Repository of Research and Investigative Information

Repository of Research and Investigative Information

Kurdistan University of Medical Sciences

Behavior parameters of pinecone derived activated carbon column for dye adsorption from aqueous solutions

(2012) Behavior parameters of pinecone derived activated carbon column for dye adsorption from aqueous solutions. Journal of Environmental Studies.

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Dyes, as they are intensively colored, cause special problems in effluent discharge, and their effects are both aesthetically displeasing and hazardous. They can prevent sunlight penetration, decreasing photosynthetic activity in aquatic environments. Some azo dyes that cause effluent to be colored have been implicated as being mutagenic/carcinogenic as well as toxic to aquatic life. Thus, it is necessary to eliminate dye from wastewater before it is discharged. In general, there are four main methods of reducing color in textile effluent streams: physical methods, chemical methods, biological methods and emerging technologies. Among physico-chemical processes, adsorption technology is considered to be one of the most effective and proven technologies with potential application in both water and wastewater treatment. Activated carbon is the most commonly used sorbent for organics removal by adsorption. It is used as adsorbent in the treatment of water, municipal wastewater, and organic industrial wastewaters, because of its ability to adsorb a wide variety of organic waste compounds, as well as its economic feasibility of use. Although commercial activated carbon is a preferred adsorbent for color removal, its widespread use is restricted due to high cost. As such, alternative non-conventional adsorbents have been investigated. It is well-known that natural materials, waste materials from industry and agriculture and bio-sorbents can be employed as inexpensive adsorbents. Many investigations have been carried out to study the feasibility of using inexpensive alternative materials as carbonaceous precursors for the dye removal. Pine is a suitable tree for decorative planting in parks and is used usually as a decorative plant in national parks. Thus, ground pinecone may be abundantly available, it would be worthwhile to develop a low-cost adsorbent from this waste material which may also be regarded as a sustainable resource, since the trees themselves do not have to be harvested. In the present study an activated carbon has been produced from pinecone since pine trees are widely available throughout the world in large concentrations in national parks, and ground pinecone may be abundantly available as an unused natural waste and sustainable resource. The main goal of this study was to evaluate the behavioral parameters of a fixed bed column packed with granular local ground pinecone-derived activated carbon, under continuous flow condition, in terms of its ability to remove two types of azo dyes Acid Blue 113 and Acid Black 1 from aqueous solutions. In this research, the adsorption characteristics of Acid Blue 113 and Acid Black 1 dyes in the batch equilibrium system and fixed bed column of granular activated carbon are investigated using the Langmuir isotherm. Materials and Methods Dried pinecone was used as raw material to produce the adsorbent. The pinecones were collected from the Mardom Park in front of Hamadan University of Medical Sciences in Iran. Acid blue 113 and Acid Black 1 were used in this study. The dye was obtained from Alvansabet dye stuff and textile auxiliary manufacturer Co. in the west of Iran. Equilibrium isotherms were measured to assess the capacity of the activated carbon using two acidic dyes, namely, Acid Blue 113 and Acid Black 1. The local Granular Activated Carbon (GAC) was derived from the ground pinecone. It was produced by exposing raw pinecones to a thermal-chemical process. First of all the pinecones were crushed and rinsed with hot water. Thereafter, they were dried at 100° C in oven, overnight. A 50 g sample was mixed with a predetermined volume of 95w/w phosphoric acid with the mass ratio of 1:10. This mixture was transferred to a stainless steel tube (with the diameter of 50 mm and length of 250 mm). This tube was transferred to a muffle furnace, which was programmed to gradually heat up to 900°C within 3 hours. This temperature was maintained for 1 hour. Subsequently, the tube and its contents were gradually cooled down to room temperature. The nitrogen BET surface area was measured to be 734m 2/g. To determine the equilibrium time of AB113 and AB1 adsorption to GPAC, an accurate amount of 0.12 g of GPAC were added to two concial flasks with the volume of 250 cm 3, containing 250 ml of each dye solution (150 mg/L). The equilibrium times for AB113 and AB1 were determined to be 250 and 167 hours, respectively. Accurately weighted amounts of GAC sorbent of 0.02 to 0.20 g with 0.02 g intervals for each dye were added to the flasks with 250 ml dye solution (150 mg/L) at the pH of 7.4±0.2 for AB113 and 7.0±0.2 for AB1. The contents of all the flasks were mixed thoroughly and stirred for 250 and 167 hours for AB113 and AB1, respectively. Continuous flow sorption experiments were conducted in a glass column (with 2 cm internal diameter and 20 cm length). The column was filled with GPAC (particle size: 297-595 μm). The mass of GPAC in the column was 19 g with the depth of 20 cm. Column studies were carried out to evaluate the column behavioral parameters. Dye solution was pumped into the column in an up-flow mode by a peristaltic pump with the flow rate of 8.07 mL/min for the depth of 20 cm. the initial dye concentration was 150 mg/L. Samples were collected at regular intervals from sampling points and were centrifuged at 3800 rpm for 5 min. Subsequently, the dye concentrations in the samples were measured spectrophotometrically. Conclusion The produced activated carbon had a surface area of 869 m 2/g based on nitrogen BET study. Based on a Langmuir isotherm model, the equilibrium isotherm analyses gave the monolayer maximum saturation capacities of these two acid dyestuffs, AB113 and AB1, as 286 and 458 mg of dye per gram carbon, respectively. Based on the fixed bed investigations for a 20 cm bed depth, the active zone fractional capacities (/) of AB113 and AB1 dyes were determined to be 0.271 and 0.369, respectively. The values of the important parameters of adsorption column behavior were calculated and are shown in Table 1. Based on the surface area, the pinecone-derived activated carbon has a high nitrogen surface. It is comparable to many commercially available activated carbons. Its equilibrium saturation capacity for both acid dyes is very high. Low value of/parameter results in the adsorption-zone height to increase in size. Therefore, it is very important to maximize the / of the active adsorption zone for the sorption of dyestuffs by activated carbon. The results of this study showed that the profile of the breakthrough curves do not follow the characteristics of the "S" shaped profile produced in ideal adsorption systems, a behavior which is associated with adsorbents of smaller molecular diameter and more simple structure. The velocity at which the active adsorption zone moves through the column is assumed to be constant except during the period it is being formed. The length of the adsorption zone was found to be more than the total bed depth for both dyes; this suggests that beds of an increased height may be required for dye adsorption. This phenomenon occurs in the adsorption of dyestuffs because, due to their large molecular structure, resistance to internal diffusion is much more. This results in the dye molecules not to have enough contact time to diffuse from the surface of the particle to the adsorption sites. Therefore, they will be pumped further up the column to fresh activated carbon, where the rate of dye uptake is higher.

Item Type: Article
Keywords: Acidic dyes; Adsorption; Column behavior; Fixed -bed column
Page Range: pp. 117-128
Journal or Publication Title: Journal of Environmental Studies
Volume: 37
Number: 60
ISSN: 10258620
Depositing User: مهندس جمال محمودپور

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