ADSORPTION OF POLYCYCLIC AROMATIC HYDROCARBONS (PHENANTHRENE AND ANTHRACENE) USING BIOSILICA OF DIATOM CYCLOTELLA STRIATA TBI MODIFIED WITH PHENYL ACETIC ACID

• Main Author: Islamianti Machmud, Fazsa
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/64735
• Institution: Institut Teknologi Bandung

PAH (Polycyclic Aromatic Hydrocarbons) pollution in coastal waters continues to increase from year to year and damages aquatic ecosystems. Based on the U.S. Environmental Protection Agency (EPA), the maximum permissible concentration of PAH in waters is 0.2 µg/L, so efforts need to be made to reduce PAH levels in the waters. The adsorption method is an alternative and effective method to reduce PAH levels because it is cheaper, simpler, and more efficient. Biominerals from Indonesian marine biota can be developed to explore biomass from aquatic ecosystems as PAH adsorbents. Biomineral derived from diatom microalgae is a biosilica with nano-sized hierarchical pores and a large surface area (hundreds of m2/g), so it has the potential to be used as an effective adsorbent for PAHs. One of the most common types of diatoms found in Indonesian waters is the diatom Cyclotella striata TBI which can produce lipids and biomass better than other types of algae. However, the biosilica shell of Cyclotella striata is still rarely studied and utilized, especially as a pollutant adsorbent for environmental remediation. To increase the affinity of biosilica to the aromatic chain of PAH, the biosilica can be modified with phenylacetate, in order to add a hydrophobic site on the silica surface so that it can interact with lipophilic ?-? and ?-sp3 with PAH. This study aims to isolate and modify the biosilica of the diatom Cyclotella striata TBI using phenylacetic acid. Furthermore, the modified biosilica was characterized and evaluated based on the adsorption capacity of PAHs (phenanthrene and anthracene). Biosilica was purified from diatom culture and modified by batch method. Then characterized using Fourier Transform Infra-Red (FTIR), Scanning Electron Microscope - Energy Dispersive X- ray (SEM-EDS), High Resolution - Transmission Electron Microscopy (HR-TEM), Brunauer-Emmett-Teller (BET) analysis, angle test contact (Water Contact Angle), and X- Ray Diffraction (XRD). The adsorption capacity was evaluated through adsorption isotherm studies using Gas Chromatography/Mass Spectrometry (GC/MS). The FTIR results showed the presence of a C=O carbonyl group from phenylacetic acid at 1703 cm-1 and a shift in the wavenumber range of the –OH group due to hydrogen bonding after modification. SEM- EDS and HR-TEM analysis showed that Cyclotella striata TBI cells had a nano-sized porous surface with a cell diameter of about 9 – 12 µm, a cell thickness of about 3 µm, and an increase in carbon content in the biosilica after modification with phenylacetate. The results of the BET characterization and contact angle test showed a reduction in surface area and an increase in hydrophobicity due to modification with phenylacetate. The XRD results show that there are differences in the diffraction pattern of the biosilica before and after modification. The PAH adsorption isotherm model for phenanthrene and anthracene Freundlich model with maximum adsorption capacity of 11.112 mg/g and 12.508 mg/g, respectively.