Removal of Dye from Textile Wastewater by Electrolytic Treatment

Removal of Dye from Textile Wastewater by Electrolytic Treatment Muhammad Shahzad Arif*, Shahid Raza Malik Department of Chemical Engineering, NFC Institute of Engineering and Fertilizer Research, Faisalabad A R T I C L E I N F O A B S T R A C T *Corresponding Author: shahzadahmed899@gmail.com DOI: 10.24081/nijesr.2017.1.0001 Keywords: Waste water, Electrolatic Treatment, Textile dye I. INTRODUCTION Water is available in huge amount in the world. But only 0.03% is available for human activity. Due to the population growth and industrial revolutions the demand of water is increasing but the source of water is constant. Due to mismanagement of water, the sources of water are reducing day by day [1]. In textile industry, water is used for many purposes e.g. dye house etc. The wastewater was drained in open streams in starting. Generally, the final effluents of textile wastewater can be categorized into three classes depending upon their toxicity level [2]. Table 1: Some typical characteristics of textile effluents Type Conductivity (µscm -1 ) COD (mgl -1 ) Highly toxic 2900 1500 Medium toxic 2500 970 Low toxic 2100 460 The effluents presence in textile wastewater is usually common and highly visible. The colour of wastewater changed on daily basis mainly depending upon the type of dye used. Large variations in ph of textile wastewater also put an adverse effect. Some dyes are used in low concentrations, therefore their removal from water was not considered as important. But with more restrictions in the wastewater regulations, a number of processes has been Textile wastewater is extremely known as containing strong dyes and highly variable ph values, which makes water unable to use and drink. Due to shortage of clean water people use this water which causes many diseases and also makes problem for washing purposes. Therefore treatment of such water before use is inevitable. Due to these impurities, the treatment of wastewater is quite difficult. The aim of the present work is to use an electrolytic technique to treat these effluents. Electrolytic treatment can be an adequate method for the removal of strong colours present in the water as well as organic materials. The removal of dye was done by different parameters like electrolysis time, ph and different initial dye concentration. 75.3% of removal was achieved which was directly analyzed by the reduction in absorbance before and after treatment. employed for the decolorization of wastewater. These processes contain adsorption, biosorption [3], oxidation and photo-oxidation, sorption on activated carbon [4], coagulation and flocculation [5]. Coagulation and flocculation can be used as pre-treatment, post treatment or main treatment process. This method is cheap and less energy consuming. Verity of coagulants is available in market, which are cheaper and can be easily handled. The disadvantage of this process is the handling of sludge produced after the treatment. This sludge contains toxic chemical. Therefore, the adverse health effects of coagulants made their used limited [6]. Biological sorption or oxidation effectively replaced this method. This method was effective for many dyes. But today available dyes are not biodegradable making this method ineffective. Also this method requires longer retention time because biological reactions are usually slow. Conventionally available aerobic processes are now ineffective for the treatment because the available dyes are quite toxic for organisms used. Currently in use methods for the treatment of textile wastewater [2] are shown in the Table 2. In 90s a newer technique, electrolysis is adopted for treatment. It is effective technique for the removal of dyes. This technique have many advantages over conventionally available techniques that there is no additional chemical required for treatment, no production of sludge or

other toxic chemicals and the degradation of pollutants into non-toxic materials. It is considered as highly effective technique for pollution control giving very high removal efficiencies [7]. Table 2: Some currently in use method for dye removal from textile wastewater Treatment method Photochemical Activated Carbon Wood chips Membrane filtration Advantage Breaking down of chemicals into nonhazards compounds Effective removal of dyes Cheap, effective removal Remove all kinds of dye Ozonation No increase in volumes Electrokinetic Low capital coagulation required Disadvantage Electricity cost Expensive, regeneration problems Longer retention time Pre and post treatment required Very short half life Large volumes of sludge In the present work, electrolytic technique is adopted for the removal of dye from the synthetically produced wastewater. Sodium chloride used as electrolyte and further no additional chemical was used. Electrolysis is an effective process for the removal of dye and other organic pollutants. The removal of dye is affected by number of factors in this technique like type of electrode used, distance between the electrodes, applied current density, dye concentration, ph, and electrolysis time. In current study, three parameters; initial dye concentration, ph and electrolysis time were studied. Other parameters were kept constant. Variety of electrodes is available in market, which are used for electrolysis. Usually anode is corroded or dissolved during treatment. Therefore, anode is selected which does not corroded soon or has very much less tendency towards corrosion. Carbon electrode was selected as anode as its corrosion tendency is almost nil; also it is cheaper and easily available. II. MATERIALS AND METHOD Acid blue 19 is anthraquinone class of dyes having molecular formula C 37 H 31 Cl 2 N 2 NaO 8 S was used for the study. Acid blue 19 have molecular weight 757.61g/mol, purchased from Sandel bar dye stuff Faisalabad. It is used without further treatment. The dye content is about 45%. NaCl was obtained from shop with 100% purity. Salfuric acid (98% concentrated) and sodium carbonate (solid perils) obtained from Ali Chemicals Faisalabad. Figure 1: Structure of Acid Blue 19 dye III. STOCK SOLUTION PREPARATION Dye solution made synthetically by mixing dye into distilled water. Initial concentration of dye in water kept 100mg/l, which is typically lowest concentration present in effluent. 0.1MNa2CO3 added to water to make solution basic. To make solution acidic 0.1MH2SO4 was added to solution and stirred for 60 minutes for homogeneity. 0.1MNaCl added to solution as electrolyte. The prepared solution used for experimentation. IV. ELECTROLYSIS EXPERIMENTS Electrolysis was carried out in a batch reactor as shown in Figure 2. Single anode and cathode of size 10mm x 10mm were used for the purpose of electrolysis and placed 20mm apart in the reactor. Carbon was used as an anode and iron (ST 37) was used as a cathode. The constant electric current was supplied by DC power supply rated at 20 volt. The ph of synthetic wastewater was adjusted by 0.1M sodium carbonate and 0.1M sulphuric acid. Sodium chloride of 0.1 molar strength was used as an electrolyte.

Figure 2: Experimental Setup In the present study, the effect of time of electrolysis, concentration of the dye and ph were studied on the removal of dye from wastewater. Other parameters like current density, voltage, electrode distance and concentration of electrolyte were kept constant for all runs. Statistical analysis was performed for the 27 data values. Each data value was reiterated thrice and average values were considered. The graphical analysis was performed to study the effect of aforementioned variables on the removal of dye from wastewater. Moreover, response surface methodology was used to evaluate the effect of interactions of two variables keeping one variable constant. In a particular run, 100 ml of synthetic wastewater was used. After adjusting the value of ph, the current density was adjusted and kept constant. It must be noted that concentration of dye, ph and electrolysis time were adjusted to the values proposed in table for each experiment. At each interval of time, 50 ml of sample was taken and let it to settle down for 20minutes. After that sample was filtered with filter paper, the remaining concentration in the sample was measured by ZAR/HEC-1830/UV- 2800 spectrophotometer. The removal efficiency was expressed as the percentage ratio of removed dye concentration to its initial concentration. V. Results and Discussion Table 1 represents the results of the experimentation. VI. EFFECT OF ELECTROLYSIS TIME Figure 3 shows the effect of time on the dye removal efficiency at initial dye concentration of 100 ppm and ph of 4, 7 and 10. It is observed that the removal of dye increased with increases in the time of electrolysis. At constant current densities, the number of flocs produced in the solution also remained constant. But with the increase in the time of electrolysis, enough flocs were produced resulting in the improvement in the removal efficiency. Moreover, it was found that the removal rate of dye was higher at the start of the electrolytic treatment. With passage of time, removal rate decreased. Table 3: Effect of initial concentration of dye, ph and electrolysis time on the removal efficiency of the dye Concentration of Dye (ppm) ph Time (min) Dye Removed (%) 100 4 15 40.89888 100 4 30 61.23596 100 4 45 75.66372 100 7 15 31.35861 100 7 30 50.63191 100 7 45 61.69036 100 10 15 21.05263 100 10 30 33.82353 100 10 45 45.57662 150 4 15 38.00905 150 4 30 57.10407 150 4 45 65.64996 150 7 15 25.54012 150 7 30 39.42901 150 7 45 51.46605 150 10 15 19.59877 150 10 30 27.39198 150 10 45 40.97222 200 4 15 34.16304 200 4 30 49.03547 200 4 45 61.10765 200 7 15 21.71545 200 7 30 36.01089 200 7 45 49.55752 200 10 15 6.368461 200 10 30 24.18499 200 10 45 33.10516 VII. EFFECT OF PH Figure 4 shows the effect of ph on the dye removal efficiency at an initial dye concentration of 100 ppm and various electrolysis time intervals. The highest removal efficiency was observed at a ph 4. As the ph values was increased, the removal efficiency decreased because at lower ph values, the test solution produces higher amounts of OH

Dye Removal (%) ions to counter balance the high hydrogen ion concentration. However, with increase in ph values, many other salt complexes are formed, hindering the removal of dye from the synthetic wastewater. Therefore, a drop in removal efficiency was observed. VIII. EFFECT OF CONCENTRATION Figure 5 shows the effect of initial dye concentration on the dye removal efficiency at various electrolysis time intervals and a constant ph of 4. As expected, at lower initial dye concentration, removal efficiency was higher but the increase in concentration of dye in the solution caused a decrease in the removal efficiency. At constant current densities, the number of flocs produced was enough for the removal of dye but with increase in dye concentration, these flocs were not enough to keep up with the removal of dye at higher concentration levels. Figure 3: Effect of ph on the dye removal efficiency at an initial dye concentration of 100 ppm and various electrolysis time intervals 80 70 60 50 40 30 20 10 0 0 20 40 60 Time (min) ph4 ph7 ph10 Figure 5: Effect of electrolysis time on the dye removal efficiency at various ph values and a constant initial dye concentration of 100 ppm Figure 4: effect of initial dye concentration on the dye removal efficiency at various electrolysis time intervals and a constant ph of 4 IX. CONCLUSIONS The present study entails the effect of electrolysis time (15 45 minutes), initial dye concentration in the synthetic water (100 200 ppm) and ph of the solution (4 10) on the removal efficiency of the dye from the synthetic water. For higher removal efficiencies, low concentrations of dye favoured the process, as the availability of cation complexes favours the process at lower initial dye concentrations. Lower ph values or acidic ph favours electrolysis for the removal of effluents from wastewater. With increase in the ph values of solution the removal of effluents from the solution

started to decrease. Moreover, with increase in the electrolysis time, the probability of collisions of cation complexes with effluent s particles enhanced, which favours the removal efficiency. X. REFERENCES [1] Allegre, C., Maisseu, M., Charbit, F., Moulin, P., 2004. Coagulation flocculation decantation of dye house effluents. J. Hazard. Mater. B116, 57 64. [2] O Mahony, T., Guibal, E., Tobin, J.M., 2002. Reactive dye biosorption by Rhizopus arrhizus biomass. Enzyme Microb. Technol. 31, 456 463. [3] Kavitha, D., Namasivayam, C., 2008. Capacity of activated carbon in the removal of acid brilliant blue: determination of equilibrium and kinetic model parameters. Chem. Eng. J. 139, 453 461. [4] Somasundaran, P., Runkana, V., 2005. Investigation of the flocculation of colloidal suspensions by controlling adsorbed layer microstructure and population balance modelling. Chem. Eng. Res. Des. 83, 905 914. [5] Dos Santos, A.B., Cervantes, F.J., van Lier, J.B., 2007. Review paper on current technologies for decolourisation of textile wastewaters: perspectives for anaerobic biotechnology. Bioresour. Technol. 98, 2369 2385. [6] T-H. Kim, C. Park, [et. al.], Wat. Res.,36, 2002, 3979-3988 [7] T. Grygar, A.S. Kuckova, [et. al.], J. Solid State Electrochem., 2003, 7, 706-713 [8] M.V.B. Zanoni, A.G. Fogg, [et. al.], Analytica Chimica Acta, 315, 1995, 41-54 [9] P.A. Carneiro, M.V.B. Zanoni, [et. al.], Portugaliae Electrochimica Acta, 21, 2003, 49-67 [10] Kim, T.K., Park, C., Shin, E.B., Kim, S., 2002. Decolorization of disperse and reactive dyes by continuous electrocoagulation process. Desalination 150, 165 175.