Development of biomass-derived cellulose for photocatalysis application

Teh, Zhi Sheng (2022) Development of biomass-derived cellulose for photocatalysis application. Final Year Project, UTAR.

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Abstract

Biomass-derived cellulose is the most abundant renewable polymer on earth. Cellulose is also increasingly being researched in wastewater treatment due to its outstanding structural features, wide availability, non-toxicity and biodegradability. In usual wastewater treatments, pollutants such as phenolic compounds, organic dyes and heavy metals cannot be treated effectively. Hence, cellulose-derived composites are gaining attention in photocatalytic degradation of these pollutants. In this study, the recently developed cellulose-derived photocatalysts were reviewed. This study was conducted in four steps: i) planning; ii) searching; iii) screening; iv) reporting. The characteristics and properties of cellulose-derived photocatalysts were studied using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). This study also reviewed the parameters affecting the photocatalytic performances such as amount of cellulose and semiconductor in composite materials, dosage of cellulose-derived photocatalysts, initial pollutant concentration and solution pH. The mechanisms of photodegradations were also studied. The characterisation results revealed that cellulose-derived photocatalysts such as cellulose-acetate-supported titanium dioxide (TiO2/CA) and cellulose-supported cerium oxide (cellulose/CeO2) possessed high surface area with well-dispersed semiconductors. The cellulose-derived photocatalysts also possessed a wide variety of functional groups and types of bonds, different chemical states and crystallinities. Besides, the cellulose-derived photocatalysts had high thermal stability and the thermal decomposing started above 100 °C, which was much higher than the photocatalysis temperature. The cellulosederived photocatalytic activities were enhanced when the ratio of cellulosederived materials in composites, ratio of metal oxides in composites, dosage of cellulose-derived photocatalysts and solution pH were at optimum values and initial pollutant concentrations were at low values. The cellulose-derived photocatalysis experimental data also fitted the pseudo-first order (PFO) kinetic model well. Methylene blue (MB), rhodamine B (RhB) and bisphenol A (BPA) were degraded similarly through the attack of hydroxyl radicals (OH ∗ ) and superoxide anions (O2 ∙ − ). Meanwhile, nitrophenol was photocatalytic degraded by photo-generated electrons with the addition of sodium borohydride (NaBH4). Hexavalent chromium (Cr (VI)) was reduced by hydrogen ions (H+ ) in acidic solutions. Most of the studied cellulose-derived photocatalysts had very high efficiency in degrading phenolic compounds, organic dyes and heavy metals. Hence, cellulose-derived composites had been proven to be promising photocatalysts for the removal of water pollutants.

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