IDENTIFICATION OF 4-NONYLPHENOL AND ITS REMOVAL VIA PLANT-BASED ADSORBENTS IN UREJE RIVER EKITI STATE

Abstract

Ureje River in Ekiti state was investigated for the presence of endocrine disrupting chemicals (EDCs) – nonylphenol and octylphenol. The extraction technique used was liquid-liquid extraction while the clean-up was done using solid phase extraction. Gas Chromatography-Mass Spectrometry was used for the identification and quantification of EDCs in the water sample. The target EDCs (nonylphenol and octylphenol) were present at concentrations that ranged from 0.58 - 0.96 µg/L and 0.59 - 0.66 µg/L respectively, and followed by their removal. Adsorbents were prepared from palm kernel shell (PKS) and stems of Siam weed. Additionally, already prepared and modified biochar from Siam weed was also used as adsorbent. The PKS was used to prepare activated carbon (ACPKS) through carbonisation at 500 oC and activation with phosphoric acid. Also, nanocellulose was prepared from the Siam weed through multiple treatments: dewaxing, bleaching treatment, alkali treatment and acid hydrolysis. The chemical composition analysis of the Siam weed shows that it contains 39.6% cellulose, 27.5% hemicellulose, 28.7% lignin and 4.2% extractives. Both the raw and the isolated products were characterised using Fourier Transform Infrared spectroscopy (FTIR), Thermo-Gravimetric Analysis (TGA), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The weak sharp band at 3345 cm-1 on the spectrum of the raw PKS reduced rapidly in the FTIR spectrum of the ACPKS. This confirms the influence of the thermal treatment (carbonisation) and activation using phosphoric acid. The XRD spectrum of the raw PKS and ACPKS are quite similar and agrees with the pattern for non graphitic carbon. The surface compactness seen on the raw Siam weed and raw PKS has become loosed in the micrograph of the cellulose nanocrystals and ACPKS, indicating that degradation of cellulosic chain had occurred. TGA results showed that huge amount of hemicellulose, cellulose and lignin content of the raw PKS and raw Siam weed volatilized. This is due to the breaking of v

several polymers to monomers. This is expected to allow disintegration of some aliphatic carbon chains inform of C-OH, C-O, C-H and C-C. Hence, the available carbon content of the PKS after carbonization became stable at higher temperatures and have the tendency to function effectively as adsorption agent. More so, the lower thermal stability of the raw Siam weed when compared with the cellulose nanocrystals is as a result of the presence of the non-cellulosic component with lower temperature of degradation. The prepared adsorbents were used in removing the EDCs except the nanocellulose whose yield was too small to be used for water treatment. The percentage removal of nonylphenol ranged from 12.5- 30.2% and then from 7.6- 9.1% for octylphenol using ACPKS. The maximum percentage removal obtained was when the contact time of the adsorbent with the water sample was at 150 minutes. For the modified Siam weed biochar, the percentage removal of the nonylphenol ranged from 21.8 – 45.8 % and 9.1% for octylphenol. The maximum percentage removal was when the contact time of the modified Siam weed biochar with the water sample was 90 minutes. The results of the characterization showed that the palm kernel shell and Siam weed processed into activated carbon and cellulose nanocrystals respectively are good agricultural wastes, which are cheap and readily available to be used as adsorbents. This will help in bringing solution to the environmental littering and burning of these materials.