Removal Of Silica Research Articles

Towards zero emission concepts: High content colloidal silica removal by using paper sludge ash as inorganic coagulant

Zero emission could be defined as using resources effectively and prevent resources depletion, or activities that are being carried out to curb waste generation, reduce emissions, in order to achieve the maximum usage of wastes through loop recycling. This research goes online with this concept in which paper sludge ash (PSA) was utilized as inorganic coagulant for the treatment of wastes from semiconductors industries. Coagulation and flocculation experiments were carried out to assess the ability of the inorganic coagulant to remove high concentration colloidal silica wastes from microelectronics industry. Three different parameters were investigated, pH, coagulant dosage, and temperature. Surprisingly high removal efficiency was obtained when pH was higher than 8. The optimum coagulant dosage was 0.25 g of inorganic coagulant per 1gram of silica at concentration of 1.8% colloidal silica. Temperature was carried out under mild conditions from (10-40 oC). Increasing the coagulant dose at 20 oC or lower could help to achieve clear effluent. Long-term operating data were gathered by using continuous flow with Hi Biah System (HBS) for treatment actual wastes. Average results obtained for the fluent for TN, TP, T. Si, COD, BOD and S.S were 11, < 1, < 50, 10, 12 < 50PPM, 16 PPM, and <100 PPM respectively.

Electrochemical capacitive energy storage in PolyHIPE derived nitrogen enriched hierarchical porous carbon nanosheets

Porous and interconnected electrodes based on carbon nanoarchitectures offer comprehensive advantages of large specific surface area and high porosity consequently increasing the specific capacitance of ultracapacitor energy storage systems. Emulsion-templated polymers, PolyHIPEs (Polymerized High Internal Phase Emulsions) are highly porous polymers with a structure of cages interconnected by windows thus provide suitable framework to create such porous carbon nanostructures. Herein, nitrogen enriched porous carbon nanosheets are synthesized by pyrolysis of polymer-silica hybrid PolyHIPE and subsequent silica removal. This nitrogen enriched porous carbon nanosheets when tested as an electrode for ultracapacitor, showed specific capacitance as high as 209 F/g at a current density of 1 A/g in 1 M H2SO4with excellent capacity retention over long cycling.

Exceptional selectivity for dissolved silicas in industrial waters using mixed oxides

The removal of silica, ubiquitous in produced and industrial waters, by novel mixed oxides is investigated in this present study. We have combined the advantage of high selectivity hydrotalcite (HTC, (Mg6Al2(OH)16(CO3)·4H2O)), with large surface area of active alumina (AA, (Al2O3)) for effective removing of the dissolved silica from cooling tower water. The batch test results indicated the combined HTC/AA is a more effective method for removing silica from CTW than using each of HTC or AA separately. The silica uptake was confirmed by Fourier transform infrared (FTIR), and Energy dispersive spectroscopy (EDS). Results indicate HTC/AA effectively removes silica from cooling tower water (CTW), even in the presence of large concentrations of competing anions, such as Cl−, NO3− HCO3−, CO32− and SO42−. The Single Path Flow Through (SPFT) tests confirmed to rapid uptake of silica by combined HTC/AA during column filtration. The experimental data of silica adsorption fit best to Freundlich isotherm model.

Upgraded Seawater-Alkaline Pre-Treatment of Lignocellulosic Biomass for Bio-Methane Production

The presence of lignin in lignocellulosic biomass leads to a protective barrier that prevents plant cell destruction by fungi and bacteria for conversion to bio-methane gas. Therefore, the aim of this study was to evaluate the effects of upgraded seawater with NaOH, NaCO2 and palm kernel ash (PKA) to produce the best alkaline solution in order to convert lignin and increase the fermentable sugars content in oil palm empty fruit bunch (OPEFB). In this study, alkaline pretreatment of EFB is carried out at room temperature using different concentration of alkaline solution which are 5%, 10%, 15% and 20% w/v of chemical (NaOH, Na2CO3 and PKA) and seawater for 48 hours. OPEFB in a size of 0.5 – 1.0 mm was soaked into the NaOH and Na2CO3 solution for 48 hours at room temperature. The surface morphology analysis of lignocellulosic biomass after pre-treatment were done by using scanning electron microscopic (SEM). Analysis of delignification using Kappa Number showed that the highest percentage of delignification were 86.6%, 69.8% and 58.8% by using concentration of 5% NaOH, 15% Na2CO3 and 20% PKSA, respectively. Morphological change on OPEFB was found when silica was cracks and creating a pore during pre-treatment. This significant increase in reducing sugar yields due to removal of silica and lignin. The results of FTIR showed lignocellulose were removed effectively from EFB fiber. This observation also supported FTIR and SEM analysis that showed significant changes in lignin structure throughout the pre-treatment process. Interestingly, with respect to all factors, upgraded seawater with NaOH demonstrated the highest delignification and fermentable sugar production.

Synthesis of self N-doped carbonaceous nanorods as stable lithium-ion battery anode materials

It’s meaningful to design and fabricate novel high-performance carbon anode materials for lithium ion batteries (LIBs). Herein, 3-aminophenol-formaldehyde resin/silica nanorods were synthesized via a sol–gel transcription method, using cetyltrimethyl ammonium bromide as the template and pentanol as co-structure directing agent. After carbonization at 600°C and removal of silica, carbonaceous nanorods with N content of 7.87wt% and specific surface area of 551.3m2g−1 were obtained. They showed a stable discharge capacity of 696.7mAhg−1 after 400 cycles. Carbonaceous nanorods (comprising 9.6wt% β-SiC) with N content of 1.22wt% and specific surface area of 1079.1m2g−1 were also obtained at 1400°C. They showed a stable discharge capacity of 457.9mAhg−1 after 400 cycles. The results prove that the synthesized N-doped carbonaceous nanorods are good anode candidates for LIBs.

Silica Removal from Rice Straw To Improve its Hydrolysis and Ethanol Production

Rice straw has high silica content compared with other lignocelluloses. Presence of silica in the outer layer of rice straw reduces enzymatic hydrolysis and ethanol production yield. In this study, silica removal from rice straw was investigated through various alkali treatments. The results showed that sodium carbonate could effectively remove silica from the straw (>91%). To investigate only the effects of silica removal and eliminate the effect of lignin removal on enzymatic hydrolysis, organosolv followed by sodium carbonate pretreatment was conducted. Organosolv pretreatment removed most of the straw lignin, while silica was not separated. Organosolv pretreatment of rice straw improved the glucose and ethanol yield from 34.4% and 39.3% for the untreated straw to only 52.9% and 51.6%, respectively, whereas further treatment with sodium carbonate increased the yields up to 94.8% and 78.7%. The results indicated that the protecting effect of silica layer was greater than that of lignin in rice straw.

Synergistic efficiency of the desilication of brackish underground water in Saudi Arabia by coupling γ-radiation and Fenton process: Membrane scaling prevention in reverse osmosis process

One of the main water resources in arid Saudi Arabia is underground water. However, this brackish water has high silica content which can cause a recalcitrant deposit on the membrane in the reverse osmosis units during its desalination. In this study, we examined the synergistic efficiency of the removal of silica from the Buwaib water sample, when combining two advanced oxidation processes, γ-irradiation and the Fenton process, using hydrogen peroxide and zero valent metal iron as source of Fe3+. This latter adsorbs effectively on silica and co-precipitate. The influence of absorbed dose, iron dosage and pH effect were investigated. This preliminary study showed that these attractive and effective hybrid processes are very efficient in removing silica.

A novel photobiological process for reverse osmosis concentrate treatment using brackish water diatoms

Abstract A unique aqueous silica removal process using naturally occurring diatoms for water reuse and desalination is described. Several strains of brackish water diatoms have been isolated and tested. Among them Pseudostaurosira and Nitzschia species showed promise. Reverse osmosis (RO) concentrate samples from two full-scale advanced water purification facilities and one brackish groundwater RO plant in Southern California have been successfully treated by this process. This new photobiological process could remove aqueous silica, as well as phosphate, ammonia, nitrate, calcium, iron and manganese very effectively. Under non-optimized conditions, 95% of 78 mg·L−1 reactive silica in an RO concentrate sample could be removed within 72 hours. In most cases, addition of nutrients was not necessary because the RO concentrate typically contains sufficient concentrations of macronutrients derived from the source water (i.e., treated wastewater and brackish groundwater). Preliminary characterization of organics indicated that there was no major generation of dissolved organics, which could potentially foul membranes in the subsequent RO process. This new algal process has a strong potential for its application in desalination and water reuse in the United States and around the world.

Single‐Handed Helical Carbonaceous Nanotubes: Preparation, Optical Activity, and Applications

Carbon-based nanomaterials have been widely studied in the past decade. Three approaches have been developed for the preparation of single-handed helical carbonaceous nanotubes. The first approach uses the carbonization of organopolymeric nanotubes, where the organic polymers are polypyrrole, 3-aminophenol-formaldehyde resin, and m-diaminobenzene-formaldehyde resin. The second approach uses the carbonization of aromatic ring-bridged polybissilsesquioxane followed by the removal of silica. Micropores exist within the walls of the carbonaceous nanotubes. The third approach uses the carbonization of organic compounds within silica nanotubes. This hard-templating approach drives the formation of helical carbonaceous nanotubes containing twisted carbonaceous nanoribbons. All of these helical carbonaceous nanotubes exhibit optical activity, which is believed to originate from the chiral π-π stacking of aromatic rings. They can be used as chirality inducers, and for lithium-ion storage.

D/H of late Miocene meteoric waters in Western Australia: Paleoenvironmental conditions inferred from the δD of (U-Th)/He-dated CID goethite

Nineteen (U-Th)/He ages were determined for eight samples from a core drilled in an ore-grade channel iron deposit (CID) of the Robe Pisolite (Robe Formation) of Mesa J in Western Australia. With one exception, uncorrected ages of the analyzed aliquots range from 6.7(±0.4) Ma to 30.2(±3.1) Ma, while molar ratios of Th/U range from 0.42 to 5.06. The exception is an aliquot with an apparent age of 2.7Ma and Th/U of 5.70. A three-component mixing model involving one generation of goethite and two generations of hematite suggests that the age of crystallization of the oolitic goethites is ∼7(±1) Ma. If so, the goethites have effectively been closed systems for ∼7 million years and should preserve a stable hydrogen isotope record of late Miocene rainfall in the vicinity of Mesa J. Cenozoic movement of the Australian continent had placed Mesa J and environs in the subtropics at a paleolatitude of about 29°S during the late Miocene.Al-adjusted δD values of oolitic goethite in the eight CID samples range from −153‰ to −146‰ and imply that the δD of the late Miocene meteoric waters ranged from −61‰ to −53‰, with an average of −56‰. These relatively negative δD values might indicate that near-coastal, late Miocene rain was derived primarily from summer-season tropical cyclones with storm tracks that extended into the subtropics of western Australia. The postulated late Miocene tropical cyclones would have occurred more often and/or exhibited greater intensity at a paleolatitude of 29°S than is the case for modern sites at approximately 30°S on the west coast of Australia (e.g., Perth).Higher fluxes of meteoric water in the Miocene summers would have facilitated dissolution and removal of BIF-sourced silica with concomitant enrichment in oxidized Fe. Moreover, wetter late Miocene summers could have promoted multiple cycles of microbially mediated dissolution and recrystallization of Fe(III) oxides in the aerobic systems. The oolitic textures may be indicative of such recycling. However, the oolitic goethites of Mesa J were closed systems after ∼7Ma. Therefore, the climate in the vicinity of Mesa J seems to have changed in the late Miocene to conditions that did not favor widespread recycling of Fe (III) oxides—perhaps changing from seasonally wet to the modern dry climate.

Removal of fouling species from brackish water reverse osmosis reject stream

ABSTRACTBrine disposal from reverse osmosis (RO) systems remains a major challenge for the desalination industry especially in inland areas where discharge options are very limited. Solutions will entail the introduction of economic treatment processes that will alleviate the brine’s negative impact on the environment and reduce its discharge volume. Such processes could act as an intermediary treatment process for the recycling of the brine through an additional RO stage which, for brackish water (BW) desalination, could lead to saving valuable water while reducing the amount of brine discharge. In this context, the study at hand attempts to evaluate the effectiveness of a one-step chemical process for the treatment of BWRO brine. This study seeks to determine optimal operating conditions relative to type, ratio, and dosage of alkalizing chemicals, pH and temperature, for substantially reducing the concentrations of scaling parameters such as calcium, magnesium, silica, and strontium. The results indicate that precipitation softening at pH = 11.5 using combined chemical dosages of NaOH and Na2CO3 in a ratio of 2:1 leads to substantial removal of calcium and magnesium (>95%) and moderately high removal of strontium and silica (>71%).

General Synthetic Method for N-Doped Macroporous Graphene-Encapsulated Mesoporous Metal Oxides and Its Application As New Anode Materials for Sodium-Ion Hybrid Supercapacitors

Employing graphene as an electrode material is advantageous for energy storage devices because it is flexible, highly electrically conductive, chemically stable, and has large theoretical surface area. However, graphene generally suffers from serious agglomeration and re-stacking due to its strong pi-pi stacking and van der Waals interactions between graphene nanosheets during charge-discharge process. To fully use the potential merits of graphene and improve the kinetics of electrode materials in energy storage devices, composites of graphene and metal oxides have been tested as electrode. Metal oxides in the composites, prevent the re-stacking of graphene. Graphene layers in the composites also suppress the volume change and agglomeration of metal oxide and provide a highly conductive matrix for metal oxide. We report a general method to synthesize mesoporous metal oxide@N-doped macroporous graphene composite by heat-treatment of electrostatically co-assembled amine-functionalized mesoporous silica/metal oxide composite and graphene oxide, and subsequent silica removal to produce mesoporous metal oxide and N-doped macroporous graphene simultaneously. Four mesoporous metal oxides (WO3-x, Co3O4, Mn2O3 and Fe3O4) were encapsulated in N-doped macroporous graphene. Used as an anode material for sodium-ion hybrid supercapacitors (Na-HSCs), mesoporous reduced tungsten oxide@N-doped macroporous graphene (m-WO3-x@NM-rGO) gives outstanding rate capability and stable cycle life. Ex situ analyses suggest that the electrochemical reaction mechanism of m-WO3-x@NM-rGO is based on Na+ intercalation/de-intercalation. To the best of our knowledge, this is the first report on Na+ intercalation/de-intercalation properties of WO3-x and its application to Na-HSCs.

Interfacial properties with bonding and failure mechanisms of wheat straw node and internode

The interfacial properties with bonding and failure mechanisms of different anatomical sections of wheat straw stem, namely node and internode, inner and outer surface, with various resins are investigated. An environmentally friendly pre-treatment was employed which led to an improved interface between resins and the micro porous surface of straw. The results showed that chemical functionalities of various surface profiles altered the bonding performance, i.e. extractive, aliphatic fraction of waxes, and silica concentrated on the outer surface, inhibited the bonding quality and the establishment of robust interface. The pre-treatment however, could significantly (P<0.05): (i) modify the surface of straw with the partial removal of extractives, waxes, and silica which made it more hydrophilic and more compatible with water based resins, (ii) cause the microcellular structure of straw to expand and hence inspire the mechanical entanglement on a micro level upon resin solidification and, (iii) increase the tensile strength of node and internode by modifying the cellulose crystallinity. The combined effects of resin, straw and interface led to hierarchical damage process, which could be modelled into four main failure mechanisms representing strong to weak bonding quality.

Paleoecology and paleoceanography of the Athel silicilyte, Ediacaran-Cambrian boundary, Sultanate of Oman.

The Athel silicilyte is an enigmatic, hundreds of meters thick, finely laminated quartz deposit, in which silica precipitated in deep water (>~100-200m) at the Ediacaran-Cambrian boundary in the South Oman Salt Basin. In contrast, Meso-Neoproterozoic sinks for marine silica were dominantly restricted to peritidal settings. The silicilyte is known to contain sterane biomarkers for demosponges, which today are benthic, obligately aerobic organisms. However, the basin has previously been described as permanently sulfidic and time-equivalent shallow-water carbonate platform and evaporitic facies lack silica. The Athel silicilyte thus represents a unique and poorly understood depositional system with implications for late Ediacaran marine chemistry and paleoecology. To address these issues, we made petrographic observations, analyzed biomarkers in the solvent-extractable bitumen, and measured whole-rock iron speciation and oxygen and silicon isotopes. These data indicate that the silicilyte is a distinct rock type both in its sedimentology and geochemistry and in the original biology present as compared to other facies from the same time period in Oman. The depositional environment of the silicilyte, as compared to the bounding shales, appears to have been more reducing at depth in sediments and possibly bottom waters with a significantly different biological community contributing to the preserved biomarkers. We propose a conceptual model for this system in which deeper, nutrient-rich waters mixed with surface seawater via episodic mixing, which stimulated primary production. The silica nucleated on this organic matter and then sank to the seafloor, forming the silicilyte in a sediment-starved system. We propose that the silicilyte may represent a type of environment that existed elsewhere during the Neoproterozoic. These environments may have represented an important locus for silica removal from the oceans.

Removal of dissolved silica from industrial waters using inorganic ion exchangers

Dissolved silica is ubiquitous in impaired waters, a fouling agent in desalination membranes, resistant to existing antiscalants, and difficult to remove from power plant feed waters, thereby inhibiting long term reuse of industrial water. Herein we report a systematic materials study of an inorganic anion exchanger, hydrotalcite (HTC, (Mg6Al2(OH)16(CO3)•4H2O)), for the highly selective removal of silica from aqueous solutions. HTCs exist in two different forms: crystalline uncalcined and calcined (550°C) phases. Variables studied in ion-exchange studies include pH, HTC concentration, duration and selectivity with competing anions. Results indicate calcined HTC effectively removes silicate anion from different waters including simulated concentrated cooling tower water (CCTW), and waters with high concentration of competing ions, such as SO42− and Cl−. The non-optimized HTC can be easily regenerated and recycled. Calcined HTC has a silica adsorption capacity of 45mg SiO2/g HTC. The single path flow through (SPFT) studies indicate that using ∼1.1g/L calcined HTC effectively removes >90% of the dissolved silica from the CCTW. A pseudo-second order kinetic model was fit the experimental data of calcined HTC. Data is supported by Fourier transform infrared (FTIR), Thermogravimetric-Mass analyses (TGA-MS), Energy dispersive spectroscopy (EDS) and powder X-ray diffraction (XRD).

Performance of teetered bed separator for non-coal applications

ABSTRACTIn the present investigation, the effect of the most important process variables, which are teeter water velocity (TW) and pressure set point (SP), on the classification and beneficiation performance of a laboratory-scale teetered bed separator (TBS) was evaluated and discussed. Pure silica sand, magnetite concentrate and their artificial mixture were used to observe the effect of mineral density. Classification test results revealed that separation cut size linearly increases with increasing TW and SP. From the beneficiation studies and the size-by-size chemical analysis of artificial mixture, it can be concluded that significant removal of silica is possible by employing TBS.

Hierarchically structured carbon/carbon nanocomposites with adjustable porosity fabricated by twin polymerization

Carbon materials with a complex core-shell structure and adjustable porosity are fabricated by subsequent surface polymerization of twin monomers on carbon black and silica particles. The twin monomers 2,2’-spirobi[4H-1,3,2-benzodioxasiline] (Spiro) and tetrafurfuryloxysilane (TFOS) are polymerized in one step to an inorganic/organic hybrid material, which contains nanostructured silica and phenolic resin or poly(furfuryl alcohol), respectively, as organic polymer. After carbonization and the removal of silica, a porous carbon shell with defined porosity is obtained. In this process, Spiro based materials produce microporous carbon and TFOS based materials produce a mesoporous carbon. Quantities of monomer, catalyst and substrate can be varied. This allows to create a library of porous carbon materials with different properties such as controlled porosity, morphology and hierarchically structuring. Thus, mesoporous carbon with a microporous shell can be achieved by using carbon black particles as substrate and Spiro as twin monomer. Furthermore, carbon hollow spheres with a double shell with hierarchically structuring can be synthesized by subsequent polymerization of TFOS and Spiro on silica particles. The porous carbon materials were characterized by quantitative elemental analysis, thermogravimetric measurements, SEM/EDX, TEM, nitrogen sorption isotherms and mercury porosimetry.

A biorefinery scheme to fractionate bamboo into high-grade dissolving pulp and ethanol

BackgroundBamboo is a highly abundant source of biomass which is underutilized despite having a chemical composition and fiber structure similar as wood. The main challenge for the industrial processing of bamboo is the high level of silica, which forms water-insoluble precipitates negetively affecting the process systems. A cost-competitive and eco-friendly scheme for the production of high-purity dissolving grade pulp from bamboo not only requires a process for silica removal, but also needs to fully utilize all of the materials dissolved in the process which includes lignin, and cellulosic and hemicellulosic sugars as well as the silica. Many investigations have been carried out to resolve the silica issue, but none of them has led to a commercial process. In this work, alkaline pretreatment of bamboo was conducted to extract silica prior to pulping process. The silica-free substrate was used to produce high-grade dissolving pulp. The dissolved silica, lignin, hemicellulosic sugars, and degraded cellulose in the spent liquors obtained from alkaline pretreatment and pulping process were recovered for providing high-value bio-based chemicals and fuel.ResultsAn integrated process which combines dissolving pulp production with the recovery of excellent sustainable biofuel and biochemical feedstocks is presented in this work. Pretreatment at 95 °C with 12% NaOH charge for 150 min extracted all the silica and about 30% of the hemicellulose from bamboo. After kraft pulping, xylanase treatment and cold caustic extraction, pulp with hemicellulose content of about 3.5% was obtained. This pulp, after bleaching, provided a cellulose acetate grade dissolving pulp with α-cellulose content higher than 97% and hemicellulose content less than 2%. The amount of silica and lignin that could be recovered from the process corresponded to 95 and 77.86% of the two components in the original chips, respectively. Enzymatic hydrolysis and fermentation of the concentrated and detoxified sugar mixture liquor showed that an ethanol recovery of 0.46 g/g sugar was achieved with 93.2% of hydrolyzed sugars being consumed. A mass balance of the overall process showed that 76.59 g of solids was recovered from 100 g (o.d.) of green bamboo.ConclusionsThe present work proposes an integrated biorefinery process that contains alkaline pre-extraction, kraft pulping, enzyme treatment and cold caustic extraction for the production of high-grade dissolving pulp and recovery of silica, lignin, and hemicellulose from bamboo. This process could alleviate the silica-associated challenges and provide feedstocks for bio-based products, thereby allowing the improvement and expansion of bamboo utilization in industrial processes.

Selection of Colloidal Silica Grouts with Respect to Gelling and Erosion Behaviour

Cembinder, Eka EXP36, and MEYCO MP320 are three colloidal silica materials that have been proposed for post-excavation grouting of deep tunnels in a radioactive waste repository. In this study, samples of these colloidal silicas were tested for their particle size distribution, gel induction time (tG), gel time (TG), and physical erosion, under mildly saline groundwater flow conditions. In order to achieve a desired gel time range, from 15 to 50 min, it is recommended that the colloidal silica is mixed with a NaCl accelerator at a 5:1 volume ratio. At 20 °C, the concentration range for the NaCl solution should be 1.5 to 1.7 M for MEYCO, 1.23 to 1.38 M for Eka EXP36, and 1.3 to 1.47 M for Cembinder. The physical erosion of the set silicas remained steady during a 10 h flow cell experiment, when grouts were subjected to 0.05 M NaCl at a superficial velocity of 2.2 × 10−5 m/s. For these test conditions, the results show that MEYCO has the highest average erosion rate (0.85 mg/h) of the three grout materials, as well as the greatest variability in this rate. Cembinder performed best with the lowest silica removal rate. Extrapolation of the measured erosion rates suggests that grout fracture dilation would not be significant under natural quiescent groundwater flow conditions, but would be high if there was hydraulic communication between the geosphere and the repository.

Combination of Gamma Irradiation and Sodium Carbonate Pretreatment on Oil Palm Empty Fruit Bunch (EFB) for High Acidic Hydrolysis Yield

Oil palm empty fruit bunch (EFB) fibres were pretreated by gamma irradiation followed by sodium carbonate (Na2CO3) before the acid hydrolysis process to produce reducing sugars using diluted sulphuric acid (H2SO4). In this study, EFB fibres were irradiated at different doses, i.e. 0, 100 and 200 kGy. Meanwhile, the gamma irradiated sample were then subjected to Na2CO3 pretreatment with 0 and 5% total titratable alkali (TTA). The effect of the pretreatment using gamma irradiation and Na2CO3 on the physical and chemical properties of the EFB fibres and the yield of the reducing sugar obtained from the acid hydrolysis process was investigated. The obtained results showed that the content of holocellulose was increased significantly with the increase of irradiation doses combined with Na2CO3 pretreatment, whereas lignin content of the EFB was decreased. The gamma irradiation and Na2CO3 pretreatment resulted in structure breakage and removal of silica of EFB fibres which can be due to the swelling of the fibres. A synergistic effect between gamma irradiation and Na2CO3 was observed, in which the yield of reducing sugars was increased by combining the gamma irradiation and Na2CO3 pretreatment.