Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 12Citation - Scopus: 14Extraction of Monophenols and Fractionation of Depolymerized Lignin Oil With Nanofiltration Membranes(Elsevier, 2023) Croes, Tim; Dutta, Abhishek; De Bie, Robin; Van Aelst, Korneel; Sels, Bert; Van der Bruggen, BartOrganic solvent nanofiltration membranes were employed to fractionate birch derived reductive catalytic fractionated (RCF) lignin oil. This lignin oil is highly depolymerized, with most, if not all chemical compounds lighter than 3 kDa. Sixteen commercially available membranes were investigated for the fractionation, in combination with methanol and ethyl acetate as solvents. Membrane performances were quantified using Gaussian fits of gel permeation chromatograms and separation factor calculations. The separation factor was found to be primarily based on affinities instead of size-exclusion. The silicon-based membranes from Borsig (Germany) and PuraMem S600 from Evonik (UK) proved best at separating lignin into different functional fractions, showing monomer separation factors up to 7.4 and providing a permeate fraction with 88 % phenolic monomer purity. These membranes were further examined in batch diafiltration and two-stage filtration. This increased the separation factor from 7.4 to 25.4, and the monomer purity of the permeate to 95 %, proving that membrane purification of the lignin-derived monophenols is technically feasible.Article Citation - WoS: 13Citation - Scopus: 17Characterization and Beneficiation of Ethiopian Kaolin for Use in Fabrication of Ceramic Membrane(IOP Publishing, 2021) Zewdie, Tsegahun Mekonnen; Prihatiningtyas, Indah; Dutta, Abhishek; Habtu, Nigus Gabbiye; Van der Bruggen, BartKaolin (china clay) is a rock material that is very rich in kaolinite. A kaolin ore from Debre Tabor, Ethiopia containing 59.2 wt% SiO2, 24.9 wt% Al2O3, 2.4 wt% Fe2O3, and 8.22 wt% loss on ignition (LOI) was physically beneficiated, chemically leached, and thermally treated for possible industrial use, especially for ceramic membrane fabrication. The leaching experiments were carried out using oxalic acid solutions as leaching reagents for the iron extraction process. The effect of acid concentration, reaction temperature, and contact time on iron leaching was investigated. It was determined that the rate of iron extraction increased with the oxalic acid concentration, leaching temperature, and contact time. A substantial reduction of iron oxide (2.4 to 0.36 wt%) from the raw kaolin was observed at operating conditions of 2.0 M oxalic acid, the temperature of 120 degrees C, and contact time of 120 min. A maximum kaolin whiteness index of 81.4% was achieved through this leaching process. Finally, the physically beneficiated, chemically leached, and thermally treated kaolin raw material was used to fabricate a low-cost kaolin-based ceramic membrane. After firing at 1100 degrees C the ceramic membrane was found to have a mass loss of 11.04 +/- 0.05%, water absorption of 8.9 +/- 0.4%, linear shrinkage of 14.5 +/- 0.05%. It was demonstrated to be chemically stable, having less than 3% mass loss in acid solution, and less than 1% mass loss in alkali solution. The newly developed membranes have thus properties comparable to commercial ceramic membranes.Article Citation - WoS: 5Citation - Scopus: 5Flat sheet metakaolin ceramic membrane for water desalination via direct contact membrane distillation(IWA Publishing, 2022) Zewdie, Tsegahun Mekonnen; Habtu, Nigus Gabbiye; Dutta, Abhishek; Van der Bruggen, BartHydrophobic metakaolin-based flat sheet membrane was developed via phase inversion and sintering technique and modified through 1H,1H,2H,2H-perfluorooctyltriethoxysilane grafting agents. The prepared membrane was characterized by different techniques such as XRD, FTIR, SEM, contact angle, porosity, and mechanical strength. Their results indicated that the wettability, structural, and mechanical properties of the prepared membrane confirm the suitability of the material for membrane distillation (MD) application. The prepared metakaolin-based flat sheet membrane acquired hydrophobic properties after surface modification with the water contact angle values of 113.2° to 143.3°. Afterward, the membrane performance was tested for different sodium chloride aqueous solutions (synthetic seawater) and various operating parameters (feed temperature, feed flow rate) using direct contact membrane distillation (DCMD). Based on the findings, the prepared membrane at metakaolin loading of 45 wt.% and sintered at 1,300 °C was achieved the best performance with >95% salt rejection and permeate flux of 6.58 + 0.3 L/m2 · h at feed temperature of 80 °C, feed concentration of 35 g/L, and feed flow rate of 60 L/h. It can be con-cluded that further optimization of membrane porosity, mechanical, and surface properties is required to maximize the permeate flux and salt rejection.Article Citation - WoS: 11Citation - Scopus: 12Numerical Modelling Assisted Design of a Compact Ultrafiltration (uf) Flat Sheet Membrane Module(MDPI, 2021) Bopape, Mokgadi F.; Van Geel, Tim; Dutta, Abhishek; Van der Bruggen, Bart; Onyango, Maurice StephenThe increasing adoption of ultra-low pressure (ULP) membrane systems for drinking water treatment in small rural communities is currently hindered by a limited number of studies on module design. Detailed knowledge on both intrinsic membrane transport properties and fluid hydrodynamics within the module is essential in understanding ULP performance prediction, mass transfer analysis for scaling-up between lab-scale and industrial scale research. In comparison to hollow fiber membranes, flat sheet membranes present certain advantages such as simple manufacture, sheet replacement for cleaning, moderate packing density and low to moderate energy usage. In the present case study, a numerical model using computational fluid dynamics (CFD) of a novel custom flat sheet membrane module has been designed in 3D to predict fluid flow conditions. The permeate flux through the membrane decreased with an increase in spacer curviness from 2.81 L/m(2)h for no (0%) curviness to 2.73 L/m(2)h for full (100%) curviness. A parametric analysis on configuration variables was carried out to determine the optimum design variables and no significant influence of spacer inflow or outflow thickness on the fluid flow were observed. The numerical model provides the necessary information on the role of geometrical and operating parameters for fabricating a module prototype where access to technical expertise is limited.Article Citation - WoS: 31Citation - Scopus: 38Resource Recovery From and Management of Wastewater in Rural South Africa: Possibilities and Practices(Elsevier, 2021) Montwedi, Masego; Munyaradzi, Mujuru; Pinoy, Luc; Dutta, Abhishek; Ikumi, David S.; Motoasca, Emilia; Van der Bruggen, BartThe continuous reduction in water resource availability is one of the major global societal challenges. Wastewater treatment plants (WWTP) play an important role in this, as they can provide water recovery. Furthermore, effective sanitation services lead to a significant reduction of health risks and protect the environment. However, WWTPs consume large amounts of energy to comply with discharge standards. At the same time, wastewater contains resources, which can be recovered for secondary uses, if treated properly. This is particularly useful for rural South Africa where challenges associated with water-based pollution, declining nutrients and water shortage, require a paradigm shift. This involves the transition of wastewater treatment plants into water, sanitation and resource (nutrients and energy) recovery facilities, leading further to social, economic and environmental sustainability. This process will involve the implementation of engineering tools for predictive modelling of the waste resource recovery systems. This review identifies the conceptual need for such a systematic shift from wastewater treatment to waste recovery facilities in rural South Africa. The targeted impact is to promote and help the uptake of the conversion of wastewater treatment systems into low cost and environmentally sustainable water and resource recovery facilities. Overall, the outlook is positive for the future use of these systems in South-Africa.