Laboratory Studies of Electrochemical Treatment of Industrial Azo Dye Effluent

Abstract

Removal of color and reduction of chemical oxygen demand (COD) in an industrial azo dye effluent containing chiefly reactive dyes were investigated under single-pass conditions at a dimensionally stable anode (DSA) in a thin electrochemical flow reactor at different current densities, flow rates, and dilutions. With 50% diluted effluent, decolorization was achieved up to 85-99% at 10-40 mA/ cm2 at 5 mL/min flow rate and 50-88% at 30-40 mA/ cm2 at high (10-15 mL/min) flow rates. The COD reduction was maximum (81%) at 39.9 mA/cm2 or above when solution-electrode contact time (Ct) was as high as 21.7 s/cm2 and decreased as Ct declined at a given current density. Cyclic voltammetric studies suggesting an indirect oxidation of dye molecules over the anode surface were carried out at a glassy carbon electrode. The effect of pH on decolorization and COD reduction was determined. An electrochemical mechanism mediated by OCl- operating in the decolorization and COD reduction processes was suggested. The effluent was further treated with NaOCI. The oxidized products from the treated effluents were isolated and confirmed to be free from chlorine-substituted products by IR spectroscopy. From the apparent pseudo-first-order rate data, the second-order rate coefficients were evaluated to be 2.9 M(-1) s(-1) at 5 mL/ min, 76.2 M(-1) s(-1) at 10 mL/min, and 156.1 M(-1) s(-1) at 15 mL/ min for color removal, and 1.19 M(-1) s(-1) at 5 mL/min, 1.79 M(-1) s(-1) at 10 mL/min, and 3.57 M(-1) s(-1) at 15 mL/min for COD reduction. Field studies were also carried out with a pilot-scale cell at the source of effluent generation of different plants corresponding to the industry. Decolorization was achieved to about 94-99% with azo dye effluents at 0.7-1.0 L/min flow costing around Indian Rupees 0.02-0.04 per liter, and to about 54-75% in other related effluents at 0.3-1.0 L/min flow under single-pass conditions.

Electrochemical oxidation of Acid Yellow 1 using diamond anode

“…Many electrode materials have been tested for electrochemical treatment of dye solutions, including Iridium or Ruthenium oxide [23][24][25], PbO 2 [26,27], Pt [19,28] SnO 2 [29] but high current efficiency, even about 100%, was obtained only using boron-doped diamond (BDD) anode [30][31][32][33][34].…”

Bromide Tolerance in Plants: A Case Study on Halophytes of Indian Coast

“…In all cases, the absorption spectral data of the samples were recorded between 200 and 600 nm on Shimadzu UV-160 spectrophotometer (Germany) with a built-in thermostat (25 ± 0.1 • C) cell compartment coupled to a temperature controlling unit using a 10 mm quartz cuvette [20]. Inductively coupled plasma atomic emission (ICP-AES) spectrometer of Perkin Elmer model Optima 2000 DV (Germany) was used to quantify the cationic elements (Na, K, Ca, and Mg) present in the concentrated HNO 3 digested plant materials.…”

Tekstil Atık Sularından C.I. Bazik Mavi 3 Boyarmaddesinin Elektrokimyasal Uygulama ile Giderilmesi

“…Elektrokimyasal işlem boyunca, çözelti içinde zaten var olan aktif türler vasıtasıyla boyarmadde moleküllerinin yükseltgenmesi meydana gelir [27]. Metal anot yüzeyinde suyun ayrışması ile oluşan •OH radikalleri vasıtasıyla boyaların parçalanması için elektrokimyasal ileri yükseltgenme prosesleri kullanılmaktadır [28,29].…”