Pyrolysis Of Rice Husk Research Articles

Cleanup of water polluted with crude oil or diesel fuel using rice husks ash

The sources of contamination of fresh and seawater are most often spills of oil and oil products by accidents with tankers or underwater pipes, as well as offshore oil platforms and oil refineries. Moreover the ships produce a large amount of oily wastewater such as bilge water which needs to be treated prior to being discharged. The bilge water is a difficult wastewater to treat as it contains seawater, particulates, used oils and detergents. Micro- and ultrafiltration are often the methods of choice to treat this water. The pretreatment of this oily wastewater prior to ultrafiltration is desirable, as the used oils and particulates can block the feed channels of the ultrafilters spiral and hollow fiber modules. In this reason, at the last time different hybrid adsorbents with high adsorption capacity and appropriate porous structure are used. The present study is an attempt to establish the possibilities to obtain black rice husk ash (BRHA) and white rice husks ash (WRHA) via pyrolysis of raw rice husks in a pilot plant fluidized-bed reactor at different conditions. The products obtained are characterized using X-ray diffraction patterns, scanning electron microscopy, FT-IR spectroscopy, thermal analysis, and low temperature nitrogen adsorption. Using batch adsorption technique, the kinetics was studied and the adsorption capacities of crude oil and diesel fuel at different temperatures as well as some hydrocarbons at 298 K onto BRHA and WRHA are determined. It was established that BRHA have been higher adsorption capacity than WRHA. At a given temperature, BRHA sorbed more crude oil than diesel fuel. The results obtained showed that the material studied has high adsorption capacity and low cost and may successfully be used as an effective adsorbent to cleanup of bilge water and spills of oil and oil products in water basins. Because the saturated BRHA with crude oil, diesel fuel or different hydrocarbons are characterized with high calorific, they can be burnt in incinerators, industrial ovens or steam generators. By this way we attain not only ecological but also economical effect.

Kinetics of oil and oil products adsorption by carbonized rice husks

Composite C/SiO 2 containing material has been obtained by pyrolysis of rice husks, carried out at a temperature of 480 °C. The material has been studied as adsorbent for purification of pollutions caused by oil and oil products. The amount and composition of the fluids, dispersed on the surface of the carbonized rice husks, has been determined applying extraction and gas chromatography–mass spectrometry method (GC–MS). The material has been characterized also with respect to the specific surface area by Brunauer–Emmett–Teller (BET) method and mercury porosimetry. Adsorption capacity of the pyrolyzed rice husks was determined in respect of water, oil and petroleum products with different densities. The material obtained by pyrolysis of rice husk has very good buoyancy characteristics, high oil sorption capacity and high hydrophobicity. The influence of the bulk density of the sorbent has been investigated as well as that of the density of the oil product on the kinetics and mechanism of sorption. It was established that the dependence between the bulk density of the adsorbent and the height of penetration of the oil in it for a specified time is inversely proportional. The height of penetration of the sorbate in the sorbent layer depends on the density of the liquid phase. The changes of the adsorption rate for the various oil products can be described by hyperbolic dependence. A correlation between surface functional groups and morphology of the adsorbent and adsorption properties of the material was created. The research provides the basis for development of a new environmental material with optimal characteristics, providing efficient adsorption of oil and oil products from aqueous medium.

Effect of temperature on gas composition and char structural features of pyrolyzed agricultural residues

The gases and chars produced during fast pyrolysis of maize stalk, rice straw, cotton straw and rice husk at temperatures ranging from 600 to 1000°C were studied by Fourier transform infrared spectroscopy, non-dispersive infrared technique, thermal conductivity detection method, ultimate analysis, X-ray diffraction, helium density measurement and N2 adsorption method. The gas yield increased by more than 80% from 600 to 1000°C, while the char and liquid yield decreased. The content of CO2, CO and CH4 accounted for more than 86%. The CO and CH4 content increased with temperature, while the CO2 content decreased. The hydroxyl, aliphatic CH, carbonyl, olefinic CC and ether groups were lost above 800°C. Carbon skeleton shrinkage increased by more than 23% when the temperature increased from 600 to 1000°C. Maximum porosity appeared at 900°C. This study revealed the relationships between gas composition/char properties and pyrolysis temperature under high heating rate conditions.

Preparation of carbon black from rice husk by hydrolysis, carbonization and pyrolysis

Carbon black is a form of amorphous carbon that is produced by incomplete combustion of petroleum- or some plant-derived materials and has a number of industrial uses. A process consisting of hydrolysis, carbonization and pyrolysis of rice husk was developed. Under optimal hydrolysis conditions (72wt.% sulfuric acid, 50°C, 10min), a hydrolysis ratio of 52.72% was achieved. After carbonization of the hydrolysis solution by water bath, the solid carbon was further pyrolyzed. As the pyrolysis temperature was increased from 400 to 800°C, the carbon content increased from 83.41% to 94.66%, the number of O–H, C–H, CO, and CC surface functional groups decreased, and based on Brunauer–Emmett–Teller (BET) results, the specific surface area and pore volume of carbon black increased from 389 to 1034m2/g and from 0.258 to 0.487cm3/g, respectively. X-ray diffraction pattern (XRD) and Raman spectroscopy analyses of samples pyrolyzed at 400–800°C showed a localized graphitic structure. It is possible that the hydrolysis/carbonization/pyrolysis process developed in this study could also be applicable to the preparation of carbon black from other types of biomass.

Characterisation of bio-oil from fast pyrolysis of rice husk in a fluidised bed reactor

Fast pyrolysis of rice husk was conducted to produce bio-oil. The physical–chemical properties of the bio-oil were analysed. The results show that bio-oil has relatively high water content (47·05%), high ash content (0·29%), high carbon residue (5·84%) and low higher heating value (16·42 MJ kg−1). The density, kinetic viscosity at room temperature and pH value of the bio-oil were 1100 kg m−3, 3·41 mm2 s−1 and 3·23 respectively. Simultaneously, the kinetic viscosity of the bio-oil decreases significantly with increasing measurement temperature from 25 to 100°C, and its prominent viscosity–temperature characteristics were proved. Analysis of chemical functional groups and chemical structure of the bio-oil through Fourier transformation infrared spectrometer and Fourier transformation nuclear magnetic resonance technologies demonstrated the complexity of chemical compositions of the rice husk bio-oil.

Reduction in time required for synthesis of high specific surface area silica from pyrolyzed rice husk by precipitation at low pH

Porous silica with a high specific surface area (SSA) was prepared from pyrolyzed rice husk (PRH) by adding H 3PO 4 to sodium silicate solution (SSS) until the pH values of 5.7, 5.0, 4.1 and 3.2 were achieved. The preparation process involved producing SSS from PRH, forming silica-polyethylene glycol (PEG) composites using SSS, H 3PO 4 and PEG, and calcinating the composites. The required preparation time was below 10 h, and the SSA of the sample prepared at pH 3.2 reached 1018 m 2/g. Decreasing pH significantly increased the amount of PEG incorporated into the silica-PEG composites, and hence more pores were generated in the lower pH sample when the PEG was destroyed by calcination at 500 °C. The process developed in this study could lead to more efficient conversion of rice husk into high value-added porous materials that might be used for the adsorption of gas and heavy metal ions.

Properties of Bio-oil from Fast Pyrolysis of Rice Husk

Physicochemical properties of bio-oil obtained from fast pyrolysis of rice husk were studied in the present work. Molecular distillation was used to separate the crude bio-oil into three fractions viz. light fraction, middle fraction and heavy fraction. Their chemical composition was analyzed by gas chromatograph and mass spectrometer (GC-MS). The thermal behavior, including evaporation and decomposition, was investigated using thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). The product distribution was significantly affected by contents of cellulose, hemicellulose and lignin. The bio-oil yield was 46.36% (by mass) and the yield of gaseous products was 27% (by mass). The chemicals in the bio-oil included acids, aldehydes, ketones, alcohols, phenols, sugars, etc. The light fraction was mainly composed of acids and compounds with lower boiling point temperature, the middle and heavy fractions were consisted of phenols and levoglucosan. The thermal stability of the bio-oil was determined by the interactions and intersolubility of compounds. It was found that the thermal stability of bio-oil was better than the light fraction, but worse than the middle and heavy fractions.

Bio-oil from pyrolysis of rice husk

Rice husk being the hard protective covering of the grain of rice (paddy), is considered as a massive agricultural residue. Pyrolysis of rice husk for the production of bio-oil wastaken into consideration in this study. Pyrolysis was performed at 400°C to 650°C under vacuum. The optimum condition of rice husk pyrolysis was 550°C for 30 minutes. The products of the rice husk pyrolysis were liquid bio-oil, solid char and gaseous mixture. The optimum yield of bio-oil was 47 wt% of dry rice husk sample. The isolated bio-oil was analysed to determine the fuel properties such as calorific value, viscosity, density, pour point, flash point, water content etc. and same were found to be 16 MJ/kg, 2.19 cSt, 1.06 g/cc, -11°C, 115°C, and 25 wt%, respectively. The obtained values were then compared with typical bio-oil characteristics. The physico-chemical characterisation of bio-oil was carried out by FT-IR spectroscopy, ICP-OES and TG analysis. The bio-char was characterised for its suitability to be used as fuel as well as adsorbent by measuring its calorific value, surface area and by methylene blue adsorption test.

Model construction and application for rice husk pyrolysis

Model construction and application for rice husk pyrolysis

Thermogravimetric analysis and the optimisation of bio-oil yield from fixed-bed pyrolysis of rice husk using response surface methodology (RSM)

The effects of pyrolysis temperature, heating rate, particle size, holding time, and gas flow rate were investigated to optimize bio-oil yield from rice husk pyrolysis. Thermogravimetric analysis showed thermal degradation of hemicellulose, cellulose and lignin, indicating faster decomposition of cellulose compared to lignin. The optimisation process was analysed by employing central composite design (CCD) in response surface methodology (RSM) using Design Expert Version 7.5.1 (StatEase, USA). A two-level fractional factorial was initially carried out and followed by RSM. The statistical analysis showed that pyrolysis temperature, heating rate, particle size and holding time significantly affected the bio-oil yield. By utilising response surface method, these four factors were investigated, analysed and optimal conditions were obtained at pyrolysis temperature of 473.37°C, heating rate of 100°C/min, particle size of 0.6mm and holding time of 1min. Confirmation runs gave 48.30% and 47.80% of bio-oil yield compared to 48.10% of predicted value. Furthermore, the pyrolytic bio-oils obtained from fixed-bed pyrolysis were examined using gas chromatographic/mass spectroscopy (GC/MS), Fourier transform infrared (FTIR) methods, elemental analyzer, pH probe and bomb calorimeter.

Treatment of p‐nitrophenol in an adsorbent‐supplemented sequencing batch reactor

The objective of this research was to evaluate the treatment of p‐nitrophenol (PNP) as a sole organic carbon source using a sequencing batch reactor (SBR) with the addition of adsorbent. Two types of adsorbents, namely powdered activated carbon (PAC) and pyrolysed rice husk (PRH) were used in this study. Two identical SBRs, each with a working volume of 10 L, were operated with fill, react, settle, draw and idle periods in the ratio of 2:8:1:0.75:0.25 for a cycle time of 12 h. The results showed that, without the addition of adsorbent, increasing the influent PNP concentration to 200 mg/L resulted in the deterioration of chemical oxygen demand (COD) removal efficiency and PNP removal efficiency in the SBRs. Improvement in the performance of the SBR was observed with the addition of PAC. When the dosage of 1.0 g PAC/cycle was applied, COD removal of 95% and almost complete removal of PNP were achieved at the influent PNP concentration of 300 mg/L. The kinetic study showed that the rates of COD and PNP removal can be described by the first‐order kinetics. The enhancement of performance in the PAC‐supplemented SBR was postulated to be due to the initial adsorption of PNP by the freshly added and the bioregenerated PAC, thus reducing the inhibition on the microorganisms. The PRH was found to be ineffective because of its relatively low adsorption capacity for PNP, compared with that of PAC.

Fast pyrolysis of rice husk under different reaction conditions

In this work, rice husk, an agricultural waste in Korea, was pyrolyzed under different reaction conditions (temperature, flow rate, feed rate, and fluidizing medium) in a fluidized bed with the influence of reaction conditions upon characteristics of the bio-oil studied. The optimal pyrolysis temperature for bio-oil production was found to be between 400 and 450 °C. Higher flow rates and feeding rates were more effective for its production. The use of the product gas as the fluidizing medium led to the highest bio-oil yield. With the exception of temperature, no single operation variable largely affected the physicochemical properties of the bio-oil.

Bioregeneration of activated carbon and activated rice husk loaded with phenolic compounds: Kinetic modeling

A kinetic model consisting of first-order desorption and biodegradation processes was developed to describe the bioregeneration of phenol- and p-nitrophenol-loaded powdered activated carbon (PAC) and pyrolyzed rice husk (PRH), respectively. Different dosages of PAC and PRH were loaded with phenol or p-nitrophenol by contacting with the respective phenolic compound at various concentrations. The kinetic model was used to fit the phenol or p-nitrophenol concentration data in the bulk solution during the bioregeneration process to determine the rate constants of desorption, k d , and biodegradation, k. The results showed that the kinetic model fitted relatively well ( R 2 > 0.9) to the experimental data for the phenol- and p-nitrophenol-loaded PAC as well as p-nitrophenol-loaded PRH. Comparison of the values of k d and k shows that k is much greater than k d . This indicates clearly that the desorption process is the rate-determining step in bioregeneration and k d can be used to characterize the rate of bioregeneration. The trend of the variation of the k d values with the dosages of PAC or PRH used suggests that higher rate of bioregeneration can be achieved under non-excess adsorbent dosage condition.

Experimental study of the effect of acid-washing pretreatment on biomass pyrolysis

The influence of acid-washing pretreatment on biomass pyrolysis was experimentally studied in a radiation reactor. The results show that the metal ions content of rice husk treated by acids is reduced markedly. The yield of tar from pyrolysis of rice husk treated by 7% HCl increased from 41.74 to 52.88%, and the yields of gas and char decrease. The influence will be more remarkable with the increase of acid concentration. The gaseous products of pyrolysis of HCl-treated rice husk mainly consist of CO and CO 2 which yields decreased metal ions content when compared with those of the raw sample. The effects of H 2SO 4, HCl, and H 3PO 4 on biomass pyrolysis are different. HCl has the strongest effect on the pyrolysis products distribution because of the least amounts of K + remained after HCl treatment. The microstructures of biomass are damaged seriously by H 2SO 4 treatment.

PENGOLAHAN SEKAM PADI MENJADI BAHAN BAKAR ALTERNATIF MELALUI PROSES PIROLISIS LAMBAT

The aim of this research is to investigate the characteristic of alternative fuel obtained from slow pyrolysis of rice husk. The focus of this research is on the chemical characteristics, the physical characteristics and the performance of stove that using bio oil from slow pyrolysis of rice husk. The reseach was conducted experimentally in the laboratory. The construction of the slow pyrolysis reactor was an externally heating double pipe counter current flow heat exchanger. The rice husk was entered the reactor using a screw conveyor. The mass flow rate of rice husk was 5 kg/h. The reactor temperature at the wall near the flame source was controlled at 300, 400, and 500oC. The moisture contents of the rice husk were about 10,1% and 20,7%. There were three valuable products, i.e. the upper part of the bio oil, the bottom part of the bio oil, and the char. The upper part of the bio oil can be used for making bio briquette binder. The bottom part of the bio oil can be used as stove fuel after mixed with the ethanol. The char can be used as carbonization briquette. The substances in the bio oil was detected by GCMS (Gas Chromatography-Mass Spectrometry) and showed that more than 15 substances were detected. The bio oil was not stable in storage more than 7 days. The stove performance using blending of bio oil and ethanol was measured by water boiling method (WBT) and was calculated around 34,3%.

Preparation of carbonized rice husk monoliths and modification of the porous structure by SiO 2 leaching

The possibility of preparing honeycomb monoliths from unconventional materials with high adsorption capacity, such as carbonized rice husk (CRH), was studied. Two schemes including modification of the porous structure by silica leaching were suggested for preparation of the monoliths: (1) preparation of CRH monoliths with the addition of Ca-montmorillonite (Ca-M) followed by leaching and (2) preliminary leaching of initial components followed by monolith extrusion. Chemical and textural properties of the materials were studied at each preparation step. The effect of temperature of rice husk (RH) pyrolysis and conditions of leaching treatment on the physico-chemical properties of CRH was investigated. By the data of nitrogen adsorption and SEM characterization, CRH has low specific surface area, pore volume less than 0.1 cm 3/g, and composed mainly of macropore channels 5–10 μm in diameter, micropores less than 17 Å in size, and a minor amount of mesopores. Treatment of the carbonized product with a 12% solution of potassium hydroxide at 80–100 °C leads to a 90–95% leaching of SiO 2 from the CRH composite and increases the specific surface area to 400 m 2/g and pore volume to 0.4 cm 3/g due to formation of mesoporous structure. The feasibility of CRH honeycomb monoliths preparation and applicability of silica leaching from the monolith material for modification of the porous structure are demonstrated. The resulting monoliths are characterized by specific surface area exceeding 300 m 2/g, pore volume 0.3 cm 3/g, and high mechanical strength.

Effect of temperature on morphology and phase transformations of nano-crystalline silica obtained from rice husk

Pyrolysis of rice husk (RH), an agricultural by-product, was studied at different temperatures (700–1100°C) in the presence of air. The changes in morphologies, compositions and phase transformations were studied critically by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry, respectively. Different phases of silica obtained from RH were observed with respect to change in temperatures. Crystallite size and the amount of silica obtained from RH at each temperature were worked out using X-ray diffractometer (XRD) plots. Nano-crystalline silica could be revealed (4.87–18.61 nm) from charred RH at different temperatures (700–1100°C). The amount of silica with respect to other carbonaceous volatile matter was calculated from the XRD plot. Acid treatment (1 : 1 HCl) of RH was also done to remove the metallic impurities. A thermal analysis of raw RH was done to study the decomposition and energy changes in it.

Quantification of bioregeneration of activated carbon and activated rice husk loaded with phenolic compounds

The bioregeneration efficiencies of powdered activated carbon (PAC) and pyrolyzed rice husk loaded with phenol and p-nitrophenol were quantified by oxygen uptake measurements using the respirometry technique in two approaches: (i) simultaneous adsorption and biodegradation and (ii) sequential adsorption and biodegradation. It was found that the applicability of the simultaneous adsorption and biodegradation approach was constrained by the requirement of adsorption preceding biodegradation in order to determine the initial adsorbent loading accurately. The sequential adsorption and biodegradation approach provides a good estimate of the upper limit of the bioregeneration efficiency for the loaded adsorbent in the simultaneous adsorption and biodegradation processes. The results showed that the mean bioregeneration efficiencies for PAC loaded with phenol and p-nitrophenol, respectively, obtained using the two approaches were in good agreement.

Upgrading of Bio-oil over Aluminum Silicate in Supercritical Ethanol

The crude bio-oil from fast pyrolysis of rice husk was upgraded in supercritical ethanol using aluminum silicate as a catalyst. The results showed that the supercritical upgrading process performed effectively and the components of upgraded bio-oil were optimized greatly. Acidic aluminum silicate facilitates esterification in supercritical ethanol to convert most acids contained in crude bio-oil into various kinds of esters. The amount of phenols that exist extensively in crude bio-oil decreased during the supercritical upgrading process. Aldehydes, such as furfural and vanillin, which are typically present in crude bio-oil, were removed during the supercritical upgrading process and not detected in upgraded bio-oil. The residue of distillated upgraded bio-oil decreased evidently compared to that of distillated crude bio-oil. The density and kinematical viscosity of upgraded bio-oil decreased compared to that of crude bio-oil. The pH value and heating value of upgraded bio-oil increased compared to that of crude bio-oil. The changes of these properties showed that the quality of upgraded bio-oil was improved.

Characterization of char from rapid pyrolysis of rice husk

In the present study, one process was selected for a fundamental study of structural evolution during rapid pyrolysis, as well as for the study of the influence of such evolution on char reactivity. Chars were prepared at different situations from rice husk. The reactivity of resultant chars was measured using non-isothermal thermogravimetric analysis. The structure of fresh and partly reacted chars was characterized using proximate and ultimate analyses, physical adsorption/desorption measurements of N 2 (− 196 °C), mercury intrusion porosimetry (414 MPa), FTIR, Helium pycnometer as well as samples visualization by scanning electronic microscopy (SEM). Appreciable differences in the physical characteristics, depending markedly on the pyrolysis stage, were observed. SEM observation showed that surface of pore in char particle became increasingly rough in the middle of pyrolysis. Micropore characteristics obtained from adsorption/desorption measurement were complex. Release of volatile material led to the development of pores with different changing trends. The surface area of char increased with pyrolysis process to a maximum value of 56.95 m 2/g at pyrolysis reaction ratio ( R p = 0.90). Macropores in char particles which were evaluated by mercury intrusion porosimetry indicated that the porosity increases continually. Combined the analysis result of density with porosity data, it was showed that particle shrinkage happened at the first stage of rapid pyrolysis. The H/C, O/C and N/C ratios of the char changed with different trends when the pyrolysis reaction ratio increased. Furthermore, FTIR studies indicated a gradual decrease in the intensities of OH, C–H and C–O stretches with pyrolysis process. At the end of reaction, most bands disappeared, resulting in a char that was mainly an aromatic polymer of carbon atoms.