Effect of Methanol Concentration on the Performance of Asymmetric Cellulose Acetate Reverse Osmosis Membranes Using Dry/Wet Phase Inversion Technique

Asymmetric membranes were prepared from a multicomponent dope polymer so- lution consisting of cellulose acetate, acetone, formamide and methanol. In this work, the dry/wet phase inversion technique is used and the presence of methanol is studied. In addition, this work also presents the fundamental issues involved in altering flat sheet casting solutions to produce solutions, potentially useful for preparing hollow fibers within, defect free selective layers. Varia- tions in the composition of multicomponent casting solution resulted in membranes with drasti- cally different reverse osmosis performance. The membrane performance are determined experi- mentally by primary parameters such as the pure water permeation rate (PWP), salt permeation rate (PR) and rejection rates. From these data, the secondary parameters such as pure water permeability constant (A), solute transport parameter (DAM/Kδ) and mass transfer coefficient (k) are determined. These parameters are important in the prediction of reverse osmosis performance and also in characterising membrane morphology. The results revealed that the presence of methanol in the dope formulation increases the percentage of salt rejection and flux flow. The relatively lower value of (DAM/Kδ) for a reference solute indicates a relatively smaller average pore size on the membrane surface. .. .. Membran asimetrik telah dihasilkan daripada larutan polimer multikomponen yang terdiri daripada selulosa asetat, aseton, formamid dan metanol. Dalam kajian ini, teknik fasa balikan kering/basah telah digunakan dan kehadiran metanol dikaji. Selain daripada itu, kajian ini juga mengemukakan isu asas yang terlibat dalam pengubahsuaian larutan tuangan kepingan rata, bagi menghasilkan larutan yang berpotensi untuk digunakan bagi penyediaan membran gentian geronggang, yang mempunyai lapisan memilih yang bebas daripada kecacatan. Pengubahsuaian komposisi larutan multikomponen telah menghasilkan membran osmosis balikan yang berbeza prestasinya. Prestasi membran ditentukan secara uji kaji oleh pemboleh ubah asas seperti fluks air tulen (PWP), kadar kebolehtelapan air garam (PR) dan kadar buangan. Daripada data tersebut, parameter sekunder seperti pemalar kebolehtelapan air tulen (A), parameter pengangkutan bahan larut (DAM/Kδ) dan pekali pemindahan jisim (k) dapat ditentukan. Parameter tersebut adalah penting dalam meramal prestasi membran osmosis balikan dan pencirian morfologi membran. Keputusan uji kaji menunjukkan bahawa kehadiran metanol dalam formulasi larutan polimer