NOPR Collection:

Preparation of a novel and highly stable Al-Fe loaded sepiolite catalyst for the CWPO of methyl orange: Optimization of physicochemical parameters, kinetics and thermodynamics studies

Tue, 01 Sep 2020 00:00:00 GMT

Title: Preparation of a novel and highly stable Al-Fe loaded sepiolite catalyst for the CWPO of methyl orange: Optimization of physicochemical parameters, kinetics and thermodynamics studies Authors: İlkerKıpçak; Kalpazan, Esin Abstract: Al-Fe loaded sepiolite catalysts with different active metal ratio have been synthesized using a Turkish sepiolite sample from Eskişehir region. Liquid phase catalytic oxidation of methyl orange azo dye has been carried out over Al-Fe/sepiolite catalysts using hydrogen peroxide as oxidant. The catalytic studies are performed in a glass reactor under atmospheric pressure by semi-batch operation. The effects of several parameters such as catalyst amount, metal loading, calcination temperature, pH, H₂O₂ concentration, reaction temperature and time on the methyl orange elimination have been examined. The elimination rate of 90.68% was achieved when studied with the catalyst with 8% active metal ratio (SepAlFe8) at pH 3.7 and 25°C. Kinetics studies show the degradation of methyl orange over the SepAlFe8 catalyst could be expressed by the pseudo-first-order reaction kinetics (k₁ = 0.0049 min^-1 at 25°C). The activation energy (E_a) of the reaction over this catalyst is foundas 29.48 kJ mol^-1. It was also found that the catalytic oxidation process is endothermic (ΔH = 26.99 kJ mol^-1) and nonspontaneous (ΔG = 96.72 kJ mol^-1 at 25°C). The catalyst is chemically stable and reusable with low release of iron. Page(s): 355-366

Influence of SnO2 nanoinclusions on the structural and dielectric properties of (PVA–PEO)/SnO2 nanocomposites

Tue, 01 Sep 2020 00:00:00 GMT

Title: Influence of SnO2 nanoinclusions on the structural and dielectric properties of (PVA–PEO)/SnO2 nanocomposites Authors: Choudhary, Shobhna; Dhatarwal, Priyanka; Sengwa, R J Abstract: Nanofiller concentration dependent, tunable-type structural, dielectric, thermo-mechanical, and optical properties of the polymer nanocomposites (PNCs) have established them as technologically smart multifunctional materials for advances in stretchable and flexible-type organoelectronic, optoelectronic, and energy harvesting/storage devices. In this work, organic-inorganic hybrid PNC films comprising poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) blend as host matrix (PVA–PEO; 50–50 wt%) dispersed with varying concentration of tin oxide (SnO₂) nanoparticles up to 5 wt% have been prepared by the solution-cast method. The influence of SnO₂ loading on the percent crystallinity of the host matrix and the structural parameters of the PEO crystallites has been examined by the X-ray diffraction (XRD) measurements of the PNC films. The results reveal that the percent crystallinity of the semicrystalline (PVA–PEO) matrix gradually enhanced, whereas the interlayer spacing, crystallite size, and interchain separation of the PEO crystallites varied anomalously with the increase of SnO₂ concentration in the PNC films. The complex dielectric permittivity, alternating current (ac) electrical conductivity, and electric modulus dispersion over the broad frequency range (20 Hz–1 MHz) of these (PVA–PEO)/SnO₂ films has been characterized by employing the dielectric relaxation spectroscopy (DRS). It has been observed that 1 wt% SnO₂ nanoinclusion abruptly reduced the interfacial, dipole polarizations, and also electrical conduction of the host matrix, whereas considerably enhanced hindrance to the PEO chain segmental motion studied at 30 °C. The temperature dependent study (30–60 °C) of the representative PNC film of 3 wt% nanofiller reveals its thermally activated non-linear dielectric polarization at fixed frequency and also Arrhenius behaviour of the dielectric relaxation processes of significantly low activation energy (≃ 0.14 eV). The structural, dielectric, and electrical properties of the (PVA–PEO)/SnO₂ films have been critically analyzed for their suitability as controllable low dielectric permittivity polymer nanodielectric (PNDs) materials for biodegradable electronic devices. Page(s): 367-374

Performance and reusability assessment of ZSM-5 for the production of lighter aromatics via pyrolysis of waste polystyrene

Tue, 01 Sep 2020 00:00:00 GMT

Title: Performance and reusability assessment of ZSM-5 for the production of lighter aromatics via pyrolysis of waste polystyrene Authors: Gaurh, Pramendra; Pramanik, Hiralal Abstract: The plastic waste poly styrene (PS) has been selected for the conversion to value added useful products using pyrolysis. The thermal and catalytic pyrolysis of polystyrene (PS) are investigated at reaction temperature ranging from 500°C to
800°C for 30 min, as an effective way to recycle polystyrene and produce valuable aromatic hydrocarbons benzene, toluene, ethyl benzene and xylene (BTEX). The catalytic pyrolysis is performed using commercial catalyst ZSM-5 which is reused repeatedly twice and further regenerated to evaluate the stability of ZSM-5 for PS pyrolysis with reference to BTEX formation. The maximum liquid yield of 96 wt. % and 86.2 wt. % are obtained at a temperature of 700°C for thermal pyrolysis and catalytic pyrolysis (fresh catalyst/1^st run), respectively. The product analyses show that liquid yield contains substantial amount of BTEX with the increase in temperature for fresh ZSM-5. The BTEX yield is significantly increased for catalytic pyrolysis (fresh catalyst/1^st run) i.e., about 75 wt. % for fresh ZSM-5 in comparison to thermal pyrolysis at a temperature of 700°C. There is very minute change in BTEX yield for the 2^nd and 3^rd run of catalytic pyrolysis using spent catalyst ZSM-5. The maximum aromatic (BTEX) of 23.71 wt. % for fresh ZSM-5 is obtained at the temperature of 700°C. However, spent ZSM-5(3^rd run) produced 20.45 wt. % BTEX at the same temperature. The regenerated ZSM-5 produced only 2 wt. % less BTEX yield in comparison to fresh ZSM-5 at the optimum temperature of 700°C. The gas chromatography and other fuel test have been performed for liquid yield characterisation. The characteristics of product prove that the liquid hydrocarbon has potential to use it as fuel. Page(s): 375-386

Fabrication of silica-based chitosan biocomposite material from volcanic ash and shrimp husk by sol gel method for adsorbent of cadmium (II) Ions

Tue, 01 Sep 2020 00:00:00 GMT

Title: Fabrication of silica-based chitosan biocomposite material from volcanic ash and shrimp husk by sol gel method for adsorbent of cadmium (II) Ions Authors: Simatupang, Lisnawaty; Situmorang, Manihar; Marpaung, Harlem; Siburian, Rikson Abstract: The utilization of volcanic ash and shrimp shell waste into composite material is very interesting to discuss as a strategy to make naturally available materials into valuable, stable and low cost adsorbent. The study is aimed to fabricate the silica-based chitosan biocomposite material from volcanic ash of Sinabung mountain and shrimp husk by sol gel method to be used as an adsorbent. The procedure is performed by converting volcanic ash into silica salt, extracting the chitosan from shrimp skeleton, and the synthesis of the silica-chitosan biocomposite by mixing the silica with chitosan in the aid of bifunctional glutaraldehyde cross-linking agent. The silica-based chitosan composite is successfully prepared from the mixture of 20 mL 58% (v/v) Na₂SiO₃with 2% (w/v) chitosan to obtain biocomposite material (SChC1). A rapid and simple method to bind the silica with chitosan is achieved. The resulting biocomposite is amorphous, in the form of small crystals, a rough surface with a large pore area between 2θ = 20-24°. Adsorption capacity of the biocomposite material has been evaluated, where it has the capability to bind cadmium ion due to the presence of amine group in the material surface. The prepared material of silica-chitosan biocomposite has the potential to be used as an adsorbent. Page(s): 387-394