Korean Journal of Chemical Engineering

Ca-pretreated Cystoseira indica algae was used as a biosorbent for the biosorption of U(VI) and Fe(II) ions in single, binary and multi-component systems by using a packed bed column. Experiments were conducted to study the effect of important design parameters such as bed height and flow rate. FTIR and XRF analyses and pH and Ca2+ ion concentration recordings showed that the biosorption of U(VI) and Fe(II) proceeded through ion-exchange mechanism. BDST, Thomas and Modified dose-response models were used for predicting breakthrough curves and for estimations of the parameters necessary for the design of a large-scale packed bed column.

Tannery wastewater can cause severe environmental problems related to its high chemical oxygen demand, high biochemical oxygen demand, high total suspended solids, high oil and grease contents together with the elevated chromium concentration and objectionable color. The one-step electrocoagulation process was carried out to simultaneously remove chromium and various pollutants from tannery wastewater at ambient temperature in the laboratory scale. Low-cost commercial iron plates were employed in this study as anodes and cathode materials. Effects of various parameters were investigated including types of electrode configuration, initial pH of wastewater (7–9), current density (15.7–24.6 Am−2) and circulating flow rate of wastewater (0–3.67 lmin−1). The optimum condition was found by applying the mono-polar electrode in a parallel connection at the current density of 22.4 Am−2, flow rate of wastewater of 3.67 lmin−1 and 20 min electrolysis time. The initial pH of wastewater ranging from 7–9 provided the similar removal efficiency. At optimum condition, more than 95% of chromium and pollutants except TKN and TDS were eliminated from the wastewater and the properties of the treated wastewater met the standard and permitted to discharge into the environment. The required energy consumption at optimum condition was less than 0.13 kWhm−3 wastewater. In addition, the COD reduction was fit very well with the first-order kinetics model.

A comparison on existing models of gas explosion predictions has been done. The advantages and drawbacks, and the possibilities and limitations of the different empirical, phenomenological, and computational fluid dynamics assessment models of gas explosions were discussed. Particular attention was paid to CFD models.

A new method of process identification for a second-order-plus-dead-time model is proposed and tested with two example systems. In the activation of the example processes for the identification, a rectangular pulse input is applied to open loop systems. The model parameters are estimated by minimizing sum of modeling errors with the least squares method. The estimation performance is examined by comparing the output pulse responses from the example system and the estimated model. The performance comparison of the proposed method and two existing techniques indicates that satisfactory parameter estimation is available from the proposed procedure. In addition, the role of sampling time and the shape of input pulse is evaluated and it is found that the sampling time of less than 0.01 minute gives good estimation while the shape of input pulse does not affect the estimation performance. Finally, the robustness of the estimation in noisy process is proved from the investigation of the performance in the processes having various levels of noise.

As a potential renewable aquatic resource, chitosan is the second most abundant biopolymer. Methanesulfonic acid is a catalyst that is strongly acidic and biodegradable. We used chitosan and methanesulfonic acid to produce platform chemicals via an acid-catalyzed hydrothermal reaction. In the methanesulfonic acid-catalyzed hydrothermal conversion of chitosan, an optimal levulinic acid yield of 28.21±1.20% was achieved under the following conditions: 2% chitosan and 0.2 M methanesulfonic acid at 200 °C for 30 min. These results indicated that a combination of chitosan and methanesulfonic acid would be suitable for platform chemical production.

Digital rock analysis using X-ray computer tomography (CT scan) is an ongoing topic for studying the porous media in geothermal, natural gas, and petroleum industries. This study provides a novel approach to calculating fluid saturation in low permeability cores utilizing X-ray computed tomography. In the present study, synthetic low permeability cores were used to analyze two-phase saturation at atmospheric pressure and temperature. In the experiments, no dopant was used for visualizing different phases. As a novelty of the paper, PHREEQC geochemical software was employed to verify the saturation of X-ray CT scanning through modeling the geochemical reaction between aqueous and gaseous phases. This study presents a novel and reliable approach to verify the saturation of X-ray CT scan through geochemical modeling. The results of this study also prove that using the saturation of mass balance as the initial condition of the geochemical modeling leads to an excellent agreement between the saturation of CT scan and geochemical modeling. According to the results obtained, there is a 24% difference between gas saturation in CT scan and mass balance method, while such discrepancy is only 13% between gas saturation in CT scan and geochemical modeling.

Based on the developed continuous production system of sodium phenol carboxylation reaction, several types of discharging devices are proposed, which are suitable for the case where the transported particles are not easy to maintain a stable state in the transported fluid. Numerical simulations of the gas-solid two-phase flow characteristics and particle distribution were performed with DPM, and the particle retention ratio and fluid loss degree were proposed to investigate the performance of the discharging devices. The results of simulations and industrial experiments showed that a guide plate installed in the “B” discharging device can solve the accumulation problem, realize the efficient and continuous delivery of the particles, and maintain a uniform distribution of particles. This study can provide a reference for the design of a gas-solid two-phase discharging device, and guide the industrial experimental operation and modification of continuous production systems for sodium phenol carboxylation.