Noor Ul Afsar

Electrodialysis Metathesis (EDM) desalination was investigated using a squad of three ion-exchange membranes (ACS, TW-A, and A3) and simulated tobacco extract liquid for selective ions removal. We have studied various factors affecting EDM desalination efficiency using a complete experimental design. First, diffusion dialysis (DD) was conducted to determine the permeation rate of different anions in tobacco liquor with different membrane materials. We conclude that A3 had the fastest permeation rate of anions. However, ACS has the lowest permeation rate for different salts. The investigation of the EDM process showed the excellent ion permeation ability of A3 by detecting the current, conductivity, and ion concentration of the target tobacco liquor in the metathesis chamber of the EDM process. The EDM had shown the most excellent chloride ion removal ability. We found that A3 was the best membrane for the EDM process of tobacco liquor.

Poly(alkyl-biphenyl pyridinium)-based anion exchange membranes with alkyl side chains were synthesized for permselective anion separation. By altering the length of the grafted side chain, the hydrophilicity and other attributes of the membranes could be controlled. The QDPAB-C5 membrane with the best comprehensive performance exhibited a Cl⁻ ion flux of 3.72 mol m⁻² h⁻¹ and a Cl⁻/SO₄²⁻ permselectivity of 15, which are significantly better than the commercial Neosepta ACS membrane. The QDPAB-C5 membranes with distinct microscopic phase separation structures formed interconnected hydrophilic/hydrophobic ion channels and exhibited excellent ion flux and permselectivity for other anionic systems (NO₃⁻/SO₄²⁻, Br⁻/SO₄²⁻, F⁻/SO₄²⁻, NO₃⁻/Cl⁻, Br⁻/Cl⁻, and F⁻/Cl⁻) as well. Furthermore, the influence of alkyl side chain length on the membranes’ ion flux and permselectivity in electrodialysis was investigated, which may be attributed to the alterations in ion channels and hydrophobic regions of the membranes. This work provides an effective strategy for the development of monovalent anion permselective membranes.

Every metal and metallurgical industry is associated with the generation of wastewater, influencing the living and non-living environment, which is alarming to environmentalists. The strict regulations about the dismissal of acid and metal into the environment and the increasing emphasis on the recycling/reuse of these effluents after proper remedy have focused the research community’s curiosity in developing distinctive approaches for the recovery of acid and metals from industrial wastewaters. This study reports the synthesis of UiO-66-(COOH)₂ using dual ligand in water as a green solvent. Then, the prepared MOF nanoparticles were introduced into the DMAM quaternized QPPO matrix through a straightforward blending approach. Four defect-free UiO-66-(COOH)₂/QPPO MMMs were prepared with four different MOF structures. The BET characterization of UiO-66-(COOH)₂ nanoparticles with a highly crystalline structure and sub-nanometer pore size (~7 Å) was confirmed by XRD. Because of the introduction of MOF nanoparticles with an electrostatic interaction and pore size screening effect, a separation coefficient (S_HCl/FeCl2) of 565 and U_HCl of 0.0089 m·h⁻¹ for U-C(60)/QPPO were perceived when the loading dosage of the MOF content was 10 wt%. The obtained results showed that the prepared defect-free MOF membrane has broad prospects in acid recovery applications.

Many tobacco stalks, dust, and fines are discharged in the tobacco industry, rich in inorganic minerals ions and nicotine salts. The high salinity and nicotine salts are challenging to be addressed by traditional treatment and are a severe threat that ought to be overcome. Thus, proper techniques can regenerate the tobacco stalks into reconstituted tobacco flakes used as cigarette filler. The electrodialysis process has been a viable approach to removing the inorganic ingredients in wastewater. We studied concentration, pH, and co-related influences with the nicotine and sugar/nicotine contents on the desalination performance. The results show that the inorganic ions such as Cl⁻, K⁺, Ca²⁺, and Mg²⁺ ions were successfully removed. When the feed concentration ranges from 3 to 15%, the removal ratio of the K⁺ ions is higher than Ca²⁺ and Mg²⁺ ions. As we reported previously, the K⁺ and Ca²⁺ ions are unfavorable for the total particulate matter emission but beneficial to decreasing the HCN delivery in mainstream cigarette smoke. Selective ED is a robust technology to reduce the harmful component delivery in cigarette smoke.

The traditional ion-exchange membranes face the trade-off effect between the ion flux and perm-selectivity, which limits their application for selective ion separation. Herein, we amalgamated various amounts of the ZSM-5 with the polyvinyl alcohol as ions transport pathways to improve the permeability of monovalent cations and exclusively reject the divalent cations. The highest contents of ZSM-5 in the mixed matrix membranes (MMMs) can be extended up to 60 wt% while the MMMs with optimized content (50 wt%) achieved high perm-selectivity of 34.4 and 3.7 for H⁺/Zn²⁺ and Li⁺/Mg²⁺ systems, respectively. The obtained results are high in comparison with the commercial CSO membrane. The presence of cationic exchange sites in the ZSM-5 initiated the fast transport of proton, while the microporous crystalline morphology restricted the active transport of larger hydrated cations from the solutions. Moreover, the participating sites and porosity of ZSM-5 granted continuous channels for ions electromigration in order to give high limiting current density to the MMMs. The SEM analysis further exhibited that using ZSM-5 as conventional fillers, gave a uniform and homogenous formation to the membranes. However, the optimized amount of fillers and the assortment of a proper dispersion phase are two critical aspects and must be considered to avoid defects and agglomeration of these enhancers during the formation of membranes.