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Showing papers in "Chemical Engineering & Technology in 2018"




Journal ArticleDOI
TL;DR: In this paper, a review of the applications of dynamic membrane (DM) filtration and factors that affect its formation, filtrration, and cleaning are introduced, and the possible future research directions and some guidelines for DM technology are given.
Abstract: In this review, the applications of Dynamic membrane (DM) filtration and factors that affect its formation, filtration and cleaning are introduced. Dynamic membrane has been studied widely in wastewater treatment in recent years. DM formation method and mechanism are explained. In detail, effects of supporting material, deposited material, formation pressure, and pH on the DM formation are discussed. And the effects of operation pressure, aeration intensity, cross-flow velocity, temperature, and other parameters are evaluated in the DM filtration process. Different DM cleaning strategies are reviewed. The applications of DM in municipal wastewater, surface water, oily water, industrial wastewater, sludge treatment, and microalgae harvesting are discussed. Finally, the possible future research directions and some guidelines for DM technology are given.

42 citations


Journal ArticleDOI
TL;DR: In this article, the performance of hollow fiber mixed matrix membranes (HFMMMs) for CO2 separation from N2 and CH4 has been investigated and the issues with fabrication of HFMMMs have been discussed.
Abstract: In the recent year, the presence of CO2 in atmosphere has been increased tremendously after industrial revolution and it has been projected that the temperature of atmosphere will be raised about 1.4 oC to 5.8 oC by 2100. Therefore, it is important to control the emission of CO2 from industries. On the other hands, it is well documented in the literature that membrane technology is preferred over the conventional technologies (i.e. adsorption, absorption and cryogenic) due to its advantages including reliability, operational simplicity, low capital cost and easy maintenance. Among the various types of membranes, hollow fiber mixed matrix membranes (HFMMMs) exhibits great potential for CO2 separation because they offer large surface area, low pressure drop, high pressure stability, high separation performance and easy scale up compared to flat sheet mixed matrix membranes (FSMMMs) and spiral wound mixed matrix membranes (SWMMMs). Thus, there have been numerous works where researchers incorporated various inorganic fillers (i.e. zeolites, carbon, metal organic frameworks (MOFs) etc.) into different types of polymeric materials for the fabrication of HFMMMs. Despite of significant progress made in the recent year; highlights on current trends, issues and transport models of HFMMMs in CO2/N2 and CO2/CH4 separation are very limited. Therefore, in the present review article, we focused on the performance and issues of various materials based HFMMMs for CO2/CH4 and CO2/N2 separation. Major features of this review are reflected in the following three aspects: (i) comprehensive study on the performance of HFMMMs for CO2/N2 and CO2/CH4 separation (ii) issues with the fabrication of HFMMMs in CO2/N2 and CO2/CH4 separation (iii) prediction of transport models for HFMMMs in gases separation. In the present review article, it has been observed that the MOF based HFMMMs showed higher CO2/N2 and CO2/CH4 separation performance compared to the zeolite, carbon and other fillers based HFMMMs. On the other hand, ZIF-8, ZIF-93 and amine functionalized MIL-based HFMMMs showed higher CO2/N2 and CO2/CH4 separation performance compared to other fillers based HFMMMs. Among MOF based HFMMMs, amine functionalized MIL based HFMMM showed great potential for CO2 separation from N2 and CH4. Furthermore, the present paper reviewed the different issues with fabrication of HFMMMs including dope fluid composition; bore fluid composition and spinning parameters. It has been found that the spinning parameters including, dope fluid flow rate, bore fluid flow rate, dry gap height, force convection gas flow rate, take up speed, jet–stretch ratio and draw ratio effects the morphology of membrane and thus, performance of HFMMMs in CO2 separation. Therefore, the achievement of optimum and proper value of spinning parameters during the fabrication of HFMMMs is also need to be explored to enhance the performance of the membranes. Besides, from the review work on the transport models used for HFMMMs in gases permeations, it has been concluded that modified Maxwell model and modified Pal model will be more appropriate model to study the transport behavior of gases through HFMMMs contains low and higher loading of fillers, respectively.

41 citations



Journal ArticleDOI
TL;DR: In this article, the selective separation mechanisms of three textile dyes with 2000 ppm of NaCl solution by nanofiltration membranes during brine recovery at three different pH medium pH-3, pH-7 and pH 10 respectively were investigated.
Abstract: The present study investigates the selective separation mechanisms of three textile dyes with 2000 ppm of NaCl solution by nanofiltration membranes during brine recovery at three different pH medium pH-3, pH-7 and pH 10 respectively. Tests were performed with the purpose of relating flux decline, brine recovery and dye rejection behavior to membrane characteristics (Molecular weight cutoff, contact angle, zeta potential), charge of the dye molecules, and solution chemistry. Salt-organic separation factor was estimated in order to rank and choose the most suitable NF membranes for brine recovery with high degree of flux. Out of these membranes tested in this study, only NF-270 was capable of operating up to 56-70% brine recovery with high flux ranging from 78.07 to 114.80 Lh-1m-2.

38 citations






Journal ArticleDOI
Stefan Szepessy1, Peter Thorwid1
TL;DR: A sharp reduction of the energy consumption of a high‐speed centrifuge was obtained following several design changes, while still maintaining separation capacity, by modifying flow paths of the rotor.
Abstract: A sharp reduction of the energy consumption of a high-speed centrifuge was obtained following several design changes, while still maintaining separation capacity. This reduction is necessary for making some applications commercially interesting, e.g., large-volume flow rates in the growing biopharma industry. The reduction was achieved by modifying flow paths of the rotor, i.e., reducing the outlet radius to minimize angular momentum losses and lowering the pressure drop of the internal flow. Further, removing air outside the rotor reduced aerodynamic losses, and using a direct drive motor, losses encountered with gear or belt drives were eliminated. This way, an average energy reduction of 50 % was obtained.

Journal ArticleDOI
TL;DR: In this paper, a core-shell hierarchical USY@Al-SBA-15 zeolite-supported NiMo catalyst was used for the direct conversion of waste cooking oil (WCO) into bio-jet fuel.
Abstract: The direct conversion of waste cooking oil (WCO) into bio-jet fuel was investigated over a core-shell hierarchical USY@Al-SBA-15 zeolite-supported NiMo catalyst. The core-shell structure showed better acid and pore size distributions. The synergetic effect of the core-shell micropore and mesopore structure significantly contributed to enhancing the selectivity for the jet fuel (C9–15 hydrocarbons) from 9.3 % over NiMo/USY up to 35.7 % over NiMo/USY@Al-SBA-15, with high isomerization (iso-/n-paraffins ratio = 2.7) and moderate aromatic fraction (18.7 %). The decarboxylation reaction was selectively enhanced. Optimal selectivity for jet fuel (39.7 %) was obtained at 380 °C and a high H2/oil ratio would decrease the yield of jet fuel. This catalyst showed excellent stability for the hydroconversion of WCO to hydrocarbons.



Journal ArticleDOI
TL;DR: In this paper, the effect of sparger orifice sizes, solid particle shapes and their loading amounts in a bubble column reactor on the absorption of oxygen in tap water were investigated, and their influence on the mass transfer coefficient and bubble hydrodynamic parameters were determined.
Abstract: The relative effects on gas–liquid mass transfer of the size of the gas sparger orifices and the properties of solid particles are not yet fully understood. In this work, the effect of sparger orifice sizes, solid particle shapes and their loading amounts in a bubble column reactor on the absorption of oxygen in tap water were investigated. Their influence on the mass transfer coefficient and bubble hydrodynamic parameters were determined. The results show that the addition of solid particles can have both positive and negative effects on the hydrodynamics and mass transfer, depending on the orifice size of the gas sparger. The introduction of ring-shaped solid particles can improve the mass transfer rate by up to 28 % without requiring any great additional power consumption.



Journal ArticleDOI
TL;DR: In this article, a robust continuous flow procedure for the synthesis of glycerol carbonate (2GLC) from green reagents was described, mediated by an inexpensive polymer-supported base catalyst using methanol as co-solvent.
Abstract: We report a robust continuous flow procedure for the synthesis of glycerol carbonate (2‐GLC) from green reagents glycerol and dimethyl carbonate (DMC), mediated by an inexpensive polymer‐supported base catalyst using methanol as co‐solvent. High conversion and selectivity were obtained, while residence times were typically shorter than 10 minutes.


Journal ArticleDOI
TL;DR: Algae; Biomass; Ecology; Microorganisms; Photobioreactors; Productivity;Biomass productivity; Central composite designs; CO2 biofixation; Micro-algae; Optimization method; Response surface techniques; Specific growth rate; Tubular photobioreactor.
Abstract: Algae; Biomass; Ecology; Microorganisms; Photobioreactors; Productivity; Biomass productivity; Central composite designs; CO2 biofixation; Micro-algae; Optimization method; Response surface techniques; Specific growth rate; Tubular photobioreactor; Carbon dioxide

Journal ArticleDOI
TL;DR: In this paper, a low-cost system composed of a basic stereomicroscope and video camera for the in situ imaging of sub-millimeter crystals through curved walls of millifluidic tubular crystallizers is described.
Abstract: A key design limitation to the effective monitoring and control of continuous crystallization processes is the ability to characterize crystals in real time. A low-cost system composed of a basic stereomicroscope and video camera for the in situ imaging of sub-millimeter crystals through curved walls of millifluidic tubular crystallizers is described. Real-time videos taken for millimeter-size slurry slugs are used to guide the experimental design for a recently developed multiphase-flow crystallization process, including the improvement of the slug aspect ratio, visualization of crystal shapes, and observation of the extent of aggregation. Design considerations are also discussed for the use of multiple stereomicroscopes in other continuous-flow tubular experiments.



Journal ArticleDOI
TL;DR: In this paper, the authors used commercial nanofiltration (NF) membranes for the treatment process of aerobically treated palm oil mill effluent (AT-POME) for the first time.
Abstract: For the first time, engineered osmosis was performed using commercial nanofiltration (NF) membranes for the treatment process of aerobically treated palm oil mill effluent (AT-POME). Compared to conventional forward-osmosis (FO) membranes with dense rejection layer, the NF-like FO membranes offer a higher water flux with minimum reverse solute flux provided appropriate solutes like divalent salts or polyelectrolytes were used in the draw solution. Both NF membranes were able to treat the AT-POME by completely preventing the color component from passing through the permeate side under FO and pressure-retarded osmosis (PRO) orientation. The water fluxes of the membranes were higher under PRO orientation owing to the reduced internal concentration polarization effect. Relatively loose membranes for the engineered osmosis application could address severe surface fouling of membranes tested under pressure-driven filtration.




Journal ArticleDOI
TL;DR: In this paper, the authors used two lab-made solvent-resistant composite nanofiltration membranes of poly(vinylidene difluoride) (PVDF) as support and poly(dimethylsiloxane) as coating layer.
Abstract: Biodiesel as alternative for conventional diesel fuel is mainly produced by the catalytic reaction of triglycerides with an alcohol. In this work, the purification of biodiesel was carried out with two lab-made solvent-resistant composite nanofiltration membranes of poly(vinylidene difluoride) (PVDF) as support and poly(dimethylsiloxane) as coating layer. Biodiesel was obtained from the esterification of partially refined soy oil with bioethanol (EtOH) and NaOH as catalyst. The best biodiesel purification performance was achieved with the PVDF-12SI membrane reaching high retention of glycerol, total glycerides, and soap. PVDF-SI membranes were found to have an excellent stability for biodiesel permeation, achieving a flux recovery ratio of EtOH as high as 0.94 after twenty cycles of use.

Journal ArticleDOI
TL;DR: In this article, a chitosan-functionalized graphene oxide (CS-GO) was synthesized and incorporated into PVDF ultrafiltration membrane, and the effect of CS-GO addition on the morphology and membrane performance was studied with water contact angle (CA), scanning electron microscopy (SEM), atomic force microscopy, porosity and pore size, permeation measurements, rejection tests and antifouling experiments.
Abstract: Chitosan-functionalized graphene oxide (CS–GO) was synthesized and incorporated into PVDF ultrafiltration membrane. The effect of CS–GO addition on the morphology and membrane performance was studied with water contact angle (CA), scanning electron microscopy (SEM), atomic force microscopy (AFM), porosity and pore size, permeation measurements, rejection tests and antifouling experiments. We found that the water flux of CS–GO/PVDF composite membrane increased by 44% after incorporating 0.6 wt% of CS-GO into the PVDF matrix versus pristine PVDF membrane. In addition, the CS-GO/PVDF membrane exhibited higher water flux, BSA rejection rate, water flux recovery ratio and lower BSA solution flux attenuation rate than unfilled PVDF membranes, CS/PVDF, and GO/PVDF membranes. The excellent water permeability and antifouling performance can be attributed to the high hydrophilicity and good dispersion of CS–GO in the matrix.