Recycling of supported nanocomposites for hazardous industrial wastewater treatment via Solar photocatalytic process

Study of the photocatalytic activity of the synthesized polyvinylidene fluoride/multi-walled carbon nanotubes/titanium dioxide (PVDF/x%(MWCNTs/8%TiO2) nanocomposites using a simple modified solvent casting technique in decontamination of hazardous industrial wastewater and Reactive Yellow 145 dye as an industrial organic pollutant (local textile dye) were evaluated. Also, different MWCNTs/8%TiO₂ weight percentages in PVDF/x%(MWCNTs/8%TiO₂) nanocomposites were prepared and evaluated. The surface morphology and the structures of the synthesized samples were characterized using SEM, ATR-FTIR, DRS, XRD, and BET. The evaluated bandgap values for MWCNTs/xTiO₂ nanocomposites are from 2.38 to 2.69 based on the weight ratios (2%, 5%, and 8%). The results of the surface area of samples and the best optical behavior obtained at MWCNTs/8%TiO₂ are reported and its photodegradation rate raised to 10.22x10^?3S^?1. The photodegradation process of Reactive Yellow 145 dye by PVDF/x%(MWCNTs/8%TiO₂) nanocomposites was monitoring using chemical oxygen demand (COD). Also, the observed PL intensity for PVDF/MWCNTs/8%TiO₂ has high photonic efficiency and photocatalytic activity. The solar photocatalytic process efficiency for an Egyptian dying factory by repeating it 10 times using PVDF/10%(MWCNTs/8%TiO₂) nanocomposites as a supported photocatalyst for the industrial wastewater treatment was evaluated by the COD method and still under Egyptian environmental law allowed COD limit (1000 ppm).     

Direct conversion of natural gas into COx-free hydrogen and MWCNTs over commercial Ni–Mo/Al2O3 catalyst: Effect of reaction parameters

A commercial hydrotreating nickel molybdate/alumina catalyst was used for the direct conversion of natural gas (NG) into CO_x-free hydrogen and a co-valuable product of multi-walled carbon nanotubes (MWCNTs). The catalytic runs were carried out atmospherically in a fixed-bed flow reactor. The effect of reaction temperature between 600 and 800 °C, and dilution of the NG feed with nitrogen as well as pretreatment of the catalyst with hydrogen were investigated. At a reaction temperature of 700 °C and dilution ratio of NG/N₂ = 20/30, the optimum yield of H₂ (～80%) was obtained with higher longevity. However, using the feed ratio of NG/N₂ = 30/20, the optimum yield of MWCNTs was obtained (669%). X-ray diffraction pattern for the catalyst after the reaction showed that the MWCNTs were grown on the catalyst at all reaction temperatures under study. TEM pictures revealed that the as-grown MWCNTs at 600, 650 and 800 °C are short and long with a low graphitization degree. At 700 °C a forest of condensed CNTs is formed, whereas both carbon nanofibers and CNTs were formed at 750 °C.     

Catalytic decomposition of methane to COx-free hydrogen and carbon nanotubes over Co–W/MgO catalysts

Bimetallic catalysts containing a series of Co/W at 40/10, 30/20, 20/30 and 10/40 wt% supported on MgO with a total metal content of 50 wt% were prepared and used for the catalytic decomposition of methane to CO_x-free hydrogen and multi-walled carbon nanotubes (MWCNTs). The solid fresh and exhausted catalysts were characterized structurally and chemically through XRD, TPR, BET, TGA, TEM and Raman spectroscopy. The 40%Co–10%W/MgO catalyst exhibited the highest activity for the production of both hydrogen and MWCNTs. The formation of a large amount of non-interacted Co₃O₄ species is considered as the main reason for the catalyst superiority in its activity. On the contrary, catalysts formulations of 20%Co–30%W and 10%Co–40%W demonstrated the formation of a large amount of hardly reducible CoWO₄ and MgWO₄ particles causing lower activity of these catalysts toward methane decomposition as evidenced through the XRD and TPR results.     

Electrochemical detection of rutin in black tartary buckwheat tea and related health-care pills with new ionic liquid-based supramolecular hydrogels

As the famous naturally occurring flavonoid, rutin exists in many foods, beverages, and their processed functional products. To realize highly efficient analysis for it, a novel supramolecular hydrogel was developed as the electrode modification material for sensor. Here 12 amino acid-based ionic liquids ([C_nmim][AA]) were synthesized and 6 of them could self-aggregate to form hydrogels. Especially, all the hydrogels possessed dual sensitivities to temperature and pH, as well as relatively excellent electrocatalytic performance. A three-layer electrochemical sensor [C_nmim][AA]/MWCNTs/CS/GCE was prepared by decorating glass carbon electrode (GCE) with hydrogels, multiwalled carbon nanotubes (MWCNTs) and chitosan (CS) to detect rutin. After comprehensive characterization, computation and systematic investigation, the results indicated that Ipa was linearly related to the concentration of rutin in the range of 0.5–5 μM and 5–100 μM with a limit of detection (LOD) of 0.05 μM (S/N = 3). The selectivity, repeatability, stability and potential in electrochemical analysis of the developed supramolecular sensor were proved after analysis of black tartary buckwheat tea and related health-care pills.     

Highly sensitive electrochemical determination of sunset yellow in commercial food products based on CHIT/GO/MWCNTs/AuNPs/GCE

Sunset yellow (SY) belongs to the azo group, commonly used in food industry. Highly consumption of SY may lead toxicity and photogenic to human health. Herein, a simple and highly sensitive electrochemical sensor was developed based on the modified glassy carbon electrode (GCE) with graphene (GO), multiwall carbon nanotubes (MWCNTs), gold nanoparticles (AuNPs) and nanocomposite membrane of chitosan (CHIT) for quantifying the level of SY in commercial food products. The CHIT/GO/MWCNTs/AuNPs were coated onto the GCE surface and analysed by using differential pulse voltammetry (DPV). The surfaces of CHIT/GO/MWCNTs/AuNPs/GCE characteristics were observed under scanning electron microscopy and transmission electron microscope. Under optimal condition, the DPV method was sensitively detected with different concentrations of SY from 10 to 90 mg mL⁻¹. The limits of detection and quantification were obtained to be 0.032 mg mL⁻¹ and 0.096 mg mL⁻¹, respectively. The proposed method was successfully applied to quantify the amount of SY in candy, jelly and soft drinks with good recovery values from 98.11% to 104.03%. Hence, the proposed sensor shows a rapid and sensitive method, low cost and simple, which an appropriate for alternative technique use for the analysis of food colorants in commercial products.     

低温溶液法制备TiO2/γ-AlO(OH)纳米复合粉体及其光催化性能

以硝酸铝为铝源,钛酸四丁酯为钛源,柠檬酸三铵为起泡剂,聚乙烯吡咯烷酮(PVP)作表面活性剂,采用低温溶液法制备TiO2/γ-AlO(OH)复合纳米粉体光催化剂;采用HRTEM、FESEM、EDS、XRD、紫外-可见漫反射光谱(UV-Vis DRS)和N2吸附-脱附(BET)等手段对复合材料进行表征;研究了γ-AlO(OH)掺杂量、PVP表面活性剂等对TiO2/γ-AlO(OH)复合纳米粉体的形貌及光催化活性的影响规律;探究了吸附作用对催化剂活性的影响。结果表明：载体材料γ-AlO(OH)纳米微球的介孔结构限制了TiO2纳米晶的团聚和长大,适当添加PVP表面活性剂可以减少复合粉体团聚,并调控其微观形貌;当γ-AlO(OH)掺杂质量分数为10%、PVP添加量为0.1 mmol时,制备的TiO2/γ-AlO(OH)复合粉体的BET比表面积为334.27 m2/g,催化性能最佳,光照30 min,对罗丹明B的降解效率为94.26%,远大于纯锐钛矿结构TiO2和市售P25催化剂。     

Study of the productivity of MWCNT over Fe and Fe–Co catalysts supported on SiO2, Al2O3 and MgO

In the present study, multi-walled carbon nanotubes (MWCNT) were prepared in good quality and quantity, MWCNT were produced using the catalytic chemical vapor deposition (CCVD) technique and the carbon source was acetylene. Different catalysts were synthesized based on iron and a mixture of iron and cobalt metal supported on SiO₂, Al₂O₃ or MgO. The effect of parameters such as iron concentration, support type, bimetallic catalyst and the method of catalyst preparation has been investigated in the production of MWCNT. The quality of as-made nanotubes was investigated by the high-resolution transmission electron microscopy (HRTEM) and thermogravimetric analysis (TGA). The best yield of MWCNT was 30 times of the amount of the used catalyst. The high yield of MWCNT was gained by 40 wt.% Fe on alumina support which was prepared by the sol–gel method. TEM analysis was done for the carbon deposit, which revealed that the walls of the MWCNT were graphitized, with regular inner channel and uniform diameter. It reflected a reasonable degree of purity. The TGA showed that MWCNT was decomposed at 635 °C by a small rate indicating a high thermal stability and well crystalline formation of the produced MWCNT.     

Synthesis of carbon nanotubes by CCVD of natural gas using hydrotreating catalysts

Carbon nanotubes have been successfully synthesized using the catalytic chemical vapor deposition (CCVD) technique over typical refining hydrotreating catalysts (hydrodesulfurization and hydrodenitrogenation) containing Ni–Mo and Co–Mo supported on Al₂O₃ catalysts at 700°C in a fixed bed horizontal reactor using natural gas as a carbon source. The catalysts and the as-grown CNTs were characterized by transmission electron microscopy, HRTEM, X-ray diffraction patterns, EDX and TGA–DTG. The obtained data clarified that the Ni–Mo catalyst gives higher yield, higher purity and selectivity for CNTs compared to Co–Mo catalyst. XRD, TEM and TGA reveal also that the Ni–Mo catalyst produces mostly CNTs with different diameters whereas the Co–Mo catalyst produces largely amorphous carbon.     

Electrochemical sensor based on imprinted sol–gel and nanomaterials for sensitive determination of bisphenol A

Bisphenol A (BPA) was reported to show potential detrimental effects on wildlife and humans through altering endocrine function. In this study, a novel electrochemical imprinted sensor for sensitive and convenient determination of BPA was developed. Multi-walled carbon nanotubes (MWCNTs) and gold nanoparticles (GNPs) were introduced for the enhancement of electronic transmission and sensitivity. Thin film of molecularly imprinted sol–gel polymers with specific binding sites for BPA was cast on gold electrode by electrochemical deposition. The resulting composites were characterized by cyclic voltammetry (CV) and UV–visible spectra. Rebinding experiments were carried out to determine the specific binding capacity and selective recognition of the sensor. The linear range was from 1.13 × 10^?7 to 8.21 × 10^?3 mol L^?1, with the limit of detection (LOD) of 3.6 × 10^?9 mol L^?1 (S/N = 3). The imprinted sensor was successfully tested to detect BPA in real samples.     

Effect of ozonation combined with heterogeneous catalysts and ultraviolet radiation on recycling of gas-station wastewater

Ozonation is extensively applied in the treatment of drinking water and wastewater due to the powerful oxidation potential of ozone. Heterogeneous catalytic ozonation (HCO) of wastewater proceeds through hydroxyl radicals as the oxidation species. The effect of ozonation alone and combined with catalysts in the presence and absence of UV-radiation was investigated to reuse the biologically pretreated gas-station wastewater instead of fresh water. Two types of catalysts: titanium dioxide (TiO₂) and activated carbon (AC) were studied. The concentration of catalyst, dark adsorption, reaction time and the improvement of biodegradability were studied. The combination of catalysts and ozonation reveals a significant improvement in the removal of contaminants present in wastewater by using the ozonation, adsorption or photocatalysis systems. Maximum dissolved organic carbon (DOC) removal of 91% was achieved by the combination of ozone, TiO₂ and the UV-radiation system. But, an increase in biodegradability from 0.12 to 0.33 was realised with ozone and the TiO₂ system. Furthermore, the biodegradability was increased with increasing catalyst concentration combined with ozone up to 1 g/L with TiO₂ and 0.5 g/L with AC.     

Impact of environmentally friendly nanoparticles on physical properties of poly p-phenylenediamine

Eggshell is a bio-friendly substance containing by weight of 95% CaCO₃ and 5% the oxides (Mn, Si, Al, Fe, Cr, Cu and Ca) and organic substances. The oxidation was used to prepare the poly(p-phenylenediamine) in the presence of potassium persulphate as an oxidant. Poly (p-phenylenediamine) and their nanocomposites with nano eggshell (ESN), carbon nanotube (CNT), and nano eggshell/carbon nanotube were prepared and compared with ground eggshell (ESG). All prepared samples were confirmed via Fourier transforms infrared spectroscopy in addition to Raman spectra. The morphology has been studied by transmission electron microscopy. The thermal stability of the synthesized polymer nanocomposites was evaluated via thermogravimetric analyzer, the results proved that the addition of ESN and ESG to CNT gives better thermal stability than each compound. The addition of (2 wt%) 0.04 gm ESN + CNTs improved the thermal stability of polymer than (1 wt%) 0.02 gm ESN + CNTs. The electrical conductivity properties were studied, the results showed efficiency in the improvement of electrical properties σ = 10⁻⁵ ohm⁻¹.cm⁻¹, which form a better composite with higher conductivity, so it can be used as a semiconductor.     

Comparison of antiwear properties of titanium-containing compounds

In search for environmentally friendly lubricant additives, titanium 2-ethylhexanoate and titanium oleate, which titanium compounds soluble in white oil, have been synthesized, as well as titanium dioxide nanoparticles modified with tetra-(2-ethylhexyl)thiuram disulfide and di(2-ethylhexyl)thiophosphonodisulfide. These titanium compounds have been characterized by elemental analysis, thermogravimetry, and IR spectroscopy. By means of the small-angle X-ray scattering technique, it has been found that the TiO₂ nanoparticles have a size of 1?C10 nm. Evaluation of antiwear properties of titanium compounds on a ChS-hMT-1 tribometer in a white oil solution shows that the decrease in wear scar diameter is 38?C49% compared with the white oil. Analysis of the friction surfaces by atomic-force microscopy and X-ray microanalysis has shown a decrease in roughness of the friction surface caused by the presence of titanium atoms in the surface layers.     

LaAl_(1/3)Fe_(2/3)O_3催化剂的制备及用于VOCs裂解制备碳纳米管

用硝酸镧、硝酸铝与硝酸铁作原料,采用柠檬酸法制备了多孔铁铝酸镧催化剂,用XRD与SEM对其结构进行表征。采用LaAl1/3Fe2/3O3催化剂,在973K下,研究了易挥发有机物(碳源)苯、环己烷、正己烷、甲苯、甲醇、丙酮催化裂解制备碳纳米管。结果表明,前3种碳源能高收率制备管径均匀的碳纳米管;甲苯、丙酮裂解得到少量不均匀的碳纳米管;甲醇裂解没有碳纳米管生成。以环己烷为碳源,研究了裂解温度对碳纳米管生成的影响,采用SEM、TEM表征了碳纳米管的形貌。     

Simulation Study of Different Modes of Miscible Carbon Dioxide Flooding

Carbon dioxide flooding has been applied worldwide as a successful enhanced oil recovery. Carbon dioxide flooding may be applied as a continuous injection or as water-alternating-gas (WAG) process. Optimization of the injection mode of carbon dioxide is important for economical field application. This paper focuses on using a fully compositional simulation model for “AEB-3C” sandstone oil reservoir of one of the Western Desert oil fields in Egypt to predict the impact of CO₂ miscible flooding on the reservoir oil recovery and net present value (NPV), to define the best mode of operation that is straight CO₂ injection or water alternating gas (WAG) processes and to show the difference between pure and impure CO₂. Moreover, several sensitivity runs were done on the oil price to show minimum profitable value of oil price when applying such a tertiary method in the subject field.The reservoir under study has been producing under a successful water flooding project since May-2010. The recovery factor by the end of water flooding project is predicted as 32%. CO₂ flooding processes have started by the end of water flooding. A significant increase in the oil recovery factor was noticed due to applying this method; it reached up to 57%. Comparisons between different modes of operations were shown which showed better results when applying WAG process than that with straight CO₂ injection. Moreover; sensitivities were done on the cycle periods in WAG processes and showed increase in the recovery factor with shortening the cycle periods. In addition to a comparison between pure and impure CO₂ which showed very close results.     

Amperometric biosensor for aflatoxin B1 based on aflatoxin-oxidase immobilized on multiwalled carbon nanotubes

An amperometric aflatoxin biosensor developed by aflatoxin-oxidase (AFO), embedded in sol-gel, linked to multiwalled carbon nanotubes (MWCNTs)-modified Pt electrode was reported for the first time. The covalent linkage between AFO and MWCNTs retained enzyme activity and responsed to the oxidation of afltoxin B₁ (AFB₁). Its apparent Michaelis-Menten constant for AFB₁ was 7.03 μmol·L^?1, showing a good affinity. The sensor exhibited a linear range from 3.2 nmol·L^?1 to 721 nmol·L^?1 (1 ng/ml to 225 ng/ml) with limits of detection of 1.6 nmol·L^?1 (signal-to-noise ratio = 3), an average response time of 44 s (less than 30 s when AFB₁ Conc. is bigger than 45 ng/ml), and a high sensitivity of 0.33 × 10² A mol^?1·L cm^?2. The active energy was 18.8 kJ mol^?1, demonstrating the significant catalyzation of AFO for oxidation of AFB₁ in this biosensor.     

A Simulation Study of Carbon Dioxide Sequestration in a Depleted Oil Reservoir

Abstract

Oil fields offer significant potential for storing carbon dioxide (CO₂) and will most likely be the first large-scale geological targets for sequestration because the infrastructure, experience, and permitting procedures already exist. In addition, almost 40 years' experience in enhanced oil recovery (EOR) allows utilization of carbon capture and storage (CCS) and CO₂ sequestration techniques in such a way as to improve recovery of petroleum fields and reduce the environmental issue of fossil fuel combustion gas products, particularly carbon dioxide. Carbon dioxide is one of the main greenhouse gases that causes global warming.

As a response to global warming, geologic sequestration of CO₂ in oil and gas reservoirs is one possibility to reduce the amount of CO₂ released to the atmosphere. This simulation study presents a synthetic geologic model that is used to sequestrate carbon dioxide beside an EOR immiscible displacement process.     

二氧化钛对克劳斯反应气体吸附性能研究

目的 为了研究二氧化钛硫磺回收催化剂对克劳斯反应过程的催化机理,开展了催化剂对H₂S、SO₂和有机硫等主要反应物的吸附性能研究。方法 针对克劳斯化学反应所涉及反应物与产物在典型的二氧化钛催化剂上的吸附与脱附情况,采用微型反应器-质谱分析表征技术,研究了H₂S、SO₂产物在单独与共存条件下的吸附性能和水蒸气与硫蒸气产物的吸附性能。结果 在典型的一级克劳斯反应器操作条件下,H₂S与SO₂均能强吸附于二氧化钛催化剂上,其中,对SO₂的吸附性强于H₂S,前者的饱和吸附量是后者的3.3倍。在反应物与产物共存的状态下,催化剂对H₂S与SO₂的吸附性均会下降,硫蒸气的吸附性强于水蒸气,但扣除硫蒸气毛细凝聚产生的吸附量后,水蒸气对克劳斯反应的阻碍效应强于硫蒸气。结论 依托研究成果所开发的二氧化钛催化剂在3套硫磺回收装置上进行了工业应用。结果表明,催化剂有机硫水解效果显著,COS和CS<...     

Antimicrobial coatings for controlling Listeria monocytogenes based on polylactide modified with titanium dioxide and illuminated with UV-A

The anti-listerial properties of biodegradable polylactide coatings modified with titanium dioxide have been studied. Free standing films were prepared by casting solutions prepared from titanium dioxide and previously extruded polylactide. It was demonstrated that polylactide alone could support 2.84 ± 0.10 log CFU reduction of Listeria monocytogenes when incubated at 23 °C for 2 h. However, the log reduction for Listeria could be increased to >4 log CFU with titanium dioxide:polylactide composites illuminated with UV-A. The inactivation kinetics of L. monocytogenes followed a diphasic die-off with an initial 30 min lag period then a progressive decline in bacterial levels over a further 90 min period. The anti-listeria effect of polylactide:titanium dioxide films was dependent on illumination with UV-A but independent on the concentration of TiO₂ incorporated in the film within the range of 1–5% w/w. The mode of L. monocytogenes inactivation was via direct contact of the pathogen with the polylactide, in addition to the generation of oxygen radicals produced by excitation of the titanium dioxide. The composite film illuminated with UV-A was equally effective against Salmonella Typhimurium and Shiga toxin producing Escherichia coli. The coating was stable to 5 repeated sanitation cycles consisting of detergent and sodium hypochlorite rinses. The polylactide-titanium dioxide coating shows potential as an antimicrobial coating although further work is required to assess if the protective film can function under commercial conditions.     

含水饱和度对灰岩热解生成CO2气产率和碳同位素的影响

以琼东南盆地的前第三系1块基底灰岩样品为替代样品,应用热模拟实验方法,进行了一系列不同含水条件下的热解实验,并对实验产物CO₂的产率和碳同位素进行了分析,探讨了莺歌海盆地基底灰岩的生气情况。结果表明,水的存在与否、含水量的多少均对灰岩热解生成CO₂有重大影响。水可以促进灰岩热解生成CO₂气体,并能够极大地降低灰岩的热解温度。与无水条件相比,含水条件下灰岩热解产物CO₂的碳同位素明显变轻。通过与前人钙质泥岩热解实验对比,并结合莺歌海盆地实际地质资料,研究认为莺歌海盆地CO₂气藏可能主要来源于中新统海相钙质泥岩,而前第三系基底灰岩的贡献很少。     

Study of Band Gap of Carbon Nanotube-Titanium Dioxide Heterostructures

The authors present a photoluminescence and UV （ultraviolet）-optical absorbance study on single walled carbon nanotubes CNTs （carbon nanotubes） and TiO2 mixtures. The authors observed variation of△ф = 0.6 eV in optical gap for micrometric anatase and 0.1 eV for nanometric rutile or anatase at a concentration of CNTs of about 1.5 weight %. The large difference in △ф is attributed to differences in dimensions of dioxide grains and in morphology of CNTs/Ti02 composites. Photoluminescence emission is drastically reduced and absorption in the UV range is increased at low CNT concentration for both anatase and rutile phases.