• Resources Recycling
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• v.15 no.2 s.70
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• pp.50-57
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• 2006

Production of activated carbon from woody fish parking cases has been studied using waste sulfuric acid as an activating agent for the purpose or promoted recycling of woody fishing port wastes. The adsorption capacity of produced activated carbon was observed to increase with activation temperature and reached its maximum at ca. $650^{\circ}C$ under the experimental conditions. However, the adsorption capacity of activated carbon became deteriorated above this temperature due to the thermal degeneration of its structure. Optimal activation time was found to be about 120 minutes and 1:3 weight ratio of raw material and activating agent was appropriate for increased adsorption capacity of activated carbon under the conditions of $550^{\circ}C$ and 60 minutes of activation time. Regarding the effect of the concentration of activating agent on activation, ca. 1.2 M of sulfuric acid was observed to be proper for an optimal activation or raw material. Comparison of the activation power of sulfuric acid with nitric acid showed that sulfuric acid was superior to nitric acid, however, with regard to the yield of activated carbon there was no significant difference between the two activating agents. The degree of dispersion of carbon particles was shown to be relatively high in neutral condition and the produced activated carbon was considered to be effectively employed for the treatment of metal ions in wastewater due to its negative surface charge in aqueous condition.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.472-477
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• 2001

Spent catalysts containing platinum were generated in petroleum refinery and other chemical industries. The reclamation of precious metals from such wastes has long been attempted in view of their rare, expensive and indispensable nature. In this study, the recovery of platinum from petroleum catalysts was attempted by a method consisting mainly of dissolving alumina substrate with sulfuric acid thereby concentrating insoluble platinum. Also, platinum dissolved partially in sulfuric acid was recovered by a cementation method using aluminum metal as a reductive agent. The effect of temperature, time, concentration of sulfuric acid. and pulp density on the dissolution of substrate was investigated. When the substrate of platinum catalyst was ${\gamma}$-AI$_2$O$_3$ about 95% alumina was dissolved in 6.0M sulfuric acid at 10$0^{\circ}C$ for 2 hours. When the substrate was the mixture of ${\gamma}$-A1$_2$O$_3$and $\alpha$-A1$_2$O$_3$about 92% was dissolved after 4 hours. As a result, more than 99% of platinum could be recovered by this method and aluminum sulfate was obtained as byproduct.

• Resources Recycling
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• v.11 no.1
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• pp.26-31
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• 2002

The recovery of $H_2$$SO_4$from sulfuric acid waste was attempted by a diffusion dialysis method using an anion extchange membrane. The effect of flow rate, temperature, concentration of metal ions on the recovery rate was studied. The recovery of $H_2$$SO_4$decreased with the concentration of $H_2$$SO_4$and flow rate. The recovery increased with the flow rate ratio of water/$H_2$$SO_4$solution upto 1 above which no further increase was observed. The flow rate did not affect the rejection of Fe and Ni ions. As a result, about 80% of $H_2$$SO_4$could be recovered from sulfuric acid wastes which contains 4.5M free$-H_2$$SO_4$at the flow rate of 0.26 $1/hr-m^2$. The concentration and purity of recovered $H_2$$SO_4$was 4.3M and 99.8%, respectively.

• Resources Recycling
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• v.13 no.1
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• pp.14-21
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• 2004

Spent catalysts containing platinum were generated in petroleum refinery and other chemical industries. The reclamation of platinum metals from such wastes has long been attempted in view of their rare, expensive and indispensable nature. In this study, the recovery of platinum from petroleum catalysts was attempted by a method consisting mainly of dissolving alumina carrier with sulfuric acid thereby concentrating insoluble platinum. Also, platinum dissolved partially in sulfuric acid was recovered by a cementation method using aluminum metal as a reductive agent. The effect of temperature, time, concentration of sulfuric acid, and pulp density on the dissolution of carrier was investigated. When the carrier of platinum catalyst was $\Upsilon-Al_2$O$_3$ about 95% alumina was dissolved in 6.0 M sulfuric acid at $100^{\circ}C$ for 2 hours. When the carrier was the mixture of $\Upsilon-Al_2$$O_3$ and $\alpha$-$Al_2$$O_3$ about 92% was dissolved after 4 hours. As a result, more than 99% of platinum could be recovered by this method and aluminum sulfate was also obtained as byproduct.

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.428-432
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• 2013

From the forest areas in Chungbuk, large amounts of wood wastes by pruning are generated, however most of them considered as by-products are not treated properly with no disposal options. In this work, among diverse wood wastes such as Quercus variabillis, Juniperus chinensis, Larix kaemoferi, and Pinus densiflora, Juniperus chinensis was found to be more effective biosorbent for the removal of lead ions than other wood wastes. Also, the enhancement of lead removal efficiency from the aqueous phase was investigated using Juniperus chinensis waste. It was observed that the optimal initial pH to increase the removal efficiency of 20 mg/L lead ions was 4.0 and the optimal dosage concentration with regard to the biosorbent for the enhanced removal of 50 mg/L lead ions was 0.6 g/100 mL. In addition, chemical treatment of Juniperus chinensis waste with sulfuric acid was required to improve the adsorption capacity for high lead concentrations (over 100 mg/L). When Juniperus chinensis waste was chemically treated with 6 M sulfuric acid, the adsorption quantities of lead ions were 180, 340, and 425 mg/g with regard to 200, 400, and 500 mg/L lead ions concentrations, respectively. These results indicate that the practical biosorbent technology developed in this study is a highly efficient method to treat the lead ion from an aqueous solution.

• KSBB Journal
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• v.22 no.4
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• pp.201-206
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• 2007

The demand of L-arabinose has been increased recently because of its advantages including clinical effect. L-arabinose can be produced from dilute acid hydrolysis of agricultural wastes. In this study, optimum conditions of L-arabinose production using dilute acid hydrolysis of agricultural wastes and nutshells were determined. Among the tested various agricultural wastes and nutshells, corn fiber was selected as the best raw material for the production of arabinose. The highest arabinose production was achieved an acid hydrolysis of corn fiber for 1 h at 130$^{\circ}C$ with 0.4% sulfuric acid. Above optimal conditions, it was obtained 20.1 g/L glucose, 10.1 g/L xylose, 7.8 g/L arabinose and 1.8 g/L galactose from 90 g/L of corn fiber. For the purification of arabinose, it was carried out to remove all of sugars except arabinose by the Candida tropicalis cultivation of acid hydrolyzate and an organic contaminants such as pigments by the active carbon treatment of fermentation broth. Moreover, experiments were carried out to eliminate an ions by exchange chromatography. Finally, we obtained 3.1 g of partially purified L-arabinose powder with about 40% yield by evaporation and vacuum drying.

• Microbiology and Biotechnology Letters
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• v.1 no.1
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• pp.31-36
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• 1973

A method for acid-hydrolysis of agricultural wastes and its utilization was investigated. In order to obtain fermentable sugar solution from cellulosic wastes such as cereal straws and hulls, in particular, of rice, barley and wheat, the chemical compositions were analyzed and optimum conditions of hydrolysis determined. The cereal straws contain 42 to 55 % of crude cellulose including hemicellulose. On the hydrolysis with 1% of sulfuric acid at 40 psig, 35.6% of the reducing sugar based on the weight of dry matter was formed from rice straw, (variety Chinheung) in 30 min. More powerful condition of hydrolysis would appear to decompose the sugar formed into other compounds, for instance, furfural. Under atmospheric pressure with 5% of the acid, rice straw was hydrolyzed to 35% of reducing sugar content in 3 hours. Candida utilis could assimilate the sugars in the hydrolyzate up to more than 97%, and a yield of the yeast cells reached 55% to the utilized sugars.

• Advances in concrete construction
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• v.11 no.2
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• pp.173-181
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• 2021

The main objective of this work is to contribute to the valorization of plastic and glass waste in the improvement of concrete properties. Waste glass after grinding was used as a partial replacement of the cement with a percentage of 15%. The plastic waste was cut and introduced as fibers with 1% by the total volume of the mixture. Mechanical and durability tests were conducted for various mixtures of concrete as compressive and flexural strengths, water absorption, ultrasonic pulse velocity, and acid attack. Also, other in-depth analyses were performed on samples of each variant such as X-ray diffraction (XRD), thermogravimetric analysis (DSC-TGA), and scanning electron microscope (SEM). The results show that the addition of glass powder or plastic fibers or a combination of both in concrete improved in the compression and flexural strengths in the long term. The highest compressive strength was obtained in the mix which combines the two wastes about 26.72% of increase compared to the control concrete. The flexural strength increased in the mixture containing the glass powder. Therefore, the mixture with two wastes exhibits better resistance to aggressive sulfuric acid attack, and incorporating glass powder improves the ultrasonic pulse velocity.

• Resources Recycling
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• v.6 no.3
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• pp.22-27
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• 1997

Recycling of radioactively contaminated metal wasles is very attractive to reduce thc final disposal volumc of the radioactive wastes, thereby maximizing the usage of nahrral rzsuunts and minimizmg the detrimental effects of thz rzdioaclive wastes on the environment. In the recycling process, many complicated processes arc involved. Among those processes the 'surface contamination removal techniques such as physical, chemical and electrochern~calm ethods are the most critical and Ircquently applied in accordance with the contamination characteristics and the chemical compositions of the metal wastes. In this sludy, the sulfuric acid-cerium method and electmchemical methods were applied lu removc the conatiminated suhce. The results showed the surface contaminalion could he lowered to the background levcl by lhasc mclhods.

• Journal of Electrochemical Science and Technology
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• v.8 no.1
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• pp.77-86
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• 2017

The valorization of domestic wastes becomes a very important research axis that can reduce the energy consumption and protect our environment. The objective of this study is to remove zinc ions from wastewater by using banana peels after their activation as sensor in the working electrode for an environmental application. Banana peels were dried, crushed and treated with sulfuric acid then mixed with polyaniline to improve their electrical conductivity. Cyclic voltammetry and chronoamperometry were used for electrochemistry tests. The obtained voltammogramms at well optimized conditions of applied potential of -1.3 V/SCE and initial zinc concentration of 0.2M during 2 hours of electrolysis, showed the reduction peak of the zinc at a potential of -1.14 V/SCE, which confirmed the activity of this electrode. The modeling of experimental data revealed that the adsorption was fitted by the Langmuir isotherm with a maximal adsorption capacity of 3.4188 mg/g. Changes in the structure of the powder after the electrosorption was noticed by SEM and EDX. Finally, the dosage of the electrolytic solution showed a diminution of the zinc concentration with yield of 99.99%.