ADSORPTION OF FLUORENE USING BIOSILICA DIATOM CYCLOTELLA STRIATA TBI MODIFIED BY PHENYLACETIC ACID

• Main Author: Rizqina, Afifah
• Format: Final Project
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/73464
• Institution: Institut Teknologi Bandung

The increase in the number of Polycyclic Aromatic Hydrocarbons (PAH) in the waters occurs due to increased human activity, especially in the industrial sector. These organic pollutants can damage ecosystems and are toxic and carcinogenic to living things. Fluorene is one of the low molecular weight PAHs with high toxicity in waters. PAH separation methods in waters can be carried out using various techniques, for example, adsorption, membrane filtration, and coagulation. Adsorption has advantages compared to other methods, which are relatively easy, effective, and fast to apply. One of the natural adsorbents that can be used to reduce levels of PAHs in the environment is diatom microalgae shells, for example, C. striata TBI which is found in Teluk Bidadari, Indonesia. Biosilica C. striata TBI has a large and porous surface, making it suitable for use as an adsorbent. However, biosilica surfaces tend to be hydrophilic, whereas PAH compounds are hydrophobic. Therefore, the biosilica surface needs to be modified with hydrophobic compounds to increase its affinity for PAH compounds. Phenylacetate acid has a hydrophobic part (phenyl group) that can interact van der Waals with PAH compounds and also contains a carboxylic group that can form hydrogen bonds with silanol groups in biosilica. This study aimed to test the adsorption ability of C. striata TBI biosilica modified by phenylacetic acid on fluorene. The stages of this research included cultivating C. striata TBI cells, extraction and characterization of biosilica shells from C. striata TBI wet biomass, modification of biosilica with phenylacetic acid, and adsorption tests at various concentrations of fluorene. After being oxidized using concentrated nitric acid followed by calcination, biosilica was successfully purified from C. striata wet biomass as 100% SiO2 (based on XRF analysis results). In the FTIR spectrum of the modified biosilica, a shift in -OH absorption was observed from 3437,15 cm-1 (before modification) to 3462,2 cm-1 (after modification with phenylacetic acid) indicating the presence of hydrogen bonds between biosilica and phenylacetic acid. Modified biosilica is also more hydrophobic than pure biosilica because the contact angle of modified biosilica is larger than that of pure biosilica. Based on adsorption tests on fluorene, fluorene adsorption by phenylacetic acid-modified biosilica followed the Langmuir isotherm model with an adsorption capacity of 210,941 mg/g.