Applications Of Osmosis Research Articles

Mass Transport through Composite Asymmetric Membranes

In recent years, membrane separation technology has emerged as efficient and promising separation process from laboratory scale applications to wide range of technical industrial applications. The development of composite asymmetric membrane is a major breakthrough in membrane research field, as this membrane offers significantly high selectivity without affecting the mechanical durability of the membranes. In this chapter, structural characteristics and different fabrication techniques of composite membranes are reviewed. Moreover the mass transfer mechanism through the composite asymmetric membrane is described in details following solution-diffusion theory, Knudsen diffusion, and series resistance model. Composite membranes are preferred over others because of the high flux and enhanced selectivity without disturbing the mechanical stability of the membranes. These membranes are now widely employed in the applications of reverse osmosis (RO), nanofiltration (NF), pervaporation, gas separation, hydrocarbon fractionations, etc. As composite asymmetric membranes are “tailor-made” in nature, membrane characteristics can be tuned accordingly depending on their end use. Therefore plentiful research opportunities still exist to elevate their performance ability in terms of stability, selectivity and fouling resistance, which will in turn augment its application domain.

Osmosis, from molecular insights to large-scale applications.

Osmosis is a universal phenomenon occurring in a broad variety of processes and fields. It is the archetype of entropic forces, both trivial in its fundamental expression - the van 't Hoff perfect gas law - and highly subtle in its physical roots. While osmosis is intimately linked with transport across membranes, it also manifests itself as an interfacial transport phenomenon: the so-called diffusio-osmosis and -phoresis, whose consequences are presently actively explored for example for the manipulation of colloidal suspensions or the development of active colloidal swimmers. Here we give a global and unifying view of the phenomenon of osmosis and its consequences with a multi-disciplinary perspective. Pushing the fundamental understanding of osmosis allows one to propose new perspectives for different fields and we highlight a number of examples along these lines, for example introducing the concepts of osmotic diodes, active separation and far from equilibrium osmosis, raising in turn fundamental questions in the thermodynamics of separation. The applications of osmosis are also obviously considerable and span very diverse fields. Here we discuss a selection of phenomena and applications where osmosis shows great promises: osmotic phenomena in membrane science (with recent developments in separation, desalination, reverse osmosis for water purification thanks in particular to the emergence of new nanomaterials); applications in biology and health (in particular discussing the kidney filtration process); osmosis and energy harvesting (in particular, osmotic power and blue energy as well as capacitive mixing); applications in detergency and cleaning, as well as for oil recovery in porous media.

EFFECT OF PIPERAZINE (PIP) CONCENTRATION AND REACTION TIME ON THE FORMATION OF THIN FILM COMPOSITE FORWARD OSMOSIS (FO) MEMBRANE

Nowadays, wide applications of forward osmosis (FO) technology have been huge attention in solving the water shortage problems. Hence, the performance of thin film composite (TFC) forward osmosis membrane via interfacial polymerization (IP) was studied. 2% and 1% w/v of piperazine (PIP) and 0.15% w/v of trimesoyl chloride (TMC) were reacted with 3 different reaction time (60s, 30s, and 10s). The fabricated membranes were then characterized by FTIR, contact angle measurement and FESEM. Pure water flux, humic acid rejection (represent NOM) and salt leakage were evaluated to obtain the best polyamide FO membrane. The results demonstrated that polyamide FO membranes fabricated with 2% w/v possess a higher hydrophilic properties compared to 1% w/v. In addition, regardless of monomer concentrations, at longest reaction time (60s), there is no significant change in water flux. Membrane fabricated at 60s of reaction time exhibited water flux of 1.90 LMH and 1.92 LMH for 2% w/v and 1% w/v of PIP concentrations, respectively. The same trend also observed for humic acid rejection (93.9%-94.6%). The salt leakage test revealed that the minimum salt reverse diffusion (0.01-0.02 GMH) could be achieved for membrane fabricated at longest reaction time of 60s for both PIP concentrations. As conclusion, manipulating monomer concentrations and reaction time is the main key to obtain an optimal polyamide layer with high membrane performance covering higher water flux, higher removal of humic acid and lower reverse salt diffusion.

Molecular Understanding of Osmosis in Semipermeable Membranes

We investigate single-file osmosis of water through a semipermeable membrane with an uncharged, a positively and a negatively charged nanopore. Molecular dynamics simulations indicate that the osmotic flux through a negatively charged pore (J_) is higher compared to the osmotic flux in a positively charged pore (J+) followed by the osmotic flux in the uncharged pore (J(0)), i.e., J_ > J+ > J(0). The molecular mechanisms governing osmosis, steady state osmosis, and the observed osmotic flux dependence on the nanopore charge are explained by computing all the molecular interactions involved and identifying the molecular interactions that play an important role during and after osmosis. This study helps in a fundamental understanding of osmosis and in the design of advanced nanoporous membranes for various applications of osmosis.