Removal of lead(II) from aqueous solution using polyacrylonitrile/zinc oxide activated carbon nanofibers

This study aimed to prepare activated carbon nanofibers (ACNFs) from polyacrylonitrile (PAN) and zinc oxide (ZnO) via electrospinning process for removal of lead from aqueous solution. The ACNFs/ZnO were characterized in term of its morphological changes, specific surface area and functional groups analysis using Field Emission Scanning Electron Microscope (FESEM), Brunauer–Emmett–Teller (BET) and Fourier Transform Infrared (FTIR) analysis, respectively. The results showed that the specific surface area (SSA) of the ACNFs/ZnO were higher than the neat ACNFs which were 163.04 m2/g as compared to 67.6 m2/g, accordingly. FESEM analysis illustrated that composite ACNFs possessed more compact fibers with presence of ZnO beads and smaller fiber diameter whereas neat ACNFs possessed more aligned nanofibers with larger fiber diameter. Adsorption study showed that the composite ACNFs possessed higher capacity which was 120.3 mg/g as compared to 77.6 mg/g of neat ACNFs. This excellent adsorption performance of ACNFs PAN/ZnO exhibits the potential of this composite adsorbent to solve the environmental issue of heavy metal contamination

Effects of different loading of magnesium oxide on activated carbon nanofibers for methane adsorption

In the last few years, with the escalating world demand for energy, natural gas had been suggested as an alternative for replacing heavy fossil fuels as it produces cleaner combustion, less harmful and economical. Moreover, continuous world’s depending on fossil fuels such as crude oils, coals and heavy fuels has become a major concerned to the entire world as the excessive burning of these fuels produced harmful gases that leading to global warming. For this reasons, in this work, PAN- based activated carbon nanofibers (ACNFs) with various loading of magnesium oxide (MgO) (0, 5, 10, and 15 wt.%) were prepared for methane (CH4) adsorption. The nanofibers (NFs) were successfully produced via electrospinning process at optimize parameters. The resultant NFs underwent three steps of pyrolysis process which are stabilization, carbonization and activation at 275 oC, 600 oC and 800 oC, respectively. The ACNFs/MgO were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric (TGA) analysis, X-ray diffraction (XRD) analysis, Brunaeur, Emmett and Teller (BET) method and CH4 adsorption tests. The adsorption equilibrium of CH4 on ACNFs/MgO was measured using a static volumetric technique. Adsorption of CH4 on the ACNFs/MgO was conducted at 30 oC for pressures up to 4 bars. The equilibrium data were stimulated using the Freundlich and Langmuir isotherms, with both models having R2 > 0.98. The results on BET surface area showed the ACNFs loading with 15 wt.% MgO has the highest surface area of 1893.09 m2/g and it was assumed to be a major contributor for higher gas adsorption capacity. From these findings, it is believed that ACNFs/MgO will become a new adsorbent with great potential for gas adsorption and storage in the near future applications

Preparation of composite activated carbon nanofibers (ACNFs) for adsorption of heavy metals

The objective of this study is to prepare a new and highly efficient nanomaterial for heavy metals adsorption. Owing to that, activated carbon nanofibers (ACNFs) from precursor polyacrylnitrile (PAN) and manganese oxide (MnO2) have been prepared via electrospinning process for removal of heavy metals (lead and cadmium) from aqueous solution. The PAN/MnO2-based ACNFs were characterized in term of its morphological changes, specific surface area and functional groups analysis using SEM, BET and FTIR analysis respectively. The results showed that the specific surface area (SSA) of the electrospun composite ACNFs was higher than the neat ACNFs which is 499m2/g as compared to 800m2/g. SEM analysis illustrated that composite ACNFs have more compact fibers with presence of MnO2 beads and smaller fiber diameter of 437.2 nm whereas neat ACNFs possessed more aligned nanofibers with average fiber diameter of 575.5 nm. From adsorption study, the removal of Pb (II) and Cd (II) using both ACNF/MnO2 and ACNFs were higher than the commercial GAC with the removal efficiency is 100% for Pb (II) and 97% for Cd (II). The high removal efficiency of ACNFs/MnO2 is attributed by its larger SSA, presence of functional groups that play role in adsorption process such as hyroxyl and carboxyl groups and the role of manganese oxide as adsorbent itself (Han,2006). This excellent adsorption performance of ACNFs exhibits the potential of this composite adsorbent to solve the environmental issue of heavy metal contamination

Preparation and characterisation of polyethersulfone/ hydrous ferric oxide mixed matrix membranes with improved hydrophilicity for treatment of oily waste water

The rapid growth in oil and gas industry has led to the large production of oily wastewater. The massive amount of oily wastewater derived from the industry has raised concerns in community especially its adverse impact to the environment. Membrane technology has been in the spotlight in recent advancement to treat the oily wastewater. The major obstacle regarding the membrane technology is fouling due to surfactant adsorption and/or oil droplets plugging the pore, which would lead to a severe decline of the flux and rejection rate. HFO nanoparticles are incorporated into the PES membrane matrix with the aim to improve the hydrophilicity, water permeability as well as the antifouling properties of the membrane. HFO is abundant and easily obtained making it the perfect candidate in developing economical and energy saving membrane operation. Hydrous ferric dioxide (HFO) nanoparticles were synthesised via chemical precipitation method and incorporated in polyethersulfone (PES) to fabricate nanocomposite mixed matrix membranes (MMMs) for ultrafiltration (UF). The resulting membranes were characterised by SEM, FTIR, contact angle goniometer, before further subjected to water permeation test. It was found that contact angle of membrane decreased remarkably with an increase in HMO nanoparticle loading (state the value/ percentage decrement). The pore size at the skin layer however decreased as observed by SEM. As for the UF experiments, pure water permeation rate increased remarkably with increasing nanoparticle loading

Incorporation of layered double hydroxide nanofillers in polyamide nanofiltration membrane for high performance of salts rejections

In this work, thin film composite (TFC) membrane embedded with self-synthesized layered double hydroxide (LDH) nanofillers was prepared via interfacial polymerization technique for nanofiltration (NF) process. Prior to filtration experiments, the morphologies and physicochemical properties of the prepared LDH nanofillers and TFC membranes were characterized using TEM, XRD, FESEM, FTIR, AFM, zeta potential analyzer and contact angle goniometer. The results revealed that the self-synthesized LDH nanofillers possessed layered structured materials with typical hexagonal plate-like shape. Meanwhile, it was found that the membrane contact angle decreased remarkably from 53° to 33.96° upon addition of 0.1 wt% LDH nanofillers in the active polyamide layer. TFN membrane of 0.1 wt% LDH loading possessed the highest water flux of 54.62 Lm −2 h −1 at 7 bar. The highest rejections of Na 2 SO 4 (97.3%), MgSO 4 (95.5%), MgCl 2 (95.2%) and NaCl (63.7%) were also achieved by the TFN embedded with 0.1 wt% LDH in polyamide layer. In addition to the excellent water flux and rejection, incorporation of LDH also enhanced the fouling resistance, proven by the improvement of pure water flux recovery by 52% after BSA filtration. The findings indicated the potential of the newly developed TFN membrane incorporated with LDH nanofillers for efficient NF membrane in water softening and pre-desalination process

Study on microstructural properties of PAN/MnO2 nanofibers via electrospinning method

This paper reported the production of precursor PAN/MnO2 nanofibers via electrospinning method and studying its microstructural properties. The nanofibers were prepared by electrospun the polymer solution of polyacrylonitrile (PAN) and Manganese Oxide (MnO2) in, N, N-Dimethylformamide as its solvent. The factors considered in this study were polymer PAN/ MnO2 concentration which will significantly affect the specific surface area, nanofibers morphology, micropore volume and diameter of the nanofibers. The nanofibers were characterized using Scanning Electron Microscopy (SEM), Brunauer Emmett and Teller (BET) surface area, and Fourier Transmission Infrared Spectroscopy (FTIR). The addition of MnO2 in polymer solution increased the specific surface area of the nanofibers up to 3.5 wt % which found to be its optimum loading. In conclusion, the precursor PAN/ MnO2 -based ACNF were successfully produced with the optimization of metal oxide loading resulting to nanofibers with higher specific surface area which will further increased its adsorption performance

Removal of lead(II) by nanofiltration-ranged thin film nanocomposite membrane incorporated UiO-66-NH2: comparative removal performance between hydraulic-driven and osmotic-driven membrane process

Backgrounds: Contamination of heavy metals has attracted great attention in scientific community in which membrane technology by using thin film composite (TFC) membrane has shown a great potential for treating contaminated water. Methods: This study aimed to develop thin film nanocomposite (TFN) incorporated with different loading of water-stable UiO-66-NH2 and its comparative performance for removing lead (Pb) from water by hydraulic-driven nanofiltration (NF) and osmotic-driven forward osmosis (FO) process. Significant findings: In terms of membrane performance for Pb(II) removal by NF process, increasing Pb(II) initial concentration and the presence of multi-valent ions; cadmium (Cd)/nickel (Ni) decreased Pb(II) rejection for TFN/UiO-66-NH2. Interestingly, under the forward osmosis (FO) process, Pb(II) initial concentration and presence of multi-valent ions (Cd/Ni) did not influence the rejection of Pb(II) in which 99% rejection was achieved for all membranes. TFN/UiO-66-NH2 offered higher FO water flux as compared to the control membrane. In comparison to NF process using the same membrane, the rejection via FO process was 30% more efficient. Results from this study has proven that the incorporation of UiO-66-NH2 improved the properties of TFN membranes making it suitable to be used for water/wastewater treatment and FO can be as another alternative technique for heavy metals removal

Adsorption of cadmium (II) ions by polyacrylonitrile-based activated carbon nanofibers/magnesium oxide as its adsorbents

In this work, activated carbon nanofibers (ACNFs) from precursor polyacrylonitrile (PAN) and magnesium oxide (MgO) were prepared via electrospinning process. The morphological properties of the PAN/MgO - based ACNFs were characterized by using Scanning Electron Microscopy (SEM) and the specific surface area (SSA) were investigated using nitrogen adsorption, Brunauer - Emmett - Teller (BET) methods. Moreover, the functional groups were analyzed by using Fourier Transform Infrared (FTIR). Besides that, the sorption study has been conducted in order to determine the adsorption capacity between electrospun ACNFs/MgO, pristine ACNFs and granular activated carbon (GAC) towards cadmium (II) i ons. The results showed that the SSA of modified ACNFs (198.80 m 2 /g) is significantly higher compared to the precursor ACNFs (15.43 m 2 /g), however the SSA obtained is quite lower compared to the average theoretical value. SEM micrograph of pristine ACNFs depicted more compact nanofibers compared to aligned nanofibers with average diameter of 200 - 700 nm. Under batch adsorption study, it was found out that Cd(II) removal of both ACNFs and ACNFs/MgO is higher compared to the commercial GAC. It has been demonst rated that the adsorption capacity of both electrospun ACNFs (ACNFs/MgO and pristine ACNFs) is higher when compared to the adsorption capacity of commercial GAC towards Cd (II) ions

Adsorption of chromium (VI) via adsorptive PES-HFO ultrafiltration mixed matrix membrane

In this work, novel Polyethersulfone (PES)/hydrous ferric dioxide (HFO) ultrafiltration (UF) mixed matrix membranes (MMMs) were prepared for adsorptive removal of Chromium(VI) by varying the weight ratio of HFO:PES in the membrane from 0 to 1.5. The membranes prepared were characterized with respect to chemical structure, surface roughness and structural morphology using FTIR, AFM and SEM-EDX, respectively. The effects of HFO loadings on the membrane pure water flux, hydrophilicity, porosity and Cr (VI) adsorption capacity were also studied. The results showed that although the membrane pore size tended to decrease with increasing HFO:PES weight ratio, the membrane water flux was not negatively affected. Instead the membrane water flux was increased with increasing HFO loadings which was attributable to the decreased contact angle value (more hydrophilic), increased porosity and greater surface roughness. Of all the membranes studied, it is found that the MMM prepared from the highest HFO:PES ratio demonstrated the highest Cr (VI) uptake capacity and is comparable to other available commercial adsorbents

Characterizations of polysulfone/ferrihydrite mixed matrix membranes for water/wastewater treatment

This study aimed to investigate the effects of ferrihydrite (Fh) nanoparticle loading on the physicochemical properties of polysulfone (PSf) membranes fabricated via the phase inversion method. The morphologies and physicochemical properties of prepared Fh and PSf/Fh mixed matrix membranes (MMMs) were characterized using transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), Fourier transmission infra-red (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), pure water flux analysis, contact angle measurement, and membrane porosity analysis. FTIR study indicated that a new O-H band was formed when Fh was added into the membrane matrix. SEM analysis showed the formation of typical asymmetric membrane structures with elongated fingerlike and looser porous layers. Increasing the loading of Fh significantly enhanced membrane pure water flux from 230.2 L/m2•h (M-Fh 0%) to 726.6 L/m2•h (M-Fh 15.3%), attributed to the improved membranes structures, membranes wettability, surface roughness, and overall porosity. The findings suggest incorporation of Fh into PSf membranes improves physicochemical properties of the membranes which are applicable for water/wastewater treatment