Abstracts:In this work, an anti-biofouling polyvinyl chloride/zinc oxide (PVC/ZnO) membrane was prepared using the phase precipitation method for application in a University of Cape Town membrane bioreactor-submerged membrane bioreactor (UCT-MBR) for treatment of actual hospital wastewater. Effects of various ZnO nanoparticle (NPs) amounts (i.e. 0.1, 0.2, 0.3, and 0.4 g) on membrane properties were studied. The hypothesis of this effort was that ZnO would act as an anti-biofouling material, thus overcoming the formation of a bio-cake layer on the PVC-ZnO membrane surface, which in turn greatly extends the long-term of the membrane. The performance of the PVC membranes with ZnO-NPs in a submerged membrane bioreactor (SMBR) was systematically investigated. The characteristics of PVC/ZnO membranes were inspected via scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurement, and pollutant removal efficiency. It was found that the ZnO nanoparticles clearly influenced the structural morphology of the membranes. The addition of 0.1 g of ZnO nanoparticles resulted in a significant increase in the mean roughness by about 140%, with smaller mean pore size and narrow pore size distribution. The addition of ZnO nanoparticles, up to 0.3 g, had a positive effect on the hydrophilicity of the PVC/ZnO membrane with decreasing the contact angle (CA) value by 17.775°. The pure water permeability (PWP) of the membrane improved by 315% with addition of 0.1 g of ZnO. The cake layer build-up on the membrane surface was reduced from 52.8 to 10.42 μm with an increase of ZnO nanoparticles up to 0.3 g, as 0.4 g ZnO had no further effect on the cake layer thickness. The long-term of PVC-0.3 g NPs was improved up to 70 days before membrane cleaning compare with 29 days for neat PVC membrane. Chemical oxygen demand (COD) removal efficiency of UCT-MBR process was approximately similar and around 73.5% for all membranes.

Abstracts:Biomass gasification has been extensively studied in different thermochemical systems, as has the potential to produce fuel gas for chemicals, fuel and electricity applications. Circulating fluidised bed systems (CFB) are of particular interest due to the high reaction rates and thermal efficiency. The study of varying particle properties and gas velocities during the solids recirculation in a CFB system has been proved to greatly influence the overall biomass gasification process. A comparison between experimental and modelling gas-solid interactions can represent a comprehensive and analytical approach for further understanding and scaling up this reaction system. However, running several experiments is expensive and time-consuming. In this work, a reliable and accurate computational fluid dynamics (CFD) framework has been developed to evaluate the hydrodynamics performance of a CFB gasifier. The multiphase CFD model was validated using a pilot-scale CFB gasifier and silica sand. The CFD and experimental data showed good agreement for the solid recirculation tests, for example when comparing predicted and measured the spatial distribution of pressure up the gasifier’s riser. It is the first time that the spatial distribution of solids around a CFB system has been numerically predicted, which can provide guidance to evaluate the hydrodynamics performance of CFB.

Abstracts:The potential effect on methane content from anaerobic digestion of municipal sludge was systematically examined by implementing wide-range concentrations of copper iron-based bimetallic (nZVI/Cu°) nanoparticles and was compared by the results with zero-valent iron nanoparticles (nZVI) influences. The effective concentrations that yielded the highest methane content were determined by tracing the iron dissolution ions. Through the experimental work, bio-digester systems were assembled and used. The most effective concentration of nZVI/Cu° was 1500 mg/L while it increased the biogas production three times the control. The bimetallic concentration of 3000 mg/L showed inhabitation of methanogens due to its disruption of cell integrity. The relatively high nZVI additives also proved biogas stimulation and exposed the sludge to only 50 and 100 mg/L nZVI concentration conversely confirmed inhibitory effects and the biogas generation decreased from 229 mL that the control produced to 192 and 209 mL respectively. The methane content results showed that the methane was constantly accelerated due to the plenty of iron ions which demonstrated that both the nanoparticles could act as electron donors and the dissolved ions could be direct electron transfer, in which methanogens work as iron oxidizer, taking electron from the nanoparticles to reduce the carbon dioxide to methane.

Abstracts:This review is focused on Sorption Enhanced Steam Methane Reforming (SESMR), an emerging process intensification of traditional Steam Methane Reforming (SMR), to produce H2 by a more environmental friendly exploitation of natural gas, thanks to in-situ CO2 capture. Ni and CaO are respectively the most investigated materials for SMR catalysis and CO2 capture, used either on separated particles or in Combined Sorbent Catalyst Materials (CSCM); the latter is potentially more advantageous from the process point of view. Preferential conditions for SESMR based on Ni and CaO are about 650 °C and 1 atm, allowing to obtain H2 with high purity (more than 95 vol% vs. 76 vol% in industrial SMR, both on dry dilution-free basis). For a continuous process, multicycle CaO regeneration is needed, by means of high temperature calcination (800–950 °C). The exploitation of Solid Oxides Fuel Cells (SOFC) flue hot gases, as well as oxy-fuel combustion, are suggested as regeneration strategies in studies concerning SESMR industrial scale-up, in combinations of packed beds or fluidised bed reactors with solid recirculation. Future studies should investigate materials stability in relevant industrial conditions, e.g. more severe regenerations under highly concentrated CO2 at high temperatures, or in presence of steam.

Abstracts:The photooxygenation of  α-terpinene was investigated as a benchmark reaction in an advanced LED-driven flow reactor module, both from an experimental and modelling point of view. Ethanol was used as a green solvent and rose Bengal was chosen as a cheap sensitizer of industrial importance. Firstly, the kinetic law based on all mechanistic steps was established for the chosen photooxygenation. From this, the set of operating parameters potentially influencing the photoreaction rate were identified. Subsequently, experiments were carried out under continuous-flow conditions to screen these operating parameters, namely concentration of α-terpinene, concentration of photosensitizer, residence time, structure of the segmented gas-liquid flow and nature of the reagent gas phase (air versus pure oxygen). Finally, the conditions enabling minimization of sensitizer bleaching were established. It was also shown that the hydrodynamic characteristics of the gas-liquid flow can have an effect on the conversion levels. From this, a simplified model was proposed to predict the conversion at the reactor’s outlet when pure oxygen was used.

Abstracts:An original process aiming at selectively extracting REEs from the hyperaccumulator plant Dicranopteris dichotoma was developed. This process relies on an enhanced ion exchange leaching step carried out in 0.5 M nitric acid solution. Once ion exchange resin is transferred into a column, REEs purification is carried out by percolating successively three solutions through resin bed: two washing steps, with water and 0.75 M nitric acid to remove competing ions and one elution step using 3 M nitric acid. These operating conditions led to 81.4% REEs purity and 78% recovery.

Abstracts:The cumene-phenol process, based on the decomposition of cumene hydroperoxide (CHP) to phenol and acetone, is currently used worldwide for phenol synthesis. Peroxidation of cumene is the key step to synthesis of phenol. Alkali solutions, such as NaOH, were added to the oxidation system traditionally. In this paper, a novel type of catalyst, ionic liquids (ILs), for the cumene oxidation was proposed to intensify the catalytic oxidation of cumene. The reaction rate was much faster in the presence of ILs than that of NaOH. The structure and constitute of the ILs influenced the conversion of cumene and the selectivity of CHP. For the imidazolium-based ILs, the selectivity of CHP under the catalysis of [C4dmim]Br (53.1%) was higher than that of [C4mim]Br (36.2%). However, the selectivity in the presence of [C4mim]OH (67.1%) was almost as the same as that of [C4dmim]OH (63.2%). It was found that the acidic proton of the imidazolium ring catalyzed the decomposition of CHP. This was proved by that the ILs with less acidic protons exhibited better selectivity of CHP. The selectivity of CHP with [MP4]Br as catalyst reached 87.7%.

Abstracts:For very lean H2/air flames in a micro-combustor with cavity flame holders, the combustion efficiency decreases rapidly at sufficiently high inlet velocity due to the occurrence of "flame tip opening". To suppress this undesirable phenomenon, we used helium (He) to replace nitrogen (N2) as dilution in the oxidant. Numerical simulation was conducted under an equivalence ratio of 0.4 for both N2 and He dilutions. The results show that the combustion efficiency is greatly improved, remaining above 98% at 32 m/s in the case of He dilution. The analysis reveals that several reasons are responsible for these results. Firstly, the heat capacity of He is smaller than N2, which leads to a higher temperature level of the gaseous mixture in reaction zone. Second, the effective Lewis number of the H2/O2/He mixture is larger than that of the H2/O2/N2 mixture. Thirdly, the magnitude of stretch rate at the flame tip for He dilution is less than the N2 counterpart. The combined effects of three aspects result in intensified reaction rate and heat release rate at the flame tip. As a consequence, the flame tip opening phenomenon can be significantly suppressed and combustion efficiency be notably increased.

Abstracts:The rapid growth of electronic devices, their subsequent obsolescence and disposal has resulted in electronic waste being one of the fastest increasing waste streams worldwide. Printed circuit boards (PCBs) contained substantial quantities of metals in concentrations significantly higher than those typically found in corresponding ores. The high value of valuable metals in the e-waste makes the recycle process attractive economically. The study was focused on an effective process to selectively recycle lead and tin from metal-rich particles of crushed PCBs by melting and centrifugation in low temperature. Centrifugal separation is an efficient technology to strengthen the transmission of multiphase flow and reaction process. The temperature had a great influence on the composition of Pb-Sn alloy, while the gravity coefficient only affected the Pb and Sn recovery values, and had little effect on the mass ratio of Pb and Sn in the obtained alloy. At an optimized temperature of 420 °C and a gravity coefficient of 1000, the recovery values of Pb and Sn were 57.16% and 59.49%, respectively. The total mass fraction and mass ratio of Pb and Sn were 93.58 wt.% and 0.87, respectively. This process provides an effective method to recycle valuable metals from PCBs.

Abstracts:Isomerization of nC5/iC5 was investigated at atmospheric conditions and temperatures of 180–260 °C in a BZSM-5 membrane reactor packed with Pt-SZ/Al catalyst. Pt-SZ/Al catalyst was synthesized by precipitation method. BZSM-5 membrane was prepared by in situ nucleation and secondary growth on the outer surface of the support. The effects of reaction temperature and sweep gas flow rate were investigated. Also, a comparison between the performance of the MR and conventional reactor was performed. The prepared sulfated zirconia is nanoscale in size and has predominantly tetragonal crystalline phase. A continuous and uniform layer of BZSM-5 was formed on support surface. Feed conversion increased with increasing temperature and selectivity decreased. Increase in the sweep gas flow rate which reduce contact time between reactant and catalyst, decreased n-C5 conversion and increased selectivity toward iC5. The positive effect of membrane was observed on iC5 selectivity in the investigated temperature range, but nC5 conversion was affected by different membrane mechanisms. An increase in RON of the product (∼10%) was also observed.