Valorization of Cellulose-Based Materials from Agricultural Waste: Comparison between Sugarcane Bagasse and Rice Straw

Efficient dye removal using manganese oxide-modified nanocellulosic films from sugarcane bagasse

Removing toxic dyes from industrial wastewater is crucial for environmental protection. This research introduced novel composite films of manganese oxide (MnO2)-modified nanocellulose (MCel) and unmodified nanocellulose (Cel) derived from sugarcane bagasse for dye removal. Nanocellulose was extracted from sugarcane bagasse and subsequently transformed into MCel through in-situ MnO2 synthesis. The MCel/Cel composites, with various MCel to Cel ratios, were fabricated into films and evaluated for their efficiency in removing methylene blue (MB). The films were characterized using Fourier transform infrared spectroscopy for functional group analysis, X-ray diffraction for crystallinity, X-ray photoelectron spectroscopy for chemical state analysis, field emission scanning electron microscopy-energy dispersive spectroscopy for morphology and elemental composition, and Thermogravimetric Analysis for thermal behaviors. Adsorption results showed that all MCel/Cel composite films achieved over 97 % removal of MB (initial concentration 100 mg L-1) within 24 h, with convenient adsorbent retrieval after adsorption. The adsorption process followed a pseudo-second order kinetic model and Langmuir adsorption isotherm. The optimal 95:5 MCel/Cel film exhibited a rate constant of 6.16 × 10-4 g mg-1 min-1 and the calculated adsorption capacity of 181.85 mg g-1. These results demonstrate significant potential for wastewater treatment and sustainable waste valorization by converting sugarcane bagasse cellulose into environmentally friendly adsorbents for contaminant removal.

Rice Byproduct Compounds: From Green Extraction to Antioxidant Properties

Currently, rice (Oryza sativa L.) production and consumption is increasing worldwide, and many efforts to decrease the substantial impact of its byproducts are needed. In recent years, the interest in utilizing rice kernels, husk, bran, and germ for the recovery of different molecules, from catalysts (to produce biodiesel) to bioactive compounds, has grown. In fact, rice byproducts are rich in secondary metabolites (phenolic compounds, flavonoids, and tocopherols) with different types of bioactivity, mainly antioxidant, antimicrobial, antidiabetic, and anti-inflammatory, which make them useful as functional ingredients. In this review, we focus our attention on the recovery of antioxidant compounds from rice byproducts by using innovative green techniques that can overcome the limitations of traditional extraction processes, such as their environmental and economic impact. In addition, traditional assays and more innovative methodologies to evaluate the antioxidant activity are discussed. Finally, the possible molecular mechanisms of action of the rice byproduct antioxidant compounds (phenolic acids, flavonoids, γ-oryzanol, and vitamin E) are discussed as well. In the future, it is expected that rice byproduct antioxidants will be important food ingredients that reduce the risk of the development of several human disorders involving oxidative stress, such as metabolic diseases, inflammatory disorders, and cancer.

Effect of Glycerol Concentrations on the Characteristics of Cellulose Films from Cattail (Typha angustifolia L.) Flowers

Plastic waste has become a big problem for the environment globally. Biodegradable polymers are a potential replacement for plastics that can have a positive outcome both environmentally and economically. In this work, we used acid hydrolysis and alkaline treatment to extract cellulose fibers from cattails. The obtained cellulose was used as a substrate for the fabrication of cellulose film using a casting technique on plastic plates. Different concentrations of the plasticizer, glycerol, were used to prepare films for comparison, and its effects on the film's characteristics were observed. The morphology, chemical structure, and thermal stability of the cattail cellulose (CTC) films were studied using techniques such as scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and thermogravimetric analysis (TGA), respectively. Measurements of transparency, moisture content (MC), water solubility (MS), and water contact angle (WCA) were also performed. Introducing glycerol into the films increased the transparency, MC, and WS values, as well as the gap width between film textures. However, it resulted in a decrease in the WCA of the films, showing that the hydrophilicity of the films is increased by the addition of glycerol. The interaction between the functional groups of cellulose and glycerol was established from the ATR-FTIR and XRD data. The obtained results indicated that glycerol affected the thermal stability and the degree of crystallinity of the produced films. Accordingly, the hydrophilicity of the cellulose film was increased by increasing the glycerol content; therefore, cattail cellulose films can be used as a biodegradable alternative to plastic in the future.