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[en] The electronics industry is one of the world’s fastest growing manufacturing industries. However, e-waste has become a serious pollution problem. This study reports the recovery of e-waste for preparing valuable MCM-48 and ordered mesoporous carbon for the first time. Specifically, this study adopts an alkali-extracted method to obtain sodium silicate precursors from electronic packaging resin ash. The influence of synthesis variables such as gelation pH, neutral/cationic surfactant ratio, hydrothermal treatment temperature, and calcination temperature on the mesophase of MCM-48 materials is investigated. Experimental results confirm that well-ordered cubic MCM-48 materials were synthesized in strongly acidic and strongly basic media. The resulting mesoporous silica had a high surface area of 1,317 m2/g, mean pore size of about 3.0 nm, and a high purity of 99.87 wt%. Ordered mesoporous carbon with high surface area (1,715 m2/g) and uniform pore size of CMK-1 type was successfully prepared by impregnating MCM-48 template using the resin waste. The carbon structure was sensitive to the sulfuric acid concentration and carbonization temperature. Converting e-waste into MCM-48 materials not only eliminates the disposal problem of e-waste, but also transforms industrial waste into a useful nanomaterial.
[en] Rice husk is a form of agricultural biomass that provides an abundant silicon source. This study used rice husk as a raw material to prepare nanosilica without adding an extra surfactant. This work investigated a dissolution-precipitation technique as a function of acid treatment, sodium silicate concentration, gelation pH, aging temperature, and aging time to establish optimum conditions for preparing silica nanoparticles. Experimental results showed that silica produced by hydrochloric acid possesses higher surface area than that of sulfuric, oxalic, and citric acids. Surface characteristics of the sample depend mainly upon gelation pH. The highest surface area and pore volume of silica samples were 634 m2/g and 0.811 cm3/g. Pore diameters were controllable from 3 to 9 nm by adjusting the solution pH value. Particles had a uniform size of 5-30 nm. The objective of this study was to develop a method of nanosilica preparation that enhances the economic benefits of re-using rice husk waste.
[en] Highlights: ► P(VDF-HFP)/SBA-15 nanocomposite membranes in DSSCs was prepared by a solution casting method. ► The ionic conductivity of the P(VDF-HFP) electrolyte membranes were improved by addition of an optimal quantity of I-SBA-15 fillers, because the mesoporous SBA-15 fillers act as a micro-electrolyte reservoir, trapping DMPII within its mesoporous stricture. ► DSSC devices based on P(VDF-HFP)/I-SBA-15 nanocomposite membrane produced the highest conversion efficiency of ca. 5.29%, while illuminated at 100 mW cm−2. - Abstract: Poly(vinylidenefluoride-co-hexafluoropropylene)/SBA-15 molecular sieves (designated as P(VDF-HFP)/SBA-15) nanocomposite membranes were prepared by a solution casting method. Prior to blending, the SBA-15 molecular sieves were impregnated with dimethylpropylimidazolium iodide (DMPII) ionic liquid. The P(VDF-HFP)/SBA-15 nanocomposite membranes were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and AC impedance spectroscopy. The room temperature ionic conductivity of the P(VDF-HFP)/SBA-15A nanocomposite polymer electrolyte was of the order of around 10−3 S cm−1. The quasi-solid-state dye-sensitized solar cells (DSSCs) were assembled by using photo-electrodes of TiO2 films on FTO/glass and the counter electrode based on the pulsed-plated Pt films. P(VDF-HFP)/I-SBA-15 nanocomposite electrolyte membrane containing dimethylpropylimidazolium iodide (DMPII) provides the best energy conversion efficiency of ca. 5.29%. This result indicates that the P(VDF-HFP)/I-SBA-15 nanocomposite membrane is a good candidate for a quasi-solid-state DSSC applications.
[en] Highlights: • The LiFePO4/porous graphene oxide/C was prepared by a hydrothermal method and a spray dry process. • The porous graphene oxide was prepared through an activation method. • The discharge capacity of the SP-LFP/1%PGO/C is 107 mAh g−1 after 1000 cycles at 10C rate. • The SP-LFP/PGO/C material shows promising candidate for high-power Li-ion battery in EV. - Abstract: A 3D spray-dried micro/mesoporous LiFePO4/porous graphene oxide/C (denoted as SP-LFP/PGO/C) composite material is synthesized via a three-step process, i.e., hydrothermal process, carbon coating, and spray dry method in sequence. The 2D porous graphene oxide (denoted as PGO) material is first prepared through an activation method. The galvanostatic charge-discharge measurements of LFP composites without graphene oxide, with 1 wt% graphene oxide, and 1 wt% PGO are conducted in the potential range of 2–3.8 V at various rates (0.1–10C). It is revealed that the SP-LFP/PGO/C material shows the best performance among three samples. The discharge capacities of the SP-LFP/PGO/C composites are observed to 160, 152, 151, 149, 144, 139, 127 mAh g−1 at 0.1C, 0.2C, 0.5C, 1C, 3C, 5C and 10C rate. In particular, the discharge capacity of the SP-LFP/PGO/C composite with 1 wt% PGO is 107 mAh g−1 after 1000 cycles at a 10C rate, and its capacity retention is ca. 97%. It is due to the unique structural and geometrical feature of SP-LFP/PGO/C composite, there the diamond-like (rhombus) LFP nanoparticles are embedded in porous GO matrix which forming a porous three-dimensional network for fast electronic and ionic transport channels.