Polyurethane membrane as an adsorbent for methyl orange and ethyl violet dyes(Membran poliuretana sebagai penjerap untuk pewarna metil oren dan etil ungu lembayung)

• Main Authors: Badri, Khairiah, Ismail, Fatem Hamimie, Shakir, Amira Shakim Abdul, Mohamad, Sharifah, Hamuzan, Hawa Aqilah, Hassan, Nurul Syakilla
• Format: Article
• Published: Malaysian Analytical Sciences Society 2018
• Subjects: Q Science (General); QD Chemistry
• Online Access: http://eprints.um.edu.my/22378/; http://www.ukm.my/mjas/mjas2018/
• Institution: Universiti Malaya

Ethyl violet (EV) and methyl orange (MO) are commercial dyes used in a large number of industries. Due to their complex chemical structures and synthetic nature, these dyes are highly stable to light and oxidation, making them non-biodegradable, highly toxic, carcinogenic and mutagenic in nature. Among all techniques, adsorption continues to attract considerable attention due to its simplistic approach and numerous benefits such as greater efficiency, capacity to remove dyes on a large scale, ease of recovery, and recyclability of adsorbents. A palm-based polyurethane (PU) membrane has been synthesised into adsorbent and its ability to adsorb the dye molecules was investigated. The PU membrane was produced via condensation polymerisation between palm-based monoester (PKOp) and 4,4-methylene diphenyl diisocyanate (MDI) with acetone as the solvent. The FTIR spectrum has confirmed the formation of urethane linkage (HN-(C)O) through the presence of N-H, C-NH, C-O-C and C=O urethane peaks which were observed at 3293 cm -1 , 1602cm -1 , 1221 cm -1 dan 1716 cm -1 , respectively. Tensile testing has demonstrated that as the thickness of membrane is increased, the elasticity also increased proportionally with increasing tensile strain ranging from 6.7 MPa to 7.42 MPa. Various adsorption parameters such as initial concentration of dyes, effect of pH, effect of adsorbent dosage and contact time were studied and optimised. The adsorption study revealed that approximately 99% of EV and 25% of MO was adsorbed by the PU membrane within a short duration of 30 minutes. The parameters were determined from Langmuir, Freundlich and Temkin adsorption isotherm models. The isotherm studies specified that the adsorption of PU membrane towards EV and MO dyes is well fitted to the Langmuir model with the value of the maximum adsorption capacities for monolayer adsorption at 9.461 mg/g for EV and 4.340 mg/g for MO.