Removal of direct dyes by coagulation: The performance of preformed polymeric aluminum species

Abstract

Removal of three direct dyes (Direct Black 19, Direct Red 28, and Direct Blue 86) by coagulation with three different Al based coagulants was investigated. The main purpose of this paper is to examine the coagulation features of polymeric aluminum coagulants in treatment of dye-polluted waters and the emphasis was placed on the roles of preformed Al species, particularly Al 13 . The performance of Al 13 in coagulation of dyes was observed through jar tests by comparing traditional Al salt, polyaluminum chloride (PACl), and purified Al 13 . The results showed that under most cases Al 13 had significantly higher efficiency in removal of direct dyes than traditional Al salt and commercial PACl with the exception of Direct Red 28 removal under high pH range. The coagulation of direct dyes could be greatly affected by pH. Reducing pH was favorable for preformed Al species in a broad pH range. For traditional Al coagulant, efficient dye removal only occurred in a relatively narrow pH range of near 6.0. The outstanding coagulation behavior of Al 13 could be ascribed to its high charge neutralization ability, relative stability and potential self-assembly tendency.

Adsorption Equilibrium, Kinetics and Thermodynamics Studies of Malachite Green Using Zeolite

“…염료의 배출과 오염을 개선하기 위하여, 수중으로 부터 염료성분을 제거하기 위한 여러 가지 방안들이 연구되었 는데, 고급산화 [3], 광촉매 [4], 흡착 [5], 막여과 [6]와 응집법 [7] 등이 Table 2에 나타냈다. …”

Modeling of Malachite Green Removal from Aqueous Solutions by Nanoscale Zerovalent Zinc Using Artificial Neural Network

“…Thereby, the removal of MG from wastewater before being discharged into surface water bodies is indispensible and significant. A variety of decolorization methods have been used for the removal of MG, including physical (adsorption), chemical (coagulating) and biological (decolorizsation-fermentation processes) [10,11]. Since the chemical treatment method is unsuited for highly soluble dyes and longer time is required for biological method, adsorption is considered the efficient method due to its comparatively low cost and high removal efficiency [12,13].…”

Removal of Anionic Dye by Natural Algerian Montmorillonite

“…Dyes in surface waters are of barrier effect on the sun light penetration and aeration of water body, and thus reduce photosynthetic activity [2]. For these reasons, several methods are used for eliminating the excess of colored organic pollutants from process or wastes effluents including biological treatments, however, unsatisfactory results were achieved by these techniques, such as coagulation-flocculation based on the addition of coagulant and flocculants (aluminium salts and polymers) [3], but coagulation generates chemical sludge and doesn't remove acid and reactive dyes of low molecular weight Biological treatment may involve aerobic and anaerobic degradation by microorganisms [4], Adsorption using activated carbon or ion exchange resins is the most popular technique for dyes removal due to its efficiency but the activated carbon cannot adsorb dispersed and pigmented, dyes nevertheless these methods are not satisfying because of the weak colorant biodegradability [5,6]. Other new processes electro coagulation, advanced oxidation processes,, and adsorption were elaborated to meet the required standards.…”