Consecutive Organosolv and Alkaline Pretreatment: An Efficient Approach toward the Production of Cellulose from Rice Straw

Cellulose separation from ramie bone by one step process with green hydrogen peroxide-citric acid

Ramie bone (RB), an agricultural waste generated in the textile industry, is a vastly productive renewable natural resource with the potential to be used as a source of cellulose. In this study, ramie bone cellulose (RB-CE) was obtained in one step using a simple and ecologically friendly hydrogen peroxide-citric acid (HPCA) treatment procedure that avoided the use of halogenated reagents and strong acids while also streamlining the treatment processes. Various analytical methods were used to investigate the chemical composition and structure, crystallinity, morphology, thermal properties, surface area and hydration properties of cellulose separated at different treatment temperatures. HPCA successfully removed lignin and hemicellulose from RB, according to chemical composition analysis and FTIR. RB-CE had a type I cellulose crystal structure, and the crystallinity improved with increasing treatment temperature, reaching 72.51 % for RB-CE90. The RB-CE showed good thermal stability with degradation temperatures ranging from 294.2 °C to 319.1 °C. Furthermore, RB-CE had a high water/oil binding capacity, with RB-CE90 having WHC and OBC of 9.68 g/g and 7.24 g/g, respectively. The current work serves as a model for the environmentally friendly and convenient extraction of cellulose from biomass, and the cellulose obtained can be employed in the field of food and composite materials.

Nanocellulose: A comprehensive review investigating its potential as an innovative material for water remediation

Rapid growth in industrialization sectors, the wastewater treatment plants become exhausted and potentially not able to give desirable discharge standards. Many industries discharge the untreated effluent into the water bodies which affects the aquatic diversity and human health. The effective disposal of industrial effluents thus has been an imperative requirement. For decades nanocellulose based materials gained immense attraction towards application in wastewater remediation and emerged out as a new biobased nanomaterial. It is light weighted, cost effective, mechanically strong and easily available. Large surface area, versatile surface functionality, biodegradability, high aspect ratio etc., make them suitable candidate in this field. Majorly cellulose based nanomaterials are used in the form of cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), or bacterial nanocellulose (BNC). This review specifically describes about a variety of extraction methods to produced nanocellulose and also discusses the modification of nanocellulose by adding functionalities in its surface chemistry. We majorly focus on the utilization of nanocellulose based materials in water remediation for the removal of different contaminants such as dyes, heavy metals, oil, microbial colony etc. This review mainly emphasizes in ray of hope towards nanocellulose materials to achieve more advancement in the water remediation fields.

Value addition of rice straw cellulose fibers as a reinforcer in packaging applications

The potential use of agro-waste in food packaging applications is receiving remarkable attention due to its sustainable approach and biodegradable properties. As typical lignocellulosic biomass, rice straw (RS) is widely produced but is usually abandoned and burned, causing tremendous environmental concerns. The exploration of using RS as the source of biodegradable packaging materials is promising for economically converting this agricultural waste into packaging material, thereby providing a considerable solution for RS disposal and an alternative solution to synthetic plastic waste. Polymers have been infused with nanoparticles, fibers, and whiskers, along with plasticizers and cross-linkers, and fillers like nanoparticles and fibers. They have also been blended with natural extracts, essential oils, and other synthetic and natural polymers to improve RS properties. There is still much research to be done before this biopolymer can be applied at an industrial level in food packaging. In this respect, RS can be valued for packaging to add value to these underutilized residues. This review article focuses on the extraction methods and functionality of cellulose fibers and their nanostructured forms from RS and their utilization in packaging applications.

Removal of lignin and silica from rice straw for enhanced accessibility of holocellulose for the production of high-value chemicals

The intricate nature and rigidity of rice straw, particularly the presence of lignin and silica, hinders the catalytic valorization, consequently decreasing the yield of target products. This study reports the concurrent removal of lignin and silica from rice straw to obtain enriched holocellulose, then transforming it to furfural (FUR) and levulinic acid (LA). Interestingly, rice straw in the form of powder displays an improved removal of lignin (51.0%) and silica (92.0%) during ammonia treatment. Encouragingly, adding organic solvents, such as THF, to the aqueous system during the pretreatment of rice straw improves the lignin removal to 60.0%. Upon improving lignin removal to 60%, the obtained holocellulose enriched solid residue yields 71.0% FUR along with 52.0% LA, which is 8 and 4-fold higher than what is obtained with parent rice straw, signifying the importance and the prerequisite of lignin and silica removal from rice straw.

Comparison of various delignification/desilication pre-treatments and indigenous fungal cellulase for improved hydrolysis of paddy straw

The efficient removal of lignin and silica from paddy straw is essential for its volarization into biofuels and other value-added products. In this work, different chemical pre-treatments viz. acid/alkali, organosolv and deep eutectic solvents were carried out to assess the extent of delignification and desilication of paddy straw. Maximum lignin and silica removal of 96.08 and 95.51% was observed with two step acid (0.5% sulphuric acid) followed by alkali (4% sodium hydroxide) pre-treatment with significantly low total lignin (2.30%) and silica content (0.80%) of the treated straw residue. The treated straw residue contained significantly high holocellulose (91.65%), cellulose (75.01%) and hemicellulose content (16.64%). Among the four indigenous fungal isolates, Penicillium mallochii (JS17) cellulase showed better accessibility for the treated straw residue with maximum release of 504.18 mg g^-1 of reducing sugars and saccharification efficiency of 56.90%. The two-step acid/alkali pre-treatment of paddy straw was highly effective for removing lignin and silica from paddy straw, thereby, resulting in enhanced enzymatic accessibility of the substrate and more efficient hydrolysis of cellulose into fermentable sugars.

Rice straw structure changes following green pretreatment with petha wastewater for economically viable bioethanol production

Energy efficient and environment friendly pretreatment processes for the production of biofuel have remained elusive and the research is further compounded by the high cost of processing lignocellulosic biomass-an essential factor for producing sustainable biofuels. In the last few decades, a number of pretreatment methods have been proposed, specifically chemical pretreatments but are either expensive or harmful to the environment. To address this urgent need, we propose a green pretreatment method that utilises the highly alkaline by-product, petha wastewater to pretreat the lignocellulosic waste rice straw (RS). The effectiveness of the pretreatment was analysed by monitoring both enhanced cellulose content and reducing sugar yield along with removal of hemicellulose and lignin. We found that PWW pretreatment yielded five times more reducing sugar than native RS with 10.12% increment in cellulose content. SEM and EDX studies further revealed that our process enhanced surface roughness and carbon content (from 32.19% increased to 41.59% and 41.66% for A and D, respectively) along with reduction in silica content (from 8.68% in RS to 4.30% and 7.72% for A and D, respectively). XRD and FTIR analyses indicate crystallinity index (CI) and alteration in lignocellulosic structure of RS, respectively. Decrease in CI was about 43.4% in A whereas only 4.5% in D as compared to native RS (CI 54.55%). Thereby we found PWW to be better substitute of an alkali for pretreatment of RS with negligible environmental impacts.