Search results for "Chemical Engineering"
showing 10 items of 5892 documents
Application of a compositional rotatable plan in modeling the propylene content in a vinyl chloride/propylene copolymer
2019
Abstract Using a fractional rotatable plan, the effect of five input parameters of the conduct of the copolymerization process on the amount of propylene built into the copolymer, obtained as a result of free radical suspension copolymerization of vinyl chloride with propylene in a batch suspension polymerization reactor, was analyzed. Using the results obtained, the analysis of variance was carried out and the influence of particular factors and their interactions on the product properties was determined. Thus, it was determined that the greatest influence on the amount of the incorporated propylene in the copolymer is exerted by the amount of propylene introduced into the system, while th…
An intelligent Proportional controller of a Seeded Batch Crystallizer
2020
Crystallization process is used in a very wide range of industrial applications. However, highly nonlinear comportment of such process and the difficulties of characterizing several phenomenological effects makes difficult to find suitable operational procedures for producing required products. In this article, we use a model-free control (MFC) for controlling the mean size of crystals produced by seeded batch cooling crystallization. The MFC method is distinguished notably in terms of the modeling strategy. Rather than developing a crystallization model within the classic population balance equation (PBE) together with the mass balance and the energy balance, as is usually done, we use a l…
New results on stability analysis and stabilization of time-delay continuous Markovian jump systems with partially known rates matrix
2015
Summary In this note, the problems of stability analysis and controller synthesis of Markovian jump systems with time-varying delay and partially known transition rates are investigated via an input–output approach. First, the system under consideration is transformed into an interconnected system, and new results on stochastic scaled small-gain condition for stochastic interconnected systems are established, which are crucial for the problems considered in this paper. Based on the system transformation and the stochastic scaled small-gain theorem, stochastic stability of the original system is examined via the stochastic version of the bounded realness of the transformed forward system. Th…
The impact of the volumetric swelling behavior on the water uptake of gas shale
2018
Abstract Water uptake of gas shales is commonly considered one of the most important factors responsible for fluid loss during flowback operations after hydraulic fracturing. Imbibition experiments cover a key role in this context to analyze the impact of several factors (such as mineralogical composition, fluids composition, anisotropic structure, volumetric swelling) that contribute to the water uptake in these unconventional reservoirs. The aim of this study is the quantification of the impact of the volumetric response (swelling and shrinkage) of gas shales on the water uptake during imbibition and desiccation processes. An experimental methodology to quantify the volumetric response du…
Metakaolin geopolymer characterization and application for ammonium removal from model solutions and landfill leachate
2016
Abstract Geopolymers are aluminosilicate compounds that are amorphous analogues of zeolites, and thus possess similar cation-exchange properties. Geopolymers have been successfully applied to remove toxic metals and organic dyes from aqueous solutions. In this study, geopolymer was synthesized from metakaolin and applied to remove ammonium (NH 4 + ) from model solutions and landfill leachate. Geopolymerization increased the ammonium removal capacity, surface area and average pore width and changed the chemical structure of metakaolin. The maximum NH 4 + removal capacity of the geopolymer was 21.07 mg g − 1 which was 46% higher than the capacity of the reference clinoptilolite–heulandite zeo…
Kinetic, isotherm and thermodynamic studies of the adsorption of methylene blue dye onto agro-based cellulosic materials
2015
AbstractThe purpose of this work is to establish the optimal experimental conditions for the removal of methylene blue (MB-as model basic dye) from aqueous solution by adsorption onto four agro-based materials, namely, cedar sawdust, pine sawdust, wheat straw, and Provence cane Arundo donax. Results show that an increase in acidity or ionic strength of the medium has generally a negative effect on the discoloration yield. From the data of pH effect, there is no need to change the initial pH of the MB solution to be treated. Equilibrium was reached after 20−30 min of agitation when cedar sawdust, pine sawdust, and Provence cane are used as adsorbents. However, in the case of wheat straw, an …
The influence of oversizing on maintenance cost in wastewater treatment plants
2021
Abstract Management of Wastewater Treatment Plants (WWTPs) is a complex process, not only from a technical point of view but also from an economic point of view. There are several factors that influence the wastewater treatment process and can cause an increase in management costs. One of these factors is the treatment capacity, in particular the WWTPs’ oversizing problem. The difference between the design population equivalent (p.e.) and the actual p.e. treated generates imbalances in the wastewater treatment process costs. This paper analyses the influence that oversizing has on the maintenance costs for WWTPs in the Valencia region (Spain). Through an econometric approach, the behaviour …
Preventive maintenance versus cost of repairs in asset management: An efficiency analysis in wastewater treatment plants
2020
Abstract The operation and management of Wastewater Treatment Plants (WWTPs) is of paramount importance to guarantee the sustainability of water resources. Just like any other production process, wastewater treatment process involves different costs, such as: energy, personnel, maintenance and reagents. Regarding maintenance costs, they have become an issue of great concern to many operators in the last years. Maintaining the facilities in good condition ensures the proper performance of these infrastructures and reduces the risk of failures. It should be known that equipment breakdowns imply an increase in operating costs, with a high risk of generating an environmental damage due to the m…
The application of electroanalytical methods to determine affinity series of metal cations for functional biosorbent groups
2018
Abstract The affinity of the selected heavy metal cations: Mn 2 + , Ni 2 + , Cu 2 + , Zn 2 + , Cd 2 + , Pb 2 + and Na + , K + , Mg 2 + , Ca 2 + was determined for the functional groups located on the surface of leached barley middlings, so called Brewer's spent grain (BSG) – a by-product of the brewing industry. A simple method for determining the affinity series, with the use of a conductivity meter and a pH-meter, was described. It was demonstrated that the affinity of cations for the functional groups located on the surface of the BSG increases in the series: Na + + 2 + 2 + ≈ Zn 2 + 2 + ≈ Ca 2 + 2 + 2 + 2 + , and the series was determined by comparing concentrations expressed in gram e…
Gangliosides in human milk and infant formula: A review on analytical techniques and contents
2017
Gangliosides (GGs) are important bioactive compounds that offer beneficial anti-infective, anti-inflammatory, and neuronal development effects. The present work reviews the techniques used to deter...