Treatment of Textile Industry Wastewaters with Sonication

Research Article

Austin Chem Eng. 2020; 7(2): 1074.

Treatment of Textile Industry Wastewaters with Sonication

Sponza DT* and Oztekin R

Department of Environmental Engineering, Dokuz Eylül University, Turkey

*Corresponding author: Delia Teresa Sponza, Department of Environmental Engineering, Dokuz Eylül University, Turkey

Received: April 25, 2020; Accepted: May 19, 2020; Published: May 26, 2020

Abstract

In this study, the effects of ambient conditions (25oC), increasing sonication time (60, 120 and 150 min), sonication temperature (30oC and 60oC), on the sonication of wastewater from textile industry wastewater (TI ww) treatment plant in Izmir, Turkey was investigated in a sonicator with a power of 640 W, a frequency of 35 kHz and a sonication time of 150 min for the treatments of Methylene Blue (MB) and Rhodamine B (RhB) dyestuffs. Dissolved chemical oxygen demand (CODdis), color and three polyphenols [4-methyl phenol (C7H8O) (4-MP), 4-hydroxyanisole (C7H8O2) (4-H), 2-methyl-4-hydroxyanisole (C8H10O2) (2-M-4-H)] removal efficiencies were observed during sonication experiments. 99.37% CODdis, 98.07% color, 96% total phenol (PHE R), 93% 4-MP, 88% 4-H and 85% 2-M-4-H maximum removal efficiencies were found after 150 min sonication time and at 60oC.

Keywords: Methylene Blue; Polyphenols; Rhodamine B; Sonication; Textile industry wastewater

Introduction

The textile industries use enormous amount of H2O and chemicals for the wet processing of textiles and also use various types of dyes to impart attractive colors of commercial importance. The wastewater let out by the textile industries generally contain about 10% of dyes used for the textile coloration [13]. These dye stuff include various types like acidic, basic, azo, reactive, anthroquinone-based compounds and among these azo dyes are widely used by the industries. Further, azo dyes contribute about 60–70% of the total dyestuff produced [14].

The application of ultrasound as an alternative to the removal of dyes in waters has become of increasing interest in recent years [24,43]. This technique is considered as an Advanced Oxidation Process (AOP) that generates hydroxyl radicals (OH•) through acoustic cavitation, which can be defined as the cyclic formation, growth and collapse of microbubbles. Fast collapse of bubbles compresses adiabatically entrapped gas and vapours which leads to short and local hot spots [6]. In the final stage of the collapse, the temperature inside the residual bubble or in the surrounding liquid is thought to be above 5000oC. The OH• and hydroperoxyl radicals (O2H•) can be generated from H2O and O2 [20]. The sonochemical activity arises mainly from acoustic cavitation in liquid media. The acoustic cavitation occurring near a solid surface will generate microjets which will facilitate the liquid to move with a higher velocity resulting in increased diffusion of solute inside the pores of the TI ww [16,17]. In the case of sonication, localized temperature raise and swelling effects due to ultrasound may also improve the diffusion. The stable cavitation bubbles oscillate which is responsible for the enhanced molecular motion and stirring effect of ultrasound. In case of cotton dyeing TI ww, the effects produced due to stable cavitation may be realized at the interface of fabric and colored solution. Mass transport intensification using a conventional approach such as very high elevated temperatures ( > 500oC), is not always feasible, due to undesired side-effects such as fabric damage. About 87% and 81% CODdis yields was achieved using 40 and 50 min ultrasounds while compared to only 48% and 28.9% CODdis removals in the absence of ultrasound in TI ww at 25oC [44].

The influence of bicarbonate (HCO3- ) and carbonate (CO3- 2 ) ions on sonolytic degradation of cationic dye, Rhodamine B (RhB), in water was investigated [22]. As a consequence of ultrasonic cavitation that generates OH•, carbonate radicals (•CO3) were secondary products of water sonochemistry when it contains dissolved HCO3- or CO3-2. The results clearly demonstrated the significant intensification of sonolytic destruction of RhB in the presence of HCO3- and CO3- 2, especially at lower dye concentrations. Degradation intensification occurs because •CO3 sonochemically formed undergo radical-radical recombination at a lesser extent than OH•. The generated •CO3 are likely able to migrate far from the cavitation bubbles towards the solution bulk and are suitable for the degradation of RhB [22]. Therefore, at low dye concentrations, •CO3 presents a more selective reactivity towards RhB molecules than OH•. In the presence of HCO3-,degradation rate reached a maximum at 3 g L-1 HCO3-, but subsequent addition retards the destruction process. In RhB solutions containing CO3- 2, the oxidation rate gradually increased with increasing CO3-2concentration up to 10 g L-1 and slightly decreased afterward. •CO3 sonochemically generated are suitable for total removal of COD of sonicated RhB solutions [22].

In a study performed by Entezari and Sharif Al-Hoseini [12] 98% color removal was accomplished in a TI ww containing 50 mg L-1 MB, at 20 kHz frequency, at 120 W power, after 30 min sonication time at 30oC with 700 rpm agitation. In this study, 78.26% color removal was observed after 150 min sonication time at 30oC at not agitated conditions. The color yield in the present study is lower than the yield obtained by Entezari and Sharif Al-Hoseini [12] at 30oC as mentioned above. This could be attributed to the differentiations in dyes present in TI ww to the operational conditions such as sonication duration, sonication frequency and to not stirred conditions of sonicated wastewater. Banerjee et al. [3] has been investigated the sonochemical decolorization of wastewater containing a basic dye, Rhodamine 6G (Rh 6G) and the effect of initial concentration, pH and use of different additives, such as CCl4, H2O2, air and UV light in combination with ultrasound on the extent of decolorization. 77.8% maximum Rh 6G decolorization was observed for the use of H2O2 with sonication.

In the peresent study, the effects of ambient conditions (25oC), increasing sonication time (60, 120 and 150 min), sonication temperature (30oC and 60oC) on the sonication of wastewater from textile industry wastewater (TI ww) treatment plant in Izmir, Turkey was investigated in a sonicator with a power of 640 W, a frequency of 35 kHz and a sonication time of 150 min for the treatments of MB and RhB dyestuffs. CODdis, color and three polyphenols [4-methyl phenol (C7H8O) (4-MP), 4-hydroxyanisole (C7H8O2) (4-H), 2-methyl-4- hydroxyanisole (C8H10O2) (2-M-4-H)] removal efficiencies were observed during sonication experiments. 99.37% CODdis, 98.07% color, 96% total phenol (PHE R), 93% 4-MP, 88% 4-H and 85% 2-M-4-H maximum removal efficiencies were found after 150 min sonication time and at 60oC.

Materials and Methods

Raw wastewater

The TI ww used in this study contains color ( > 70.9 m-1), total phenol ( > 37 mg L-1), CODdis ( > 770 mg L-1) and high biological oxygen demand 5-days (BOD5) ( > 251 mg L-1) concentrations with a BOD5/CODdis ratio of 0.33. The characterization of TI ww was shown in Table 1 for minimum, medium and maximum values.