Search Results (12)

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. Full article

This study addresses the environmental and health hazards posed by Pb(II) and iodine, two significant contaminants. The objective was to explore the adsorption of these substances from aqueous solutions using biochar derived from the leaf midribs of the date palm through a slow pyrolysis process. The pyrolysis was conducted in two stages within a vacuum furnace: initially at 300 °C for 1 h followed by overnight cooling, and then at 600 °C with a similar cooling process. The resulting biochar was characterized for its microstructural features and functional groups using scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. It exhibited a porous structure with large numbers of pores (20 to 50 μm in size) and functional groups including O-H, C-H, and C=C, which are integral to its adsorption capabilities. For the adsorption studies, a 100 ppm Pb(II) ion solution was treated with varying amounts of biochar (20, 40, 60, and 80 mg) for 24 h. In parallel, iodine adsorption was tested, with biochar quantities ranging from 0.1 to 0.4 g/50 mL. Both treatments were followed by filtration and analysis using atomic absorption spectroscopy to determine the remaining concentrations of Pb(II) and iodine. The study also explored the effect of varying incubation periods (up to 30 h) on iodine adsorption. The results were significant; 100% adsorption of Pb(II) was achieved with the addition of 60 mg of biochar per 10 mL of solution. In contrast, for iodine, a maximum adsorption of 39.7% was observed with 30 mg or 40 mg of biochar per 50 mL. These findings demonstrate the potential of date palm-derived biochar as an effective and sustainable material for the removal of Pb(II) and iodine from contaminated water, offering valuable insights for environmental remediation strategies. Full article

Heavy metals such as copper, often discharged from industrial processes and agricultural activities, pose significant environmental and health risks due to their toxicity, particularly in the soluble form of Cu (II). This study investigates the effectiveness of biochar produced from date palm leaf midrib waste via a two-step pyrolysis process, as a sustainable and economical adsorbent for removing Cu (II) from aqueous solutions The biochar was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET) surface area analysis. Adsorption experiments were conducted to evaluate the effects of pH, adsorbent dosage, contact time, and initial Cu (II) concentration. The maximum adsorption capacity was observed at pH 6, with a capacity of 70 mg/g. The adsorption data were best described by the pseudo-second-order kinetic model, indicating chemisorption as the primary mechanism. Thermodynamic studies indicated that the adsorption process was spontaneous and exothermic, with a Gibbs free energy change (ΔG) of −1.245 kJ/mol at 25 °C, enthalpy change (ΔH) of −15.71 kJ/mol, and entropy change (ΔS) of 48.36 J/mol·K. Reusability tests demonstrated that the biochar retained over 85% of its initial adsorption capacity after five cycles, with capacities of 60 mg/g in the first cycle, decreasing to 52 mg/g by the fifth cycle. This study highlights the potential of biochar derived from date palm waste as an efficient, sustainable adsorbent for the removal of Cu (II) from wastewater, contributing to both environmental management and waste valorization. Future research should focus on optimizing the biochar production process and exploring its application for the removal of other contaminants. Full article

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. Full article

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. Full article

A rotating biological contactor (RBC) offers a low energy footprint but suffers from performance instability, making it less popular for domestic wastewater treatment. This paper presents a study on an RBC integrated with membrane technology in which membrane filtration was used as a post-treatment step (RBC–ME) to achieve enhanced biological performance. The RBC and RBC–ME systems were operated under different hydraulic retention times (HRTs) of 12, 18, 24, and 48 h, and the effects of HRT on biological performance and effluent filterability were assessed. The results show that RBC–ME demonstrates superior biological performance than the standalone RBC. The RBC–ME bioreactor achieved 87.9 ± 3.2% of chemical oxygen demand (COD), 98.9 ± 1.1% ammonium, 45.2 ± 0.7% total nitrogen (TN), and 97.9 ± 0.1% turbidity removals. A comparison of the HRTs showed that COD and TN removal efficiency was the highest at 48 h, with 92.4 ± 2.4% and 48.6 ± 1.3% removal efficiencies, respectively. The longer HRTs also lead to better RBC effluent filterability. The steady-state permeability increased respectively by 2.4%, 9.5%, and 19.1% at HRTs of 18, 24, and 48 h, compared to 12 h. Our analysis of membrane fouling shows that fouling resistance decreased at higher HRTs. Overall, RBC–ME offered a promising alternative for traditional suspended growth processes with higher microbial activity and enhanced biological performance, which is in line with the requirements of sustainable development and environment-friendly treatment. Full article

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. Full article

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. Full article

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. Full article

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 <0.4 kWh/m³. 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. Full article

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. Full article

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. Full article