A novel approach for the production of nitrogen doped TiO2 nanoparticles

In this study a visible light active nitrogen doped nanostructure titanium dioxide was synthesized by a simple mixing of Degussa P25 and Urea powder and further thermal treatment under the adequate conditions. Photocatalytic activity of produced nanoparticles was verified by providing of photocatalytic degradation of phenol aqueous solution. Mainly this work was focused on the investigation of the following effects: urea concentration, temperature treatment, catalyst loading and initial phenol concentration. Kinetics study was also carried out. The approach appears to be successful and may be applied for example during the photocatalytic treatment of wastewater streams without or with a limited aid of UV lamps. Copyright © 2015, AIDIC Servizi S.r.l

A Service Oriented Framework for Analysing Social Network Activities

AbstractAnalysing and monitoring Social Networking activities raise multiple challenges for the evolution of Service Oriented Systems Engineering. This is particularly evident for event detection in social networks and, more in general, for large-scale Social Analytics, which require continuous processing of data. In this paper we present a service oriented framework exploring effective ways to leverage the opportunities coming from innovations and evolutions in computational power, storage, and infrastructures, with particular focus on modern architectures including in-memory database technology, in-database computation, massive parallel processing, Open Data Services, and scalability with multi-node clusters in Cloud. A prototype of this system was experimented in the contest of a specific kind of social event, an art exhibition of sculptures, where the system collected and analyzed in real-time the tweets issued in an entire region, including exhibition sites, and continuously updated analytical dashboards placed in one of the exhibition rooms

CFD model of a spinning disk reactor for nanoparticle production

The use of a spinning disk reactor (SDR) was investigated for the continuous production of nanoparticles of hydroxyapatite. SDR is an effective apparatus for the production of nanoparticles by wet chemical synthesis. Rotation of the disc surface at high speed creates high centrifugal fields, which promote thin film flow with a thickness in the range 50-500 ?m. Films are highly sheared and have numerous unstable surface ripples, giving rise to intense mixing. SDR performances are strongly affected by the adopted operating conditions such as the influence of rotation speed that determines the attainment of micro-mixing and the feeding point location that has a great influence on the particle size distribution of the product. The experimental device consists of a cylindrical vessel with an inner disk, 8.5 cm in diameter, made by PVC coated by an acrylic layer. The rotational velocity of the disc is controlled and ranges from 0 to 147 rad/s. The reagent solutions are fed over the disk at a distance of 5 mm from the disc surface through tubes, 1 mm in diameter. A computational fluid dynamic model, validated in a previous work, was used to optimize the operative conditions of SDR. Through the CFD model it is possible to analyse the hydrodynamic of the thin liquid film formed on the disk at different speed rotations and to individuate the best mixing conditions between the reagents varying the feeding point positions. The production of hydroxyapatite was also investigated adding the reaction kinetic to model the product formation in the liquid phase and the population balance equation to predict particle size distribution. The simulation results were compared with available experimental data showing that the CFD model is fully capable to describe the process and qualifies as a suitable engineering tool to perform the SDR process design. Copyright © 2015, AIDIC Servizi S.r.l

Synthesis and characterization of nanometric titania coated on granular alumina for arsenic removal

The adsorption process is widely used for the treatment of drinking water sources containing high levels of arsenic. The choice of the adsorbent is crucial for the efficiency of the process. Very good performances were obtained in the past by activated alumina, while more recent studies have shown that also other media such as titanium oxide can provide high removal rates. In the present work, four types of adsorbents were tested for their removal capability of pentavalent arsenic from liquid solutions. Specifically, it was investigated if modifications of activated alumina by coating with titanium oxide nanoparticles or by reducing particle size might improve their performance. The adsorbents were firstly characterized by X-ray diffraction, BET specific area measurement and SEM analysis. Then, kinetics, equilibrium isotherm experiments were conducted in batch mode at fixed pH. All the tested adsorbents showed satisfactory arsenic removal, with the best performance obtained by the mesoporous gamma-alumina which had the lowest grain size. The titanium coating did not appear to significantly improve adsorption capacity. The kinetic data were best fitted by the pseudo-second order model, while both the Freundlich and the Langmuir equations well represented the adsorption isotherm data

Optimal configuration of a photocatalytic lab-reactor by using immobilized nanostructured TiO2

In this study, TiO2 nanoparticles (NPs) and glass balls coated by an N-doped TiO2 nanostructured layer were used for photocatalytic degradation of organic compounds in aqueous solutions. Preliminary batch photocatalytic experiments were carried out on the degradation of methylene blue (MB) in aqueous solutions by using two types of reactor: the first one was a cylindrical vessels fitted with a mechanical stirrer where the TiO2 NPs were suspended, whereas the second one consisted of a rectangular box with the glass spheres located at the bottom. For an initial MB concentration of 7 ppm a conversion of around 50 % was detected after 120 min for both the cases. An UV lamp was used for the light irradiation. Then, the catalytic effectiveness of the coated glass balls was checked on a system of industrial interest: the reduction of the organic compounds in an olive mill wastewater (OMW) stream. In this case a more performing configuration of the reactor was adopted by positioning the glass balls over a wire and feeding an air stream under the wire itself, moreover a visible light lamp was used alternatively to the UV lamp. For an initial COD of the OMW equal to 1100 mg/l, a conversion of 57 % was obtained after 120 minutes by using the UV lamp and a conversion of 99% with the use of a visible lamp. This latter result demonstrated the possibility of a strong purification of OMW by using the developed N-doped immobilized TiO2 catalyst under visible light

Antibacterial and anti-inflammatory green nanocomposites

This work deals with the production of a green technology membrane to produce drinkable water from polluted fresh water resources disseminated in rural area, that is by using a small and compact water purification plant. The material adopted for this purpose is non woven-tissue based on green nanocomposites of Chitin Nanofibrils (CN) bonded with nano silver and electrospun with chitosan and polypeptides. Nonwoven materials obtained as electrospun of a blending of nanochitin fibrils and lignin, by using polyethylene oxide as solvent. The adopted blend was carefully prepared as sol-gel material at suitable temperature, mixing conditions and time of ageing. The non-woven tissue was produced by means of a pilot scale electrospinning machine model Nanospider NS LAB 500 supplied by Elmarco. Very uniform membrane with a diameter less than 150 nm were produced. Stress tests showed a good resistance of multiple layer samples

The boundary flux. New perspectives for membrane process design

In the last decades much effort was put in understanding fouling phenomena on membranes. Many new concepts have been introduced in time, and parallel to this many parameters capable to quantify fouling issues and fouling evolution. One successful approach was the introduction of the critical flux theory. At first validated for microfiltration, the theory applied to ultrafiltration and nanofiltration, too. The possibility to measure a maximum value of the permeate flux for a given system without incurring in fouling issues was a breakthrough in membrane process design. Nevertheless, the application to the concept remains very limited: in many cases, in particular on systems where fouling is a main issue, critical fluxes were found to be very low, lower than economical feasibility permits to make membrane technology advantageous. Despite these arguments, the knowledge of the critical flux value still remains and must be considered as a good starting point for process design concerning productivity and longevity. In 2011, a new concept was introduced, that is the threshold flux. In this case, the concept evaluates the maximum permeate flow rate characterized by a low constant rate fouling regime, due to formation of a secondary, selective layer of foulant on the membrane surface. This concept, more than the critical flux, may be a new practical tool for membrane process designers. In this paper a brief review on critical and threshold flux will be reported and analyzed. In fact, critical and threshold flux concepts share many common aspects which merge perfectly into a new concept that is the boundary flux. The validation will occur mainly by the analysis of previous collected data by the authors, during the treatment of olive mill wastewater. A novel membrane process design method based on the boundary flux will then be presented

Hydroxyapatite Production by an Intensification Process

Hydroxyapatite (HAP) is a worthwhile compound for its biomedical applications. Nanoparticles (NPs) and nanostructured HAP scaffolds promote and intensify the interaction between artificial material and natural bone due to their high surface/volume ratio. In this chapter, first, the technique for the production of HPA nanoparticles smaller than 100 nm is addressed. It consists of the use of a rotating disk reactor to optimize the reaction-precipitation process. The centrifugal force dispersed into the liquid layer over the disk surface enables the attainment of micromixing conditions between the reagents and maximizes the reaction rate as a consequence. The reaction between calcium chloride and ammonium phosphate in the presence of ammonium hydroxide was adopted. NPs minimum size, equal to 78 μm, was obtained using a rotational velocity of 147 rad/s and feeding points of reagents 3 cm from the disk center. A computational fluid dynamics (CFD) model of the liquid layer was specifically developed for the interpretation of the obtained experimental results on the production of pure HAP. In the second part of the chapter, the feasibility of producing Mg2+ doped hydroxyapatite (Mg-HAP) by adding MgCl2 and using the same technique is reported. Satisfactory results were obtained: nanoparticles were between 50 and 70 μm in size and Mg2+/Ca2+ molar ratio was equal to 0.06, according to the composition target

Adsorption of phenol/tyrosol from aqueous solutions on macro-reticular aromatic and macro-porous polystyrene cross-linked with divinylbenzene polymeric resins

The current work aims at separating by adsorption of low-molecular-weight organic compounds in a nanofiltration concentrate of the olive mill wastewaters. The experimental investigations on adsorption of phenol/tyrosol in single and binary systems were conducted in batch mode by using the commercially available macroporous resins FPX66 and MN202. The structures of such resins were examined by FTIR before and after adsorption. The operating parameters affecting the adsorption process such as resin dosage, contact time, pH, and initial concentration of phenol/tyrosol were investigated. Fast phenol and tyrosol uptakes were observed for both resins. It can be attributed to their physical properties, for instance high specific area and microporous area. The adsorption selectivity of phenol is larger than tyrosol when using FPX66 resin, but smaller if MN202 resin is used. Acidic pH appeared to be always favourable for the adsorption. A synergetic effect between solutes was observed since adsorption of phenol and tyrosol in the binary systems was faster than the individual sorption of each solute. Five isotherms namely Langmuir, Freundlich, DubininRadushkevich, Temkin and Redlich-Peterson were selected to fit the obtained equilibrium experimental data. Finally, desorption of the examined compounds with ethanol (EtOH) allowed a maximum around 85 % of phenol, and equal to 94 % of tyrosol on FPX66 and MN202 resins