SINTESIS NANOKOMPOSIT TiO2–KITOSAN SEBAGAI FOTOKATALIS UNTUK FOTODEGRADASI ZAT WARNA DAN FOTOREDUKSI LOGAM BERAT; SYNTHESIS OF TIO2-CHITOSAN NANOCOMPOSIT AS PHOTOCATALYST IN DYE PHOTODEGRADATION AND HEAVY METAL PHOTOREDUCTION

FAJRIATI, IMELDA, Pekik Nurwantoro

2016 | Tesis | FMIPA

In order to improve photocatalyst method for the treatment of dye and heavy metal, TiO2-chitosan nanocomposite has been synthesized as photocatalyst to increase TiO2 activity and stability for simultaneous dye photodegradation and heavy metal photoreduction. The synthesis was carried out by means of sol-gel method using titanium(IV)-isopropoxide (TTIP) as sol precursor and chitosan as host material in room temperature. The synthesis was started by preparing sol precursor followed by aging process to produce nanocrystal. In the preparation of sol-gel, the pH of sol precursor, the aging process and TTIP concentration were systematically investigated to obtain nanocrystal photocatalys with maximum performances. The nanocomposites were then characterized using XRD, FTIR, DR-UV, TG/DTA, SEM-EDX and TEM to determine size, crystallinity, and band gap energy (Eg) of TiO2 particles as well as the surface area of the nanocomposite. The photocatalytic activity of the nanocomposite was tested in the photodegradation of acidic methyl orange (MO) and basic methylene blue (MB) dyes and in the photoreduction of Cu(II). Characterization results indicate that TiO2 particles formed in the chitosan has nanoparticle dimensions (8-10 nm) and crystalline phase, with higher Eg and surface area than that of bulk TiO2 synthesized without chitosan. TiO2 nanoparticle formed in the chitosan produces TiO2-chitosan nanocomposite via covalent and hydrogen bond. The size and crystallinity of TiO2 particles in the chitosan are affected by pH and aging time, with the highest results obtained at pH 2-3 and aging time of 7 days. This study also shows that the size of TiO2 particles is controlled by TTIP concentration, i.e. the size of TiO2 nanoparticles increases along with the addition of TTIP concentration. The catalytic activity test shows that TiO2-chitosan nanocomposite has effective performance in dye photodegradation and heavy metal photoreduction as compared to that of TiO2 bulk. The effectiveness of photocatalyst is also influenced by pH and light exposure time, with the highest result for photodegradation of MO, MB, and photoreduction of Cu(II) are obtained at pH 4, 8 and 7 respectively, after 3 hours of light exposure. The amount of TiO2 in the TiO2-chitosan nanocomposite has been observed to influence to photocatalytic activity. The photocatalytic activity of nanocomposite with low TiO2 and high Eg is dominated by the Eg. While, the photocatalytic activity of nanocomposite with high TiO2 and low Eg was governed by the amount of TiO2. However, both TiO2 and Eg has been found to affect the photocatalytc activity of nanocomposite containing relatively high amount of TiO2 and Eg. The result of repeated test using the same nanocomposite suggests that photocatalyst can be used up to 3 times which still gives effective photodegradation and photoreduction of more than 50% from the initial concentration.

Kata Kunci : N