H2SO4 Concentration Research Articles

Promoted acid leaching of Zn from hazardous zinc-containing metallurgical dusts: Focusing on transformation of Zn phases in selective reduction roasting

As hazardous wastes from metallurgical processes, high zinc dust (HZD) was considered as a potential alternative resource of Zn. The acid leaching of HZD was a principal step and therefore was highly relevant to efficient utilization. Unfortunately, zinc ferrite (ZnFe2O4) in HZD was difficult to be leached by hydrometallurgical methods. Therefore, in this study, to enhance the recovery of zinc, selective reduction roasting was used to decompose ZnFe2O4. The transformation of Zn phases during the reduction process was investigated by thermodynamic calculation, XRD analysis. The results showed that ZnFe2O4 was converted into acid-soluble ZnO in H2 at 600 °C, while the further reduction of ZnO to Zn(g) and the volatilization of ZnO was avoided. However, the soluble ZnSO4 in HZD was also reduced to acid-insoluble ZnS. Consequently, a novel method of reduction roasting combined with water leaching was proposed to pretreat HZD. In water leaching, the solid-liquid ratio was1:10 (g/mL). When H2SO4 concentration was 80 g/L, the leaching ratio of Zn was 94.24% after pretreatment, higher than that of direct leaching of HZD (87.76%). Therefore, acid leaching of Zn was promoted by water leaching and reduction roasting pretreatment, which will bring considerable benefits to the high zinc dust recycling enterprises.

Energy-efficient leaching process for preparation of aluminum sulfate and synergistic extraction of Li and Ga from circulating fluidized bed fly ash

ABSTRACT Sequential leaching and extraction of precious metals from high aluminum (Al) circulating fluidized bed (CFB) fly ash in China, which associated with lithium (Li) and gallium (Ga), is one of the most significant ways for value-added utilization. However, industrial application has been limited due to serious corrosion of equipment, significant energy consumption, and complex purification processes. To sufficiently leach valuable metals from CFB fly ash, a novel energy-efficient sulfuric acid (H2SO4) leaching process using dilution heat was developed, and the effects of iron (Fe) amount in the raw materials on the extraction process of Al, Li, and Ga as well as the as-prepared Al-based products were studied to efficiently obtain the qualified aluminum sulfate (Al2(SO4)3) products. The leaching behavior of each target element was systematically investigated by the laboratory and pilot-scale experiments. The extraction efficiencies for Al, Li, and Ga were 95.2%, 94.2%, and 87.7%, respectively, when the acid leaching process was conducted at the temperature of 140°C for 2 h, with the H2SO4 concentration of 40% and the solid-to-liquid ratio of 1/3, In the Pilot-scale experiment, the temperature of the reaction system can reach 120°C, 140°C, and 160°C by regulating the amount of H2SO4 added to release different heat, and efficient leaching of the target elements was achieved by the energy-efficient sulfuric acid leaching process. To obtain qualified Al2(SO4)3 products from fly ash, carbothermal reduction magnetic separation, and acid leaching were used for Fe removal from raw fly ash, and the Fe content in the as-prepared Al2(SO4)3 products was only 0.45% and 0.29%, which reached the standards of Class II qualified products and Class II first-grade products, respectively. This paper might provide an energy-efficient process for efficient and high-value utilization of solid waste fly ash.

Adsorption of sodium from saline water with natural and acid activated Ethiopian bentonite

In the present study, natural and acid activated local bentonite were investigated for removal of sodium for reduction of water salinity. Local bentonite from was collected from Warsisso area of Afar region, eastern part of Ethiopia and activated with H2SO4. The raw and activated bentonites were characterized with XRD, SEM, FTIR and BET. The raw and activated bentonites were used for adsorption of sodium from aqueous water for reduction of salinity of water. The effects of H2SO4 concentration, activation time, concertation of initial sodium concentration, adsorption time, pH of solution and adsorbent dosage on the sodium removal were studied. SEM results shows smooth aggregate with closely packed flakes for natural bentonite while the surface foe activated bentonite is foggy and ragged appearance. The specific surface area of natural bentonite is 57.6 m2/g while a maximum of 238.24 m2/g was observed for bentonite activated with 3 M H2SO4 activated for time period of 6 h. A maximum of 18% sodium adsorption was achieved at this maximum specific area condition. An optimum removal of sodium by activated bentonite was 19.4% at adsorption conditions of time 180 min, salt concentration of 3486 ppm, solution pH of 10 and adsorbent dosage of 0.5 g. The experimental data were analyzed by Freundlich, Langmuir, Dubinin-Radushkevic (D-R) and Temkin isotherms models. The results revealed that Langmuir isotherm provided a better fit to the experimental data with correlation coefficients of 0.967 and 0.979 for raw and activated bentonite, respectively. Adsorption kinetics as well was studied with pseudo first order and pseudo second order, intraparticle diffusion and Elovich models. And pseudo second order model also found best to explain adsorption kinetics with 0.994 and 0.999 correlation coefficients.

Effects of Temperature and Sulfuric Acid and Iron (II) Concentrations on the Efficacy of Decontamination of Spent Ion-Exchange Resins Containing Hematite

The effect of H2SO4 and FeSO4 concentrations and temperature on the efficacy of decontamination of spent ion-exchange resins was estimated. The study was performed on model spent ion-exchange resins purposefully contaminated with hematite and Co-57 radionuclide. It was found that an increase in solution temperature up to 50 °C and the addition of FeSO4 increases the efficacy of decontamination of spent ion-exchange resins by 1 M and 2 M H2SO4 solutions by 1–2 orders of magnitude, whereas the decontamination factor value here is >103. Since under static conditions, the secondary adsorption of Co-57 was observed, the extra washing of ion-exchange resins by 3 M solution of NaNO3 is required. Decontamination under dynamic conditions excludes the secondary adsorption of Co-57, so that the necessity of the extra stage of washing can be skipped. Under dynamic conditions, the consumption of a solution of the composition H2SO4 (1 mol/L) + FeSO4 (0.2 mol/L) is 1.5-fold lower in comparison with the 2M solution of H2SO4 at compatible values of the decontamination factor. Such an approach enables reduction in the volume of secondary waste and the equipment corrosion due to the decrease in H2SO4 concentration.

Evaluation of Public-Health Risk of Heavy Metals Contaminants and Physicochemical Parameters in Adulteration Palm Oil Commonly Consumed in Calabar, Nigeria

Edible palm oil has been the parity of the human diet from generation to generation and has contributed both to nutrition and health. These studies investigated some selected heavy metals and physicochemical parameters in palm oil. Eleven (11) samples of ready-consumed edible palm oil were bought randomly from the selected market in calabar metropolis. The samples were digested with 25ml of concentrated H2SO4, for heavy metals analysis using Atomic Absorption Spectrophotometer (AAS). The physiochemical parameters in selected markets include the following FFA, IV, PV, and protein content were also analyzed using standard methods. The results showed that FFA value range from 9.26 to 12%, Iodine value range from 45.78 to 21.40 MgKOH/g, Peroxide value range from 3.60 to 0.03 Meq/kg, and protein content ranges from 0.06 to 0.2 mg were significantly (p<0.05) higher in some markets in comparison to the control. The results of heavy metals showed that Zn 8.06±0.06, Cd 1.01±0.05, N 1.00±0.00, C 125.91±0.09, Pb 9.30±0.07 Cobalt, Lead zinc were above the detectable limit of the WHO standard while Cd and Ni were within the permissibility limit. The results obtained from this study indicate that the palm oil sold in calabar metropolis may cause a public health risk if proper monitoring is not maintained by regulatory agencies. Thus, there is a need for improved screening of our local processed palm oil from the time of production to the time of consumption.

Enhanced removal of Pb from electrolytic manganese anode slime and preparation of chemical MnO2

ABSTRACT Electrolytic manganese anode slime (EMAS) is produced during the production of electrolytic manganese metal. In this study, a method based on vacuum carbothermal reduction was used for Pb removal in EMAS. A Pb-removal efficiency of 99.85% and MnO purity in EMAS of 97.34 wt.% were obtained for a reduction temperature of 950°C and a carbon mass ratio of 10% for a holding time of 100 min. The dense structure of the EMAS was destroyed, a large number of multidimensional pores and cracks were formed, and the Pb-containing compound was reduced to elemental Pb by the vacuum carbothermal reduction. A recovery efficiency for chemical MnO2 of 36.6% was obtained via preparation from Pb-removed EMAS through the ‘roasting-pickling disproportionation’ process, with an acid washing time of 100 min, acid washing temperature of 70°C, H2SO4 concentration of 0.8 mol·L−1, liquid–solid mass ratio of 7 mL·g−1, calcination temperature of 60°C and calcination time of 2.5 h. Moreover, the crystal form of the prepared chemical MnO2 was found to be basically the same as that of electrolytic MnO2, and its specific surface area, micropore volume and discharge capacity were all higher than that of electrolytic MnO2. This study provides a new method for Pb removal and recycling for EMAS. Highlights Vacuum carbothermal reduction method was used for Pb removal in EMAS. The removal efficiency of Pb was 99.85%. Chemical MnO2 with excellent discharge performance was prepared using treated EMAS. This study provides a new method for EMAS resource utilization.

Corrosion Resilience of 2101 LDX Duplex Stainless Steels in Varying Sulphate Anion Concentrations

The general and localized corrosion resilience of 2101 LDX duplex stainless steel (2101ST) was assessed in specific concentrations of H2SO4 electrolyte by Potentiodynamic polarization, potentiostatic evaluation, open circuit potential analysis and optical illustration characterization. Data output shows 2010ST exhibited sufficient resistance to general corrosion (0.28 mm/y and 1.01 mm/y) at low concentrations of H2SO4 solution (1M and 2 M H2SO4) whose values correlates to polarization resistance of 42.47 Ω and 19.74 Ω. Further increment in H2SO4 concentration results in substantial increase in degradation rate which culminated at 58.32 mm/y at 6M H2SO4 and polarization resistance of 0.10 Ω. Due to the destructive action of SO42- anions. Corrosion potential shifts indicates dominant anodic dissolution reactions with respect to H2SO4 concentration. Metastable pitting activity was observed on the plot following anodic polarization but prior to passivation of the steel. The metastable pitting current and passivation potential of the steel grew with increase in H2SO4 concentration. This weakened the localized corrosion resistance of the steel at higher H2SO4 solution. This is evident in the decrease in passivation range values plot configuration. Open circuit potential plots depict significant passivation of the steel at 1M H2SO4 solution compared to the plot at 6M H2SO4 which indicates strong tendency to corrode despite its thermodynamic stability. Optical images of 2101ST exterior after corrosion at 1M H2SO4 solution shows mild surface deterioration coupled with miniature corrosion pits. This contrasts the morphology of the steel at 6M H2SO4 which showed the presence of deep and enlarged, corrosion pits, and a badly etched surface showing the grain boundary coupled with a severely degraded exterior.

Extraction of Cellulose Nanoparticles via Modified Thermochemical Processes from Agricultural Wastes

Agricultural waste is a critical environmental problem and a major challenge facing environmental pollution. Cellulose extraction from agricultural (wheat straw) wastes is a motivating, sustainable source, and environmentally friendly alternative. In the present investigation, the bleaching process, a thermochemical treatment, was used to treat the agricultural wastes to produce nano-cellulose to reduce its negative environmental effects. The first step of the extraction process begins with removing contaminants, waxes, and other extracts from wheat straw with an alkaline treatment. The second step is the bleaching process with NaClO, followed by treatment with different concentrations of H2SO4 and NaOH. All the products were characterized using Scanning X-Ray Diffraction (XRD), Electron Microscope (SEM), and Fourier Transform Infrared (FT-IR). The results showed that cellulose production had an average diameter of 45.06, 56.75, and 30.66 nm when extracted with 40, 50, and 60% H2SO4 concentrations. Also, the XRD and FT-IR results confirm the high purity of the produced cellulose nanoparticles (CNPs).

Protection of Oil Refinery Furnaces Bricks Using Coatings of Nano Zirconia-Glass Composites

The process of ceramic or refractory surfaces coating is one of the methods used to protect the ceramic body from chemical effects resulting from operating conditions, especially in the applications that include acid gases emissions such as furnaces of petroleum refining units. A mixture of low-melting glass frit was used, reinforced with nano powders of zirconia and Partial Stabilized Zirconia with yttria (3Y-PSZ) with different additives 5wt% and 10 wt%, as well as the addition of nano-alumina for the same percentage of addition. The medium alumina refractory brick which used in lining petroleum refining units was used as a basis for coating.
 The coating process was implemented after mixing and preparation of a homogeneous suspension in the presence of water, then drying and sintering until glazing at a temperature of 850 oC. X-ray diffraction technique was used to show the structural characterization of the glazing, which indicated that a glass frit layer was transformed into a mixture of ceramic-glass (crystalline glass), where the crystalline structures of the nano powders were clearly visible. Surface roughness showed low values for frit added with 5wt% of (3Y-PSZ) as well as the frit to which was added 10 %wt of (3Y-PSZ with 5wt% alumina). Moreover, all samples showed clear chemical resistance against acids, including concentrated H2SO4. Thermal shock resistance varied for vitrification mixtures, but it was good for vitrified samples, adding 10%wt of (3Y-PSZ) with 5wt% alumina as well as adding silicate to the mixture, and these mixtures are considered to be the best in medium alumina refractory surfaces coating.

Insight into the sulfonation conditions on the activity of sub-bituminous coal as acidic catalyst during the transesterification of spent corn oil; effect of sonication waves

The impact of the sulfonation conditions on the catalytic activity of coal as an acidic catalyst was assessed by normal stirring (NS.Coal) and sonication waves (SS.Coal) based on the Response Surface methodology. The NS.Coal exhibits acid density and surface area of 8.8 mmol/g and 27.8 m2/g, respectively. This was obtained after 90 min at sulfonation conditions of 150 °C temperature and 95% H2SO4 concentration. In the existence of sonication waves for 60 min (240 W), SS.Coal shows acid density and surface area of 14.2 mmol/g and 45.8 m2/g, respectively. This demonstrates significant efficiency for the sonication-induced sulfonation processes during the synthesis of sulfonated coal as an acidic catalyst. The activities of NS.Coal and SS.Coal acidic catalysts were evaluated during the transesterification of corn oil. The best yield was obtained by NS.Coal (4 wt, %) is 99.3% after 60 min at 60 °C in the presence of 14:1 methanol/oil ratio. The archived yields using SS.Coal at loading values of 2 wt, %, 3 wt, %, and 4 wt, % are 99.6%, 99.84%, and 99.85%, respectively after 20 min. The kinetic properties of reactions were illustrated based on the Pseudo-First order assumption. The thermodynamic studies demonstrate the endothermic properties of the corn oil transesterification reactions. The determined activation energy by NS.Coal and SS.Coal are 26.22 kJ/mol and 17.7 kJ/mol, respectively reflect the possible use of them as effective catalysts at low energy and mild conditions.

Experimental and theoretical evaluation of aqueous black mustard seeds extract as sustainable-green inhibitor for mild steel corrosion in H2SO4 acid solutions

The inhibitory potential of aqueous black mustard seed (BMS) extract on mild steel corrosion in H2SO4 solutions was tested using various chemicals (Hydrogen Evolution, HE, and Weight Loss, WL) and electrochemical (Electrochemical Impedance Spectroscopy, EIS, and Potentiodynamic Polarization, PDP) methods. The adsorption process was characterized using scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and contact angle technique. Computational studies were also used to improve the visualization of the adsorption mechanism of the active components found in BMS on the metal surface. The results showed that aqueous BMS extract had a superior ability to inhibit mild steel corrosion in 2 M H2SO4 (IE% = 94.83 at 3.5 g/L). Polarization outcomes demonstrated that the BMS functioned as a mixed-type inhibitor. The findings are consistent with the Langmuir adsorption isotherm. FT-IR, contact angle, and SEM successfully showed the formation of a dense and ordered BMS-adsorbed film. The calculated Ea in the absence and presence of BMS revealed that physisorption and chemisorption played a role in the inhibition mechanism. Using DFT quantum-chemical calculations and MD simulations, a relationship can be established between the electronic structure of Sinigrin, the main component in BMS, and its ability to inhibit corrosion. BMS extract showed exceptional inhibitory activity in a wide range of H2SO4 concentrations. One of the important aspects of this study is the possibility of applying BMS as a greener alternative to design environmentally friendly materials in working on corrosion problems of metallic equipment in acidic environments.

Uranyl extraction from aqueous solution by emulsion liquid membrane process

In this study, the elimination of Uranyl from aqueous solution is studied using an advanced technique of extraction; emulsion liquid membrane (ELM). Experimental results for the extraction of Uranyl are presented. The membrane phase consists of Kerosene as a diluent, Cyanex 302 as a carrier and sorbiton monooleate (Span 80) as a surfactant. Sulfuric acid solution as an internal aqueous phase. At the optimum conditions, the main variables studied which influenced the ELM extraction of Uranyl were the concentration of surfactant (3%), carrier (0.3%), internal phase (1 N H2SO4), types of internal phase (H2SO4 sulfuric acid), diluent (Kerosene), stirring speed (200 rpm), and the effect of volume ratios of the internal phase to the organic phase 1:1 (A/O) and of the emulsion to the feed solution 20/200 (Vemul/Vext). The results indicate that the removal percentage was obtained 100% in less than 20 min.This study also evaluated the effect of H2SO4 concentration in the internal aqueous phase on the stripping of Uranyl. The ELM treatment process represents a very interesting advanced separation process for the removal of Uranyl from aqueous solutions.

A study to understand the role of ethylene glycol in the oxidative acid dissolution of chalcopyrite

Recent investigations suggest that ethylene glycol (EG) performs two important functions in the oxidative dissolution of chalcopyrite with hydrogen peroxide: it prevents H2O2 dismutation on the chalcopyrite surface and, secondly, it hinders H2O2 decomposition due to the presence of dissolved copper and iron in the leach liquor. Of these two, retarding the H2O2 breakdown probably contributes most to the observed improvement in copper leaching; however, the nature of the role that EG plays in the solution is unclear. For that reason, a systematic study was undertaken, at different concentrations of sulfuric acid and EG, to reveal the role of EG in the leaching process. The results of this investigation show that EG hinders H2O2 degradation by decreasing the copper and iron activities in the solution through Cu (II)-EG and Fe (II, III)-EG complex formation. Likewise, the slowing effect strongly depends on the H2SO4 concentration because the Fenton reaction, which is responsible for the decomposition, increases its efficiency with lower acid concentrations (<0.1 M). Thus, successful leaching could be attained with concentrations above 0.7 M and 0.1 M of sulfuric acid and EG, respectively; otherwise, rapid H2O2 degradation and simultaneous EG mineralization (complete oxidation, in other words, oxidation to CO2 and H2O) are favored as a consequence of the reactions between H2O2 and the leached metals and the OH* radicals produced in the leach liquor, respectively. In view of these results, a brief discussion is presented on the implications of chalcopyrite leaching with H2O2, showing alternatives to increase its performance.

Loading behavior of p-toluenesulfonic acid in biochar and its application to prepare 5-hydroxymethylfurfural

A carbon-based solid acid catalyst was prepared from papermaking sludge via calcining followed by sulfonation with p-toluenesulfonic acid. The micromorphology of several catalysts were compared via SEM, FT-IR, N2 adsorption-desorption, XPS, and UV spectrum. It was found that the micromorphologies of biochar surface modified with concentrated H2SO4, p-toluenesulfonic acid, and sulfanilic acid were different and closely related to the binding mechanism. The biochar and p-toluenesulfonic acid exhibited π-π* stacking and hydrophobic effects. The suitable pores and gaps on the biochar surface were the key to the loading of p-toluenesulfonic acid. However, no π-π* stacking and hydrophobic effects were observed between the biochar and sulfanilic acid. The amidation grafting of sulfanilic acid to the biochar surface could lift the restriction of surface pore structure. The catalytic performance of these catalysts was evaluated via fructose, glucose, and cellulose degradation to 5-hydroxymethylfurfural (HMF). The HMF yield from fructose, glucose, and cellulose was 92.9%, 60.7%, and 28.6%, respectively, with the carbon-based solid acid catalyst. The carbon-based solid acid catalyst prepared from papermaking sludge and p-toluenesulfonic acid has the following advantages: a simple process, is environmentally friendly, and has good catalytic performance; as such, it has the prospect of industrialization.

Co-production of hydrochar, levulinic acid and value-added chemicals by microwave-assisted hydrothermal carbonization of seaweed

Seaweed is considered a third-generation biomass for transport biofuel production with great potential for bioenergy and biorefinery applications. Microwave-assisted hydrothermal carbonization (HTC) offers a conversion route for seaweed valorization to multiple value-added products. However, the HTC products (such as hydrochar and process liquor) are highly dependent on feedstock properties and HTC conditions. This study investigated the valorization of Laminaria digitata to a range of products (primarily including hydrochar, levulinic acid and 5-hydroxymethylfurfural) through microwave-assisted HTC at a range of low temperatures (160, 180 and 200 °C) and levels of dilute acid addition (1, 2 and 4% H2SO4 concentration). The work suggests an optimized process at a temperature of 200 °C with 4% H2SO4, with levulinic acid and 5-hydroxymethylfurfural in the process liquor achieved the highest yields of 12.5% (12.5 g per 100 g dry L. digitata) and 5.8%, respectively. The obtained hydrochar had a higher heating value of 25.5 MJ/kg volatile solids, comparable to lignite coal. At such a condition the total carbon recovery in the produced hydrochar and process liquor accounted for 84% of carbon in the original seaweed. The 200 °C derived hydrochar presented the highest carbon content of 65.4%, but the lowest abundance in oxygen-containing functional groups compared to the hydrochars obtained under other conditions (160 and 180 °C). The economic benefits of the process might be significantly increased if hydrochar was upgraded into activated carbon instead of being used as a solid fuel.

Electrical and Structural Properties of CVD-Graphene Oxidized Using KMnO4/H2SO4 Solution

We report the electrical properties of graphene grown via chemical vapor deposition (CVD-graphene) and oxidized using a KMnO4/dilute H2SO4 mixture. CVD-graphene was successfully oxidized without any pores or peeling off from the substrates. When the H2SO4 concentration was increased, the electrical resistance of the oxidized graphene (OG) increased. In particular, OG-20 shows a nonlinear current–voltage curve similar to that of a diode owing to direct tunneling through the interfaces between the nanosized sp2 and sp3 regions. The changes in electrical properties occurred because of structural evolution. As the H2SO4 concentration increased, the number of oxygen functional groups (epoxide/hydroxyl and carboxyl groups) in the OG increased. In addition, a reduction in the average distance between defects in the OG was determined using Raman spectroscopy. Oxidation using a KMnO4/dilute H2SO4 mixture results in CVD-graphene with modified electrical properties for graphene-based applications.

Hidrolisis Eceng Gondok (Eichhornia Crassipes) Menjadi Glukosa Menggunakan Rotating Microwave Reactor

Water hyacinth is lignocellulosic biomass that has the potential for glucose production because it contains 64.51% cellulose. Hydrolysis of water hyacinth was done in a rotating reactor with a microwave as a heat source. This study aims to obtain glucose by determining the hydrolysis reaction rate constant of power and sulfuric acid (H2SO4) concentration function and to find the best conditions for this hydrolysis process. Several research variables were H2SO4 concentration (0.5 N; 1 N; and 1.5 N), microwave power (600 W and 800 W) and reaction time of 60 minutes. Parameters measured were hydrolyzate temperature, glucose, and cellulose content. The hydrolysis reaction rate constant obtained based on the Arrhenius equation was k =1.30 x 10-2 e-132.172/T and the relationship between H2SO4 concentration and microwave power was C = 0.001P. The best conditions were obtained using 1 N H2SO4 and microwave power of 600 W with final glucose content of 486 mg/L.

Pembuatan Gelatin dari Tulang Ikan Nila (Oreochromis niloticus) Menggunakan Metode Asam untuk Pengental Sirup Nanas

Imports of gelatin in Indonesia have increased according to demand. Gelatin is a protein derivative from collagen fibers derived from bone extraction. Gelatin contains protein, water and minerals. Gelatin is used to thicken, concentrate, and stabilize fluids such as water, acetic acid, and alcohol. The raw material used in the study was tilapia bone due to the lack of utilization of tilapia bone waste treatment. The purpose of this study was to examine the effect of sulfuric acid concentration on gelatin yield and to apply gelatin as a thickener for pineapple syrup. The methods are degreasing, extraction, and application of pineapple syrup. Variations in the concentration of H2SO4 were 1%, 3%, 5%, and variations in immersion time were 10 hours, 24 hours, and 36 hours. The analysis carried out on tilapia bone gelatin consisted of yield, acidity (pH) and viscosity. The best yield was produced using 1% H2SO4 and 10 hours immersion, which was 13.77%. The largest pH was produced at 2.47 with the use of 5% H2SO4 and immersion for 24 hours, and the largest viscosity was produced at 7.66 cP with the use of 5% H2SO4 and immersion for 36 hours.

Enhancement of Fermentable Sugars Obtained from&lt;i&gt; Amorphophallus&lt;/i&gt; Spp. Tuber for Bioethanol Production by Optimizing Temperature and Pretreatment Concentration

Biofuels have been regaining popularity due to the increasing price of non-renewable fuels and the higher carbon dioxide emissions. Biofuels are manufactured from plant products and are mainly composed of lignocellulose and starch materials. This investigation aims to produce increased fermentable sugars for enhanced bioethanol production from tubers procured from northern Thailand. Varying concentrations of H2SO4 is used to pretreat the tubers. Before hydrolyzing with cellulase enzymes, the tubers were chopped into small pieces (1-2 cm), dried in a solar oven, powdered. The obtained results confirmed that the fermentable/ reducing sugar content of Amorphophallus spp. (suweg) tuber increased from 2.6 g/L to 19.01 g/L after enzymatic hydrolysis. The enzymes act as an excellent way to speed up the hydrolysis process. The theoretical potential of bioethanol production was calculated under ideal conditions, with the highest bioethanol concentration obtained is 9.69 ± 0.12 g/L at 0.4 % H2SO4 (pretreatment conc.) and 75 °C. The enhanced fermentable sugars obtained from starchy tubers may be utilized for bioethanol production to overcome depleting fossil fuels.

INVESTIGATION OF MECHANISAM OF METAL ION ADSORPTION FROM AQUEOUS SOLUTIONS USING PROSOPIS JULYFLORA ROOTS: BATCH AND FIXED BED COLUMN STUDIES

&lt;p&gt;Adsorption of heavy metal ions (Cr, Pb &amp;amp; Zn) using prosopis julyflora roots has been investigated by batch adsorption and fixed bed column process. The various properties of adsorbent were analysed and the FT-IR spectra &amp;amp; SEM studies of prosopis julyflora powder, before and after adsorption of metal ions also examined. From the batch adsorption study, maximum amount of metal ion adsorption was found to be 87.12% for Cr (VI), 92.28% for Pb (II) and 95.62% for Zn (II) metal ions. The Freundlich isotherm model fitted well than the Langmuir adsorption isotherm with high regression values. From the column study, optimum bed height of 5 cm, flow rate of 5 mL/min and metal ion concentration of 100 mg/L was obtained by breakthrough analysis. The fixed bed column study followed Thomas &amp;amp; Yoon-Nelson model plots with good correlations and maximum desorption rate was achieved by adding 0.3M of concentrated H2SO4.&lt;/p&gt;&#x0D;