Recent Progress on Nanomaterial-Based Membranes for Water Treatment

Nanomaterials have emerged as the new future generation materials for high-performance water treatment membranes with potential for solving the worldwide water pollution issue. The incorporation of nanomaterials in membranes increases water permeability, mechanical strength, separation efficiency, and reduces fouling of the membrane. Thus, the nanomaterials pave a new pathway for ultra-fast and extremely selective water purification membranes. Membrane enhancements after the inclusion of many nanomaterials, including nanoparticles (NPs), two-dimensional (2-D) layer materials, nanofibers, nanosheets, and other nanocomposite structural materials, are discussed in this review. Furthermore, the applications of these membranes with nanomaterials in water treatment applications, that are vast in number, are highlighted. The goal is to demonstrate the significance of nanomaterials in the membrane industry for water treatment applications. It was found that nanomaterials and nanotechnology offer great potential for the advancement of sustainable water and wastewater treatment.

Innovative BPPO Anion Exchange Membranes Formulation Using Diffusion Dialysis-Enhanced Acid Regeneration System

Recycling of acid from aqueous waste streams is crucial not only from the environmental point of view but also for maturing the feasible method (diffusion dialysis). Anion exchange membrane (AEM)–based diffusion dialysis process is one of the beneficial ways to recover acid from aqueous waste streams. In this article, the synthesis of a series of brominated poly (2, 6–dimethyl-1, 4–phenylene oxide) (BPPO)-based anion exchange membranes (AEMs) through quaternization with triphenylphosphine (TPP) were reported for acid recovery via diffusion dialysis process. The successful synthesis of the prepared membranes was confirmed by Fourier transform infrared (FTIR) spectroscopy. The as-synthesized anion exchange membranes represented water uptake (W_R) of 44 to 66%, ion exchange capacity of (IEC) of 1.22 to 1.86 mmol/g, and linear swelling ratio (LSR) of 8 to 20%. They exhibited excellent thermal, mechanical, and acid stability. They showed homogeneous morphology. The acid recovery performance of the synthesized AEMs was investigated in a two compartment stack using simulated mixture of HCl and FeCl₂ as feed solution at room temperature. For the synthesized anion exchange membranes TPP–43 to TPP–100, the diffusion dialysis coefficient of acid (U_H⁺) was in the range of 6.7 to 26.3 (10⁻³ m/h) whereas separation factor (S) was in the range of 27 to 49 at 25 °C. Obtained results revealed that diffusion dialysis performance of the synthesized AEMs was higher than the commercial membrane DF–120B (U_H⁺ = 0.004 m/h, S = 24.3) at room temperature. It showed that the prepared AEMs here could be excellent candidates for the diffusion dialysis process.

Experimentally measured methane hydrate phase equilibria and ionic liquids inhibition performance in Qatar's seawater

Qatar has the third-largest natural gas reserves in the world and is the second largest Liquefied natural gas (LNG) exporter in the world. These reserves are mainly located in its offshore North Field where the gas is extracted, transported to the onshore units, and is converted to LNG for international export. The formation of natural gas hydrates in the offshore subsea lines can cause unwanted blockages and hinder the smooth supply of gas supply from offshore to onshore units. In the present work, the formation and dissociation of methane gas hydrates have been studied in the ultra pure water system (UPW), artificial seawater (ASW), and Qatar seawater (QSW) at different conditions (4-10 MPa) using standard rocking cell rig. The naturally occurring seawater was collected from Ras Laffan seacoast located in Doha, Qatar. The seawater sample was examined for elemental analysis (SO₄, Cl, Na, Ca, Mg, K, and Fe) using inductively coupled plasma atomic emission spectroscopy (ICP-AES) technique and its other properties like density, electrical conductivity, and pH were also measured. The experimental results show that the CH₄ pure water HLVE curve is suppressed by about 3 K in Qatar seawater and 2 K in artificial seawater. The hydrate inhibition strength of the Ionic liquids (ILs) salts 3-Ethyl-1-methyl-1H-imidazol-3-ium methane-sulfonate [C₇H₁₄N₂O₃S] and 3-Ethyl-1-methyl-1H-imidazol-3-ium dicyanoazanide [C₈H₁₁N₅] was evaluated in both the ultra pure water and Qatar seawater systems. Their performance was compared with methanol and other ILs salts reported in the literature. The selected ILs exhibited poor hydrate inhibition effect in the ultra pure water systems, but they show a noticeable thermodynamic and kinetic hydrate inhibition effect in the Qatar seawater system. The computational 3D molecular models of ILs and methanol were generated to cognize the plausible hydrate inhibition mechanism in the presence of these inhibitors.

Effect of Membrane Fouling on Fertilizer-Drawn Forward Osmosis Desalination Performance

Fertilizer-drawn forward osmosis (FDFO) has garnered immense attention for its application in the agricultural field and its potential to reuse wastewater sustainably. Membrane fouling, however, remains to be a challenge for the process. This study aims to investigate the influence of membrane fouling on the performance of the FDFO process. Synthetic wastewater (SWW) and multi-component fertilizer (MCF) were used as feed solution (FS) and draw solution (DS) with cellulose triacetate (CTA) forward osmosis (FO) membrane orientation. The performance was evaluated through water flux (WF), percentage recovery and percentage of salt reject. The WF declined from 10.32 LMH (L/m²·h) to 3.30 LMH when ultra-pure water as FS was switched with concentration FS indicating the dependence of the performance on the type of FS used. Accelerated fouling experiments conducted to verify the fouling behavior showed a decline in the water flux from 8.6 LMH to 3.09 LMH with SWW and 13.1 LMH to 3.42 LMH when deionized water was used as FS. The effects of osmotic backwashing and in situ flushing as physical cleaning methods of the foul membrane were studied through water flux and salt recovery percentage. Both cleaning methods yielded a WF close to the baseline. Osmotic backwashing yielded better results by eliminating foulant–foulant and foulant–membrane adhesion. The cleaning methods were able to recover 75% of phosphate and 60% of nitrate salts. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) results validated the effectiveness of the methods for the physical cleaning of foul membranes. This study underlines the importance of the FS used in FDFO and the effectiveness of osmotic backwashing as a cleaning method of FO membranes.

Modeling and simulation of fertilizer drawn forward osmosis process using Aspen Plus-MATLAB model

Although experimental studies on the impact of feed (FS) and draw solutions (DS) on the forward osmosis (FO) applications are reported in literature, systematic mathematical modeling considering the dynamic change in solution properties is lacking. In this study, asymmetric FO membrane simulation model was established using Aspen Plus-MATLAB subroutines algorithm to account for the effect of concentration polarization (CP), types of FS and DS and in their properties on FO performance. The developed model was validated by comparing the simulation with experimental results. The model successfully predict the performance of FO process under wide varieties of operational conditions, FS and DS flow rates and concentrations. The model showed that the variation of MCFDS concentration had a marked effect on water flux (WF) in contrast to flow rate. The WFs obtained from seawater (SW) increased from 5.28 L/m².h to 42.08 L/m².h as MCFDS changes from 150 g/L to 300 g/L which corresponding to 11.66% to 45.33% of water recovery. As for synthetic aquaculture wastewater (SAWW), 9.70 L/m².h to 37.32 L/m².h of WFs were exhibited with the increase of MCFDS concentration from 50 g/L to 200 g/L, respectively. The effect of concentrated external CP (CECP) was found to be significant in case of SW and negligible with SAWW. Whereas, increasing MCFDS concentration increases the severity effect of dilutive internal CP (DICP). The degree of DICP depends on the solute resistivity (K_D) of porous layer, which were elevated (4.22-5.88 s/m) as MCFDS concentration increases (150-300 g/L). The study demonstrated the effectiveness and suitability of the developed Aspen Plus-MATLAB model simulating the FO process.