Coupled 1D-2D hydrodynamic inundation model for sewer overflow: Influence of modeling parameters

AbstractThis paper presents outcome of our investigation on the influence of modeling parameters on 1D-2D hydrodynamic inundation model for sewer overflow, developed through coupling of an existing 1D sewer network model (SWMM) and 2D inundation model (BREZO). The 1D-2D hydrodynamic model was developed for the purpose of examining flood incidence due to surcharged water on overland surface. The investigation was carried out by performing sensitivity analysis on the developed model. For the sensitivity analysis, modeling parameters, such as mesh resolution Digital Elevation Model (DEM) resolution and roughness were considered. The outcome of the study shows the model is sensitive to changes in these parameters. The performance of the model is significantly influenced, by the Manning's friction value, the DEM resolution and the area of the triangular mesh. Also, changes in the aforementioned modeling parameters influence the Flood characteristics, such as the inundation extent, the flow depth and the velocity across the model domain

Modelling and thermodynamic properties of pure CO2 and flue gas sorption data on South African coals using Langmuir, Freundlich, Temkin, and extended Langmuir isotherm models

Carbon sequestration in unmineable coal seams has been proposed as one of the most attractive technologies to mitigate carbon dioxide (CO2) emissions in which CO2 is stored in the microporous structure of the coal matrix in an adsorbed state. The CO2 adsorption process is hence considered one of the more effective methodologies in environmental sciences. Thus, adsorption isotherm measurements and modelling are key important scientific measures required in understanding the adsorption system, mechanism, and process optimization in coalbeds. In this paper, three renowned and reliable adsorption isotherm models were employed including Langmuir, Freundlich, and Temkin for pure CO2 adsorption data, and the extended-Langmuir model for multicomponent, such as flue gas mixture-adsorption data as investigated in this research work. Also, significant thermodynamics properties including the standard enthalpy change (ΔH∘), entropy change (ΔS∘), and Gibbs free energy (ΔG∘) were assessed using the van’t Hoff equation. The statistical evaluation of the goodness-of-fit was done using three (3) statistical data analysis methods including correlation coefficient (R2), standard deviation (σ), and standard error (SE). The Langmuir isotherm model accurately represent the pure CO2 adsorption on the coals than Freundlich and Temkin. The extended Langmuir gives best experimental data fit for the flue gas. The thermodynamic evaluations revealed that CO2 adsorption on the South African coals is feasible, spontaneous, and exothermic; and the adsorption mechanism is a combined physical and chemical interaction between the adsorbate and the adsorbent.The National Research Foundation (NRF) of South Africa.https://www.springer.com/journal/40789am2023Chemical Engineerin

Effect of flow pattern in superstructure-based optimisation of fixed-site carrier membrane gas separation during post-combustion CO2 capture

The authors would like to acknowledge the University of the Witwatersrand Research Office for support.Membrane-based gas separation continues to be an area of interest that is being explored for various applications and efforts are being made to enable large-scale implementation and commercialisation. Works on techno-economic studies in areas such as carbon capture, natural gas sweetening, and biogas upgrading has been reported. Various simulation studies have reported the effect of the membrane flow pattern on permeate recovery and purity. The simulation studies in this area have been limited to single-stage and two-stage membrane processes, while many of these studies considered polymer membranes, facilitated transport has barely been investigated. In addition, optimisation studies that compared different flow patterns in the membrane module have been few. The facilitation of gas permeation decreases as pressure is increased due to carrier saturation. However, an increased pressure increases the driving force, and a trade-off should be achieved. The different membrane flow patterns also have inherent driving force potential. In this work, a superstructurebased model that also embeds a fixed site carrier permeation membrane has been developed for CO2 capture from a coal-fired power plant and three scenarios based on the different flow patterns, i.e., co-current, countercurrent and crossflow, were analysed to determine the effect of the flow pattern in the membrane module. The main objective of the optimisation was to minimise the cost of capture. The counter-current flow pattern resulted in the lowest cost of capture as it resulted in the most energy-efficient process system. The co-current flowbased optimisation results in configuration result in an 18 % increase in cost compared to the counter-current flow pattern optimisation run due to a 29 % increase in energy consumption. The crossflow pattern optimisation results in a 9 % increase in the annualised cost of capture compared to the counter-current flow.http://www.aidic.it/cetam2023Chemical Engineerin

Effect of loading and functionalization of carbon nanotube on the performance of blended polysulfone/polyethersulfone membrane during treatment of wastewater containing phenol and benzene

In this study, a carbon nanotube (CNT)-infused blended polymer membrane was prepared and evaluated for phenol and benzene removal from petroleum industry wastewater. A 25:75 (by weight %) blended polysulfone/polyethersulfone (PSF/PES) membrane infused with CNTs was prepared and tested. The effect of functionalization of the CNTs on the quality and performance of the membrane was also investigated. The membranes were loaded with CNTs at different loadings: 0.5 wt. %, 1 wt. %, 1.5 wt. % pure CNTs (pCNTs) and 1 wt. % functionalized CNTs (fCNTs), to gain an insight into the effect of the amount of CNT on the quality and performance of the membranes. Physicochemical properties of the as-prepared membranes were obtained using scanning electron microscopy (SEM) for morphology, Raman spectroscopy for purity of the CNTs, Fourier transform infrared (FTIR) for surface chemistry, thermogravimetric analysis (TGA) for thermal stability, atomic force microscopy (AFM) for surface nature and nano-tensile analysis for the mechanical strength of the membranes. The performance of the membrane was tested with synthetic wastewater containing 20 ppm of phenol and 20 ppm of benzene using a dead-end filtration cell at a pressure ranging from 100 to 300 kPa. The results show that embedding CNTs in the blended polymer (PSF/PES) increased both the porosity and water absorption capacity of the membranes, thereby resulting in enhanced water flux up to 309 L/m2h for 1.5 wt. % pCNTs and 326 L/m2h for 1 wt. % functionalized CNT-loaded membrane. Infusing the polysulfone/polyethersulfone (PSF/PES) membrane with CNTs enhanced the thermal stability and mechanical strength. Results from AFM indicate enhanced hydrophilicity of the membranes, translating in the enhancement of anti-fouling properties of the membranes. However, the % rejection of membranes with CNTs decreased with an increase in pCNTs concentration and pressure, while it increased the membrane with fCNTs. The % rejection of benzene in the pCNTs membrane decreased with 13.5% and 7.55% in fCNT membrane while phenol decreased with 55.6% in pCNT membrane and 42.9% in the FCNT membrane. This can be attributed to poor CNT dispersion resulting in increased pore sizes observed when CNT concentration increases. Optimization of membrane synthesis might be required to enhance the separation performance of the membranes.University of the Witwatersrand Postgraduate Merit Award and John Davidson Educational Trust.http://www.mdpi.com/journal/membranespm2021Chemical Engineerin

Effectiveness of carbon polymeric nanofiltration composite membrane in treating industrial textile wastewater

Today, the trend is towards the use of low-cost materials to develop green processes in the aim to reduce cost and impact on environment. The use of low-cost materials of natural origin has been proven to be very promising for the fabrication of ceramic membranes for wastewater treatment. In this article, fabrication and testing of high performance microporous carbon membrane for nanofiltration (NF) separation based on mineral coal and phenolic resin are reported. The preparation of the NF composite membrane involved carbonizing a polymeric precursor deposited on a porous supported membrane, using the vacuum slip-casting process to obtain a homogeneous NF top layer almost without defects by one-step coating-carbonization cycle. To ensure a better final membrane texture, several parameters including the viscosity of the casting suspension, the casting time and the carbonization temperature were considered. A crack-free NF membrane with a thickness layer of 1.36 μm, a mean pore size of 1.1 nm, and a molecular weight cut-off of 400 Da was obtained using 1 min casting time and 45% of phenolic resin. These membranes were tested in the treatment of textile wastewater. Promising results in terms of permeate flux and pollutant retention (COD (72%), salinity (45%)) were obtained. The results further showed that the treated wastewater could be recycled into the textile industry or can be discharged into the municipal sewerage in compliance with legislations. In addition, a carbonization temperature of 650°C yielded best membranes in terms of average pores size and membrane permeability with minimum energy consumption.www.deswater.comam2023Chemical Engineerin

Evaluation of corrosion inhibition of essential oil-based inhibitors on aluminum alloys

There is a high demand for eco-friendly, effective, and highperformance corrosion inhibitors for industrial applications. Thus, the corrosion property of aluminum alloys was studied in essential oil-containing sodium chloride solution at various concentrations. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), surface tests, and weight loss analysis were used to study the corrosion inhibition mechanism of the essential oil. The essential oil showed the highest inhibition efficiency of 97.01% at 1000 ppm. A high efficiency of 96.03% was achieved even after 168 h of exposure. The potentiodynamic polarization test showed that the essential oil is a mixed-type inhibitor. EIS results show better adsorption of the oil on the surface of the aluminum at increased inhibitor concentrations. The Langmuir’s adsorption isotherm model was found to describe the adsorption behavior. The surface morphology of the uninhibited and inhibited specimens examined by a scanning electron microscope equipped with an energydispersive X-ray spectroscope confirmed the protective film of the inhibitor molecules on the aluminum surface.http://pubs.acs.org/journal/acsodfam2023Chemical Engineerin

Effect of silica sodalite loading on SOD/PSF membranes during treatment of phenol-containing wastewater

In this study, silica sodalite (SSOD) was prepared via topotactic conversion and different silica sodalite loadings were infused into the polysulfone (PSF) for application in phenol-containing water treatment. The composite membranes were fabricated through the phase inversion technique. Physicochemical characteristics of the nanoparticles and membranes were checked using a Scanning Electron Microscope (SEM), Brunauer Emmett–Teller (BET), and Fourier Transform Infrared (FTIR) for surface morphology, textural properties, and surface chemistry, respectively. A nanotensile test, Atomic Force Microscopy (AFM), and contact angle measurement were used to check the mechanical properties, surface roughness, and hydrophilicity of the membranes, respectively. SEM results revealed that the pure polysulfone surface is highly porous with large evident pores. However, the pores decreased with increasing SSOD loading. The performance of the fabricated membranes was evaluated using a dead-end filtration device at varying feed pressure during phenol-containing water treatment. The concentration of phenol in water used in this study was 20 mg/L. The pure PSF displayed the maximum phenol rejection of 95 55% at 4 bar, compared to the composite membranes having 61.35% and 64.75% phenol rejection for 5 wt.% SSOD loading and 10 wt.% SSOD loading, respectively. In this study, a novel Psf-infused SSOD membrane was successfully fabricated for the treatment of synthetic phenol-containing water to alleviate the challenges associated with it.https://www.mdpi.com/journal/membranesam2023Chemical Engineerin

Preparation and evaluation of nanocomposite sodalite/-Al2O3 tubular membranes for H2/CO2 separation

Nanocomposite sodalite/ceramic membranes supported on -Al2O3 tubular support were prepared via the pore-plugging hydrothermal (PPH) synthesis protocol using one interruption and two interruption steps. In parallel, thin-film membranes were prepared via the direct hydrothermal synthesis technique. The as-synthesized membranes were evaluated for H2/CO2 separation in the context of pre-combustion CO2 capture. Scanning electron microscopy (SEM) was used to check the surface morphology while x-ray diffraction (XRD) was used to check the crystallinity of the sodalite crystals and as-synthesized membranes. Single gas permeation of H2, CO2, N2 and mixture gas H2/CO2 was used to probe the quality of the membranes. Gas permeation results revealed nanocomposite membrane prepared via the PPH synthesis protocols using two interruption steps displayed the best performance. This was attributed to the enhanced pore-plugging effect of sodalite crystals in the pores of the support after the second interruption step. The nanocomposite membrane displayed H2 permeance of 7.97 107 mols1m2Pa1 at 100 C and 0.48 MPa feed pressure with an ideal selectivity of 8.76. Regarding H2/CO2 mixture, the H2 permeance reduced from 8.03 107 mols1m2Pa1 to 1.06 107 mols1m2Pa1 at 25 C and feed pressure of 0.18 MPa. In the presence of CO2, selectivity of the nanocomposite membrane reduced to 4.24.The Department of Science and Innovation Research Foundation (DSI-NRF) South Africa’s SARChI Clean Coal Technology.http://www.mdpi.com/journal/membranesam2021Chemical Engineerin

Effect of silica sodalite functionalization and PVA coating on performance of sodalite infused PSF membrane during treatment of acid mine drainage

In this study, silica sodalite (SSOD) nanoparticles were synthesized by topotactic conversion and functionalized using HNO3/H2SO4 (1:3). The SSOD and functionalized SSOD (fSSOD) nanoparticles were infused into a Polysulfone (Psf) membrane to produce mixed matrix membranes. The membranes were fabricated via the phase inversion method. The membranes and the nanoparticles were characterized using Scanning Electron Microscopy (SEM) to check the morphology of the nanoparticles and the membranes and Fourier Transform Infrared to check the surface chemistry of the nanoparticles and the membranes. Thermal stability of the nanoparticles and the membranes was evaluated using Themogravimetry analysis (TGA) and the degree of hydrophilicity of the membranes was checked via contact angle measurements. The mechanical strength of the membranes and their surface nature (roughness) were checked using a nanotensile instrument and Atomic Force Microscopy (AFM), respectively. The textural property of the nanoparticles were checked by conducting N2 physisorption experiments on the nanoparticles at 77 K. AMD-treatment performance of the fabricated membranes was evaluated in a dead-end filtration cell using a synthetic acid mine drainage (AMD) solution prepared by dissolving a known amount of MgCl2, MnCl2 4H2O, Na2SO4, Al(NO3)3, Fe(NO3)3 9H2O, and Ca2OH2 in deionized water. Results from the N2 physisorption experiments on the nanoparticles at 77 K showed a reduction in surface area and increase in pore diameter of the nanoparticles after functionalization. Performance of the membranes during AMD treatment shows that, at 4 bar, a 10% fSSOD/Psf membrane displayed improved heavy metal rejection >50% for all heavy metals considered, expect the SSOD-loaded membrane that showed a rejection <13% (except for Al3+ 89%). In addition, coating the membranes with a PVA layer improved the antifouling property of the membranes. The effects of multiple PVA coating and behaviour of the membranes during real AMD are not reported in this study, these should be investigated in a future study. Therefore, the newly developed functionalized SSOD infused Psf membranes could find applications in the treatment of AMD or for the removal of heavy metals from wastewater.The University of the Witwatersrand and the Council of Scientific and Industrial Research (CSIR).https://www.mdpi.com/journal/membranesam2022Chemical Engineerin

Socio-economic impacts of energy access through off-grid systems in rural communities: a case study of southwest Nigeria

The development of resilient energy systems is important for sustainable cities and communities. However, in countries with insufficient national energy supply, electricity distributors rarely consider remote communities due to their distant settlement, low electricity demand and poor payment capabilities. The United Nations has set a goal to deliver universal energy access by 2030; hence, it has become imperative to deploy clean and affordable off-grid mini-grid solutions to previously abandoned communities. Access to energy in rural communities is expected to result in unlocking their economic potentials. This paper investigates the impact of a solar hybrid mini-grid on the socio-economic growth of local entrepreneurs in Gbamu Gbamu village, Nigeria. A total of 83 micro- and small-enterprises has been surveyed; descriptive statistics, paired-sample t-test, cross-tabulation and χ2 test, were used to assess the performance of businesses before and after electrification. The outcomes include the number of business enterprises created, employment statistics, energy expenses and income generated. Regression analysis was conducted on the relationship between the average income generated by businesses and independent socio-economic variables such as gender, marital status, household size, age, education level,The Royal Society.https://royalsocietypublishing.org/journal/rstadm2022Chemical Engineerin