Tailoring the permeability and flux stability of forward osmosis membrane with tert-butylamine functionalized carbon nanotubes for paracetamol removal

Abstract

The discharge of pharmaceutical wastewater is an adversity to the nature. Some of the pharmaceutical product (PP) wastes are highly resistant towards bio-degradation hence physical-based separation technology such as forward osmosis (FO) has been introduced for the treatment. Despite exhibiting high water flux, commercial FO membrane often suffers from fouling and unsatisfactory solute rejection. In this study, carbon nanotubes (CNT) which has high self-bundling tendency was functionalized with tert-butylamine (TBA), a bulky tertiary amine. The agglomeration of the aminated CNT was suppressed via steric hindrance and surface charge repulsion. The nanofillers was then incorporated into the polyamide (PA) layer of thin film nanocomposite (TFN) during interfacial polymerization process to provide the required hydrophilicity and surface charges. Using synthetic paracetamol (PCT) solution as the feed solution (FS), the experimental outcome showed that the incorporation of amino-functionalized CNT (ACNT) successfully enhanced the hydrophilicity and flux stability of the FO membranes. Compared to the control thin film composite (TFC) membrane, ACNT-TFN membrane exhibited an improved water flux from 3.58 L.m-2.h-1 to 9.01 L.m-2.h-1, without sacrificing the PCT rejection (99.7 %). This study improves the understanding on the superior benefits of FO for enhancing the pharmaceutical waste removal and stimulates insight for more nanofillers-induced modification on the FO membrane, in order to make it truly useful for more water separation applications in the future.