Kapok Fibre as Membrane Distillation for Humic Acid Wastewater Treatment

Abstract

Membrane distillation (MD) is a process of combining membrane with thermal desalination where it operates at two different temperatures which are hot and cold. A vapour pressure resulted between the temperature differences of two sides of the membrane is called permeate flux. In this study, kapok fibre, which provides hydrophobic properties, has been chosen as an alternative solution for synthetic membrane in the MD process. Therefore, the primary purpose of this research is to investigate the effect of feed temperature ranging from 40 to 70℃ towards the separation of pure water from humic acid (HA) wastewater. An experimental investigation for the performance of vacuum membrane distillation (VMD) system was performed to treat the HA wastewater to produce pure water. The experimental set up of VMD was set with kapok fibre acting as a barrier that separates the collected pure water from HA wastewater, which is conducted for four hours. Based on this study, the increase in the amount of calculated permeate flux correlates to the increase of feed temperature. The calculated permeate flux is 0.237 kgh-1m-2 at the temperature of 40℃. The amount of calculated flux increases steadily to 0.4 and 0.6 kgh-1m-2 respectively for every 10℃ increments. Furthermore, the physical properties of kapok fibre were analysed by using a scanning electron microscope (SEM). Surface morphology of the kapok fibre at the condition of before and after the MD process were studied without subjecting any chemical treatment on it. Accordingly, the physical properties of the kapok fibre were seen different after the MD process conducted. Additionally, the hydrophobic properties of the kapok fibre were evaluated by using an absorption test. The absorption test was conducted at varies temperature, which results in the highest percentage of absorptivity 4.823 % at 60℃. The hydrophobic kapok fibre has shown excellent properties that can be applied in the MD process and utilised in wastewater treatment.