step through the wet transfer process. Several measurement/analysis techniques were used in order to evaluate the properties of the surfaces and to assess the quality of the transferred graphene. The techniques included water contact angle (CA), atomic force microscopy (AFM), and field emission scanning electron microscopy (FESEM). Potassium chloride (KCl) ions were used for the transport study through the developed graphene-based membranes. The results revealed that 70% rejection of KCI ions was recorded for the graphene/polyvinylidene difluoride (PVDF1) membrane, followed by 67% rejection for the graphene/polyethersulfone (PES) membrane, and 65% rejection for graphene/PVDF3 membrane. It was revealed that the smoothest substrate was the most effective in rejecting the ions. Although defects such as tears and cracks within the graphene layer were still evolving in this new transfer method, however, the use of Nylon 6,6 interfacial polymerization allowed sealing the tears and cracks within the graphene monolayer. This enhanced the KCl ions rejection of up to 85% through the defect-sealed graphene/polymer composite membranes.

Recent progress in environmentally friendly bio-electrochemical devices for simultaneous water desalination and wastewater treatment.

Bio-electrochemical systems (BESs) use electroactive micro-organisms for degrading organic materials in wastes for energy and/or chemical production. Microbial based desalination system is a cost-effective and environmentally friendly technique that can be used for water desalination with simultaneous wastewater treatment and energy harvesting. These systems can be used as a standalone technology for water desalination such as microbial desalination cell, microbial electrolysis desalination cell, or a hybrid with other desalination technology. This review summarized the recent progress in using BESs for water desalination, including microbial fuel cell-based desalination (MDC) and microbial electrolysis cell-based desalination (MEDC). The different scaling up trials to commercialize this technology, including the controlling parameters, are discussed. Moreover, the different hybrid desalination systems based on BES are summarized. Finally, the challenges facing the commercialization of the MDC systems were summarized.

Porous Al2O3-CNT Nanocomposite Membrane Produced by Spark Plasma Sintering with Tailored Microstructure and Properties for Water Treatment.

Ceramic-based nanocomposite membranes are gaining great attention in various applications, such as water treatment; gas separation; oil and gas, amid their superior fouling resistance and remarkable chemical/thermal stability. Here, we report for the first time the use of spark plasma sintering (SPS) process to fabricate a porous alumina-carbon nanotubes (Al2O3-CNT) nanocomposite membrane for water treatment. The challenge is this work is to achieve a balance between the amount of porosity, desired for a high water flux, and the membrane strength level, required to resist the applied pressure during a water flow experiment. The effect of SPS process parameters (pressure, temperature, heating rate, and holding time) on the microstructure and properties of the developed membrane was investigated and correlated. A powder mixture composed of Al2O3 and 5 wt % CNT was prepared with the addition of starch as a pore former and gum Arabic and sodium dodecyl sulfate as dispersants. The powder mixture was then sintered using SPS to produce a solid but porous nanocomposite membrane. The structure and microstructure of the developed membrane were characterized using X-ray diffraction and field emission scanning electron microscopy. The performance of the membrane was assessed in terms of porosity, permeability, and mechanical properties. Moreover, the adsorption capability of the membrane was performed by evaluating its removal efficacy for cadmium (II) from water. The microstructural analysis revealed that CNT were distributed within the alumina matrix and located mainly along the grain boundaries. The permeability and strength were highly influenced by the sintering pressure and temperature, respectively. The results indicated that the membrane sintered at a pressure of 10 MPa, temperature of 1100 °C, holding time of 5 min, and heating rate of 200 °C/min exhibited the best combination of permeability and strength. This developed membrane showed a significant removal efficiency of 97% for cadmium (II) in an aqueous solution.

Antibiofouling Performance by Polyethersulfone Membranes Cast with Oxidized Multiwalled Carbon Nanotubes and Arabic Gum.

Despite extensive research efforts focusing on tackling membrane biofouling, one of the biggest problems associated with membrane technology, there has been little headway in this area. This study presents novel polyethersulfone (PES) membranes synthesized via a phase inversion method at incremental loadings of functionalized oxidized multiwalled carbon nanotubes (OMWCNT) along with 1 wt. % arabic gum (AG). The synthesized OMWCNT were examined using scanning electron microscopy and transmission electron microscopy for morphological changes compared to the commercially obtained carbon nanotubes. Additionally energy-dispersive X-ray spectroscopy was carried out on the raw and OMWCNT materials, indicating an almost 2-fold increase in oxygen content in the latter sample. The cast PES/OMWCNT membranes were extensively characterized, and underwent a series of performance testing using bovine serum albumin solution for fouling tests and model Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial species for anti-biofouling experiments. Results indicated that the composite PES membranes, which incorporated the OMWCNT and AG, possessed significantly stronger hydrophilicity and negative surface charge as evidenced by water contact angle and zeta potential data, respectively, when compared to plain PES membranes. Furthermore atomic force microscopy analysis showed that the PES/OMWCNT membranes exhibited significantly lower surface roughness values. Together, these membrane surface features were held responsible for the anti-adhesive nature of the hybrid membranes seen during biofouling tests. Importantly, the prepared membranes were able to inhibit bacterial colonization upon incubation with both Gram-positive and Gram-negative bacterial suspensions. The PES/OMWCNT membranes also presented more resilient normalized flux values when compared to neat PES and commercial membrane samples during filtration of both bacterial suspensions and real treated sewage effluents. Taken together, the results of this study allude to OMWCNT and AG as promising additives, for incorporation into polymeric membranes to enhance biofouling resistance.

Antibacterial Properties of Polysulfone Membranes Blended with Arabic Gum.

Polysulfone (PS) membranes blended with different loadings of arabic gum (AG) were synthesized using phase inversion method and the antibacterial properties of the synthesized membranes were tested using a number Gram-negative (Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacterial species. It was shown that AG addition to the dope polymer solutions essentially changed porous structure, hydrophilicity and zeta potential of the cast PS/AG membranes. These changes were due to the amphiphilic properties of AG macromolecules that contained negatively charged hydrophilic residues. A pronounced decrease in bacterial attachment was seen in the field emission scanning electron microscopy (FESEM) images for PS/AG membrane samples compared to both commercial (Microdyn-Nadir) and bare PS (without AG) membranes. AG loading dependent trend was observed where the prevention of bacterial colonization on the membrane surface was strongest at the highest (7 wt. %) AG loading in the casting solution. Possible mechanisms for the prevention of bacterial colonization were discussed. Significantly, the inhibition of bacterial attachment and growth on PS/AG membranes was observed for both Gram-positive and Gram-negative bacterial models, rendering these novel membranes with strong biofouling resistance attractive for water treatment applications.

Corrigendum to "Effect of Carboxylic Functional Group Functionalized on Carbon Nanotubes Surface on the Removal of Lead from Water".

[This corrects the article DOI: 10.1155/2010/603978.].

Characterization and Separation Performance of a Novel Polyethersulfone Membrane Blended with Acacia Gum.

Novel polyethersulfone (PES) membranes blended with 0.1-3.0 wt. % of Acacia gum (AG) as a pore-former and antifouling agent were fabricated using phase inversion technique. The effect of AG on the pore-size, porosity, surface morphology, surface charge, hydrophilicity, and mechanical properties of PES/AG membranes was studied by scanning electron microscopy (SEM), Raman spectroscopy, contact angle and zeta potential measurements. The antifouling -properties of PES/AG membranes were evaluated using Escherichia coli bacteria and bovine serum albumine (BSA). The use of AG as an additive to PES membranes was found to increase the surface charge, hydrophilicity (by 20%), porosity (by 77%) and permeate flux (by about 130%). Moreover, PES/AG membranes demonstrated higher antifouling and tensile stress (by 31%) when compared to pure PES membranes. It was shown that the prepared PES/AG membranes efficiently removed lead ions from aqueous solutions. Both the sieving mechanism of the membrane and chelation of lead with AG macromolecules incorporated in the membrane matrix contributed to lead removal. The obtained results indicated that AG can be used as a novel pore-former, hydrophilizing and antifouling agent, as well as an enhancer to the mechanical and rejection properties of the PES membranes.

Novel Aluminum Oxide-Impregnated Carbon Nanotube Membrane for the Removal of Cadmium from Aqueous Solution.

An aluminum oxide-impregnated carbon nanotube (CNT-Al2O3) membrane was developed via a novel approach and used in the removal of toxic metal cadmium ions, Cd(II). The membrane did not require any binder to hold the carbon nanotubes (CNTs) together. Instead, the Al2O3 particles impregnated on the surface of the CNTs were sintered together during heating at 1400 °C. Impregnated CNTs were characterized using XRD, while the CNT-Al2O3 membrane was characterized using scanning electron microscopy (SEM). Water flux, contact angle, and porosity measurements were performed on the membrane prior to the Cd(II) ion removal experiment, which was conducted in a specially devised continuous filtration system. The results demonstrated the extreme hydrophilic behavior of the developed membrane, which yielded a high water flux through the membrane. The filtration system removed 84% of the Cd(II) ions at pH 7 using CNT membrane with 10% Al2O3 loading. A maximum adsorption capacity of 54 mg/g was predicted by the Langmuir isotherm model for the CNT membrane with 10% Al2O3 loading. This high adsorption capacity indicated that adsorption was the main mechanism involved in the removal of Cd(II) ions.

Enhanced Adsorption of Selenium Ions from Aqueous Solution Using Iron Oxide Impregnated Carbon Nanotubes.

The aim of this research was to investigate the potential of raw and iron oxide impregnated carbon nanotubes (CNTs) as adsorbents for the removal of selenium (Se) ions from wastewater. The original and modified CNTs with different loadings of Fe2O3 nanoparticles were characterized using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffractometer (XRD), Brunauer, Emmett, and Teller (BET) surface area analyzer, thermogravimetric analysis (TGA), zeta potential, and energy dispersive X-ray spectroscopy (EDS). The adsorption parameters of the selenium ions from water using raw CNTs and iron oxide impregnated carbon nanotubes (CNT-Fe2O3) were optimized. Total removal of 1 ppm Se ions from water was achieved when 25 mg of CNTs impregnated with 20 wt.% of iron oxide nanoparticles is used. Freundlich and Langmuir isotherm models were used to study the nature of the adsorption process. Pseudo-first and pseudo-second-order models were employed to study the kinetics of selenium ions adsorption onto the surface of iron oxide impregnated CNTs. Maximum adsorption capacity of the Fe2O3 impregnated CNTs, predicted by Langmuir isotherm model, was found to be 111 mg/g. This new finding might revolutionize the adsorption treatment process and application by introducing a new type of nanoadsorbent that has super adsorption capacity towards Se ions.

Fast Disinfection of Escherichia coli Bacteria Using Carbon Nanotubes Interaction with Microwave Radiation.

Water disinfection has attracted the attention of scientists worldwide due to water scarcity. The most significant challenges are determining how to achieve proper disinfection without producing harmful byproducts obtained usually using conventional chemical disinfectants and developing new point-of-use methods for the removal and inactivation of waterborne pathogens. The removal of contaminants and reuse of the treated water would provide significant reductions in cost, time, liabilities, and labour to the industry and result in improved environmental stewardship. The present study demonstrates a new approach for the removal of Escherichia coli (E. coli) from water using as-produced and modified/functionalized carbon nanotubes (CNTs) with 1-octadecanol groups (C18) under the effect of microwave irradiation. Scanning/transmission electron microscopy, thermogravimetric analysis, and FTIR spectroscopy were used to characterise the morphological/structural and thermal properties of CNTs. The 1-octadecanol (C18) functional group was attached to the surface of CNTs via Fischer esterification. The produced CNTs were tested for their efficiency in destroying the pathogenic bacteria (E. coli) in water with and without the effect of microwave radiation. A low removal rate (3-5%) of (E. coli) bacteria was obtained when CNTs alone were used, indicating that CNTs did not cause bacterial cellular death. When combined with microwave radiation, the unmodified CNTs were able to remove up to 98% of bacteria from water, while a higher removal of bacteria (up to 100%) was achieved when CNTs-C18 was used under the same conditions.

Effect of carboxylic functional group functionalized on carbon nanotubes surface on the removal of lead from water.

The adsorption mechanism of the removal of lead from water by using carboxylic functional group (COOH) functionalized on the surface of carbon nanotubes was investigated. Four independent variables including pH, CNTs dosage, contact time, and agitation speed were carried out to determine the influence of these parameters on the adsorption capacity of the lead from water. The morphology of the synthesized multiwall carbon nanotubes (MWCNTs) was characterized by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) in order to measure the diameter and the length of the CNTs. The diameters of the carbon nanotubes were varied from 20 to 40 nm with average diameter at 24 nm and 10 micrometer in length. Results of the study showed that 100% of lead was removed by using COOH-MCNTs at pH 7, 150 rpm, and 2 hours. These high removal efficiencies were likely attributed to the strong affinity of lead to the physical and chemical properties of the CNTs. The adsorption isotherms plots were well fitted with experimental data.