Phosphate removal by Ion exchange in batch mode

Water with phosphate concentrations above 2 μM may adversely affect aquatic life and human health. In this study, the parameters affecting phosphate removal from aqueous solutions by ion exchange were investigated – contact time and temperature, initial pH, initial phosphate concentration and resin dosage, and the presence of other ions. The best phosphate removal (99%) from 100 mg-P/L initial solution was observed at pH 10 and 25 °C after 3 hours of contact time. No negative phosphate removal results were obtained from phosphate solutions containing sulfate, nitrate and ammonium ions, i.e., resembling real wastewater. Desorption (with NaOH or NaCl) and recovery (with CaO) studies of phosphate sorbed by resin were also carried out, as well as thermodynamic investigations. The proportional desorbability of phosphate from the resin with NaCl was 85.6%. The recovery efficiency of phosphate was 79.4%. The sorption process was spontaneous and endothermic. The ion exchange mechanism was determined using different internal and external diffusion models. The mechanism controlling the removal of phosphate from aqueous solution is both internal and external diffusion. Application of the Langmuir and Freundlich isotherm models showed that the experimental results fit well with the Freundlich model.

Contribution to the Study of Phosphorus Adsorption Kinetics on the Superficial Sediments of a Recently Development Artificial Estuary: Vridi Channel (Côte d'Ivoire)

The aim of this study is to characterize phosphates adsorption kinetics on the superficial sediments of Vridi channel from its new hydromorphology. So, three scenarios have been carried out taking account the different waters seasons of this estuary by using pH and temperature as relevant parameters. In the first scenario, the experiments carried out at pH = 8 and T = 20°C to simulate phosphates adsorption on these sediments in its great cold season. In the second, the experiments carried out at pH = 8 and T = 25° C to simulate phosphates adsorption on these substrates in its hot season and small cold season. In the third, the experiments carried out at pH = 7 and T = 30°C to simulate phosphates adsorption on these sediments in its flood season. The experiences were carried out according to US EPA/530/SW-87/006-F protocol. KH2PO4 solutions were used as phosphates synthetic solutions. The experimental data were modeling by Lagergeen kinetics model (pseudo-order 1), Blanchard kinetics model (pseudo-order 2), Elovich kinetics model, Weber and Morris kinetics model and, external diffusion kinetics model. The results have showed phosphates adsorption on these sediments increase in the experiments carried out at pH = 8 and T = 20°C to those carried out at pH = 7 and T = 30°C. All experimental data have been well modeling by Blanchard kinetics model. So, these phosphates adsorption kinetics are pseudo-order 2 and the chemisorption is the dominant mechanism. The results obtained by the experimental data modeling by Weber and Morris kinetics model and external diffusion kinetics model showed that this process is not limiting by the molecular diffusion process. The experimental data have been again well modeling by Elovich kinetics model. That has confirmed the chemisorption character of this adsorption, and showed this chemisorption is activated.

The catalytic kinetics and cfd simulation of multi-stage combined removal of acrylonitrile tail gas

There is no kinetic data and rate equation that can be used directly for catalytic combustion of acrylonitrile tail gas, which leads to the multi-stage combined catalytic kinetic model of acrylonitrile tail gas collaborative removal. In the actual application process, affected by the internal and external diffusion, this paper proposes the multi-stage combined catalytic kinetic research and CFD simulation analysis of acrylonitrile tail gas collaborative removal. Based on the judgment of multi-stage combined catalytic reaction rules of acrylonitrile tail gas collaborative removal, the multi-stage combined catalytic reaction network of acrylonitrile tail gas collaborative removal is solved by matrix transformation. The possible reaction path in the multi-stage combined catalytic reaction network of acrylonitrile tail gas collaborative removal is solved. For quantitative calculation of product distribution, each step of reaction parameters and dynamic factors are required. According to the mechanism of positive carbon ion reaction, materials were used Studio software and genetic algorithm are used to calculate the dynamic factors and determine the dynamic parameters; the grid automatic generator AutoGrid5 embedded in the Fine/TurboTM software package is used to generate the CFD simulation network, and the iterative algorithm is used to calculate the limit value of the CFD simulation; the S-A model in the CFD simulation platform is used to get the modified value of the dynamic mathematical model, and the dynamic factors and parameters are brought into it to establish the CA mathematical model of multi-stage combined catalytic kinetics for the CO removal of olefine and nitrile tail gas. The experimental results show that, under the same experimental device and parameters, the internal and external diffusion effects of the multi-stage combined catalytic kinetic model of acrylonitrile tail gas collaborative removal are detected. The multi-stage combined catalytic kinetic model of acrylonitrile tail gas collaborative removal in this study uses 10-20 mesh catalyst, and the retention time of acrylonitrile tail gas is less than 4.62 s, the internal and external diffusion will not affect the acrylonitrile tail gas collaborative removal The practical application of the kinetic model for the removal of multi-stage combined catalysis.

RESEARCH INTO KINETIC REGULARITIES OF THE REACTION OF OXIDATIVE DEHYDROGENATION OF METHYLCYCLOHEXANE OVER MODIFIED ZEOLITES

Kinetic regularities of the oxidative dehydrogenation reaction of methylcyclohexane on the -clinoptilolite catalyst were investigated. Absence of internal and external diffusion inhibition was established, the reaction proceeds in the kinetic area, in which all diffusion stages proceed much faster than all chemical stages that make up the mechanism of this reaction. The influence of partial pressures of reagents, the reaction temperature and the space velocity of the reaction mixture on the course of the reaction was studied and optimal conditions for obtaining the intentional reaction product determined.

External diffusion of B2B e-procurement and firm financial performance: role of information transparency and supply chain coordination

PurposeThe purpose of this paper is to understand the process through which external diffusion of business-to-business (B2B) e-procurement impacts firm performance. The research model has been developed to empirically examine the role of information transparency and supply chain coordination in improving the firm financial performance by external diffusion of e-procurement.Design/methodology/approachThe survey is conducted in India with a target population of purchasing professionals working on the B2B e-procurement platform. The measurement model was first tested by using confirmatory factor analysis for reliability and validity, then structural equation modeling (SEM) was used to test the hypotheses of the research model using AMOS 22. The phantom model approach has been used for testing multiple mediators.FindingsThe result of the study highlights the importance of information transparency and supply chain coordination in enhancing the firm financial performance by external diffusion of e-procurement. The results establish the role of information transparency in enhancing firm performance by improving supply chain coordination. The results also indicate that supply chain coordination mediates the relationship between external diffusion of e-procurement and firm financial performance.Originality/valueThis is the first study that has focused on the external diffusion of e-procurement and its impact on firm performance. Also, this study attempted to understand the process through which external diffusion of e-procurement impacts the firm financial performance.

Analysis of the performance of the industrial Co-Mo catalyst for hydrotreatment

The process of hydrotreatment of diesel fuel (fraction 180–320 °C) over fresh and spent (after two-year operation in an industrial reactor) Co-Mo catalyst was studied. It was established that the sulfur contents were rather close to one another in the diesel fuel samples treated using the fresh and spent catalysts, even though the specific surface area was 40 % smaller in the spent catalyst compared to that in the fresh sample. Dependence of effective constant keff of hydrodesulfurization on the temperature of low-temperature hydrotreatment (below 320–330 °C) was characteristic of the kinetic range of heterogeneous catalysis complicated by external diffusion resistance. When the temperature was elevated up to 420 °C, the process of diesel hydrotreatment transferred to the external diffusion region. Activation energies of hydrodesulfurization were comparable over the spent and fresh catalysts (81.1 and 80.5 kJ/mol, respectively). A hypothesis of the specific catalyst deactivation was discussed.