Development of a nano-filtration membrane using different linear aliphatic amines and linear cross-linkers for purification of expensive and precious organic solvents
Theseparation, purification, and recovery of precious organic solvents is a huge challenge for many industriesincludingpetroleumandpharmaceuticalcompanies,sincethesecompaniesusehugequantities of organic solvents [1-2]. Natural dissolvable nanofiltration(ON)has atremendous potential for supplantingafewenergy-concentratedcrudepurgingtechniques,similartorefiningandextraction[3-4- 5]. The importance of OSN is obvious from the fact that one cubic meter of methanol requires 1750 MJ of energy for distillation since the process of distillation is comprised of heating, evaporation, and condensation while OSN can purify the same volume of methanol by consuming 3 MJ of energy [6-7]. Additionally, OSN is a useful technology since it is simpler to use than conventional purification and separationmethods.Themembrane'sporestructure,whichinfluencesbothitsselectivityandpermeance, hasasignificantimpactonhowwellthemembranesperform[8-9].Ingeneral,thetrade-offbetweenflux andselectivityaffectsthemembrane'sperformance.Asaresult,themembranes'fluxandpermeabilityare affectedbythetailoringandtuningoftheirporestructure.Therefore,designinganefficientnanofiltration membranes with ideal porosity is highly desirable. Interfacial polymerization (IP) is highly versatile as it provides a freedom of selection of various monomersfortargetingaspecificapplicationsuchasnanofiltrationandreverseosmosisThepotentialfor organicsolventnanofiltration(ON)toreplacevariousenergy-intensivetraditionalpurificationtechniques, suchasdistillationandextraction,isenormous.[8-9].Despitethefactthatmanydifferentmonomershave been successfully used by utilizing IP to create thin film composite nanofiltration TFC-NF membranes, one of the main limitations of such membranes continues to be the poor selection of closely related comparable nanometer sized solutes. Many efforts are still being made to develop potential monomers with the perfect properties for creating membranes that operate excellently [10-11]. Another strategy is also getting more popular in which different porous additives are added to the TFC membrane either at thesupportleveloractivelayerlevel.Theseadditivesincludecarbonorganicframeworks(COFs),metal organic frameworks (MOFs), hyper-cross-linked porous polymers (HCPs), and natural polymers such as chitosan[12-13-14-15]. However,maintainingthecrystallinity ofsuch additives,particularlyMOFsthat lead to crystalline membranes, is extremely difficult while other additions suffer from aggregation and agglomeration that results in membrane flaws that impair the performance of the membranes [16]. Therefore,changingthechemistryofthereacting monomerduringIPcansignificantlyalterthestructure of the resultant active layers of the membranes. The current study was carried out by using linear aliphatic amines 4A-3P and 4A on a crosslinked PAN support. The study was carried out through interfacial polymerization between either 4A-3P and TPC or 4A and TPC on crosslinked PAN. In comparison to the previous studies where cyclic amines such as piperazine or aromatic amines such as meta-phenylenediamine (MPD) are used, we have used linear aliphatic amines 4A and 4A-3P crosslinked with organic phase containing terephthaloyl chloride (TPC) asacross-linker.TheIPreactionwascarriedoutbetweenamineandTPConacrosslinkedPANsupport. The fabricated membrane was extensively characterized by using scanning electron microscope (SEM), ATR-FTIR, water contact angle (WCA), energy dispersive X-ray (EDX) and elemental mapping . The fabricated membrane was used for OSN applications by using dead-end filtration setup.
Observation of volcanic gases with a simple alkaline filter paper method at Sakurajima Volcano in Kagoshima, Japan.
There are many active volcanoes in Kagoshima Prefecture, including Sakurajima Volcano. So, the volcanic disaster prevention is an urgent issue. Also, Hirabayashi of Tokyo Institute of Technology reported that the molar ratio of HCl/SO2 is large during periods of high HCl/SO2 and conversely small during periods of low HCl/SO2 , and that explosions increase one month after the molar ratio of HCl/SO2 increases during periods of no explosions. We decided to determine the composition ratio of volcanic gases (sulfur dioxide, hydrogen chloride, and hydrogen fluoride) emitted from Sakurajima crater in order to understand and predict volcanic activities. Th us, we established a simple collection method for volcanic gases using alkaline filter paper and a quantitative method using a self m ade absorbance photometer so that even high school students could perform the measurement at many points, and we discussed the data from various perspectives. Furthermore, since last year, we have found a correlation between the variation of Cl-/SO2 ratio and the number of eruptions at Sakurajima volcano. Also, a model for the behavior of volcanic gases was developed based on a comparison of the amount of volcanic ash and the number of eruptions.