This work tests the technical applicability of sewage sludge and isolated dead cells of Aeromasss hydrophyla and Branhamella spp for the elimination of inorganic pollutants such as Zn(II), Pb(II), Cd(II), and/or Cu(II) using synthetic wastewater with their initial concentrations of 100 mg/L, respectively. The sludge samples were collected from local sewage treatment plants. The effects of dose and pH on heavy metals removal were evaluated in batch studies and their removal performances were compared to those of previous studies. Both the Freundlich and the Langmuir models were plotted to study their biosorption using activated sludge and the bacteria. Isotherm data, resulting from the batch studies, were compared to the modeling results of Geochem. It was evident that the activated sludge could achieve 99% of Zn(II), Cd(II), Cu(II) and Pb(II) removal with 100 mg/L of concentration at pH 6.0 and 3 g/L of dose. Under the same conditions, 97% of Cd(II), Cu(II) and/or Pb(II) was removed by Aeromasss hydrophyla and Branhamella spp, as indicated by their adsorption capacities (activated sludge: 99.07 mg Pb2+/g; dewatered sludge: 57.15 mg Pb2+/g; digested sludge: 83.58 mg Pb2+/g; 24.47 mg Cd2+/g; Aeromasss hydrophylla: 71.91 mg Pb2+/g; Branhamella spp: 37.52 mg Cu2+/g). Of the four heavy metals studied, Pb(II) had the highest metal adsorption capacity for all adsorbents studied (Pb2+>Cu2+> Cd2+>Zn2+). The modeling results of the Geochem fitted well with the isotherm data of the batch studies at varying concentrations from 20 to 100 mg/L. The thermodynamic constant at pH 4 were comparable to those obtained from previous works. This indicates a reliable prediction over varying metal concentrations and pHs of the batch studies. In spite of the promising results, the treated effluents still could not meet the required effluent limits set by local legislation. Therefore, it is necessary to subsequently treat the samples using biological processes such as activated sludge.
Membrane distillation (MD) is an arising desalination technology due to several of its outstanding advantages over the conventional reverse osmosis (RO) and thermal desalination technologies. It is thermally driven and utilizes the hydrophobic membranes to separate the volatile solutes from the nonvolatile solution. In MD process, the vapor from the aqueous solution transports through the hydrophobic membrane and condensates at the other side of the membrane as the high-quality product. The membranes applied in MD process should have high liquid entry pressure (LEP), low thermal conductivity, optimum membrane thickness, optimum mean pore size and narrow pore size distribution, as well as high porosity and low tortuosity to ensure the excellent MD performance. Besides desalination, MD can also be applied in the removal of heavy metals and the recovery of valuable materials. This chapter describes the fundamental principles, membranes, and applications of MD. Besides that, the hydrophobization of membranes which includes the use of low surface energy membrane materials, functionalization with low surface energy materials as well as the applications of nanotechnology has also been discussed.
Poly(vinyl alcohol)/poly(ethylene glycol) (PVA/PEG) copolymer was prepared using casting technique. The obtained PVA/PEG thin films have been irradiated with gamma rays with doses ranging from 1.5 to 20 Gy. The resultant effect of gamma irradiation on the thermal properties of PVA/PEG has been investigated using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The onset temperature of decomposition T o and activation energy of thermal decomposition E a were calculated, results indicating that the PVA/PEG thin film decomposes in one main weight loss stage. Also, the gamma irradiation in dose range 4–12 Gy led to a more compact structure of PVA/PEG copolymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. The variation of transition temperatures with gamma dose has been determined using DTA. The PVA/PEG thermograms were characterized by the appearance of an endothermic peak due to melting of crystalline phase. In addition, structural property studies using X‐ray diffraction and infrared spectroscopy were performed on both nonirradiated and irradiated samples. Furthermore, the transmission of the PVA/PEG samples and any color changes were studied. The color intensity ( E was greatly increased with increasing the gamma dose and was accompanied by a significant increase in the blue and green color components. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Lead (Pb) exposure can be harmful to public health, especially through drinking water. One of the promising treatment methods for lead contaminated water is the adsorption-filtration method. To ensure the cost-effectiveness of the process, naturally derived adsorbent shall be utilised. In this study, hydroxyapatite particles, Ca10(PO4)6(OH)2 (HAP) derived from waste cockle shell, were incorporated into the outer layer of polysulfone/HAP (PSf/HAP) dual-layer hollow fibre (DLHF) membrane to enhance the removal of lead from the water source due to its hydrophilic nature and excellent adsorption capacity. The PSf/HAP DLHF membranes at different HAP loadings in the outer layer (0, 10, 20, 30 and 40 wt%) were fabricated via the co-extrusion phase inversion technique. The performance of the DLHF membranes was evaluated in terms of pure water flux, permeability and adsorption capacity towards lead. The results indicated that the HAP was successfully incorporated into the outer layer of the membrane, as visibly confirmed by microscopic analysis. The trend was towards an increase in pure water flux, permeability and lead adsorption capacity as the HAP loading increased to the optimum loading of 30 wt%. The optimized DLHF membrane displayed a reduced water contact angle by 95%, indicating its improved surface hydrophilicity, which positively affects the pure water flux and permeability of the membrane. Furthermore, the DLHF membrane possessed the highest lead adsorption capacity, 141.2 mg/g. The development of a hybrid inorganic–organic DLHF membrane via the incorporation of the naturally derived HAP in the outer layer is a cost-effective approach to treat lead contaminated water.
Flexible hollow fiber polymeric membrane based thin film substrate sputtered with thin layer photocatalyst is a novel configuration for photocatalytic applications. This article focuses on the fabrication of copper oxide/polyvinylidene fluoride thin film hollow fiber membrane (CuxO/PVDF TF HFM) by using radio frequency (RF) magnetron sputtering of CuxO over PVDF hollow fiber membrane (HFM). Different phase of copper oxide (CuxO) detected on the layer of PVDF HFM by X-ray diffraction (XRD) and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and confirmed by X-ray photoelectron spectroscopy (XPS), depending on oxygen flow rate. 10–20 mL/min O2 flow rate produces Cu2O phase while 25 and 30 mL/min produces CuO phase. Sputtered Cu2O/PVDF TF HFM at 20 mL/min O2 shows bigger grain size of 2.1 nm with 0.35 nm of dislocation density and 0.019 nm of lattice strain. The higher the O2 flow rate, the thicker and the more uniform the sputtered CuxO/PVDF TF HFM was produced as indicated by field emission scanning electron microscopy (FESEM). The atomic force microscopy (AFM) analysis showed the increasing surface roughness of the sputtered 10 mL/min CuxO/PVDF TF HFM at 8.26 nm, as compared to the neat PVDF HFM at 6.15 nm. About 74 % of 2 mg/L bisphenol A (BPA) in synthetic wastewater was successfully photodegraded and filtered while outstanding 91 % removal of BPA in real treated sewage wastewater achieved using 20 mL/min Cu2O/PVDF TF HFM after 360 min light irradiation. About 71.33 % of regeneration efficiency was achieved after 3 consecutive cycles that this technique promises the good reusability with strong adhesion capability.
No abstract is provided for this article.
For the first time, the novel of PVDF-Pt-Pd/RGO-CeO2 composite nanofibers were successfully fabricated by a facile and effective approach of electrospinning method. The as-synthesized PVDF-Pt-Pd/RGO-CeO2 composite nanofibers were characterized in term of surface morphology, crystallinity and structural properties. Morphological and structural characterizations indicated that the Pt-Pd/RGO-CeO catalysts were successfully decorated homogenously on the surface of PVDF nanofiber. The as-prepared PVDF-Pt-Pd/RGO-CeO2 composite nanofibers with the large specific surface area could possibly open up as the new catalyst material for DMFC application.
