Rice Straw Waste Research Articles

Preparation of Potassium-Posphate-embedded Amorphous Silicate Material from Rice Straw Waste

Rice straw is one of the agricultural wastes that increased every year. Since rice straw ash contains 74.6% of silica, this material is potentially used to produce silica. Thus, the purpose of this study was to investigate the possibility process for generating potassium-phosphate-embedded amorphous silica material. To extract silica from rice straw waste, we used potassium hydroxide solution followed by an acid precipitation treatment. Based on the experimental results, the proposed method is potential to be used as an alternative technique for getting silica material. In addition, the method has a positive impact on the environment because this is potential for reducing the amount of rice straw waste, whereas at the same time this provides an added value to the rice straw waste itself.

Investigations on the Kinetics of Acid Catalyzed Hemicellulose Hydrolysis Derived from Waste Rice Straw for the Production of Bio-ethanol

Objectives: To understand the monophasic kinetic behavior of hemicellulose hydrolysis and determination of thermodynamic parameters involved in dilute acid pretreatment by tartaric acid. Methods/Statistical Analysis: Biomass samples from thatched roofs were collected and analyzed for cellulose, hemicellulose and lignin through Neutral Detergent Fibre (NDF), Acid Detergent Fibre (ADF) and Acid Detergent Lignin (ADL) methods. The ground biomass was hydrolysed with tartaric acid, saccharified applying cellulase, xylanase at different time/agitation speed for obtaining reducing sugar and finally fermented for ethanol yield. The kinetics of hemicellulose hydrolysis was critically studied in the present work. Findings: The maximum yield of xylose and reducing sugars after hydrolysis and saccharification at optimum conditions were 134 mg/g and 494.8 mg/g using tartaric acid as hydrolyzing media. Pichia stipitis was very effective for conversion of pentoses and hexoses during fermentation. The maximum ethanol yield of 25.1% using tartaric acid was obtained after fermentation. Overall, the present works depicts the introduction of a new hydrolytic agent, tartaric acid and a comprehensive view of the complete bio processing of waste rice straw to bioethanol. The amount of ethanol yield was from 17% to 25.1%. It was noticed that the ethanol content was directly proportional with the increase in age of the samples. An increasing trend of ethanol with time was visible until 9th hour. High ethanol yield was obtained in this study since Pichia stipitisstrain could utilize both hexose sugars and pentose sugars together. Applications/Improvements: Thatched rice straw roof can be better utilized for ethanol making with natural degradation of lignin due to aging instead of increasing environment pollution using significantly less synthetic enzymes.

BIOSORPTION OF Cr(VI) USING RICE STRAW WASTE

Ponte Academic JournalApr 2017, Volume 73, Issue 4 BIOSORPTION OF Cr(VI) USING RICE STRAW WASTEAuthor(s): Andi Kurniawan ,Dr. SukandarJ. Ponte - Apr 2017 - Volume 73 - Issue 4 doi: 10.21506/j.ponte.2017.4.16 Abstract:Water pollution is one of the main environmental problems. One of the pollutants that become serious problem in aquatic ecosystems is heavy metal such as Cr(VI) that can be harmful to living organisms including human. Thus, the technology to solve Cr(VI) pollution is needed. One of the low cost and environmentally safe technologies to solve the problem is biosorption. The present study investigated the biosorption of Cr(VI) using rice straw waste. This substance is selected because easily available and relatively inexpensive. The result of this study showed that the rice straw waste had promising ability to adsorb Cr(VI). The optimum time of biosorption was 120 minute. The biosorption characteristics were fitted well to the Langmuir adsorption model. The result of this study suggested that the biosorption of Cr(VI) to rice straw waste occurred through physicochemical interactions in this case ion exchange mechanism and electrostatic interaction. According to the result of this study, the rice straw waste is prospective biosorbent to solve aquatic ecosystem pollutions especially heavy metal pollution such as Cr(VI) contamination Download full text:Check if you have access through your login credentials or your institution Username Password

The effect of pretreatment using sodium hydroxide and acetic acid to biogas production from rice straw waste

Rice straw is agricultural waste containing high potency to be treated to biogas. However, the usage of rice straw is still limited due to high lignin content that will cause low biodegradability. The aim of this research was to study the effect of pretreatment using NaOH and acetic acid to biogas production from rice straw. NaOH was varied from 2%w, 4%w, and 6%w; and acetic acid was varied from 0,075 M, 0,15 M dan 0,75 M. The rice straw was cut into 1 cm size and submerged for 30 minutes in NaOH and acetic acid solution. The rice straw then filtered and neutralized before sending to anaerobic digestion process using rumen fluid bacteria. Biogas produced was measured using water displacement method. The result showed that the optimum concentration of NaOH solution was 4%w that resulted in biogas volume of 21,1 ml/gTS. Meanwhile, the optimum concentration of acetic acid pretreatment was 0,075 M that produced biogas volume of 14,5 ml/gTS. These results suggest that pretreatment using NaOH solution is more effective for decreasing the lignin content from rice straw.

Unravelling the capability of Pyrenophora phaeocomes S-1 for the production of ligno-hemicellulolytic enzyme cocktail and simultaneous bio-delignification of rice straw for enhanced enzymatic saccharification

A natural variant of Pyrenophora phaeocomes isolated from natural biodiversity was able to grow on various agricultural residues by co-producing laccase, xylanase and mannanase. Solid state fermentation of rice straw induced the highest productivities corresponding to 10,859.51±46.74, 22.01±1.00 and 10.45±0.128IUgds−1 for laccase, xylanase and mannanase respectively after 4days. Besides producing the ligno-hemicellulolytic enzyme cocktail, 40days cultivation of P. phaeocomes S-1 on rice straw brought about the 63 and 51% degradation of lignin and hemicellulose. These components were further removed with mild alkali extraction revealing the overall losses amounting to 78 and 60% respectively for lignin, and hemicellulose. The biologically pretreated straw upon enzymatic hydrolysis revealed 50% saccharification efficiency releasing 470mgg−1 sugars. Application of this knowledge will lead to efficient management of waste rice straw with low cost production of industrially important enzymes cocktail and its biological delignification for effective enzymatic hydrolysis to free sugars.

Lignocellulosic materials as solid support agents for Bjerkandera adusta SM46 to enhance polycyclic aromatic hydrocarbon degradation on sea sand and sea water media

Abstract The utilization of white rot fungi (WRF) as degrader agents in extreme environments is still limited by their specific growth requirements. This study examined the ability of Bjerkandera adusta SM46 (GenBank accession number: KU055648 ), a recently isolated WRF from Saragamine mountain, Japan, to treat sea sand and sea water contaminated with polycyclic aromatic hydrocarbons (PAHs) for potential applications in the bioremediation processes. Several PAHs (2–5 rings) were used as pollutants under saline-alkaline stress conditions. Among four lignocellulosic materials, i.e., wood meal, kapok fibre, rice straw, and pulp waste, rice straw was a lignocellulosic material selected as the most suitable support based on the fungal growth, ligninolytic enzymes production, and degradation rates of PAHs after inoculation with B. adusta SM46. Rice straw-immobilized B. adusta (RSIB) showed faster growth and colonization, and increased laccase (Lac), manganese peroxidase (MnP), and lignin peroxidase (LiP) activity. The optimum granule size of rice straw as an immobilizing agent for B. adusta was 840 µm. Lac, MnP, and LiP activities were monitored for 15 and 30 d. Low-molecular-weight PAHs (LMW-PAHs, 2–3 rings) were the most extensively degraded by RSIB. When grown on high-molecular-weight PAHs (HMW-PAHS, 4–5 rings), degradation rates varied between 16% and 63% on contaminated sea sand and between 22% and 61% on contaminated sea water. RSIB may also be used as an alternative method to more effectively and efficiently produce ligninolytic enzymes than the submerged culture method.

Effect of acid-digested rice straw waste feeding methods on the 3HV fraction of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production

Abstract The effect of different feeding methods of the acid-digested rice straw hydrolysate on the contents and composition of polyhydroxyalkanoates (PHAs) accumulated by Cupriavidus necator was studied. The results showed that the inhibitory effects of furanic compounds on bacterial PHAs synthesis can be alleviated by dilution, and the hydrolysate-to-media (H/M) ratio of 2:8 was appropriate for poly-3-hydroxybutyrate-co-3-hydroxyvalerate [P(3HB-co-3HV)] synthesis. At the H/M ratio of 2:8, the accumulated PHAs content could be increased by using the split-fed method, and the rice straw hydrolysate fed in 4-pulses resulted in the highest P(3HB-co-3HV) concentration in this study. However, the 3-hydroxyvalerate (3HV) mol% decreased with increasing PHAs concentration, thus, the repeatedly-fed method was used to achieve a desirable 3HV fraction range of 20–30% for medical applications. The repeated feeding of the hydrolysate increased the 3HV fraction of the accumulated P(3HB-co-3HV) to the 20–30% range. Overall, this study demonstrates that the feeding methods of rice straw hydrolysates containing multiple carbon sources can be optimized for synthesis of desired PHAs.

Removal of Some Heavy Metals From Aqueous Solution Using Biosorbent Materials and Nanoparticles

A batch sorption experiments were carried out to study the role of biosorbent and nano-particles on removal of some heavy metals from aqueous solution. The rice straw waste was used as biosorbent material) by-product of agricultural activity). In addition, Nano-Hydroxyapatite (60 nm) and nano-Zero Valent Iron (25 nm) were used as nanoparticles. The batch sorption was done using rice straw waste (RSW) with three sizes as 0.125, 0.25 and 0.5 mm with Pb2+ and Ni2+ with concentrations up to 28.14 and 100 mg/l, respectively. Also, the sorption experiment was conducted using nano-particles (n-HAP and n-ZVI) and phosphate rock for Pb2+ and Ni2+ with concentration up to 20 mg/l for Ni and 18.0 mg/l for Pb. The results indicated that RSW (0.250 mm) was best size for heavy metals removal. The rice straw waste has more ability for retention of heavy metals such as Ni and Pb according to linear and Freundlich sorption models. Also, the results indicated that maximum sorption capacity of heavy metals was occurred on Nano-Hydroxyapatite (n-HAP) for both Pb and Ni. These results may be due to the functional groups found in Nano-Hydroxyapatite. When RSW mixed with n-HAP, the results indicated maximum removal percentage of heavy metals. The removal percentage of Pb (99.70%) was more than Ni (38.25%) indicated that the ability of Pb to bind with RSW or n-HAP more than Ni. The current results are very useful in the treatment of wastewaters for the removal of heavy metals, making them suitable for agricultural purposes. The present study recommends a future studies to understand the role of nanomaterials on removal the different heavy metals under different conditions.

Quantification of temperature effect on batch production of bio-hydrogen from rice crop wastes in an anaerobic bio reactor

Rice is an important cereal crop and different types of wastes are produced from it such as; rice straw as a crop residue, rice husk and rice bran as agro-industrial waste and rice waste as a food waste, which are needed to be tested for bio-hydrogen production under similar set of experimental conditions. The bio-hydrogen production potential of these wastes was compared by co-digestion with heat shocked sludge under mesophilic thermophilic temperatures by using an anaerobic bio reactor under no pH control conditions. It was observed that the bio-hydrogen production potential increased with an increase in temperature from 37 °C to 55 °C for all wastes, except for rice waste. Although, the highest experimental yield of 40.04 mL/VSrem was produced from thermophilic rice straw, but the maximum bio-hydrogen production rate of 97.08 mL/h was observed from rice bran after 29.03 h under thermophilic conditions. The bio-hydrogen production period of rice bran was 33–38% smaller than rice straw due to which the highest yield was observed from rice straw. The lignin content of rice husk was 19.34%, which was double than rice straw and hence the rice husk produced the least experimental yield of 23.05 mL/VSrem under mesophilic conditions. Increasing the temperature from mesophilic to thermophilic conditions changed the final pH by 1.79%, −8.33%, 5.17% and 5.41% for rice straw, rice bran, rice husk and rice waste, respectively. The optimum pH range of bio-hydrogen production from rice straw, bran and husk was observed from pH 7 to pH 6. The average yield of wastes produced from rice crop was 30.36 and 33.16 mL/VSrem under mesophilic and thermophilic conditions, respectively. The quadratic modeling found useful in order to explain more than 90% variation caused by incubation time and temperature on cumulative bio-hydrogen production, drop in pH and VFA production. The 3D and 2D plots developed on the basis of quadratic modeling explained the process parameter is in better way as compared to conventional representation of experimental results. As a whole, increasing temperature not only increased bio-hydrogen yield, but also decrease the volatile fatty acid production.

Synthesis of silica particles from rice straw waste using a simple extraction method

The purpose of this study was to synthesize silica particles from rice straw waste using a simple extraction method. The experiment was conducted by heating and extracting rice straw waste into basic solution. To get silica particles, the extracted solution was then put into acid solution and heated to remove the remained solvent. The experimental results showed that the aggregated silica particles with sizes of about 200 nm were successfully produced. The XRD and FTIR analysis showed that the final product was silica and free of graphite. However, we found that some KCl component in the final product in which this was possibly from the use of KOH as the extraction agent. Therefore, further studies are still required to synthesize high purity silica particles from rice straw waste.

Increased 3HV Concentration in the Bacterial Production of 3-Hydroxybutyrate (3HB) and 3-Hydroxyvalerate (3HV) Copolymer with Acid-Digested Rice Straw Waste

Bacterial synthesis of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) copolymer [P(3HB-co-3HV)] using the hydrolysate of rice straw waste as a carbon source was affected by the composition of the hydrolysate, which depends highly on the rice straw pretreatment condition. Acid digestion with 2 % sulfuric acid generated larger production of P(3HB-co-3HV) than 6 % sulfuric acid, but 3HV concentration in the copolymer produced with 2 % acid hydrolysate was only 8.8 % compared to 18.1 % with 6 % acid hydrolysate. To obtain a higher 3HV mole fraction for enhanced flexibility of the copolymer, an additional heating was conducted with the 2 % acid hydrolysate after removal of residual rice straw. As the additional heating time increased a higher concentration of levulinic acid was generated, and consequently, the mole fraction of 3HV in P(3HB-co-3HV) increased. Among the conditions tested (i.e., 20-, 40-, 60-min), 60-min additional heating following 2 % sulfuric acid digestion achieved the highest 3HV mole fraction of 22.9 %. However, a longer heating time decreased the P(3HB-co-3HV) productivity, probably due to the increased intermediates concentrations acting as inhibitors in the hydrolysates. Therefore, the use of additional heating needs to consider both the increase in the 3HV mole fraction and the decrease in the P(3HB-co-3HV) productivity.

Saccharification Waste Biomass Rice Straw IR-64 by Using Xylanase from Indigenous Marine Bacteria Bacillus safensis LBF-002

Abstract — Agricultural residues have an enormous potential as renewable carbon and energy sources. Saccharification of agricultural by microbial hydrolytic enzymes is the first step of bioconversion of organic material into reducing sugar. The main purpose of this research is converting rice straw IR-64 waste biomass into reducing sugar xylo-oligosaccharides by using xylanase from indigenous marine bacteria Bacillus safensis LBF-002. The optimation of xylanase in rice straw medium are using stability of pH and temperature were resulted higher activity in pH 7 and 50 °C which result 2.228 U/mL in 24 h incubation. The xylanase was concentrated with PEG 6000 in ratio (1:1) become 16.578 U/mL and was used for hydrolyze the rice straw for getting the sugar reduction product. The sugar reduction component from rice straw saccharification was analyzed using Thin Layer Chromatography and also High Performance Liquid Chromatography (HPLC). The present study was a first effort to explore marine bacteria Bacillus safensis LBF-002 to produce and obtain the optimum condition for producing xylooligosaccharide from rice straw waste. The best result for hydrolysis experiment showed in saccharafication with 2.5% rice straw and crude enzyme xylanase 4 U/mL for 1 h and 2 h incubation which is resulted xylose, xylobiose, and xylohexose.

Isolation, Screening and Characterization of Cellulase Producing Bacterial Isolates from Municipal Solid Wastes and Rice Straw Wastes

Cellulolytic bacteria were isolated and screened from municipal solid wastes and rice straw wastes using Carboxy Methyl Cellulose (CMC) agar medium as a selective medium. Production of clear zones by the bacterial isolates on CMC agar medium supplemented with 1% CMC was considered as indicative of extracellular cellulase activity. The size of transparent zone diameter was considered as proportional to the level of cellulase production. These bacterial isolates were identified as Bacillus sp., Pseudomonas sp. and Serratia sp. based on morphological, cultural and biochemical characteristics. A basal medium containing CMC, KH2PO4, K2HPO4, MgSO4, (NH4)2SO4, CaCl2 and FeSO4 at pH 7.0 was used for cellulase production. The assay of cellulase in term of CMCase was performed by measuring the release of reducing sugar. Different physicochemical parameters were optimized for cellulase production at shake flask fermentation. Time course study revealed that maximum level of cellulase was produced by Bacillus and Serratia isolates after 24 h of cultivation and by Pseudomonas isolates after 42 h of cultivation. Optimum level of cellulase was produced by Pseudomonas and Bacillus isolates at 37°C, and that by Serratia isolate was at 35°C. Optimum pH for cellulase production by these bacterial isolates was 7.0. Optimum temperature and pH for the activity of cellulase from these isolates were 40°C and 7.0, respectively. The cellulase from these isolates was found almost stable up to 55°C and at pH 7.0 for 1 h. The crude cellulase could liberate reducing sugar from filter paper through hydrolysis. Results showed that bacterial isolates produced significant level of cellulase with cellulose degrading capability.

Valorization of rice straw waste: production of porcelain tiles

Abstract The rice industry generates huge amounts of rice straw ashes (RSA). This paper presents the results of an experimental research work about the incorporation of RSA waste as a new alternative raw material for production of porcelain tiles. The RSA replaces, partially or completely, the non-plastic raw materials (quartz (feldspathic sand in this research) and feldspar), that together with the clays, constitute the major constituents of formulations of porcelain tiles. A standard industrial composition (0% RSA) and two more compositions in which feldspar and feldspathic sand were replaced with two percentages of RSA (12.5% RSA and 60% RSA) were formulated, keeping the clay content constant. The mixtures were processed, reproducing industrial porcelain tile manufacturing conditions by the dry route and fired at peak temperatures varying from 1140-1260 ºC. The results showed that additions of 12.5% RSA in replacement of feldspar and feldspathic sand allowed producing porcelain tiles that did not display marked changes in processing behaviour, in addition to obtain a microstructure and the typical mineralogical phases of porcelain tile. Thus, an alternative use of an agricultural waste material is proposed, which can be translated into economic and environmental benefits.

The role of a novel fungal strainTrichoderma atrovirideRVF3 in improving humic acid content in mature compost and vermicompost via ligninolytic and celluloxylanolytic activities

With the rising concerns about indiscriminate use of chemical fertilizers and accumulation of agro-industrial wastes in huge quantities, the present experiment was conducted to elucidate the effect of a novel fungal strain of Trichoderma atroviride in hastening the compost/vermicompost production process and for the production of humic acid (HA) rich compost and vermicompost. Rice (Oryza sativa) straw and distillation waste of geranium (Pelargonium graveolens), two important agricultural/industrial crop wastes were subjected to composting and vermicomposting. T.atroviride strains GVF10 (cellulase and xylanase producing), and RVF3 (ligninase and celluloxylanase producing) were inoculated alone or in combination. The HA content was found to increase maximally in rice vermicompost treated with ligninase producing strain RVF3 (85% with respect to HA standard) followed by geranium vermicompost + RVF3. The addition of the strain GVF10 increased HA content to about 35-62% with respect to HA standard. The addition of the fungal inoculum reduced the composting/vermicomposting time from 110 to 90days. Our results indicate that the use of selected fungal strain(s) hold potential to produce qualitatively superior compost and vermicompost with high HA content in a shorter period. Use of appropriate fungal strains may increase the efficiency of composting/vermicomposting processes producing compost and vermicompost with higher HA content, and alleviating the problems of solid waste accumulation and declining soil fertility.

Lightweight Magnesium Oxychloride-Based Building Units from Egyptian Raw Magnesite

Water resistant magnesium oxychloride (MOC)-based building products were prepared from different two samples of raw magnesite and rice straw waste up to 10 mass-%. Active magnesium oxide as starting material for the preparation of MOC was prepared from raw magnesite by calcination at temperatures of 650 and 1000°C. MOC-based lightweight building units can be prepared with a bulk density range between 1.0–1.4 g/cm3 with a compressive strength of up to 27 MPa and a modulus of rupture of up to 11 MPa. Selected samples were investigated using XRD and TEM. The XRD characterization results revealed the formation of phase 5, phase 3 and chlorartinite. The TEM informed that these phases are at nano scale.

Biodegradation of cellulosic and lignocellulosic waste by Pseudoxanthomonas sp R-28

A microbial consortium, designated Con R, was established by successive sub-cultivation which can degrade 83% of filter paper after 15 days of incubation over control. Among the 14 bacterial isolates obtained from Con R, only bacterial isolate (R-28) was capable of degrading filter paper. Based on 16S rRNA gene sequence, R-28 was identified as Pseudoxanthomonas sp R-28. After 5 days of incubation, degradation efficiencies of Pseudoxanthomonas sp R-28 on filter paper and pure cellulosic waste were 96% and 95% respectively as compared to control. Pseudoxanthomonas sp R-28 also degraded 60% of non-pretreated rice straw after 7 days as compared to control. The degradation kinetics through a modified logistic model showed high correlation coefficient (R2) of 0.965 and 0.665 for cellulosic and rice straw waste degradation respectively. Micro scale structural analysis showed the development of fissures and gaps over time which further supported the degradation potential of Pseudoxanthomonas sp R-28.

Comparison of Co-gasification of Wastes Mixtures Obtained from Rice Production Wastes Using Air or Oxygen

The world annual production of rice is higher than 700.7 million tons, which generates rice husk and straw wastes. Rice culture also produces big amounts of polyethylene (PE) bags used in rice packs and for seeds and fertilizer storage that usually end up in landfills, due to their degree of contamination. The energetic valorisation of these wastes may be accomplished by different processes, co-gasification is one of the most viable, as it leads to the production of a synthetic gaseous mixture (bio-syngas) that can be used for energy production to be used during rice milling processes. Gasification of rice husks has some challenges, due to these wastes high content of silica and alkali metals that lead to the formation of solids with lower melting point, thus, leading to bed agglomeration that causes reactor erosion and serious damage. PE has lower ash content and much higher energetic content than rice husks. However, PE polymeric structure may lead to the formation of higher tar contents, which compromise most gasification gas utilisations. Co-gasification of PE and rice husks allows taking advantages of each waste favourable characteristic, diluting the unsuitable features. Co-gasification of these wastes was done in presence of steam blended with air or oxygen. Steam promoted the gasification reactions and favoured H2 production. Air or oxygen promoted the partial oxidation of the feedstocks to be co-gasified and supplied the energy necessary for the endothermic gasification reactions. The use of air has a low cost, but has the great disadvantage of diluting the bio-syngas produced, thus lowering its energetic content. On the other hand, the use of oxygen solves the problems related to gas dilution with nitrogen, but increases the operating cost. Bio-syngas composition obtained by co-gasification trials done with air enriched with different oxygen contents was compared with those obtained with air or pure oxygen to determine the best approach considering both the technical and economical sustainability.

Utilization of Rice Straw Waste in The Production of Crude Cellulase by Aspergillus Niger for Biodeingking Processes

Rice straw is agricultural waste that contains cellulose and has not been used optimally. The agricultural wastes contain cellulose which can be utilized for the production of cellulase enzymes. Cellulase produced from cellulose hydrolysis process in such materials through enzymatic hydrolysis. This study aimed to determine the effect of substrate type and temperature delignification on cellulase enzyme production and determine the effect of the number of additional enzymes of each substrate at biodeinking process. Variable used is the temperature used in the delignification process (100oC and 120oC), the addition of substrate (2,3,4,5,6%), additional doses of the application biodeinking (1,2,3,4,5%). Research conducted by softening rice straw to 30 mesh size media then delignification using 100 ° C and 120 ° C for 150 minutes, and fermented with Aspergillus niger in liquid inoculum, growth curves, and the crude cellulase production. The resulting crude cellulase was applied to the process biodeinking. Fieldwork results showed that at a temperature of 120oC delignification can reduce lignin content in straw was 48.7%. Highest crude cellulase activity of delignification results 120oC 4% resulting from the addition of media on the production of the enzyme activity of crude enzyme with 118.055 units / ml. Biodeinking application results showed that the addition of 3% crude cellulase with medium straw delignification results of 120oC can raise the value of paper brightness of 35.39% to 42.86% or 17:42%.

Adsorption Kinetics, Equilibrium, and Thermodynamics of Copper From Aqueous Solutions using Silicon Carbide Derived from Rice Waste

Adsorption of Cu(II) from aqueous solution on a novel adsorbent, silicon carbide ash (SiC ash), was studied using batch technique. The adsorbent was prepared by pyrolysis of Egyptian rice waste (rice straw and rice husk) and was characterized by scanning electron microscopy (SEM), energy-dispersive x-ray (EDX), Fourier-transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), and surface area analysis by Brunauer-Emmett-Teller (BET) Theory. The influence of pH, contact time, initial Cu(II) concentration, adsorbent dose, agitation speed, and temperature was investigated. Adsorption kinetics was analyzed using the pseudo-first-order, the pseudo-second-order, and intraparticular diffusion model. The adsorption process was found to follow a pseudo-second-order rate mechanism. The adsorption isotherm data could be well described by the Langmuir and Freundlich than the Dubinin–Radushkevich adsorption model. The adsorption capacity of 22.06 mg g−1for SiC ash was obtained at pH = 5 and temperature of 298 K. Thermodynamic parameters, change in the free energy (ΔG°), the enthalpy (ΔH°), and the entropy (ΔS°), were also calculated. The overall adsorption process was exothermic, spontaneous in nature, and proceeds with decreased randomness as the entropy is negative value. Adsorption process was successfully applied to remove Cu(II) from an industrial wastewater sample.