PVDF/Fe2O3 mixed matrix membrane for oily wastewater treatment

Oily wastewater has been recognized as one of the most concerned environmental pollutions that come from a variety of sources. The increasing of these uncontrollable oily wastewater discharges consequently leads to environmental problems. The current barrier in this situation is when dealing with finely emulsified oily wastewater streams with small droplet size (< 20 μm in diameter). To tackle this issue, it is found that the utilization of the membrane technology is most effective due to its highly effective separation process and simplicity. Nevertheless, traditional filtration membranes are mostly afflicted with low flux and rejection rate as a consequence of easy fouling caused by the plugging of oil and surfactant. Thus, the wettability and antifouling properties of the membrane play an important role in dealing with this issue. The aim of this study was to evaluate the performance and operation of the membrane when treating oily wastewater. PVDF was chosen as the host polymer based on its outstanding properties and 0.2 wt% of Fe2O3 loading was utilized to enhance the hydrophilicity of the membrane. The effects of mixed matrix membrane (MMM) and neat poly (vinylidene fluoride) (PVDF) membrane relating to their differences in the SEM images, water flux and oil rejection were studied. The presence of additive in the polymeric composition has helped to achieve 40% higher flux increment with an oil removal efficacy of ~97 %, as compared to the unmodified PVDF membrane

Phenol degradation behavior via photocatalytic of ZnO/Ag2CO3/Ag2O nanoparticles

The present study successfully conducted the synthesis of ZnO/Ag2CO3/Ag2O nanocomposite using co-precipitate technique and phase transformation route. The resulting nanocomposite photocatalyst were characterized by TEM and UV–vis spectra, while their photocatalytic activities were subsequently tested in the mineralization of phenol solution. Meanwhile, the heterojunction of Ag2CO3/Ag2O over ZnO lattice that influenced the surface-phase structure of the nanocomposites managed to generate higher absorption in visible light region in UV NIR spectra. In addition, the surface phase structure was produced via Ag2O crystal growth over Ag2CO3 which was heterojunctioned on ZnO lattice, thus leading to an effective charge carrier transfer that indirectly suppressed the recombination of photogenerated electrons and holes. The results of the current research on the photocatalytic behaviour of the nanocomposites demonstrated that the phenol peak area for ZnO/Ag2CO3/Ag2O under UV light decreased 25.4 % compared to visible light radiation of 14.1 %. The presence of photo-oxidation products was detected in the liquid phase products in phenol-oxidation even though phenol was not completely removed. Overall, it was remarkable to discover that the formation of Ag2CO3/Ag2O mixed phase heterojunction over the surface of ZnO significantly enhanced the photocatalytic activity under visible light irradiation

Adsorption of cesium from aqueous solution using chitosan beads

Due to rapid population growth, technological advancement and industrial revolution, the rate of generated waste effluents has become a grave concern. Cesium, which possesses high fission yield, is generally transferred into liquid wastes, especially those emanated from nuclear power plants, reprocessing of spent fuels, nuclear weapon testing, and radionuclides production facilities for medical applications. Radiocesium (137Cs) is one of the hazardous radionuclides which have adverse effects on human health and the environment. Thus, from a health point of view, the removal of cesium from wastewater is imperative. Several techniques have been introduced as solution, and recently, adsorption has been gaining increasing attention among the scientific community owing to a number of reasons. Hence, this research presents an experimental work on sorption of cesium from wastewaters. In this study, chitosan was used as an adsorbent. The effects of several critical parameters, namely contact time, initial concentration, and absorbent dosage on the absorbent performance were investigated. From the findings, the optimum condition for the adsorption of cesium was optimized at pH 1 at 300 mg/L for 5 hours of contact time. The sorption data fitted well with Freundlich adsorption model, with the value of R2 = 0.9940, and was best described by pseudo-first-order model with the value of correlation coefficient, R2 = 0.9952

Structural characterization of acid and alkali treated-corncob waste: a potential resources biosorbent

Corncob is an agricultural scrap obtained in bulk quantities during the production of corn. This agriculture waste is a potential resource to act as a biosorbent for the removal of heavy metals. Therefore, the objective of this study is to highlight a structural and surface characterization of raw corncob, H3PO4-pretreated corncob, and KOH-pretreated corncob since modification of raw corncob with different methods may change the surface area and also the electrical nature and surface functional groups of corncob, the removal capability of corncob as adsorbent could also be affected. The biomass samples were characterized via Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmett–Teller (BET) analysis. The FTIR result shows that the major functional groups of corncob such as –OH, C–O, C–H, and C=C experienced a slight shift due to the presence of KOH and H3PO4. Treatments with KOH and H3PO4 improved the BET surface area with the values of 8.8920 and 6.7894 m2/g, respectively, compared with raw corncob (0.5011 m2/g). The results indicate that the pretreatment of corncob influenced the functional groups and surface area of the raw corncob. Improved surface area may increase the ability of the corncob as adsorbent in heavy metals removal

PVDF/HMO ultrafiltration membrane for efficient oil/water separation

In this research, hydrous manganese oxide (HMO) nanoparticles was adopted in polyvinylidene fluoride (PVDF) to improve the ability of the mixed matrix membrane (MMM) to separate oil/water emulsions. The MMMs – which were added with various amounts of HMO loading (3, 5, 7 and 10 wt%) – were characterized for its physicochemical properties, morphological structure, and nanoparticles dispersion of the PVDF/HMO membrane. Evidently, the presence of these nanoparticles increased the hydrophilicity and oleophobicity of the PVDF/HMO membrane as compared to those of the pristine PVDF. Concurrently, the water contact angle was reduced from 99 to 58 while oil contact angle increased from 0 to 35 . The presence of -OH groups and Mn element channeling the PVDF/HMO membrane wetting properties, which in turn improved the membrane’s affinity towards water molecules and aversion to oil droplets. The PVDF/HMO membrane that contained 10 wt% of HMO loading exhibited a water flux (402 L/m2 h) – 10 times greater than the pristine PVDF membrane with 93% oil rejection rate

Chitosan/silica composite membrane: Performance on water permeability and rejection of lead(II) ion from aqueous solution

Heavy metal such as lead can be classified as non-biodegradable inorganic pollutants which can contaminate the soils, ground water, sediments and surface water. It cannot be broken down or decomposed by living organism and can continue to exist over a prolonged period, generating harmful effects to the living things. Thus, lead removal is necessary in order to reduce the amount of heavy metals contaminated in water. The purpose of this study was to fabricate chitosan/silica based composite membrane for removal of Pb(II) metal ions from aqueous solution by membrane filtration technique. The composite membranes were characterized in terms of morphological studies and functional group analysis by using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR) analysis, respectively. The membrane permeation performance, in terms of water permeability and rejection of Pb(II) ions from aqueous solution, was conducted by using membrane permeation system. SEM images illustrated that the presence of macrovoids on the cross-section of the chitosan/silica composite membrane has improved the morphology of pure chitosan membrane and assisted in the rejection of Pb(II) ions. Meanwhile, FTIR-ATR spectra showed the presence of new adsorption peaks, contributed by silica interaction with hydroxyl group of chitosan. The addition of silica to chitosan membrane has significantly enhanced the pure water permeability from 37.36 L/m2h to 42.43 L/m2h. Furthermore, the rejection of Pb(II) metal ions by chitosan/silica composite membrane was slightly higher compared to pure chitosan membrane with the removal efficiency of 13.78% at 0.5 bar applied pressure. These findings indicate the potential use of silica to improve chitosan membrane properties and reduce heavy metal pollution in water

Photocatalytic PVDF ultrafiltration membrane incorporated with visible-light driven ternary heterojunction: pure water flux behavior

Photocatalytic PVDF-ZnO/Ag2CO3/Ag2O mixed matrix membranes (MMM) were prepared by wet-phase inversion method. Incorporating the ZnO/Ag2CO3/Ag2O photocatalyst into the membrane surface resulted in a more hydrophilic membrane surface. The PVDF-ZnO/Ag2CO3/Ag2O membrane exhibited remarkable ability on pure water flux filtration under visible light irradiation due to the photoinduced hydrophilicity of ZnO/Ag2CO3/Ag2O. Thus, when pure water is filtered under visible light (photo-filtration), the flux found slightly higher than flux in the dark. Apart of that, membranes with higher loading of ZnO/Ag2CO3/Ag2O photocatalyst, have higher flux increment during light irradiation. The highest loading of ZnO/Ag2CO3/Ag2O photocatalyst showed the highest PWF increment up to ~9.81% after 180 min of light irradiation. Throughout this study, the excellent performance of PVDF-ZnO/Ag2CO3/Ag2O membrane provided valuable insight for photocatalytic membrane application in water production field

Synthesis of zeolitic imidazolate framework-8 modified graphene oxide composite and its application for lead removal

BACKGROUND: The removal of lead ions (Pb2+) from industrial wastewater can be achieved using adsorption technology. Composites of zeolitic imidazolate framework-8 (ZIF-8) and graphene oxide (GO) were prepared via room temperature synthesis (RTS) using RO water as the solvent and by mixing GO with separated parts of ZIF-8 precursors before its combination. Three weight percentages of GO, 10wt%, 30wt% and 50wt%, were used to synthesize ZGH10, ZGH30 and ZGH50 to determine optimum preparation and application conditions. Results: ZGH30 showed the most outstanding performance as an adsorbent for Pb2+ removal from aqueous solution. As captured by field emission scanning electron microscopy image, ZGH30 showed an adequate amount of ZIF-8 grown on all surfaces of thr GO sheet, with an appropriate exposure of GO sheet layers for further Pb2+ interaction. The Pb2+ adsorption test revealed that ZGH30 obtained the optimum operating values between pH 5 and 6, using 10 mg dosage and it could remove ≤97% of 100 mg L−1 Pb2+. Additionally, ZGH30 achieved the most rapid equilibrium time within 10 min, similar to ZGH50, as compared to their individual components, ZIF-8 (240 min) and GO (300 min). The mechanism of Pb2+ adsorption fitted well with a Langmuir isotherm and pseudo-second-order kinetic model. The theoretical maximum adsorption capacities obtained through Langmuir isotherm were 200, 454.55, 476.19, 555.56 and 454.55 mg g−1 , for GO, ZH, ZGH10, ZGH30 and ZGH50, respectively

Pb(II) removal and its adsorption from aqueous solution using zinc oxide/graphene oxide composite

Eliminating soluble lead ion from wastewater through adsorption has been more critical with the nonstop anthropogenic activity releasing it as waste. This study focuses on synthesizing zinc oxide-modified graphene oxide (ZnO/GO) following the solvothermal method and evaluating its capacity in adsorbing Pb(II) ion. The synthesized ZnO/GO was characterized using X-ray Diffraction (XRD), Fourier-transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDX) analysis; the results revealed that the graphene oxide (GO) had successfully bonded with zinc oxide (ZnO). The adsorption of Pb(II) on the functionalized ZnO/GO was studied under different experimental conditions, which confirmed the high adsorption capacity of ZnO/GO in removing Pb(II). The optimum pH and adsorbent dosage of ZnO/GO were at pH 5 and 0.16 g/L and the maximum adsorption capacity reached 909.09 mg/g. The most rapid adsorption occurred in the first 30 minutes of contact time with the equilibrium time achieved in 160 minutes and the adsorption isotherm and kinetic followed the Langmuir and pseudo-first order model. Therefore, the newly synthesized ZnO/GO showed superior adsorption capacity for Pb(II) compared to its pure GO