Seawater Desalination by Modified Membrane Distillation: Effect of Hydrophilic Surface Modifying Macromolecules Addition into PVDF Hollow Fiber Membrane.

Mochammad Purwanto,Juhana Jaafar,Nindita Cahya Kusuma,Yanuardi Raharjo,Atikah Mohd Nasir,Ma'Rup Ali Sudrajat,Mohd Hafiz Dzarfan Othman,Mukhlis A Rahman,Nurul Widiastuti,Mohd Haiqal Abd Aziz

doi:10.3390/membranes11120924

Abstract

Hollow fiber membranes of polyvinylidene fluoride (PVDF) were prepared by incorporating varying concentrations of hydrophilic surface-modifying macromolecules (LSMM) and a constant amount of polyethylene glycol (PEG) additives. The membranes were fabricated by the dry-wet spinning technique. The prepared hollow fiber membranes were dip-coated by hydrophobic surface-modifying macromolecules (BSMM) as the final step fabrication. The additives combination is aimed to produce hollow fiber membranes with high flux permeation and high salt rejection in the matter of seawater desalination application. This study prepares hollow fiber membranes from the formulation of 18 wt. % of PVDF mixed with 5 wt. % of PEG and 3, 4, and 5 wt. % of LSMM. The membranes are then dip-coated with 1 wt. % of BSMM. The effect of LSMM loading on hydrophobicity, morphology, average pore size, surface porosity, and membrane performance is investigated. Coating modification on LSMM membranes showed an increase in contact angle up to 57% of pure, unmodified PVDF/PEG membranes, which made the fabricated membranes at least passable when hydrophobicity was considered as one main characteristic. Furthermore, The PVDF/PEG/4LSMM-BSMM membrane exhibits 161 °C of melting point as characterized by the DSC. This value indicates an improvement of thermal behavior shows so as the fabricated membranes are desirable for membrane distillation operation conditions range. Based on the results, it can be concluded that PVDF/PEG membranes with the use of LSMM and BSMM combination could enhance the permeate flux up to 81.32 kg·m−2·h−1 at the maximum, with stable salt rejection around 99.9%, and these are found to be potential for seawater desalination application.

Highlights

Licensee MDPI, Basel, Switzerland.Water shortage is one of the most critical issues that need to be overcome properly since the majority of mankind’s daily activities are water-dependent
The effect of incorporation of LSMM in polyvinylidene fluoride (PVDF)/polyethylene glycol (PEG) hollow fiber membrane coated by by hydrophobic surface-modifying macromolecules (BSMM) was investigated
The characterization results that the PVDF/PEG/LSMMBSMM hollow fiber membranes had two layers of finger-like structure morphology and tended to be hydrophilic with water contact angle results variated from 94.43◦ to 107.94◦

Summary

Introduction

Licensee MDPI, Basel, Switzerland.Water shortage is one of the most critical issues that need to be overcome properly since the majority of mankind’s daily activities are water-dependent. The increase in the human population reflects much need for a clean water supply [1]. Clean water sources from nature do not become replenished to accommodate the population’s water usage needs, which continuously produce wastewater. This causes unfair distribution of clean water, and it affects many people around the world, especially. Existing water treatment processes using other than MD are still requiring high energy to be operated, which is something that needs to be avoided due to lower efficiency and higher operating cost [3]. Hybridizing the synergy between innovative and low energy-driven technology of MD and infinite water resource such as seawater is a highly potential solution toward having sustainable water reclamation technology

Methods

Discussion

Conclusion