Search

Industrial sectors, pivotal for the economic prosperity of nations, rely heavily on affordable, reliable, and environmentally friendly energy sources. Industries like iron and steel, oil refineries, and coal-fired power plants, while instrumental to national economies, are also the most significant contributors to waste gases that contain substantial volumes of carbon monoxide (CO). CO can be converted to a highly efficient and carbon free fuel, hydrogen (H2) through a well-known water gas shift reaction. However, the untapped potential of H2 from waste industrial streams is yet to be explored. This is the first article that investigates the potential of H2 production from industrial waste gases. The available resource (i.e., CO) and its H2 production potential are estimated. The article also provides insights into the principal challenges and potential avenues for long-term adoption. The results showed that 249.14 MTPY of CO are available to produce 17.44 MTPY of H2 annually. This suggests a significant potential for H2 production from waste gases to revolutionize industrial waste management and contribute significantly towards Sustainable Development Goals 7, 9, and 13ensuring access to affordable, reliable, sustainable, and modern energy for all and taking decisive climate action, respectively.

In this study, mixed-matrix membranes (MMMs) were fabricated using a composite of UiO-66 and polyaniline (PANI) integrated into a polyether-block-amide (PEBAX) matrix. The successful synthesis of the UiO-66 and PANI@UiO-66 composites and their incorporation into the PEBAX matrix were validated through X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, Brunauer–Emmett–Teller (BET) analysis, and Thermogravimetric Analysis (TGA). Quantitative permeation tests revealed that the CO2 permeability in UiO-66 based MMMs increased by 90 % at 30 % filler loading (from 82 to 156 Barrer), and by 45 % (from 82 to 119 Barrer) in PANI@UiO-66 based MMMs, alongside substantial improvements in selectivity. For UiO-66 membranes we observed a selectivity drop for both gas pairs (CO2/CH4 and CO2/N2) that led to our motivation to modify the MOF. The CO2/CH4 selectivity of the PANI@UiO-66 based MMMs enhanced from 22 to 29 (34%) and the CO2/N2 selectivity from 48 to 57 (18%). Mixed-gas permeation tests further confirmed the efficacy of the membranes in real-world separation scenarios. The diffusivity and solubility results provide insights into the gas transport mechanisms, revealing the synergistic effects of filler incorporation on membrane performance. The integration of UiO-66 and PANI with PEBAX offers a promising pathway for developing efficient and effective gas separation technologies, aligning with the industrial requirements for environmental sustainability and energy efficiency.

This study provides a comprehensive analysis of the ash content resulting from the combustion of heavy fuel oil (HFO) at the Assiut Thermal Power Plant in Egypt, with a specific focus on the enrichment of trace metals and their environmental implications. We meticulously quantified the concentrations of Na, K, Mg, Fe, Ca, and Al in both HFO and the resultant ash. The calculated pollution indices, such as the Single Element Pollution Index (SEPI), Combined Pollution Index (CPI), and Pollution Load Index (PLI), reveal the severe environmental impact. The SEPI values for metals in ash ranged from 384.62 for Al to 34,000 for K, indicating a high contamination level. The CPI was 12,373.4, signifying a severe metal accumulation, while the PLI was 655.1, reflecting a significant pollution load. These findings underscore the urgent need for immediate and effective pollution control measures and sustainable waste management practices. The results provide a foundation for future research on advanced pollution control technologies and the long-term environmental impacts of trace metal accumulation, contributing to the development of improved environmental management strategies.

This study explores the adsorption efficiency of biochar derived from palm trees and Ficus nitida for the removal of various contaminants, including Cu(II), Pb(II), iodine, and chlorpyrifos from aqueous solutions. Biochar was prepared using a two-step pyrolysis process for date palm biochar and single-step pyrolysis for Ficus nitida biochar. Characterization techniques such as SEM, EDX, and FTIR revealed a significant surface area and a variety of functional groups in both types of biochar, essential for effective adsorption. The date palm biochar exhibited superior adsorption capacities for Cu(II) and Pb(II) ions, achieving efficiencies up to 99.9% and 100%, respectively, due to its high content of oxygen-containing functional groups that facilitated strong complexation and ion exchange mechanisms. Conversely, Ficus nitida biochar demonstrated a higher adsorption capacity for iodine, reaching 68% adsorption compared to 39.7% for date palm biochar, owing to its greater surface area and microporosity. In the case of chlorpyrifos, Ficus nitida biochar again outperformed date palm biochar, achieving a maximum adsorption efficiency of 87% after 24 h of incubation, compared to 50.8% for date palm biochar. The study also examines the effect of incubation time on adsorption efficiency, showing that the adsorption of chlorpyrifos by date palm biochar increased significantly with time, reaching a maximum of 62.9% after 48 h, with no further improvement beyond 12 h. These results highlight the importance of biochar characteristics, such as surface area, pore structure, and functional groups, in determining adsorption efficiency. The findings suggest that optimizing pyrolysis conditions and surface modifications could further enhance the performance of biochar as a cost-effective and sustainable solution for water purification and environmental remediation.

Water pollution remains a critical concern, one necessitated by rapidly increasing industrialization and urbanization. Among the various strategies for water purification, membrane technology stands out, with polyethersulfone (PES) often being the material of choice due to its robust mechanical properties, thermal stability, and chemical resistance. However, PES-based membranes tend to exhibit low hydrophilicity, leading to reduced flux and poor anti-fouling performance. This study addresses these limitations by incorporating titanium dioxide nanotubes (TiO2NTs) into PES nanofiltration membranes to enhance their hydrophilic properties. The TiO2NTs, characterized through FTIR, XRD, BET, and SEM, were embedded in PES at varying concentrations using a non-solvent induced phase inversion (NIPS) method. The fabricated mixed matrix membranes (MMMs) were subjected to testing for water permeability and solute rejection capabilities. Remarkably, membranes with a 1 wt% TiO2NT loading displayed a significant increase in pure water flux, from 36 to 72 L m2 h−1 bar−1, a 300-fold increase in selectivity compared to the pristine sample, and a dye rejection of 99%. Furthermore, long-term stability tests showed only a slight reduction in permeate flux over a time of 36 h, while dye removal efficiency was maintained, thus confirming the membrane’s stability. Anti-fouling tests revealed a 93% flux recovery ratio, indicating excellent resistance to fouling. These results suggest that the inclusion of TiO2 NTs offers a promising avenue for the development of efficient and stable anti-fouling PES-based membranes for water purification.

Membrane fouling is a major bottleneck of almost all pressure-driven membrane filtration processes that limits their widespread applications. Improvement of hydrodynamics conditions is one of the most effective methods for membrane fouling control. This paper assesses a rotating biological contactor (RBC) integrated with membrane (RBC-MI) filtration that potentially offers inherent membrane fouling control as well as enhances biological performance, in which the membrane is placed inside the RBC bioreactor. Results show that the RBC-MI system achieves 84% of COD, 96.7% ammonium, 74% total nitrogen, 89% total phosphorus, and 96% turbidity removals. The integration of membrane placed inside the bioreactor doubles the permeability as compared to the external placement. Higher hydraulic performance is achieved at the low membrane-to-disk gap and higher disk rotational speed. The energy analysis shows that the RBC-MI consumes only 0.18 kWhm−3 signifying its viability as promission option to the energy-intensive conventional treatment systems.

A new generation of solvents called ternary deep eutectic solvents have emerged as a promising candidate to replace ionic liquids (IL) in CO2 capturing due to its inherent advantages of both, superbase and deep eutectic solvents (DES). In this work, the binary and ternary DES were synthesized to investigate the effect of superbase on the performance of DES based membrane systems for acid gas capture. The reline DES system was chosen as binary DES and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was used as superbase. The ternary DES was prepared by mixing DBU in reline DES system in different molar ratios. The permeability and selectivity of the synthesized membrane for CO2, CH4, and N2 were investigated in pure and mixed gas experiments. Moreover, the effect of the DES molar ratio, operating conditions of feed on the DES based supported liquid membranes (SLMs) performance was studied comprehensively. These novel ternary DES SLMs showed significant permeability and selectivity values up to 38.12 Barrer and 58.65 respectively. These values were found to be significantly higher than the permeability and selectivity value of binary DES-SLM i.e. 31 Barrer and 51.67 respectively. The improved gas performance results of ternary DES can be attributed to the basicity and fast reaction kinetics of the superbase/DBU. The ternary DES can potentially alternate the ILs and commonly used binary DESs in CO2 capturing process due to their high affinity towards CO2 gas.

Mixed Matrix Membranes (MMM) with enhanced selectivity and permeability are preferred for gas separations. The porous metal-organic frameworks (MOFs) materials incorporated in them play a crucial part in improving the performance of MMM. In this study, Zeolitic imidazolate frameworks (ZIF-90) are selected to fabricate Polyetherimide (PEI) MMMs owing to their lucrative structural and chemical properties. This work reports new controlled post-synthetic modifications of ZIF-90 (50-PSM-ZIF-90) with ethanolamine to control the diffusion and uptake of CO2. Physical and chemical properties of ZIF-90, such as stability and presence of aldehyde functionality in the imidazolate linker, allow for easy modulation of the ZIF-90 pores and window size to tune the gas transport properties across ZIF-90-based membranes. Effects of these materials were investigated on the performance of MMMs and compared with pure PEI membranes. Performance of the MMMs was evaluated in terms of permeability of different gases and selective separation of CO2 and H2 gas. Results presented that the permeability of all membranes was in the following order, i.e., P(H2) > P(CO2) > P(O2) > P(CH4) > P(C2H6) > P(C3H8) > P(N2), demonstrating that kinetic gas diffusion is the predominant gas transport mode in these membranes. Among all the membranes, permeability of pure PEI membrane was highest for all gases due to the uniform porous morphology. The pure PEI membrane showed highest permeability of H2, which is 486.5 Barrer, followed by 49 Barrer for O2, 29 Barrer for N2, 142 Barrer for CO2, 41 Barrer for CH4, 40 Barrer for C2H6 and 39.6 Barrer for C3H8. Results also confirm the superiority of controlled PSM-ZIF-90-PEI membrane over the pure PEI and ZIF-90-PEI membranes in CO2 and H2 separation performance. The 50-PSM-ZIF-90 PEI membrane exhibited a 20% increase in CO2 separation from methane and a 26% increase over nitrogen compared to the ZIF-90-PEI membrane. The 50-PSM-ZIF-90 PEI membrane showed 15% more H2/O2 separation and 9% more H2/CH4 separation than ZIF-90 PEI membrane. Overall, this study represents the role of controlled PSM in enhancing the property of new materials like ZIF and its application in MMMs fabrication to develop a promising approach for the CO2 capture and separation.

Microalgae-based products have gained growing interest leading to an increase in large-scale cultivation. However, the high energy associated with microalgae harvesting becomes one of the bottlenecks. This study evaluated an energy-efficient microalga harvesting via ultra-low-pressure membrane (ULPM) filtration (

The poly deep eutectic solvents (PDESs), a potential substituent to ionic liquids, have emerged as relatively new material and have been successfully applied in catalysis, nanotechnology, and, more importantly, in gas separation. Herein, the PDESs were incorporated for the first time in the CO2 capturing membranes to exploit their inherent advantages in the acid gas capture. The PDESs were synthesized by mixing choline chloride (hydrogen bond acceptor-HBA) and two hydrogen bond donors-HBDs (polyacrylic acid and polyacrylamide) separately in different molar ratios. The physical changes of the resulting homogeneous mixture along with the Fourier Transform Infrared confirmed the successful synthesis of the PDESs. Afterward, these PDESs were impregnated into microporous polyvinylidene fluoride (PVDF) membrane support to fabricate supported liquid membranes (SLMs). The gas performance of the prepared PDES-SLMs was tested under pure and mixed-gas conditions for CO2, CH4, and N2. The PDES-SLMs showed a significantly high CO2/CH4 and CO2/N2 selectivities of the order of 55.5 and 60, respectively. To evaluate their practical implication, the SLMs were investigated systematically under different operating conditions such as choline content, temperature, volume fraction of the CO2 in the feed, and the activation energy required for CO2 capture. The synthesized SLMs showed exceptional results in both permeability and selectivity viewpoint. The remarkable SLMs gas performance can be ascribed to the basicity, molar free volume, and the H-bonding strength of the synthesized PDESs. The green potential, low cost, and the promising gas separation performance make theses PDESs a favorable alternative to the competing PILs in capturing the greenhouse acid gases.

In this study, the polyether sulfone (PES) based membranes containing various concentrations of graphene oxide (GO), polyvinylpyrrolidone (PVP), and polyethylene glycol (PEG) were synthesized via the phase immersion method. This study aims to evaluate the effect of GO addition on the structural properties and performance of the membranes. The membranes were analyzed by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared spectroscopy (FTIR). The FTIR-ATR spectra indicated the presence of hydroxyl and carboxylic acid groups on the surface of GO-incorporated membranes, which improved their dispersion in the polymeric matrix and hydrophilicity. The SEM analysis of the GO-containing PES membranes confirmed the formation of a well-defined finger-like porous structure presenting adequate water flux (95 l.m ^–2 .h ^–1 ) and salt rejection (72%) compared to the pristine PES membranes (46 l.m ^–2 .h ^–1 and ∼35%, respectively). In addition, the significantly large wettability and considerably improved antibacterial characteristic (against S. aureus and E. coli strains ) of the GO-PES membranes are considered impressive features.

Covalent organic frameworks (COFs) are emerging crystalline polymeric materials with highly ordered intrinsic and uniform pores. Their synthesis involves reticular chemistry, which offers the freedom of choosing building precursors from a large bank with distinct geometries and functionalities. The pore sizes of COFs, as well as their geometry and functionalities, can be pre-designed, giving them an immense opportunity in various fields. In this mini-review, we will focus on the use of COFs in the removal of environmentally hazardous metal ions and chemicals through adsorption and separation. The review will introduce basic aspects of COFs and their advantages over other purification materials. Various fabrication strategies of COFs will be introduced in relation to the separation field. Finally, the challenges of COFs and their future perspectives in this field will be briefly outlined.

High-performance Mixed-Matrix Membranes (MMMs) comprising of two kinds of porous fillers UiO-66 and Zeolite 4Aand their combination were fabricated with polysulfone (PSf) polymer matrix. For the very first time, UiO-66 and Zeolite 4A were jointly used as nanofillers in MMMs with the objective of complimenting synergistic effects. The individual and complimentary effects of nanofillers were investigated on membrane morphology and performance, pure water flux, humic acid rejection, static humic acid adsorption, and antifouling properties of membranes. Scanning Electron Microscopy (SEM) analysis of membranes confirmed that all MMMs possessed wider macrovoids with higher nanofiller loadings than neat PSf membranes and the MMMs (PSf/UiO-66 and PSf/Zeolite 4A-UiO-66) showed tendency of agglomeration with high nanofiller loadings (1 wt% and 2 wt%). All MMMs exhibited better hydrophilicity and lower static humic acid adsorption than neat PSf membranes. Pure water flux of MMMs was higher than neat PSf membranes but the tradeoff between permeability and selectivity was witnessed in the MMMs with single nanofiller. However, MMMs with combined nanofillers (PSf/Zeolite 4A-UiO-66) showed no such tradeoff, and an increase in both permeability and selectivity was achieved. All MMMs with lower nanofiller loadings (0.5 wt% and 1 wt%) showed improved flux recovery. PSf/Zeolite 4A-UiO-66 (0.5 wt%) membranes showed the superior antifouling properties without sacrificing permeability and selectivity.

During the production of oil and gas, a large amount of oily wastewater is generated, which would pollute the environment if discharged without proper treatment. As one of the most promising treatment options, membrane material used for oily wastewater treatment should possess desirable properties of high hydraulic performance combined with high membrane fouling resistance. This project employs the vapor induced phase separation (VIPS) technique to develop a hydrophilic polyvinylidene fluoride (PVDF) membrane with polyethylene glycol (PEG) as an additive for produced water treatment. Results show that thanks to its slow nonsolvent intake, the VIPS method hinders additive leaching during the cast film immersion. The results also reveal that the exposure of the film to the open air before immersion greatly influences the structure of the developed membranes. By extending the exposure time from 0 to 30 min, the membrane morphology change from typical asymmetric with large macrovoids to the macrovoid-free porous symmetric membrane with a granular structure, which corresponds to 35% increment of steady-state permeability to 189 L·m−2h−1bar−1, while maintaining >90% of oil rejection. It was also found that more PEG content resides in the membrane matrix when the exposure time is extended, contributes to the elevation of surface hydrophilicity, which improves the membrane antifouling properties. Overall results demonstrate the potential of VIPS method for the fabrication of hydrophilic PVDF membrane by helping to preserve hydrophilic additive in the membrane matrices.

A membrane bioreactor enhances the overall biological performance of a conventional activated sludge system for wastewater treatment by producing high-quality effluent suitable for reuse. However, membrane fouling hinders the widespread application of membrane bioreactors by reducing the hydraulic performance, shortening membrane lifespan, and increasing the operational costs for membrane fouling management. This study assesses the combined effect of membrane surface corrugation and a tilted panel in enhancing the impact of air bubbling for membrane fouling control in activated sludge filtration, applicable for membrane bioreactors. The filterability performance of such a system was further tested under variable parameters: Filtration cycle, aeration rate, and intermittent aeration. Results show that a combination of surface corrugation and panel tilting enhances the impact of aeration and leads to 87% permeance increment. The results of the parametric study shows that the highest permeance was achieved under short filtration−relaxation cycle of 5 min, high aeration rate of 1.5 L/min, and short switching period of 2.5 min, to yield the permeances of 465 ± 18, 447 ± 2, and 369 ± 9 L/(m2h bar), respectively. The high permeances lead to higher operational flux that helps to lower the membrane area as well as energy consumption. Initial estimation of the fully aerated system yields the energy input of 0.152 kWh/m3, much lower than data from the full-scale references of 3. Further energy savings and a lower system footprint can still be achieved by applying the two-sided panel with a switching system, which will be addressed in the future.

Flue gas contains high amount of low-grade heat and water vapor that are attractive for recovery. This study assesses performance of a hybrid of water scrubber and membrane distillation (MD) to recover both heat and water from a simulated flue gas. The former help to condense the water vapor to form a hot liquid flow which later used as the feed for the MD unit. The system simultaneously recovers water and heat through the MD permeate. Results show that the system performance is dictated by the MD performance since most heat and water can be recovered by the scrubber unit. The scrubber achieved nearly complete water and heat recovery because the flue gas flows were supersaturated with steam condensed in the water scrubber unit. The recovered water and heat in the scrubber contains in the hot liquid used as the feed for the MD unit. The MD performance is affected by both the temperature and the flow rate of the flue gas. The MD fluxes increases at higher flue gas temperatures and higher flow rates because of higher enthalpy of the flue gas inputs. The maximum obtained water and heat fluxes of 12 kg m−2 h−1 and 2505 kJm−2 h−1 respectively, obtained at flue gas temperature of 99 °C and at flow rate of 5.56 L min−1. The MD flux was also found stable over the testing period at this optimum condition. Further study on assessing a more realistic flue gas composition is required to capture complexity of the process, particularly to address the impacts of particulates and acid gases.

The present work is focused on preparation, characterization, and antibacterial activity evaluation of graphene oxide/polyethersulfone mixed matrix filtration membranes. Graphene oxide (GO) was synthesized via improved Hummer’s method and characterized by XRD, FTIR, and SEM. FT-IR spectra showed the presence of carboxylic acid and hydroxyl groups on GO nanosheets. Different concentrations of the synthesized GO at 0.25, 0.5, and 1.0 wt. % were incorporated in polyethersulfone (PES) matrix via phase inversion method to fabricate GO-PES membranes. Increasing porosity and formation of wider, finger-like channels were observed with increased GO concentrations relative to pristine membranes as evident from scanning electron microscopy (SEM) micrographs of the fabricated membranes. However, membranes prepared with 1 wt. % GO appear to contain aggregation and narrowing of pore morphology. GO-incorporated membranes demonstrated enhanced flux, water-retaining capacities, and wettability as compared to pristine PES membranes. Shake flask and colony counting methods were employed to carry out antibacterial testing of synthesized GO and fabricated GO-PES membranes against Salmonella typhi (S. typhi)—a gram-negative bacteria present in water that is known as causative agent of typhoid. Synthesized GO showed significant reduction up to 70.8% in S. typhi cell count. In the case of fabricated membranes, variable concentrations of GO are observed to significantly influence the percentage viability of S. typhi, with reduction percentages observed at 41, 60, and 69% for 0.25, 0.5, and 1.0 wt. % GO-incorporated membranes relative to 17% in the case of pristine PES membranes. The results indicate a good potential for applying GO/PES composite membranes for water filtration application.

Membrane fouling is seen as the main culprit that hinders the widespread of membrane application in liquid-based filtration. Therefore, fouling management is key for the successful implementation of membrane processes, and it is done across all magnitudes. For optimum operation, membrane developments and surface modifications have largely been reported, including membrane surface patterning. Membrane surface patterning involves structural modification of the membrane surface to induce secondary flow due to eddies, which mitigate foulant agglomeration and increase the effective surface area for improved permeance and antifouling properties. This paper reviews surface patterning approaches used for fouling mitigation in water and wastewater treatments. The focus is given on the pattern formation methods and their effect on overall process performances.