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HEXADECYL TRIMETHYL AMMONIUM BROMIDE-MODIFIED MONTMORILLONITE AS A LOW-COST SORBENT FOR THE REMOVAL OF METHYL RED FROM LIQUID-MEDIUM Y. Omidi, B. Kamareei, H. Nourmoradi, H. Basiri and S. Heidari Abstract In this study, montmorillonite (MMT) modified by a cationic surfactant (Hexadecyltrimethyl ammonium bromide, HDTMA) was used as adsorbent to the removal of methyl red (MR) from aqueous solution. The effect of different parameters includes surfactant loading rate, contact time, pH, adsorbent dosage, and initial MR content was investigated on the sorption. The sorption capacity was increased by increasing the surfactants loading rate up to 120% cation exchange capacity (CEC) of the clay. The contact time 30 min and pH of 6 were selected as the optimum for the uptake of MR. The maximum uptake capacity was obtained 1428.5 mg/g. The experimental data of the sorption was well fitted by pseudo-second-order kinetic and Freundlich isotherm models. The results show that the HDTMA-modified MMT can be applied as an effective and low cost sorbent for the removal of MR dye from aqueous solution. Keywords Adsorption, Montmorillonite, Surfactant, Methyl Red چکیده در این مطالعه، مونت مورینولیت (MMT) اصلاح شده با یک سورفکتانت کاتیونی (هگزا دسیل تری متیل آمونیوم بروماید، HDTMA) برای حذف متیل رد از محلول آبی استفاده گردید. اثر پارامترهای مختلف مانند میزان بارگذاری سورفکتانت، زمان تماس، پی اچ، دوز جاذب وغلظت اولیه متیل رد روی ظرفیت جذب، بررسی گردید. ظرفیت جذب جاذب با افزایش میزان بارگذاری سورفکتانت تا 120% ظرفیت تبادل یونی مونت مورینولیت، افزایش داشته است. ظرفیت جذب بهینه جاذب (28/84 میلی گرم بر گرم) در زمان 30 دقیقه و پی اچ برابر 6 بدست آمد. داده های آزمایشگاهی به خوبی با مدل های کینتیک درجه دوم کاذب و ایزوترم فروندلیچ متناسب بودند. نتایج نشان داد که HDTMA-MMT میتواند به عنوان یک جاذب موثر و ارزان برای حذف متیل رد از محلول آبی بکار برده شود. منبع دانلود 29-1-9.pdf

A Comparison of Bituminous Coal-Based and Coconut Shell-Based Activated Carbon for Removal of Trace Hazardous Air Pollutants in Landfill Gas Original Article, C49 Athappan A, L. Sattler M. Journal. Civil Eng. Urban. 3(6):331-337. 2013 ABSTRACT:This study explored adsorption as a method of controlling hazardous air pollutant emissions from landfill gas (LFG). In particular, the study compared bituminous coal-based (BPL) and coconut shell-based (OVC) activated carbons as adsorbents for the hazardous landfill gas constituents para-, ortho-, and meta-xylene; ethylbenzene; and methyl ethyl ketone (MEK). Experiments were designed to replicate typical field usage conditions, using ambient temperature and relative humidity values, and testing the carbon as is, without pretreatment to remove moisture. BPL and OVC carbons from Calgon Carbon were tested in vials, with initial headspace concentrations ranging from 2130 to 5020 ppmv (86 to 120 mg/m3). Pollutant concentration remaining in the headspace at equilibrium was measured using an SRI 8610 gas chromatograph with flame ionization detector. Tests were conducted at 45-70% relative humidity and room temperature. Adsorption curve fits of Langmuir and Freundlich isotherms (LI and FI) were determined for each compound and each type of activated carbon. For MEK, BPL and OVC adsorption capacities were similar for all concentrations. For ethylbenzene and the xylene isomers, however, OVC coconut shell-based carbon had a higher adsorption capacity at lower concentrations, but BPL coal-based carbon had a higher capacity at higher concentrations. This is likely due to the greater external surface area for OVC carbon, and the greater internal surface area for BPL carbon. For both carbons, at low concentrations adsorption capacity was highest for ethylbenzene, at intermediate concentrations highest for para-xylene, and at high concentrations highest for ortho-xylene. For ethylbenzene and MEK, the Freundlich isotherm fit the data better; for the xylenes, the Langmuir isotherm generally fit the data better. Manufacturer isotherms, developed for ideal conditions, predicted significantly higher maximum adsorption capacities than those determined in this research. Both bituminous coal-based and coconut shell-based activated carbons showed promise for removing hazardous air pollutants from landfill gas, for different concentration levels. Keywords:Adsorption, Landfill Gas, Hazardous Air Pollutants, Xylene, Ethylbenzene, MEK منبع: [Hidden Content] دانلود: [Hidden Content].,49-331-337.pdf J. Civil Eng. Urban.,49-331-337.pdf

Comparison of Different Methods for Linear Regression of Pseudo Second Order Adsorption Kinetics of Cadmium Original Article, C11 H. Ghoveisi, J. Farhoudi, MH. Omid, A. Mahdavi Mazdeh Journal. Civil Eng. Urban. 3(2): 73-76. 2013 ABSTRACT:The present paper would discuss the four linear regression of kinetic model of pseudo second order to describe the adsorption phenomenon. The adsorption parameters have been estimated by means of nonlinear method of pseudo second order as well as four linear regression methods are assessed. The results showed that, the nonlinear method of pseudo second order is a suitable method in estimating of adsorption parameters. A type 1 pseudo second order linear kinetic model has the highest coefficient of determination. It was also found that, among the regression methods, all of them except the regression type 2 would be useful recommendation for estimation of adsorption parameters. Keywords: Adsorption, Adsorption Potential, Adsorption Kinetics, Linear Regression منبع: [Hidden Content] دانلود: [Hidden Content] JCEU-C11-2013.pdf