Rice Husk Research Articles

Intensification of n-butyl ethanoate synthesis using ultrasound over ammonium sulphate supported on silica extracted from rice husk ash as an efficient heterogeneous catalyst

ABSTRACT The silica extracted from rice husk ash was used as support to load ammonium sulphate ((NH4)2SO4) (10–40 wt.%) and ammonium sulphate supported on rice husk silica ((NH4)2SO4/RHS) catalysts were characterised by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and scanning electron microscope (SEM) with EDS techniques. The catalyst was further used to convert butan-1-ol to n-butyl ethanoate in an ultrasonic batch reactor. The study demonstrated the influence of ultrasound and operating parameters on the conversion. The maximum conversion of 88.77% was attained at the optimal operating conditions of temperature 353 K, molar ratio 1:2 (ethanoic acid to butan-1-ol), catalyst loading 4% (w/w), duty cycle 75% and ultrasound power 80 W. When compared with the conventional process, the reaction time was reduced by 54% in ultrasound-assisted synthesis over conventional synthesis. It has been observed that intensification benefits as it lowers reaction time for the ultrasound-assisted approach.

Rice husk-derived self-healing superhydrophobic films using solvent-less approach for drag reduction and oil absorption behaviour

The present work focuses on a sustainable approach to transform rice-husk waste into self-healing superhydrophobic films with potential application for drag-reduction and oil absorption. Rice husk was transformed into amorphous nano silica particles (d50 ∼ 150 nm) exhibiting mesoporosity with a surface area of 400 m2/g. Superhydrophobic films fabricated using a solvent-less approach showed the transition from flattened to nano-globular morphology with increasing silica content in polydimethylsiloxane (PDMS), leading to exceptional superhydrophobicity. The optimized film with a particle fraction of 60 % exhibited high de-wetting (> 150º) and mechanical strength (∼7 MPa). The film showed extremely low water droplet adhesion of ∼19 μN, similar to lotus leaf owing to high negative Laplace pressure. Significantly, the film exhibited persisting de-wettability and endurance under harsh chemical, thermal, and mechanical conditions. The robustness is further fortified with room temperature self-healing and real-time self-regeneration characteristics, persisting even after exposure to strong acids and significant abrasion. The multidimensional aspects of the film embarked with a 70 % drag reduction and effective oil-water separation. The present work not only provides a sustainable pathway for managing agricultural waste but also a practical and easy-to-implement approach to tackle oil spill incidents.

Production of Porous Silica from Rice Husk Using Cetyltrimethylammonium Bromide to Remove Dyes in Aqueous Solution

Production of Porous Silica from Rice Husk Using Cetyltrimethylammonium Bromide to Remove Dyes in Aqueous Solution

Xylitol production by Barnettozyma populi Y-12728 with different immobilization strategies

One of the new xylitol producer microorganisms is Barnettozyma populi Y-12728 and it has great potential for the industry with its pure xylitol production capability. Different immobilization strategies, the usability of baffled or normal flasks with different agitation speeds, and various lignocellulosic hydrolysates were studied in this research. The highest xylitol production and yield values were 11.99 g xylitol/L and 40.28 % for the C1 trial at 70 ml medium with a suspended cell. For the immobilization strategy, 1 % polyethyleneimine concentration, 1.5 mm surface lattice thicknesses, and 8 3D cubes were determined to be the optimum conditions with 17.84 g/L xylitol production and 0.473 g xylitol/g xylose yield values in a 70 ml volume medium at 200 rpm, 30 °C, and 6.0 initial pH for 3 days. Rice husk, wheat bran, and oat husk hydrolysates were also used as a substrate for xylitol fermentation. The highest xylitol production was 2.26 g/L for lignocellulosic hydrolysates. In this research, FDM (Fused Deposition Modelling) based 3D printed cubes are used for the immobilization agent of Barnettozyma populi NRRL Y-12728 for the first time. The results revealed that FDM-based 3D-printed cubes could be used to immobilize cells and improve productivity for xylitol production.

Pharmaceutical Pollutants: Ecotoxicological Impacts and the Use of Agro-Industrial Waste for Their Removal from Aquatic Environments.

Medicines are pharmaceutical substances used to treat, prevent, or relieve symptoms of different diseases in animals and humans. However, their large-scale production and use worldwide cause their release to the environment. Pharmaceutical molecules are currently considered emerging pollutants that enter water bodies due to inadequate management, affecting water quality and generating adverse effects on aquatic organisms. Hence, different alternatives for pharmaceuticals removal from water have been sought; among them, the use of agro-industrial wastes has been proposed, mainly because of its high availability and low cost. This review highlights the adverse ecotoxicological effects related to the presence of different pharmaceuticals on aquatic environments and analyzes 94 investigations, from 2012 to 2024, on the removal of 17 antibiotics, highlighting sulfamethoxazole as the most reported, as well as 6 non-steroidal anti-inflammatory drugs (NSAIDs) such as diclofenac and ibuprofen, and 27 pharmaceutical drugs with different pharmacological activities. The removal of these drugs was evaluated using agro-industrial wastes such as wheat straw, mung bean husk, bagasse, bamboo, olive stones, rice straw, pinewood, rice husk, among others. On average, 60% of the agro-industrial wastes were transformed into biochar to be used as a biosorbents for pharmaceuticals removal. The diversity in experimental conditions among the removal studies makes it difficult to stablish which agro-industrial waste has the greatest removal capacity; therefore, in this review, the drug mass removal rate (DMRR) was calculated, a parameter used with comparative purposes. Almond shell-activated biochar showed the highest removal rate for antibiotics (1940 mg/g·h), while cork powder (CP) (10,420 mg/g·h) showed the highest for NSAIDs. Therefore, scientific evidence demonstrates that agro-industrial waste is a promising alternative for the removal of emerging pollutants such as pharmaceuticals substances.

Terra Preta production from Ghanaian and Zambian soils using domestic wastes

Quests for productive soils to close yield gaps call for innovative strategies. This study tested an off-site formation of the Amazonian Terra Preta (TP) in a potential modern analogon under coastal savannah climatic conditions of Ghana. Four Ghanaian and two Zambian soils; two types of biochar (i.e., rice husk biochar and charcoal residues); domestic wastes (i.e., kitchen leftovers, animal manures, human urine, and kitchen ash) were mixed with the soils wetted to 100% water holding capacity, and incubated under aerobic conditions for nine months. Indicators of the TP include total carbon (C), pH, base saturation, basic cations, and plant-available P, which were measured using standard methods of soil analysis. The TP formation enhanced soil pH by 0.02 to 2.9, ranging from pH 7.2 to 8.2, with charcoal residues having the highest effect on pH. The modern TP was characterized by relatively high total C, pH, K, Ca, Mg, Na, base saturation, and plant-available P. These properties reflect unique interactions between the chars, wastes, and soils, suggesting the potential for on-site TP formation. It calls for further studies, commitment, and perseverance in their formation in the future.

Adsorption isotherms and removal of lead (II) and cadmium (II) from aqueous media using nanobiochar and rice husk

Removal of Cd(II) and Pb(II) from aqueous solutions is a challenging task and the search for novel adsorbents is underway. This study examined the efficiency of nanobiochar (NB) and rice husk (RH) in the adsorption and removal of Cd(II) and Pb(II) from water. The effect of various physicochemical parameters such as initial pH, initial Cd and Pb concentration, adsorbent dosage, and contact time were tested. SEM/EDX images confirmed the adsorption of Pb and Cd with surface physical and chemical changes. The maximum Pb removal was noted at pH 6 using NB (96%) and at pH 8 for RH (90%), and the maximum Cd removal by NB was recorded at 8 pH (91%) and by RH at pH 6 (87%). The decline in adsorption intensity at lower pH suggested protonation of the adsorbent surface causing cation-cation repulsion. Most of the adsorption occurred within the initial 60 min. A continuous gradual increase in the adsorption with time suggested multilayer formation. Of the three isotherms, the Freundlich model fits the present data best, implying an infinite surface coverage and indicating the potential for multilayer adsorption of Pb and Cd on the surfaces of RH and NB adsorbents. In conclusion, this study highlights the promising potential of NB as a cost-effective adsorbent for the removal of Cd and Pb ions from aqueous solutions.

Characteristic study of Candida rugosa lipase immobilized on lignocellulosic wastes: effect of support material.

For the first time is reported the comparison of solid biocatalysts derived from Candida rugosa lipase (CRL) immobilized on different lignocellulosic wastes (rice husk, brewer's spent grain, hemp tea waste, green tea waste, vine bark, and spent coffee grounds) focusing on the characterization of these materials and their impact on the lipase-support interaction. The wastes were subjected to meticulous characterization by ATR-FTIR, BET, and SEM analysis, besides lignin content and hydrophobicity determination. Investigating parameters influencing immobilization performance revealed the importance of morphology, textural properties, and hydrophobic interactions revealed the importance of morphology, textural properties and especially hydrophobic interactions which resulted in positive correlations between surface hydrophobicity and lipase immobilization efficiency. Hemp tea waste and spent coffee grounds demonstrated superior immobilization performances (7.20 U/g and 8.74 U/g immobilized activity, 102.3% and 33.5% efficiency, 13.4% and 15.4% recovery, respectively). Moreover, they demonstrated good temporal stability (100% and 92% residual activity after 120days, respectively) and retained 100% of their immobilized activity after five reuses in the hydrolysis of p-nitrophenyl palmitate in hexane. In addition, the study of enzymatic desorption caused by ionic strength and detergent treatments indicated mixed hydrophobic and electrostatic interactions in rice husk, vine bark, and spent coffee grounds supports, while hemp tea waste and green tea waste were dominated by hydrophobic interactions.

New Eco-Cements Made with Marabou Weed Biomass Ash

Biomass ash is currently attracting the attention of science and industry as an inexhaustible eco-friendly alternative to pozzolans traditionally used in commercial cement manufacture (fly ash, silica fume, natural/calcined pozzolan). This paper explores a new line of research into Marabou weed ash (MA), an alternative to better-known conventional agro-industry waste materials (rice husk, bagasse cane, bamboo, forest waste, etc.) produced in Cuba from an invasive plant harvested as biomass for bioenergy production. The study entailed full characterization of MA using a variety of instrumental techniques, analysis of pozzolanic reactivity in the pozzolan/lime system, and, finally its influence on the physical and mechanical properties of binary pastes and mortars containing 10% and 20% MA replacement content. The results indicate that MA has a very low acid oxide content and a high loss on ignition (30%) and K2O content (6.9%), which produces medium–low pozzolanic activity. Despite an observed increase in the blended mortars’ total and capillary water absorption capacity and electrical resistivity and a loss in mechanical strength approximately equivalent to the replacement percentage, the 10% and 20% MA blended cements meet the regulatory chemical, physical, and mechanical requirements specified. Marabou weed ash is therefore a viable future supplementary cementitious material.

Enhancing Rice Seedling Growth in Acidic Soil Using Fermented Raw Rice Husk as Soil Amendment

Enhancing Rice Seedling Growth in Acidic Soil Using Fermented Raw Rice Husk as Soil Amendment

Influence of waste glass and rice husk ash on the dynamic compressive properties and variable-angle shear characteristics of concrete after high-temperature treatment: Experimental and numerical study

This study investigates the use of glass sand, glass powder, and rice husk ash in concrete to mitigate the depletion of natural river sand and cement resources. High-temperature environments were simulated using a muffle furnace, and dynamic compression and variable-angle shear tests were conducted to assess the effects of these recycled materials on the mechanical properties of concrete under normal and high-temperature conditions. Results show that while the dynamic compressive strength of ordinary concrete decreases with increasing temperature, the addition of waste glass and rice husk ash enhances strength and modifies the temperature-strength relationship. Rice husk ash increases the strain rate sensitivity, resulting in higher stress rates and more gradual stress-strain curves. Glass sand concrete exhibited improved energy absorption and resistance to dynamic loads, especially with rice husk ash at elevated temperatures. Additionally, concrete containing glass demonstrated superior cohesion and internal friction angles. An improved plastic damage model was validated through simulations, showing enhanced damage resistance in concrete with rice husk ash at temperatures below 400 °C. This study highlights the potential of waste glass and rice husk ash in improving concrete performance and damage resistance.

Selection of suitable filter materials for subsurface flow constructed wetland systems for wastewater treatment in rice noodle handicraft village

This study aims to select suitable filter materials for Subsurface Flow Constructed Wetlands (SSF CW) to treat wastewater from rice noodle handicraft villages, based on a combination of new materials (plastic waste and rice husk) and traditional substrates (limestone, gravel, and sand). Four SSF CW models using different filter materials were tested during three months, including CW1 (limestone, gravel, and sand), CW2 (sand, plastic waste, and gravel), CW3 (sand + rice husk, limestone, and gravel), and CW4 (sand + rice husk, plastic waste, and gravel). The results indicated that CW3 and CW4 systems were more effective to plant growth. Replacing limestone with plastic waste did not show a significant difference in treatment efficiency (p > 0.05), however the addition of rice husk decreased the efficiency of organic matter treatment while increasing nutrient treatment efficiency (p < 0.05). The highest treatment efficiencies for TSS and COD were observed in CW1, at 83.89 ± 1.38 % and 79.56 ± 1.36 %, respectively. Meanwhile, the highest treatment efficiencies for TN, NH4+, and TP were recorded in CW4, at 80.14 ± 2.76 %, 88.39 ± 1.62 %, and 82.22 ± 2.51 %, respectively. The effluent water from all four SSF CW models met the Vietnamese standard for wastewater quality (QCVN 40:2011/BTNMT, column B). This study demonstrates the potential of using a combination of plastic waste, rice husk, and sand as suitable filter substrates for SSF CW in treating wastewater from rice noodle handicraft villages.

Stress-Responsive Gene Expression, Metabolic, Physiological, and Agronomic Responses by Consortium Nano-Silica with Trichoderma against Drought Stress in Bread Wheat

The exploitation of drought is a critical worldwide challenge that influences wheat growth and productivity. This study aimed to investigate a synergistic amendment strategy for drought using the single and combined application of plant growth-promoting microorganisms (PGPM) (Trichoderma harzianum) and biogenic silica nanoparticles (SiO2NPs) from rice husk ash (RHA) on Saudi Arabia’s Spring wheat Summit cultivar (Triticum aestivum L.) for 102 DAS (days after sowing). The significant improvement was due to the application of 600 ppm SiO2NPs and T. harzianum + 600 ppm SiO2NPs, which enhanced the physiological properties of chlorophyll a, carotenoids, total pigments, osmolytes, and antioxidant contents of drought-stressed wheat plants as adaptive strategies. The results suggest that the expression of the studied genes (TaP5CS1, TaZFP34, TaWRKY1, TaMPK3, TaLEA, and the wheat housekeeping gene TaActin) in wheat remarkably enhanced wheat tolerance to drought stress. We discovered that the genes and metabolites involved significantly contributed to defense responses, making them potential targets for assessing drought tolerance levels. The drought tolerance indices of wheat were revealed by the mean productivity (MP), stress sensitivity index (SSI), yield stability index (YSI), and stress tolerance index (STI). We employed four databases, such as BAR, InterPro, phytozome, and the KEGG pathway, to predict and decipher the putative domains in prior gene sequencing. As a result, we discovered that these genes may be involved in a range of important biological functions in specific tissues at different developmental stages, including response to drought stress, proline accumulation, plant growth and development, and defense response. In conclusion, the sole and/or dual T. harzianum application to the wheat cultivar improved drought tolerance strength. These findings could be insightful data for wheat production in Saudi Arabia under various water regimes.

Potential Utilization of Rice Waste in the Construction Sector: A Multi-Criteria Decision Analysis Approach

Effective management of agricultural waste is an important contribution to environmental sustainability and economic development, especially considering the significant volume of agricultural residues produced worldwide. Rice is a widely cultivated crop in Colombia, and its high production results in a high amount of wastes, which is often underutilized due to a lack of knowledge regarding its potential value-added applications. On the other hand, the construction industry has become increasingly aware of the necessity to develop materials with reduced environmental impact. Therefore, this study explores the application of the Analytic Hierarchy Process (AHP) to evaluate various alternatives for utilizing rice waste in construction materials; the alternatives were evaluated based on criteria tailored to the needs of local agricultural communities in the Tolima region of Colombia. The findings highlight the potential of rice husk ash (RHA) as an environmentally responsible alternative in the construction sector, offering a viable solution for waste management while contributing to the economic development of small-scale farmers.

The role of rice husk in Oreochromis niloticus safety enhancement by bio-adsorbing copper oxide nanoparticles following its green synthesis: an endeavor to advance environmental sustainability

Lowering nanoparticles (NPs) toxicity before discharge into aquatic environments and employing agricultural waste materials for environmental sustainability are necessary nowadays. Since this has never been done, this work examines how green CuO NPs treated with rice husk (RH) as a bio-adsorbent may be safer for Nile tilapia (Oreochromis niloticus) than chemically manufactured ones. So, five groups of fish were randomly placed in glass aquaria. One group was a control, and four groups received 50 mg/L green and chemically produced CuO NPs (GS and CS) with and without RH for 24, 48, and 96 h. RH was collected from all groups, and the results showed GS-CuO NPs had a greater adsorptive capacity than CS-CuO NPs after all time intervals. After analyzing fish indicators in all groups compared to the control, higher Cu bioaccumulation was exhibited in the liver and gills. The liver and gills showed elevated levels of glutathione peroxidase (GPx), catalase (CAT), and thiobarbituric acid reactive substances (TBARS), while the levels of glutathione reduced (GSH) were significantly lower. In addition, Cu exposure impaired liver and gill histology. Finally, our results indicated that using RH as an adsorbent for CuO NPs after their green synthesis instead of chemical synthesis before they enter the aquatic environment can enhance the overall health of fish and environmental sustainability.

Molecular docking and controlled release of NPK nanocomposites using mesoporous nanosilica synthesized from rice husk

Molecular docking and controlled release of NPK nanocomposites using mesoporous nanosilica synthesized from rice husk

Biochar addition influences C and N dynamics during biochar co-composting and the nutrient content of the biochar co-compost

This study investigated the effects of corn cob biochar (CCB) and rice husk biochar (RHB) additions (at 0%, 5%, and 10% w/w) on nitrogen and carbon dynamics during co-composting with poultry litter, rice straw, and domestic bio-waste. The study further assessed the temperature, moisture, pH, and nutrient contents of the mature biochar co-composts, and their potential phytotoxicity effects on amaranth, cucumber, cowpea, and tomato. Biochar additions decreased NH4+-N and NO3- contents, but bacteria and fungi populations increased during the composting process. The mature biochar co-composts showed higher pH (9.0–9.7), and increased total carbon (24.7–37.6%), nitrogen (1.8–2.4%), phosphorus (6.5–8.1 g kg−1), potassium (26.8–42.5 g kg−1), calcium (25.1–49.5 g kg−1), and magnesium (4.8–7.2 g kg−1) contents compared to the compost without biochar. Germination indices (GI) recorded in all the plants tested with the different composts were greater than 60%. Regardless of the biochar additions, all composts treatments showed no or very minimal phytotoxic effects on cucumber, amaranth and cowpea seeds. We conclude that rice husk and corn cob biochar co-composts are nutrient-rich and safe soil amendment for crop production.

Rice husk biochar is more effective in blocking the cadmium and lead accumulation in two Brassica vegetables grown on a contaminated field than sugarcane bagasse biochar.

Heavy metal-contaminated soil has a great impact on yield reduction of vegetable crops and soil microbial community destruction. Biochar-derived waste biomass is one of the most commonly applied soil conditioners in heavy metal-contaminated soil. Different heavy metal-contaminated soil added with suitable biochars represent an intriguing way of the safe production of crops. This study investigated the effects of two types of biochar [rice husk biochar (RHB) and sugarcane bagasse biochar (SBB)] on Cd and Pb accumulation in Shanghaiqing (SHQ, a variety of Brassica campestris L.) and Fengyou 737 (FY, a variety of Brassica napus), as well as on the soil microbial community, through a field experiment. RHB and SBB were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmet-Teller method. The results showed that RHB and SBB displayed the higher pH, cation exchange capacity and pore properties, and the addition of RHB and SBB enhanced soil pH and rhizosphere microorganisms promoting vegetables yield. RHB treatments were more effective than SBB in reducing upward transfer of Cd and Pb, blocking the accumulation of Cd and Pb in the edible parts of SHQ and FY, and decreasing soil Cd and Pb bioavailability. Additionally, RHB and SBB changed the composition of the rhizosphere soil microbial community. The application of biochar promoted the growth of ecologically beneficial bacteria (Nitrospira, Opitutus, and Gemmatimonas) and fungi (Mortierella and Holtermanniella), whereas reducing the enrichment of plant pathogenic fungi (Alternaria, Stagonosporopsis, Lectera, and Periconia) in rhizosphere soil. Our findings demonstrated that the application of RHB significantly reduces Cd and Pb accumulation in the edible parts by decreasing the soil Cd and Pb bioavailability and altering the rhizosphere microbial community composition in two Brassica vegetables grown on Cd/Pb-contaminated soils. Thus, the application of two biochar, especially RHB is a feasible strategy for the safe production of vegetable crops in Cd/Pb co-contaminated soils.

Characterisation and properties of Nanohybrid Dental Composite (NhDC) reinforced with zirconia and alumina

A trial nanohybrid dental composite (NHDC) was developed using silica extracted from biowaste rice. Aim: This study aims to test the effect of mixture of the silica and other filler which is zirconia and alumina, focusing on the characterization and their properties. Nano-silica obtained from rice husk was used as NHDC filler. Methods: Nanosilica white powder, derived from rice husk, was used. There were three groups: Group I, Zr (2%) and Al (3%); group II, Zr (3%) and Al (2%); and group III, Zr (3%). The distribution of filler particles and the chemical structure of filler particles were determined by FESEM images and FTIR test. Then, testing on Vickers hardness (VHN) and fracture strength (FS) of the samples was performed. Results: The distribution of filler particles showed a uniform distribution, and each peak element of the fillers was shown in the FTIR spectrum images. There was significantly increased on VHN and FS after addition of zirconia and alumina. Conclusion: This study concluded that zirconia and alumina strengthen the NHDC properties with addition of zirconia and alumina filler.

Evaluation of Fresh and Hardened Properties of Concrete made with Rice Husk Ash admixed with Snail Shell Ash

Evaluation of Fresh and Hardened Properties of Concrete made with Rice Husk Ash admixed with Snail Shell Ash