platinum extraction from different secondary sources has been experimentally tested by many researchers. in this article, dissolution of platinum in aqua-regia solution from two types of spent catalysts (reforming and nitric acid production) was kinetically studied. a variety of kinetic models for heterogeneous solid-liquid reactions, including homogeneous diffusion model, shrinking core model,...

background & aims of the study: nitrogenous compounds could directly create many problems for human's health and the environment. thus, removal of nitrogenous compounds is necessary. among the most important problems, decreasing dissolved oxygen, toxicity for aquatics, eutrophication, converting aerobic medium into anaerobic one and corrosion could be noted. the aim of this study was deter...

a structured mathematical model of anaerobic conversion of complex organic materials in non-ideally cyclic-batch reactors for biogas production has been developed. the  model is based on multiple-reaction stoichiometry (enzymatic hydrolysis, acidogenesis, acetogenesis and methanogenesis), microbial growth kinetics, conventional material balances in the liquid and gas phases for a cyclic-batch r...

Reaction behaviors and kinetics of catalytic oxidation of toluene with different feed flows over Pt/Zr(x)-HMS catalysts with Si/Zr ratio equal to 5, 10, 20 and 35 were investigated over a wide temperature range (200 – 500 oC). Results show that Pt/Zr(x)-HMS performs more easily toluene oxidation. The kinetic data were fitted by the Power-law and Mars–van Krevelen kinetic models. The fitting res...

In this work the effect of the accuracy of a FAE detonation modeling on the generated blast wave is investigated. First, a one-dimensional numerical simulation with a reduced chemical kinetics of C2H2-O2-Ar, involving 25 elementary reactions, is used as the base model. The properties of the blast calculated with this model is compared with those of simpler models, the similarity solution of Tay...

in this work dynamic recrystallization behavior of aisi 403 martensitic stainless steel was studied using hot compression tests over temperature range of 900 c -1200 c and strain rate range of 0.001 s-1 - 1 s-1. the obtained flow curves showed that the hot compression behavior of the alloy is controlled by dynamic recrystallization. the flow stress and strain corresponding to the critical, pe...

an agricultural waste i.e. rice husk has been used as a cheap adsorbent for the removal ofleadas a harmful heavy metal from contaminated water via adsorption. the adsorption capacity of rice husk was calculated by equilibrium models. the results showed that the adsorption process has the best accordance with langmuir model. the kinetics of the adsorption was also investigated and obtained that ...

The combined model approach uses kinetic analysis of both plasma insulin and C-peptide dynamics to estimate prehepatic insulin secretion rates and parameters of insulin and C-peptide kinetics. The original model used single-compartment kinetics to describe both insulin and C-peptide despite knowledge that C-peptide follows two-compartment kinetics. The performance of the model under rapidly cha...

Pt/Zr(x)-HMS/HZSM-5 catalysts with various Si/Zr ratios (as x) were used for investigation of the kinetics of n-heptane reforming process under 350 - 450 oC reaction temperature, 35 to 80 ml min-1 flowing rate of hydrogen and 2 to 5 ml h-1 flowing rate of n-heptane. In the present work, two kinetics (power law and Langmuir - Hinshelwood) models were selected and examined to describe the kinetic...

V2O5/SiO2 catalyst was utilized to oxidize SO2 to SO3 species in the presence of oxygen mainly for producing sulfuric acid. For this catalyst, the active phase was a mixture of vanadium pentoxide and basic sulfate/pyrosulfate material. This active phase at the reaction temperature behaved as a liquid filling up the pores of the silica support. On the other hand, amounts of the SO3 and V5+ speci...