Efficient removal of Reactive Black 5 from aqueous media using glycidyl methacrylate resin modified with tetraethelenepentamine

Abstract

Glycidyl methacrylate/methelenebisacrylimide resin loaded with tetraethelenepentamine ligand was prepared and investigated. The adsorption characteristics of the obtained resin towards Reactive Black 5 (RB5) from aqueous solutions at different experimental conditions were established by means of batch and column methods. The mechanism of interaction between RB5 and resin's active sites was discussed. The resin showed high affinity for the adsorption of RB5 where an uptake value of 0.63 mmol/g was reported for the obtained resin, at 25 °C. The kinetics and thermodynamic behavior of the adsorption reaction were also defined. These data indicated an endothermic spontaneous adsorption process and kinetically followed the pseudo-second order model. Breakthrough curves for the removal of RB5 were studied at different flow rates and bed heights. The critical bed height for the studied resin column was found to be 0.764 cm at flow rate of 8 mL/min. The adsorbed dye was eluted from the investigated resin effectively. Regeneration and durability of the loaded resin towards the successive resin were also clarified.

Introduction

Color effluents have been produced ever since the dyeing technique was invented. Various kinds of synthetic dyestuffs appear in the effluents of wastewater in various industries such as dyestuff, textiles, leather, paper…, etc. It is recognized that public perception of water quality is greatly influenced by the color. Color is the first contaminant to be recognized in wastewater [1]. The presence of very small amounts of dyes in water (less than 1 ppm for some dyes) is highly visible and undesirable [2]. Over 100,000 commercially available dyes exist and more than 7 × 10⁵ tonnes per year are produced annually [3], [4]. Reactive dyes are the most common dyes used due to their advantages, such as bright colors, excellent colorfastness and ease of application [5], [6]. Due to their good solubility, reactive dyes are common water pollutants and they may frequently be found in trace quantities in industrial wastewater. An indication of the scale of the problem is given by the fact that two percent of dyes that are produced are discharged directly in aqueous effluent [2], [3]. Unless coloring materials are properly removed, dye wastewater significantly affects photosynthetic activity in aquatic life due to reduced light penetration [7]. Conventional methods for the removal of dyes in effluents include physical, chemical, and biological processes [8]. Unfortunately, reactive dyes are resistant to bacterial activity and biological treatment alone will take a long time to be effective [9]. Furthermore, it is difficult to remove reactive dyes using chemical coagulation due to the dye's high solubility in water [10]. Therefore, alternative technology must be developed to solve this problem. The use of adsorption techniques for color removal from wastewater has already received considerable attention and several adsorbents have been developed for this purpose [11], [12], [13], [14], [15]. Adsorption onto activated carbon appears to be the best prospect of eliminating this dye. In spite of its good efficiency, this adsorbent is expensive and difficult to regenerate after use. Therefore, many researches in recent years have focused on the use of various low-cost adsorbents instead of activated carbon [16]. Recently, chelating resins represent an important category of promising adsorbents. They are highly selective, efficient and easily regenerable relative to other adsorbent materials [17], [18]. Recently, the use of chelating and chelating resins for the removal of some dyes from aqueous solutions was reported by many authors [19], [20], [21]. The ultimate goal of this study is to develop new adsorbent based on glycidyl methacrylate for the removal of Reactive Black 5 (RB5) from aqueous solutions. The CI Reactive Black 5 is one of the common reactive dyes and was chosen as a target pollutant. It has high metamery (have shade differences under different light conditions) and high thermal sensitive properties. The photocatalytic degradation of RB5 is a complicated process with a mechanism involving several chemical and photocatalytic stages and a great number of intermediates. The interaction of the Reactive Black 5 dye with the glycidyl methacrylate resin results in the formation of mixed colloids (dye/resin) that can settle after a long contact time or can be recovered (after maturation) by filtration. Protonated amino groups neutralize anionic charges of the dye (coagulation effect), before neutralized dyes aggregate and settle (flocculating effect) [22], [23], [24]. The factors affecting the removal behavior will be studied. Thermodynamic as well as kinetic properties of the removal process will also be clarified.