Synthesis of poly(3-hydroxybutyrate)/copper sulfide composites films and their photocatalytic application

Abstract

The objectives of this study were to synthesise and characterise poly(3- hydroxybutyrate)/copper sulfide (PHB/CuS) composites and to assess the potential of these composites in the form of films as photocatalyst for the degradation of 2,4,6- trichlorophenol (TCP). The CuS was prepared by the reaction between copper(II) chloride dihydrate and thiourea which was later immobilised onto PHB biopolymer by aqueous to organic phase transfer method, i.e., hydrosol to organosol. Based on UV-Vis and Raman spectroscopy as well as XRD analysis, it was confirmed that the hydrosol contain mostly CuS with the existence of Cu2S in trace amount. This trace amount of Cu2S can be minimised by prolonged refluxing of the reaction mixture. The amount of Cu in the composite film was determined using AAS technique. Pristine PHB and the synthesised photocatalysts containing various amount of CuS were investigated for photodegradation of TCP using UV-visible light (350-800 nm). Pristine PHB was capable to degrade TCP to a maximum of 70% degradation at 5 h. However, the PHB/CuS composite film afforded higher TCP degradation in shorter time. The photodegradation results also revealed that the higher amount of CuS in the composite led to better photodegradation of TCP under UV-visible light. In this study, complete degradation of TCP was achieved after 2 h of irradiation upon utilisation of PHB/CuS film containing 0.312 wt% of CuS.