Synthesis and performance evaluation of peS/chitosan membranes coated with polyamide for acid mine drainage treatment

Abstract

Membrane purification techniques for recovery of succinic acid obtained from fermentation broth during bioconversion of lignocellulosic biomass : current advances and future perspectives

Recently, the bioconversion of biomass into biofuels and biocommodities has received significant attention. Although green technologies for biofuel and biocommodity production are advancing, the productivity and yield from these techniques are low. Over the past years, various recovery and purification techniques have been developed and successfully employed to improve these technologies. However, these technologies still require improvement regarding the energyconsumption-related costs, low yield and product purity. In the context of sustainable green production, this review presents a broad review of membrane purification technologies/methods for succinic acid, a biocommodity obtained from lignocellulosic biomass. In addition, a short overview of the global market for sustainable green chemistry and circular economy systems or zero waste approach towards a sustainable waste management is presented. Succinic acid, the available feedstocks for its production and its industrial applications are also highlighted. Downstream separation processes of succinic acid and the current studies on different downstream processing techniques are critically reviewed. Furthermore, critical analysis of membrane-based downstream processes of succinic acid production from fermentation broth is highlighted. A short review of the integrated-membrane-based process is discussed, as well, because integrating “one-pot” lignocellulosic bioconversion to succinic acid with downstream separation processing is considered a critical issue to address. In conclusion, speculations on outlook are suggested.The National Research Foundation of South Africa.https://www.mdpi.com/journal/sustainabilityChemical 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

Evaluation of adsorption and kinetics of neem leaf powder (Azadirachta indica) as a bio-sorbent for desulfurization of dibenzothiophene (DBT) from synthetic diesel

The need for a sustainable environment has necessitated the development of a green adsorbent that is efficient, cheap, and readily available to serve as an alternative adsorbent for the removal of the refractory sulfur-containing compound from diesel. In this current study, neem-leaf powder (NLP) was activated using H2SO4 and tested in desulfurization adsorption experiments of synthetic diesel containing Dibenzothiopene (DBT) during a batch operation. The synthetic diesel contained 0.1 g of DBT in 100 mL of hexane. Before testing, physio-chemical characteristics of the adsorbent were checked via Fourier transmission infrared (FTIR) spectroscopy for surface chemistry; via N2 physisorption at 77 K for textural properties; SEM quipped with EDX for morphology and elemental composition; and XRD for purity and crystallinity. The results showed that the physico-chemical nature of the adsorbent played a significant role in enhancing the adsorption capacity of the material for DBT. Activated NLP displayed DBT removal of 65.78% at 30 °C using 0.8 g of the adsorbent. Furthermore, the behaviour of the adsorbent during the adsorption could be adequately described using the Freundlich isotherm model. Pseudo-first-order and pseudo-second-order kinetics model describe well the adsorption kinetics of DBT onto the activated NLP.L’Oréal-UNESCO foundation for Women in Science, Sub-Saharan African Fellowship.https://www.sciencedirect.com/journal/journal-of-saudi-chemical-societyhj2023Chemical Engineerin

Performance evaluation of green adsorbent (neem leaf powder) for desulfurization of petroleum distillate

The release of sulfur-containing compounds during direct combustion of diesel fuel has caused environment issues which require urgent attention. Recently, stringent environmental regulations by the Environmental Protection Agency (EPA) to minimise the total sulfur-containing compounds released into the atmosphere have intensified the research in this area. In this present study, adsorption experiments in batch mode were conducted using an activated green adsorbent (Neem leaves powder) to reduce the amount of dibenzothiophene (DBT) in a synthetic oil. The synthetic oil was prepared by dissolving 0.1 g of dibenzothiophene (DBT) in 100 mL of hexane. Various analytical techniques were used such as; Scanning electron microscopy (SEM) to check the morphological structure of the adsorbent. Nitrogen adsorption and desorption experiments (Brunauer-Emmett-Teller, BET) at 77 K were used to check the surface area, pore size and pore volume of the adsorbent. N2 physio-sorption at 77 K before and after adsorption showed adsorption of DBT molecules onto the surface of the adsorbent after adsorption experiment. The results showed about 65.78 % removal of DBT at temperature of 30o C and adsorbent amount of 0.8 g. Therefore, neem leave powder could be an alternative cheap adsorbent to reduce the concentration of organo-sulfur compound in petroleum distillates. This may offer new perception into the development and application of green materials in sustainable, innovative and effective waste management and abatement of environmental pollution.L’Oréal-UNESCO foundation for Women in Science, Sub-Saharan African Fellowship.http://www.cetjournal.itpm2021Chemical 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

Inactivation of antibiotic-resistant bacteria and antibiotic-resistance genes in wastewater streams: Current challenges and future perspectives

The discovery of antibiotics, which was once regarded as a timely medical intervention now leaves a bitter aftertaste: antimicrobial resistance (AMR), due to the unregulated use of these compounds and the poor management receiving wastewaters before discharge into pristine environments or the recycling of such treated waters. Wastewater treatment plants (WWTPs) have been regarded a central sink for the mostly unmetabolized or partially metabolised antibiotics and is also pivotal to the incidence of antibiotic resistance bacteria (ARBs) and their resistance genes (ARGs), which consistently contribute to the global disease burden and deteriorating prophylaxis. In this regard, we highlighted WWTP-antibiotics consumption-ARBs-ARGs nexus, which might be critical to understanding the epidemiology of AMR and also guide the precise prevention and remediation of such occurrences. We also discovered the unsophistication of conventional WWTPs and treatment techniques for adequate treatment of antibiotics, ARBs and ARGs, due to their lack of compliance with environmental sustainability, then ultimately assessed the prospects of cold atmospheric plasma (CAP). Herein, we observed that CAP technologies not only has the capability to disinfect wastewater polluted with copious amounts of chemicals and biologicals, but also have a potential to augment bioelectricity generation, when integrated into bio electrochemical modules, which future WWTPs should be retrofitted to accommodate. Therefore, further research should be conducted to unveil more of the unknowns, which only a snippet has been highlighted in this study

Potentials of torrefied pine sawdust as a renewable source of fuel for pyro-gasification : Nigerian and South African perspective

Abstract: The impacts of fossil energy on the climate and environment emphasize the need for alternative energy resources. The use of waste wood is one such method to potentially reduce fossil-based energy dependence. However, raw biomass fuel properties are generally poor and unpredictable, thus requiring pretreatment to maximize their energy potentials for an efficient conversion to syngas via pyrogasification. Two species of pine sawdust (PSD) wastes generated in abundance from large-scale timber industries in Nigeria and South Africa were investigated for improvements in their fuel properties after torrefaction. Samples were torrefied under optimum conditions of 300 °C and 45 min. Different analytical procedures show that the higher heating value (HHV), enhancement factor, energy density, and solid yield of the Nigerian PSD exceeded those of their South African counterpart by 2.38, 5.37, 3.49, and 11.15%, respectively. The HHV of the torrefied fuels increased by 57.29 and 37.9% for the Nigerian and South African PSDs, respectively, when compared to the raw fuels. Also investigated were improvements in their H/C and O/C ratios and thermal degradation at varied heating rates