Novel combinatorial extensions to breakthrough curve modeling of an adsorption column — Depth filtration hybrid process

Ehsan Salehi,Mahdi Askari,Yaser Darvishi 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.86 No.-

This work introduces novel scenarios for the breakthrough curve modeling of an adsorption column/depthfiltration hybrid system. Four well-known theoretical breakthrough models including Thomas,Adams–Bohart, Yoon–Nelson, and BDST were employed to describe the normalized concentrationprofiles. In thefirst approach, the theoretical models were combined for better estimation of thebreakthrough curves and the Thomas/Yoon–Nelson and Thomas/BDST combinations were obtained asthe best extensions. In the second approach, an adsorption-transport model was developed for the depthfilter to obtain the transient concentration gradient across thefilter medium thickness. The model wasthen combined with the theoretical breakthrough models to predict the adsorption columnbreakthrough curves. Results revealed that a decrease in the feedflowrate andfilter pore size couldintensify the concentration polarization on thefilter surface. Both model extensions could successfullyapproximate the breakthrough curves of the hybrid system with more than 99% agreement withthe experimental data, while the prediction accuracy of the original breakthrough models seldomexceeds 93%.

Dynamic removal of n-hexane from water using nanocomposite membranes: Serial coating of para-aminobenzoate alumoxane, boehmite-epoxide and chitosan on Kevlar fabrics

Hanieh Karimnezhad,Ehsan Salehi,Laleh Rajabi,Sara Azimi,Ali Ashraf Derakhshan,Meisam Ansari 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6

Nanocomposite membranes were fabricated by dip-coating technique. Para-aminobenzoate alumoxane,boehmite–epoxide and chitosan were consecutively coated on the Kevlar fabric surface. The membraneswere utilized for removing n-hexane fromwater using a gravity-driven dead-end filtration setup. UV–vis,FTIR and SEM analyses were performed for characterization. Water affinity analyses revealed highlyhydrophilic nature of the modified membranes. Effect of pH was examined with the pH 2 providing thebest condition for oil–water separation. Maximum flux and rejection were obtained as 1128 Lm-2 h-1)and 94%, respectively. Deposited oil layer was effectively removed from the membrane surface using hotcitric acid solution.

Process intensification and optimization for efficient production of dimethyl carbonate through urea alcoholysis using low-cost anhydrous zinc acetate catalyst

Masoud Mandooie,Ehsan Salehi 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.125 No.-

Anhydrous zinc acetate was used as a low-cost catalyst for the urea alcoholysis to produce dimethyl carbonate(DMC). Important operating variables including reaction time, temperature and catalyst amountwere optimized using response surface methodology. Optimization was assessed through two differentapproaches. In the first approach, only DMC yield was maximized. N-methyl methyl carbamate(NMMC, the unfavorable byproduct) yield was minimized along with maximizing DMC yield in the secondapproach. Sobol sensitivity analysis uncovered that reaction temperature and the binary interactionof reaction temperature/catalyst amount were the most influential parameters on DMC yield with 57.01%and 29.17% impacts, respectively. Moreover, temperature and reaction time with 61.13% and 19.74%impacts were the most effective variables on NMMC yield. The multi-objective optimization results weremore suitable for application in continuous production of DMC due to avoiding NMMC production. Amodified continuous process was also proposed for DMC production. The main advantage of the preposedprocess was immediate extraction out of DMC from the reaction zone. To investigate the possible reactionmechanism, the Binding Energies (BEs) of the reactants were assessed using Density-Functional-Theory. Results illustrated that the highest BE values belong to the interaction of zinc with the nitrogen of methylcarbamate (MC).

ZIF-8 derived porous carbon/ZnO as an effective nanocomposite adsorbent for removal of acetic acid

Amidi Mohammadali,Salehi Ehsan 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.10

A porous carbon/zinc oxide nanocomposite adsorbent was prepared by carbonization/oxidation of ZIF8 metal-organic framework (MOF) and then used to investigate the adsorption of acetic acid from water. Preliminary tests revealed that the adsorbent composed of 25% porous carbon/zinc oxide and 75% zeolite could result in superior acetic acid removal. Response surface methodology and central composite design algorithm (CCD) were used to optimize the operating variables affecting the acid removal. The optimal conditions were obtained at the initial acid concentration of 257.5 mg/L, the adsorbent amount of 152.5 mg, the contact time of 32.5 min and the sample volume of 28.75 mL. In the optimal conditions, an adsorption capacity equal to 106 mg/g was obtained. The experimental equilibrium adsorption was well-described by the Langmuir isotherm model, reflecting the monolayer chemisorption of the acid on the active sites. In addition, adsorption on the developed adsorbent followed the pseudo-second-order kinetics, and according to the thermodynamic study results, the adsorption was exothermic and spontaneous. In conclusion, the adsorption capacity of the porous carbon/zinc oxide-zeolite composite was fair, while its removal rate was extremely higher compared to that of the similar adsorbents.

Adsorption/Ozonation integration for intensified ethyl acetate plant wastewater treatment: Process optimization and sensitivity analysis assessment

Mahdi Rahimi,Ehsan Salehi,Masoud Mandooie,Nayyereh Khalili 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-

For the first time, the ethyl acetate production plant wastewater was treated using a batch adsorption/ozonation integrated process. The wastewater contained alcoholic pollutants (majorly, ethanol) andthe discharge of this wastewater could result in serious risks to the environment. The operational variablesincluding reaction time (10 to 60 min), temperature (20 to 60 C), ozone flowrate (4 to 12 L/min)and granular activated carbon (GAC) dose (5 to 15 g) were optimized by applying response surfacemethodology, where the removal of chemical oxygen demand (COD) was aimed to be maximized asthe target variable. The optimal conditions were obtained at the reaction time of 60 min, temperatureof 60 C, GAC dose of 10 g and ozone flowrate of 8 L/min, which resulted in COD removal of 98.5 %. Characterization analyses revealed that ozonation could support in-situ regeneration of the GAC and providea synergistic effect on the COD removal enhancement. The separation kinetics of the integrated processwas also assessed and found to be superior than those of the standalone operations. Sobol sensitivityanalysis results uncovered that the reaction temperature by 85 % and the binary interaction of the reactiontime and temperature by near 7 % impact shares were the most effective parameters on the CODremoval. Isothermal studies showed that the adsorption of ethanol on GAC is physical, multilayer andheterogeneous. Consequently, the integrated adsorption/ozonation process has been approved as apotential method for the treatment of ethyl acetate plant wastewater.

Fuzzy Hype-Plane Variable Sliding Mode Control to Reduce Joint Vibrations

Mahmoud Reza Safaei Nasrabad,Ehsan Pouladi,Ghasem Sahamijoo,Alireza Salehi,Farzin Piltan,Nasri b. Sulaiman 보안공학연구지원센터 2014 International Journal of u- and e- Service, Scienc Vol.7 No.5

The sliding mode controller is used to speed up the error convergence when the error is greater than one. To reduce the error terminal sliding mode controller is recommended in this research. Fuzzy hype-plane variable sliding mode controller is adopted to guarantee the error convergence to zero in a finite time when the error is around the zero. The chattering in the conventional sliding model control systems is avoided with the employed continuous controller. To increase the system robustness in presence of uncertainty fuzzy logic controller is recommended. This technique is used to adjust the band of terminals. The simulation results show that the proposed scheme has strong robust against the uncertainties and disturbances, as well as leads to the convergence of the output to the desired value quickly and precisely than employing either sliding mode controller or terminal sliding mode controller alone.

A comprehensive review on zinc-based mixed metal oxide catalysts for dimethyl carbonate synthesis via urea alcoholysis process

Masoud Mandooie,Mahdi Rahimi,Golara Nikravesh,Ehsan Salehi 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-

Urea alcoholysis is one of the environmental-friendly and economic methods for dimethyl carbonate(DMC) production. Various catalysts such as bases, organic tin, acids, ionic liquids and metal oxides havebeen used for synthesis of DMC through urea alcoholysis process. Based on literature survey, catalystscontaining both acidic and basic sites, are more suited for catalyzing the reaction; however, the basicityplays more conspicuous role. Zinc-based mixed metal oxides (MMOs) have emerged as potential catalystsfor this purpose mainly due to the amphoteric nature of ZnO as well as basic/acidic sites abundance. Thisarticle reviews zinc-based MMO catalysts focusing on catalytic performances and mechanisms, synthesizingmethods, characterizations and operating conditions of the reactors during a 20-years period. Literature survey uncovered that pure ZnO catalyst could exhibit a maximum of 37% DMC yield underthe utmost operating conditions. However, zinc-based MMO catalysts (binary or ternary) showed superiorperformance in DMC conversion through the urea alcoholysis process, usually under moderate operatingconditions, mainly due to synergetic effects among metal oxide phases. Among MMO catalysts,ZnO/CaO binary metal oxide and Zn/Ce/La ternary metal oxide catalysts tabulated the highest DMC productionyields of 41.2% and 50.4% respectively. Moreover, two different catalyst-test modes includingbatch and continuous, and three catalyst synthesizing methods including sol–gel, co-precipitation andurea precipitation (UPM) have been spotlighted in this review.

Evaluation of peroxymonosulfate/O3/UV process on a real polluted water with landfill leachate: Feasibility and comparative study

Farshid Ghanbari,Masoumeh Khatebasreh,Mostafa Mahdavianpour,Ali Mashayekh-Salehi,Ehsan Aghayani,Kun-Yi Andrew Lin,Behnam Kazemi Noredinvand 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.7

Landfill leachate is classified as special wastewater because it contains a large amount of hazardous materials that can lead to the pollution of surface water, generating polluted water with landfill leachate (PWLL) with high organic load. This study investigated the treatment of PWLL by peroxymonosulfate (PMS)/O3/UV process. The effects of several operating parameters such as pH, reaction time, O3 and PMS dosage were investigated in detail. The results showed that PMS/O3/UV removed total organic carbon (TOC) (74%), color (98%), ammonia (93%), chemical oxygen demand (COD) (81%), and biochemical oxygen demand (BOD) (69%) in 75 min at optimal conditions (pH=7, PMS=5mM, O3=1.7 mg/min). According to the results, O3 and UV can well activate PMS and promote the ability of the process to remove TOC from PWLL. Adding ferrous ion to PMS/O3/UV increased the TOC removal efficiency (77%), but cobalt ions had no significant effect on the TOC removal. The elimination of TOC by the PMS/O3/UV process follows pseudo-first-order kinetic model with the reaction rate constant of 0.0203 min1. Compared to peroxone/ UV, PMS/O3/UV showed high yield in TOC, COD, color and ammonia removal. Thus the PMS/O3/UV process can be a new approach for treatment of polluted water in low volume.