Removal of crystal violet from waste water

Transcription

1 SIRJ-AZASN Volume 1 Issue 1 (2014) ISSN Scrutiny International Research Journal of Advanced Zoology, Animal Science and Nutrition (SIRJ-AZASN) Removal of crystal violet from waste water Thangadurai Vanitha, Research Department of Chemistry, Aditanar College of Arts and Science, Tiruchendur , Tamilnadu, India Article history: Submitted 29 April 2014; Accepted 16 May 2014 Abstract The adsorption of crystal violet on to carbon material prepared from bamboo tree leaf was studied by using batch adsorption experiment. Adsorption of C was decreased with increases in the concentration of the dye. The percentage removal of dye was maximum only at lower concentration. Adsorption of CV dye increases with increase in the amount of adsorbent. The percentage removal was found to be maximum in basic medium. The adsorption removal was found to be maximum in basic medium. The adsorption process was reached in equilibrium within 30min. The adsorption of dye was decreased with increases in the size of the adsorbent. The percentage removal was maximum only at lower particle size. The high value of monolayer adsorption capacity indicates that the prepared carbon material can be used as an alternative material for commercial activated carbon. Key words: Adsorption, crystal violet dye, bamboo tree leaf, carbon material Corresponding author Introduction Thangadurai Vanitha, Research Department of Chemistry, Aditanar College of Arts and Science, Tiruchendur , Tamilnadu, India. E Mail ID: jeyavanitha@gmail.com Now a day the population growth increases the need for textile leather, food processing, dying, cosmetic, paper and dye manufacturing industries. This increased production lead to the release of toxic and hazardous wastes into the environment in liquid, solids or gaseous form. This causes enormous atmospheric change occurs, it has increased sever environmental problem is called environmental pollution. This can be defined as an unfavorable change in our surrounding partly or completely due to man s activities directly or indirectly through radiation, chemical addition, physical addition or addition of micro organism. This causes damage to his health.

2 Any substance which causes pollution is termed as pollutant. They are discharged from industries, agriculture, automobiles and household activities into the environment. Recently, the word pollution was used with reference to contaminating of water, soil and air. Pollution means addition of any foreign material or any physical changes in the natural water or air which may affect the living life. Several biological, physical and chemical methods have been used for the treatment of industrial textile waste water including microbial biodegradation, membrane filtration, oxidation and ozonation. However, many of these technologies are cost prohibitive, especially when applied for treating large waste streams. Consequently, adsorption techniques seem to have the most potential for future use in industrial waste water treatment, because of their proven efficiency in removal of organic and mineral pollutants and for economic consideration. The most widely used adsorbent for this purpose is activated carbon, but its overlying coast has led to search for cheaper alternative material. Hence it is a thought of interest to study the adsorption of dye material on different type of charcoal was proposed. In the present study carbonaceous material prepared from bamboo tree leaf (BTLC) was used as an adsorbent for the removal of crystal violet. Materials and Methods Synthetic waste water preparation 0.5g of dye was weighted out accurately and it was transferred into 1000ml standerd measuring flask through the funnel. It was dissolved in deionised of water and then made upto the mark. It was used as the stock solution. Conductivity water was prepared by the method of Vogal (1978). Carbonaceous substrate preparation was followed by the method of Hedal (Hedal et al., 2003). Experimental procedure The procedure and methods followed to investigate the adsorption using the carbonaceous substrate are given below in detail. Batch experiments for desorption kinetics The adsorption of dye was studied using batch experiment. The amount of dye crystal violet present in the solution after adsorption process was studied spectrophotometrically by varying the property that consider Effect of initial concentration Effect of dose of adsorbent Effect of ph Effect of contact time Effect of particle size of adsorbent 24

3 Effect of initial concentration The dye solution of various initial concentratios was prepared. Exactly 100ml of each of the dye solution with different required initial concentration of dye was treated with known dose of adsorbent of fixed particle size at solution ph and equilibrated for 30min. with constant shaking in a mechanical shaker at 30±1 C. The percentage removal of dye and the amount of dye adsorbed were calculated. Effect of dose of adsorbent In these set of adsorption experiments, the values of percentage removal of dyes by adsorption and amount adsorbed on various adsorbents were obtained with different dose of adsorbent with optimum initial concentration of dyes and contact time, with fixed particle size at 30±1 C and the solution ph. Effect of ph The batch type adsorption experiments were carried out with optimum conditions of initial concentration of dye, contact time and dose of adsorbent with a fixed particle size at various solution ph by adding the required values of 0.1M HCl /0.1M NOH solution. The ph of the dye solution was measured by using digital ph meter. The values of percentage removal were computed and plotted against the ph of the dye solution. Effect of time In order to study the kinetics/dynamics of adsorption of dye, the adsorption experiments were conducted by varying the contract time at fixed optimum initial concentration of dyes with a fixed dose of adsorbent and particle size at 30±1 C and at the ph of the solution. The bottles were placed in a mechanical shaker. The bottles were withdrawn from the shaker at different time intervals viz 5, 10, 15, 20, 25, 30, 40, 50 and 60min, to find out the equilibrium concentration. The other procedures employed were similar to that of the general procedures employed for adsorption studies. The results obtained were analyzed by using first order kinetic equation. Effect of particle size of adsorbent Adsorbent studies of dyes were carried out of different particle size of adsorbent with various adsorbent size (range microns), under constant optimum initial concentration of dyes, contact time (30min) optimum dose of adsorbent and ph the dye solution at 30±1 C. The values of percentage removal of dye adsorbed were calculated and plotted against the particle size of the adsorbents. Calculation The percentage removal of dye was calculated as follows Percentage removal of dye = Ci-Ce/Ci 100 Ci=initial concentration of dye molecules before adsorption Ce =initial concentration of dye molecules after adsorption UV visible spectrum of crystal violet 25

4 Results and Discussion The effect of initial concentration on the percentage removal of dye was studied by varying the amount of dye concentration and keeping the other factors as constant. Generally the percentage removal of dye decreases with increase in the amount of dye concentration and the relevant data are given in Tab Result was clear that the removal of dye was maximum only at lower concentrations. The percentage removal of crystal violet was varied from %. The variation of percentage removal of dye with respect to concentration of dye was more significant. It was observed that the percentage removal of dye decreases with increase in the concentration of dye solution. It means that the adsorption is highly dependent on the initial concentration of dye. This is because at lower concentration, the ratio of dye molecules to the available surface area is low, subsequently, the adsorption is high. However, at high concentration the available sites of adsorption becomes fewer and hence the percentage removal of dye is less. This is already reported in literature (Hashemian et al., 2007; Kannan and Meenakshisundaram, 2002). The above experimental data shows that the optimum initial concentration for the removal of crystal violet was 150ppm. Adsorption isotherm In order to analyze the adsorption data, the Freundlich and Langmuir adsorption isotherms were employed (Benefields et al., 1982). Freundlich isotherm Freundlich adsorption isotherm is given by the equation. = log +? 1? log? Where x/m is the amount of dye adsorbed (mg g -1 ) per unit mass of the adsorbent at equilibrium; m is the mass of the adsorbent, k and 1/n are the Freundlich constants, which are the measures of adsorption capacity (mg g -1 ) and intensity of adsorption, respectively. The value of 1/n indicates the nature of the adsorption process. Table no. 1: Freundlich constant Dye (1/n) k r CV The value of r closer to unit indicates the linear relationship between log x/m and log Ce. In the present study the computed values of adsorption intensity were found to be fraction, indicating that the adsorption process was favorable for the low cost adsorbent prepared from bamboo tree leaf. Langmuir isotherm Langmuir adsorption isotherm is given by the expression. 26

5 (Ce/qe) = (1/ab) + (Ce/a) A plot of (Ce/qe) Vs Ce was found to be linear with (1/ab) value as the intercept and (1/a) value as the slope. This plot is known as Langmuir adsorption isotherm plot. The applicability of Langmuir adsorption isotherm indicates the formation of mono-layer and also the nature of adsorption process. Further, the essential characteristics of the Langmuir isotherm can be described in terms of a dimensionless constant viz., separation factor are equilibrium parameter, RL, which is defined by the equation. RL = 1/(1+bCi) Table no. 2: Langmuir constants Adsorbent 1/ab 1/a a b RL r Crystal Violet The linear relationship was obtained between, Ce/qe & Vs C e (r=0.992) linear. The value of RL was fraction. The above results clearly show the adsorption obey Langmuir adsorption isotherm and it is a favorable process. The Langmuir isotherm assumes that the surface is homogenous. The linearity in the plot shows the formation of mono-layer coverage of crystal violet on the adsorbent surface mono-layer adsorbent capacity a of the adsorbent for the adsorbent of crystal violet was The a value obtained for the removal of dyes was comparable with the reported values in literature (Kadirvelu et al., 2005). Table no. 3: Monolayer adsorbent capacity for crystal violet removal Adsorbent Phosphoric acid treated male a (mg g-1) Flowers of coconut tree Sulphuric acid treated male flowers of coconut tree Orange peel Effect of dose of adsorbent The effect of amount of adsorbent on the adsorption process was studied by varying the weight of the substrate and keeping the other factors as constant. Generally the amount of adsorption increases with increase in the amount of substrate. From the results, it was clear that the removal of dye was maximum at higher adsorbent dosage. The percentage removal of crystal violet was varied from %. The crystal violet solution was completely decolorized at higher adsorbent 27

6 dosage. The small increase in the amount of dose shows a significant change in the removal of crystal violet. The above experimental data shows the optimum dose for the removal crystal violet is 0.100g. It was observed that the amount of dye adsorbed increase with an increase in adsorbent dosage. The effect of adsorbent dosage on the percentage removal of dye solution was significant. The increase in the % removal of dye was obvious due to increase in adsorbent surface area. This was similar to the one observed earlier (Kannan and Meenakshisundaram, 2002). Effect of ph variation The effect of ph on the adsorption process was studied by varying the ph of the medium and keeping the other factors as constant. From the results, it was observed that, the removal of dye with respect to ph was not linear. The % removal of crystal violet dye was affected in acidic medium. The removal of dyes was maximum only in the basic medium. It was observed that the ph of the medium played a significant role on the % removal of dye. Removal of dyes was found to be minimum in high acidic medium. This was similar to the one reported in literature (Iqbal and Ashiq, 2007). The low adsorption of dyes in highly acidic solution shows possibility of development of positive charge on the adsorbent surface which inhibits the adsorption of cationic dye over it. Effect of contact time variation The effect of contact time in the adsorption process was studied by varying the contact time 7 keeping other factors as constant. The result shows that there is a considerable effect on adsorption of dye crystal violet increase the contact time. The % removal of crystal violet was varied from The effect was more significant in the case of decolourizatio of crystal violet at the maximum contact time, the % removal was found to be almost constant. The adsorption of dye on substrate reached equilibrium within 30mins. After 30mins there was a slight increase in the % removal of dyes. Therefore 30mins is fixed as the optimum contact time for the dye removal. Effect particle size of the adsorbent The effect of particle size of adsorbent on the adsorption process was studied by varying the particle size of the adsorbent and keeping other factors as constant. Generally, the amount of adsorption increases with decrease in the particle size of the From the results, it was clear that that the removal of dye was maximum at similar particle size of the adsorbent. The variation of % removal was not linear with respect to particle size of the adsorbent. The % removal of crystal violet was varied from %. In crystal violet dye, the % removal of dye was found to be maximum in the particle size of <75µ. 28

7 In general the decrease in particle size will show an increase in the available surface area. Therefore, the percentage removal of dye was maximum in lower particle size of an adsorbent. The optimum particle size for the removal of dye was fixed as <75µ. Reference Vogal, A.I., Text book of quantitative inorganic analysis. Elbs (iv edi., longman publication, London Hedal Uddin, A.B.M., Amat Ngilmi, Abmad Suraj and Mohad Asri Mohad, Nawi, Malausian J Chem., 5(1): Hashemian, S., Dadfarina, S. and Gafoori, F., African j biotechnol, 7(5): Kannan, N. and Meenakshisundaram, M., Water, air, soil pollut., 138: Benefields, L. D., Judkins, J. F. and Weand, B.l., Process chemistry for water and waste water treatment, prentice hall, inc., Kadirvelu, K., Karthika, C., Vennilamani, N. and Pattabhi, Chemosphere, 60: Iqbal, M.J. and Ashiq, M.N., Haz. Mat., 139: