Search results for "Slurry"

Supercritical water gasification of microalgae and their constituents in a continuous reactor

2016

The supercritical water gasification of Nannochloropsis gaditana microalgae has been studied in term of process development at 24 MPa and 663 °C. Gasification has been investigated using a 200 cm3 down flow reactor working continuously. The effect of microalgae slurry concentration, with or without alkali catalysts, was studied. Moreover, the role played by different constituents of microalgae on gasification was investigated. Particularly, gasification of amino acids, carbohydrates and model mixtures among them was studied. Nannochloropsis gaditana was successfully gasified up to 97.4 wt% as gasification efficiency and 86.0 wt% as carbon efficiency. The product gas is mainly composed of hy…

Uptake and bioavailability of persistant organic pollutants by plants grown in contaminated soil

2005

This paper assesses the uptake of persistent organic pollutants (POP's) into plants. In particular, uptake of alpha-endosulfan, beta-endosulfan and endosulfan sulfate from lettuce. The lettuce plants were grown on compost that had previously been contaminated at 10 and 50 microg g(-1) per POP. The soil was slurry spiked by adding the appropriate amount of POP in acetone in an approximate ratio of 1 ratio 2, w/v soil ratio solvent. The solvent was left to evaporate at ambient temperature for 24 hours. Lettuce plants were grown under artificial daylight for 12 hours a day. The influence of soil ageing on the recovery of POP's from spiked soil samples was also assessed. The average recovery of…

Modeling of an annular photocatalytic reactor for water purification: oxidation of pesticides.

2004

Photocatalytic oxidation (PCO) over titanium dioxide (TiO2) is a “green” sustainable process for the treatment and purification of water and wastewater. However, the application of PCO for wastewater treatment on an industrial scale is currently hindered by a lack of simple mathematical models that can be readily applied to reactor design. Current models are either too simplistic or too rigorous to be useful in photocatalytic reactor design, scale-up, and optimization. In this paper a simple mathematical model is presented for slurry, annular, photocatalytic reactors that still retains the essential elements of a rigorous approach while providing simple solutions. The model extends the appl…

Cold vapour atomic fluorescence determination of mercury in milk by slurry sampling using multicommutation

2004

Abstract A highly sensitive mechanized method has been developed for the determination of mercury in milk by atomic fluorescence spectrometry (AFS). Samples were sonicated for 10 min in an ultrasound water bath in the presence of 8% (v/v) aqua regia, 2% (v/v) antifoam A and 1% (m/v) hydroxilamine hydrochloride, and after that, they were treated with 8 mmol l −1 KBr and 1.6 mmol l −1 KBrO 3 in an hydrochloric medium. Atomic fluorescence measurements were made by multicommutation, which provides a fast alternative in quality control analysis, due to the easy treatment of a large number of samples (approximately 70 h −1 ), and is an environmentally friendly procedure, which involves a waste ge…

Application of the slurry technique to biological materials: a survey of literature

1991

The literature on the application of the slurry technique to biological materials is reviewed. It is obvious from the various applications that the most frequently employed atomization method for slurry analysis in biological materials is electrothermal atomization using either graphite tube or platform atomizers. The slurry technique is particularly useful when certified reference materials are not available and when the standard addition method is to be avoided. The literature survey revealed that this technique compares favourably with other methods for the determination of trace metals in biological materials.

The role of nano-sized iron particles in slurry phase Fischer–Tropsch synthesis

2003

Abstract The slurry phase Fischer–Tropsch (F–T) activity of three α-Fe2O3-based materials, two unsupported nano-sized, NANOCAT (3 nm) and BASF (20–80 nm), and a supported micron-sized (32.5 μm ) UCI, are compared with respect to total hydrocarbon production from synthesis gas (H2/CO∼2/1) at 513 K. Low temperature Mossbauer spectra of the quenched slurry samples after 120 h on-line show that all three catalysts are essentially a mixture of oxide and carbide phases with magnetite (Fe3O4) being the dominant phase. TEM images of the quenched samples reveal unexpected particle characteristics. While both unsupported nano-sized materials essentially avoid expected agglomeration, the micron-sized …

Validation of a two-dimensional modeling of an externally irradiated slurry photoreactor

2015

Abstract A two-dimensional model describing the behavior of a batch cylindrical photoreactor has been validated through a series of photocatalytic reactivity runs. The light intensity radiation field produced by 1–6 external UV fluorescent lamps was modeled together with Langmuir–Hinshelwood kinetics and 4-nitrophenol (NP) and Degussa P25 TiO 2 were used as the probe molecule and the catalyst, respectively. The experiments were carried out under different conditions of light intensity, photocatalyst amount and substrate concentration. The model parameters were the kinetic constant of substrate adsorption, desorption and degradation and the exponent of the power law expressing the kinetics d…

Problems of soil and groundwater pollution in the disposal of “marble” slurries in NW Sicily

2007

This work deals with disposal of slurries generated during the cutting and polishing processes of slabs of decorative sedimentary carbonate rocks in the north western Sicily. At present, they are used as fillers of dismantled quarries near the sawmills and, as a final step of reclamation, are covered with earth layers. In spite of such inexpensive solution, there is lack of knowledge about the composition of the waste. In order to assess if there is any threat for the environment and to suggest indications for alternative solutions, such as recycling or inactivation processes, the slurries were analysed by XR diffraction, simultaneous thermal analysis, ICP/MS, ionic chromatography, FTIR, UV…

Volatile fatty acids (VFAs) and methane from food waste and cow slurry: Comparison of biogas and VFA fermentation processes

2018

Two-Dimensional Modeling of an Externally Irradiated Slurry Photoreactor

2013

Abstract A batch cylindrical photocatalytic reactor, externally irradiated by 1–6 UV fluorescent lamps and containing a stirred slurry of polycrystalline TiO2, was modeled by coupling a modified Langmuir–Hinshelwood kinetics together with a two-dimensional light intensity field. The radiation field has been determined on the main assumptions of diffuse radiation, isotropic scattering and negligible backward reflected photon flow. The model has been applied to the photocatalytic oxidation of organic substrates which do not undergo homogeneous photochemical degradation. The model is characterized by the following four parameters: the kinetic constants of substrate adsorption, desorption and d…