Jurnal Rekayasa Kimia & Lingkungan
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Preparation and Characterization of Nanocrystalline Cellulose from Cassava Stem Wastes by Electromagnetic Induction
Full text linkCassava stems were one of the largest agricultural by products in Indonesia, especially in Lampung Province. It is known that cassava stems have a fairly high lignocellulose content, especially cellulose which reaches 39.29%. The high cellulose content in cassava stems has great potential to be used as raw material for Nanocrystalline Cellulose (NCC). The preparation of nanocrystalline cellulose consists of four main stages, namely: pre-hydrolysis, delignification, bleaching, and acid hydrolysis. The pre-hydrolysis stage was carried out by boiling a solution of CH3COOH and cassava stem powder for 60 minutes at a temperature of 105oC. Cassava stem powder was then delignified using a 25% NaOH solution heated to a temperature of 105oC for 1 hour. The bleaching stage used a 3.5% NaOCl solution at a temperature of 50oC for 60 minutes and was carried out twice. The last step is acid hydrolysis using 2.5N HCl solution for 15 minutes at a temperature of 105oC, then the electromagnetic induction treatment is varied with temperature variations of 30oC, 50oC, and 70oC for 60 minutes. The prepared nanocrystalline cellulose were tested for lignocellulose, XRD and PSA. From the test results, the best variation of nanocrystal cellulose preparation was acid hydrolysis treatment with 70oC electromagnetic induction for 60 minutes, namely an increase in the percentage of cellulose 62.93%, crystallinity 90.68%, and an average particle size of 18.04m with some particles measuring nanometers. From the results of the research, it was concluded that electromagnetic induction increased crystallinity and decreased the size of nanocrystalline cellulose
Biosorbent Prepared from Calotropis Gigantean Stems for Adsorption of Cu(II) Ions from Aqueous Solution
Full text linkCalotropis gigantea stems (CGS) has the potential to use as biosorbent for adsorption of Cu(II) ions. In this study, the CGS biosorbent (CGSB) was prepared by drying and grounding. The effect of independent variables on adsorption capacity were investigated. As the result, the maximum adsorption capacity of 53.457 mg/g was obtained the optimal condition which was initial Cu(II) ions concentration of 567.47 mg/L, CGSB size of less than 230 mesh, CGSB mass of 1 g, temperature of 27 oC, pH 5, and contact time of 60 min. The CGSB surface morphology was analysed using SEM. The adsorption of Cu(II) ions fitted well with pseudo first-order adsorption kinetic (PFO-AK) model (R2=0.99), and the PFO-AK adsorption capacity and rate constant obtained were 70.194 mg/g and 0.0877 g/mg.min, respectively. The adsorption isotherm of Cu(II) ions was in accordance with Freundlich model (R2=0.99), and the intensity and volume constants attained were 0.876 and 1.017 L/mg, respectively. This result showed that physical adsorption occurred dominantly than chemical adsorption. The application of CGSB on the wastewater of initial Cu(II) ions concentration of 389.31 mg/L from ex-mine pool of acid mine drainage (AMD) in Jantang village, Lhoong District, Aceh Besar, Aceh Province resulted in adsorption capacity of 37.52 mg/g with adsorption efficiency of 66.13%
Improvement of the Efficiency of TiO2 Photocatalysts with Natural Dye Sensitizers Anthocyanin for the Degradation of Methylene Blue: Review
Full text linkOne of the potential methods utilized for dye degradation is photocatalitic, due to its low cost, highly effective, and environmentally friendly. Effectivenes of TiO2 photocatalysts can be enhanced by adding a dye sensitizer. Dye-sensitizer material absorbs visible light to facilitate electron excitation process. Addition of dye-sensitizer on TiO2 photocatalyst promotes it to be more responsive to visible light. Natural anthocyanin dyes are often used as sensitizers of TiO2 semiconductors. Anthocyanins are, usually in the purple to the red color range, a group of natural dyes found in the flowers, leaves, and fruit of plants. The essential principles of dye sensitization to TiO2 have been explored in this review. It is feasible to reduce the band gap energy in the TiO2 photocatalyst by modifying it using a natural dye sensitized modification. Dye sensitizers on TiO2 nanotubes plate have the potential to be employed in a dye degradation photocatalytic syste
Utilization of Natural Extracts as Corrosion Inhibitors in the Seawater Environment
Full text linkInfrastructures in coastal area are mostly made of metal which is susceptible to corrosion due to direct contact with the seawater. The Seawater greatly affects the corrosion rate of metals because it contains chloride ions which can penetrate metal surface. The process of corrosioncan beinhibited or slowed by decreasing the corrosion rate in one way, namelythe addition ofcorrosion inhibitors derived from natural materials containing tannin compounds. This study proposed organic corrosion inhibitors which were derived from natural material extracts (coffee leaves andcatappaleaves), the effect of time variations on the efficiency of organic inhibitors was investigated, and the efficiency of each inhibitor organic was compared. The corrosion rate with and without inhibitors was analysed by using the method of weight loss. The results showed that the corrosion rate canbe reducedby adding the natural ingredients extract. The addition of 2% concentration coffee leaves extract resulted in the lowest corrosion rate with the addition of 0.00226 mmpy. The addition ofcatappaleaves extract concentration as much as 2% yield the lowest corrosion rate with the addition of 0.0012 mmpy. The highest efficiency of inhibition system was obtained by using 2%catappaleaves extract at 14 days soaking time at 69.23%, and the lowest by using 1% coffee leaves extract
Sodium Hydroxide Treatment for Cellulose Fiber Accessibility from Corncobs under Microwave Assistive
Full text linkCorncob is abundantly available lignocellulosic biomass resources obtained from crops harvesting and found to be solid waste accumulation on a field. Less corncob is used as a solid fuel for cooking, and a more significant portion is vanished on the field by burning. Promisingly, corncob contains considerable cellulose as one value-added component potentially utilized as biomaterial or biofuel feedstock. However, the presence of lignin in natural lignocellulosic biomass results in recalcitrant structure and hinders cellulose accessibility. This study aimed to investigate microwave-assisted alkaline treatment to retain cellulose in the solid product while removing other impurities in corncob, especially hemicellulose and lignin. Sodium hydroxide was selected as a chemical with some variations in concentration. The chemical treatment was carried out under 400 W microwave power with various residence times and a 1:10 solid to liquor ratio. The cellulose content upgraded from 26.97% to 71.26% while reducing hemicellulose and lignin from 38.49% to 18.15% and 19.28% to 6.4%, respectively, on chemical treatment using 8% sodium hydroxide concentration for 20 minutes residence time. Scanning electron microscope (SEM) and Fourier transform infrared (FTIR) analysis also confirmed the results. The treated corncob also increased its crystallinity from 30.11% to 52.91%
Removal of Fe (II) ions from Aqueous solution using Rice-husk Adsorbents in fixed-bed column
Full text linkRice husk has been converted into activated carbon for the adsorbent to remove the heavy metal from the aqueous solution. This study aimed to convert rice husk to activated carbon (AC) for use in the adsorption of Fe ions in a fixed-bed column. Rice husk was first pyrolyzed in an atmosphere of nitrogen gas at 400 oC, then a chemical activation method using sodium hydroxide. The rice husk activated carbon (RH-AC) was characterized using Fourier transform infrared (FTIR) and Scanning electron microscope (SEM) to identify the functional group and microstructure of carbon. The performance of the carbon was tested on the Fe removal from an aqueous solution in a continuous column. The adsorption process was carried out using Fe solution with an initial concentration of 3 mg/L as an artificial sample. The amount of carbon is 25, and 50 g were filled in an adsorber column with a diameter of 5.4 cm and height of 40 cm. SEM images revealed that the activated carbons shown with well-developed pore sizes and pore structure were produced after the chemical activation. The FTIR absorption bands observed in the RH-AC sample confirmed the presence of hydroxyl (-OH), carbonyl, and carboxylic (-COOH) groups of RH-AC adsorbent. The highest Fe removal efficiencies were 91.9% on chemically activated carbon and column mass 50 g at 400 minutes. The overall study revealed the potential value of chemically activated RH-AC as a possible commercial adsorbent in a continuous column wastewater treatment strategy
Recent Development and Application of TiO2 Nanotubes Photocatalytic Activity for Degradation Synthetic Dyes A Review
Full text linkSynthetic dyes waste from textile industries, produce of the problematic pollutants in wastewater. TiO2 based photocatalysis are materials that exhibit excellent absorption behavior for organic compounds in wastewater due it properties including nontoxicity, high photocatalysis degradation ability, and chemical stabilities. However, several challenges exist regarding TiO2 nanotubes pure applications for dyes degradation such as poor affinity, high band gap energy, and difficulty of recovery and easy to recombination so it would decrease effectiveness of the photocatalysis process. Therefore, more design and optimization testing need to be conducted on the treatment conditions in order to reach higher removal efficiencies with lower costs. The modified physical properties by adding metal dopant, nonmetal, and sensitizer significantly enhanced photocatalysis activity. These parameters, which affect photocatalysis activity on degrade dyes waste pollutants, are discussed in the current review. As a result, the photocatalysis becomes more expected, and encourages to further research development.Keywords:TiO2, nanotubes, degradation, synthetic, dye
The Leaching of Natural Dyes from Avocado (Persea Americana Mill) Seeds Using the Ultrasonic-Assisted Extraction Method and Its Application to Cellulose Fibers
Full text linkThe textile industry uses synthetic dyes because they are cheaper and easier to obtain. Moreover, the color availability is guaranteed and more varied. However, these synthetic dyes have a negative impact on health and the environment. The natural dye from avocado (Persea Americana Mill) seeds can become an alternative for synthetic dyes. Polyphenol compounds, such as tannins and flavonoids, are natural color sources found in avocado seeds. The extraction of natural dyes from avocado seeds is carried out by using a non-conventional method, namely ultrasonic-assisted extraction which has great efficiency and short operating time. In this study, researchers examined the parameters that affect the yield of dye extraction from avocado seeds, namely solvent concentration and extraction time. In addition, researchers also conducted qualitative analysis on the pigment content in the yield of extraction using UV-Visible Spectrophotometry and GC-MS tests. The results indicated that the highest yield obtained from avocado seeds was 16.6742% with 90 minutes extraction time using 70% ethanol solvent. Furthermore, if the dye is applied to cellulose fibers, such as the cotton cloth, the color will change depending on the fixator added. Based on the result of the UV-Visible Spectrophotometry test, the avocado seeds contain flavonoids. Meanwhile, from the result of the GC-MS test, the compound with the largest percentage detected in avocado seeds is the 13-Tetradecynoic acid, methyl ester (C15H26O2). The compound contains a chromophore, such as a carbonyl group (C = O) which is a common feature of flavonoids
Application of Mn-Fe Layered Double Hydroxide as an Adsorbent for the Removal of Arsenic from Synthetic Acid Mine Drainage
No full textThe Mn-Fe layered double hydroxide using chloride in the interlayer anion was successfully synthesizedusing chemical co-precipitation methods. The Mn-Fe LDH was then applied as adsorbent for arsenic removal from synthetic acid mine drainage. The adsorbent characterizations of SEM and XRD analysis showed that the Mn-Fe LDH had many different functional groups and a high specific surface area for the adsorption processes. The morphological structure of Mn-Fe LDH by the SEM-EDS analysis method shows a round shape structure with a particle size of about 1 m, and the XRF analysis method shows that the Mn and Fe elements dominate more than other components. Batch adsorption experimental conducted using the Mn-Fe LDH with the interlayer anion of chloride as an adsorbent to study the effect of contact time, equilibrium pH, and temperature on the arsenic removal. The Mn-Fe LDH showed high adsorption uptake capacity and selectivity for the arsenic in the synthetic acid mine drainage. The adsorption and ion exchange between interlayer chloride anions in Mn-Fe LDH and As (V) solution was the main adsorption mechanism. Therefore, the Mn-Fe LDH can be used as an adsorbent in water and wastewater treatment. In contrast, this research has the potential to be processed and developed into advanced materials
Organo-Silica Membrane Prepared from TEOS-TEVS Modified with Organic-Acid Catalyst for Brackish Water Desalination
Full text linkThe sol gel process is one of the processes used in the manufacture of thin films on membranes because it can control the pore size in the resulting silica matrix. In addition, another way to build membrane size can be done by adding catalysts and precursors to be used. In this study, using a combination of tetraethyl ortho silicate (TEOS) and triethoxy vinyl silane (TEVS) precursors and citric acid as a catalyst to produce a silica matrix with mesoporous size so that it is suitable for application in the desalination process. The organo silica membrane was calcined at 350 C for 1 hour using the RTP calcination technique under vacuum, thus preventing the decomposition of carbon in the silica matrix. The membrane was dipcoated 4 times to obtain 4 layers. The FTIR (Fourier-transform Infrared Spectroscopy) test was carried out to see the functional groups on xerogel, namely silanol, siloxane and carbon. In addition, the performance of this membrane is carried out by desalination through pervaporation using 0.3% NaCl feed water with variations in feed air temperature, namely 25, 40and 60. The resulting flux of air value increased with increasing feed water temperature, namely 6.1; 11.2; and 12.1kg.m-2h-1while the resulting salt rejection was 99.72; 99.64 and 99.23%. So that the organo silica membrane is suitable when applied to the desalination process through pervaporation