ABSTRACT. Keywords: Cadmium Removal, sawdust, adsorption. Corresponding Author: P. Akhila Swathanthra 1. INTRODUCTION:

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1 International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.5 (Aug.- Sep. 214) Removal of Cadmium Ions by adsorption onto Sawdust as adsorbent from aqueous solutions P.AKHILA SWATHANTHRA 1 AND V.V.BASAVA RAO 2 1 Faculty of Chemical Engineering, SVU, Tirupati, AP, India 2 Faculty of Chemical Engineering, OU, HYD, TG, India ABSTRACT The waste water from electro plating industries, small scale industries, smelting, battery manufacture, tanneries etc., are contaminating the nearby water source by increasing the metal concentrations like chromium, copper, cadmium, zinc etc.this paper has researched on the adsorption of Cadmium in water using saw dust. The dependence on contact time, ph, Concentration, amount of adsorbent of the adsorption was studied. Batch experiments results showed that the adsorptive capacity of sawdust mg/g was observed at ph 6. The Langmuir Isotherm model and Freundlich Isotherm model were used to then adsorption equilibrium of cadmium on sawdust. The both isotherms constants for adsorption of Cadmium on sawdust were determined and the goodness of fitness was obtained with Langmuir and Freundlich adsorption isotherms from the equilibrium adsorption data. Keywords: Cadmium Removal, sawdust, adsorption. Corresponding Author: P. Akhila Swathanthra 1. INTRODUCTION: Effluent treatment has become important because of its possible environmental impact as well as its possible adverse effects on human health.[1].heavy Metals like Chromium, Nickel, Cadmium, Zinc and Copper are, at elevated concentrations, detrimental to human health and ecosystem stability, and threshold values have been set for these metals for waste water discharged into environment and for drinking water. In order to reduce pollution, contaminated waters need to be cleaned [2]. The effects of acute cadmium poisoning in humans are high blood pressure, kidney damage and destruction of testicular tissue and red blood cells. Therefore, these wastewaters are to be treated using low cost methods. Many conventional methods like Ion Exchange, electrolysis, membrane filtration, Chemical precipitation etc, for removing of metal ions from industrial effluents suffer with high capital and regeneration costs of the materials. Therefore, these are not suitable for the small scale industries [3]. Compared with conventional methods for the removal of toxic metals from waste water by using low cost adsorbents more advantages such as low operating cost, minimization of chemical sludge, high efficiency of R S. Publication (rspublication.com), rspublicationhouse@gmail.com Page 291

2 International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.5 (Aug.- Sep. 214) heavy metal removal from diluted solutions, regeneration of biosorbents, possibility of metal recovery and environmental friendly[4]. Based on the Langmuir and Freundlich equation the adsorption of Cadmium in water by sawdust will be discussed. 2. MATERIALS AND METHODS: All the chemicals used in this study were of analytical grade and were proceed from Sd. Fine Chem. Ltd. The adsorbent was selected for removal of Cadmium by sawdust. The adsorbent were grounded and wasted with deionised water. The adsorbents were dried at room temperature (32 ±1 C) till a constant weight of the adsorbents was achieved (after 2 hrs). Adsorption is an effective and versatile method for removing Cadmium ADSORBENT PREPARATION: Firstly, the adsorbent is washed and dried at room temperature to avoid the release of color by adsorbent into the aqueous solution. The activation of adsorbents is carried out by treating it with concentrated sulphuric acid (.1N) and is kept in an oven maintained at a temperature range of 15 C for 24hr. Again it is washed with distilled water to remove the free acid CADMIUM SOLUTION PREPARATION: Cadmium solutions were prepared by dissolving a weighed quantity of cadmium chloride monohydrate in deionzed distilled water. Before the adsorption study, the ph of the Cadmium solution was adjusted to required value with.1n H 2 S 4 and.1 N NaOH Solutions using ph meter (ELICO, LI 613) BATCH ADSORPTION STUDIES: The batch experiments are carried out in 25ml borosil conical flasks by shaking a pre-weighed amount of the saw dust with 1ml of the aqueous cadmium solutions of known concentration and P H value. The metal solutions were agitated in a rotary shaker at 12 rpm for a desired time. The samples were withdrawn from the shaken at the predetermined time intervals and adsorbent was separated by filtration. Cadmium concentration in the filtrate was estimated using AAS. The experiments were carried out by varying the cadmium concentration in the solution (5mg/L- 5mg/L), at P H 6. The adsorbent dosage.2-1gr/1ml for contact time is 6hrs, with initial metal concentration of 1mg/L at room temperature 3 ±2 C and solution P H 6. The samples were collected at different time intervals 15 min to 15 min and the adsorbent was separated by filtered using filter paper. % removal of copper = (C int _ Cfin ) 1/ C int Where C int and C fin are the initial and final cadmium concentrations, respectively. R S. Publication (rspublication.com), rspublicationhouse@gmail.com Page 292

3 qe International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.5 (Aug.- Sep. 214) 3. RESULTS AND DISCUSSION: 3.1 Effect of contact time: The contact time was evaluated as one of the important parameter for the adsorption of cadmium on adsorbent. Fig 1 shows the percentage removal of cadmium for different initial concentration ranging from 5 mg/l to 5 mg/l at ph 6. It was observed that, while increasing the cadmium concentration from 5 mg/l to 5 mg/l. The percentage removal increases with rise in contact time up to 9 min after then it is almost constant mg/lit 1 mg/lit 2 mg/lit 3 mg/lit 4 mg/lit 5 mg/lit Time(min) Fig-1: Effect of contact time on cadmium removal by using sawdust at different initial concentrations 3.2 Effect of Initial concentration: The Initial metal concentration in the aqueous solution has a bearing on the removal efficiency [Fig.2]. Hence, same aqueous solutions with different initial metal concentrations (5-5 mg/l) were agitated with a fixed dosage of sawdust (2 g/lit) at every 1 min interval the residual cadmium concentration was measured by using atomic adsorption spectrophotometer and tabulated. The Percentage removal of cadmium decreases from 87 to 48% after completion of 2 hrs contact time and adsorption capacity increases from to 12 mg/g initial concentration(mg/l) qe Fig-2: Effect of initial concentration on cadmium removal by using sawdust at different initial concentrations R S. Publication (rspublication.com), rspublicationhouse@gmail.com Page 293

4 International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.5 (Aug.- Sep. 214) 3.3 Effect of ph: Adsorption of heavy metal ions depend on the ph of solution. As the ph of the cadmium solution observed from 2 to 1, the removal percentage of cadmium increased up to ph 6 and then decline rather rapidly with further increase in ph [Fig.3]. According to Namasivayam and Ranganathan[5], precipitation of cadmium starts at ph 8.2. Therefore, in this study the effect of ph on cadmium adsorption was performed at ph range 2-1. At low ph, cadmium ions had to compete with H + ions for adsorption sites on the adsorbent surface. As the ph increased, this competition weakens and more cadmium ions were able to replace H + bound to the adsorbent surface. Similar findings were reported by Taty-Costodes et al.[6]. Therefore, all further studies were carried out at ph ph Fig-3: Effect of ph on cadmium removal by using sawdust 3.4 Effect of Adsorbent dose: Removal of Cadmium increases with increase of adsorbent dosage. The percentage removal increases from 83% to 96% by increasing the adsorbent dosage from 2 1 gm/l. [Fig.4], for a constant initial concentration of 2 mg/l in the solution. The increase in cadmium removal percentage with increasing adsorbent amount is due to the increasing surface area and available sites for adsorption. However, the adsorption capacity decreases from 9.65 to 1.995mg/g by increasing the adsorbent amount from 2 to 1 grams /lit(fig.5) gr time(min) 4 gr 6 gr 8 gr 1 gr Fig-4:Effect Adsorbent dose on cadmium removal by using sawdust at different adsorbent doses R S. Publication (rspublication.com), rspublicationhouse@gmail.com Page 294

5 qe International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.5 (Aug.- Sep. 214) Ad.dose(gr) qe Fig-5: Effect of Adsorbent dose on cadmium removal by using sawdust 3.5 Scanning electron microscopy (SEM): SEM micrographs of the material showed a surface porosity, as can be verified by the images of Fig.6 These micrographs irregular and porous surfaces could be observed. Based on this fact, it was concluded that the material presented an adequate morphology for metal adsorption. The SEM images were obtained and found that the treated Saw Dust was showing that the surface of the adsorbent is more clear with openings of the pores. Fig-6: SEM images of sawdust before and after treatment 3.6.ADSORPTION ISOTHERM MODELS: Fig 7 and 8 show the Freundlich and Langmuir isotherms at equilibrium data of sawdust in removing cadmium from aqueous solutions. The isotherm data given in table 1 and 2.The isotherms are in conformity with Freundlich isotherm Langmuir Adsorption Isotherm Model: The Langmuir adsorption isotherm plot between Ce/q e verses Ce, From Fig.6 shows the Langmuir constant q m, which is a measure of the monolayer adsorption capacity of saw dust is obtained 13.38mg/gr. The Langmuir constant b, is found to be.26. A high value of regression correlation coefficient (R 2 =.9961) is obtained. The dimensionless parameter R L, which is a R S. Publication (rspublication.com), rspublicationhouse@gmail.com Page 295

6 ln qe Ce/qe International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.5 (Aug.- Sep. 214) measure of adsorption favorability is found to be.288(< R L <1) which confirms the favorable adsorption process for removal of cadmium by saw dust. R L, also known as the separation factor[7], given by R L = 1/(1+bC ) Langmuir equation is Ce/q e = 1/(bq m ) + (1/q m ) Ce y =.74x R² = Ce Fig-7: Langmuir isotherm for adsorption of cadmium Freundlich Adsorption Isotherm Model: Freundlich isotherm is analyzed based on adsorption Cadmium by using the same equilibrium data of saw dust. Freundlich constants, K f and n are obtained by plotting the graph between log q e versus log Ce [Fig.7]. The values of K f and n are 1.6 and respectively. It is found that the regression correlation coefficient obtained from Freundlich isotherm model for this adsorbent is.9679 which is lower than the Langmuir isotherm model as given in Table.1 and 2. ln q e = ln K f + (1/n) lnce y =.449x +.65 R² = ln 3 Ce Fig 8: Freundlich isotherm for adsorption of cadmium R S. Publication (rspublication.com), rspublicationhouse@gmail.com Page 296

7 International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.5 (Aug.- Sep. 214) Table 1: L-Constants Adsorbent ph Q b R L R 2 Saw dust Table2 : Adsorbent Saw dust F- Constants 1/n n k R CONCLUSIONS: The results obtained were similar to or better than those already reported in the literature. Taking into account of sawdust is readily obtained from sawmills and it is considered a waste product. This material is a low cost and environmentally friendly alternative material. In this way, its use should be seriously considered for this task. The cadmium adsorption was found to be dependent on agitation time, ph and contact time, Temperature. The adsorption of cadmium was found to be fitted the Langmuir isotherm model, which suggests monolayer coverage of adsorbent surface. This work showed that sawdust could be used as a good adsorbent material for cadmium removal from dilute aqueous solution Following conclusions are drawn from the above discussed results: 1. Adsorbent prepared from sawdust could be used for the removal of cadmium from aqueous solutions. 2. The equilibrium time the adsorption of cadmium on the adsorbate prepared from sawdust in the present study from aqueous solutions is found to be in 15 minutes. 3. The maximum percentage removal was observed (96%) at ph The adsorption isotherm data of cadmium on sawdust with best modeled by both Langmuir and Freundlich isotherm. 5. This study indicates that sawdust has rapid adsorption rate and good adsorption capacity for cadmium. 6. Removal of Cadmium increases with increasing of adsorbent dosage at ph Removal of cadmium decreases with increasing of the initial concentration and also with ph, However adsorption capacity is increasing with increasing initial concentration of cadmium. 8. Adsorption capacity decreasing with increasing of amount of adsorbent. R S. Publication (rspublication.com), rspublicationhouse@gmail.com Page 297

8 International Journal of Emerging Trends in Engineering and Development Issue 4, Vol.5 (Aug.- Sep. 214) REFERENCES: 1., N. V farinella, G.D matos, M.A.Z Arruda, Grape bagasse s a potential biosorbent of metals in effluent treatments, Bioresours Technilogy 98(27) , Gong Zhengjun, tang Congcong, Tang Lu, Chen Jun,. Removal of Cadmium from aqueous solution by adsorption on peanut shell International Conference on Agricultural and Natural resources Engineering, Advances in Biomedical Engineering, Vol 3 3. P. Rajesh Kumar, P. Akhila Swtahnthra, V.V.Basava Rao and S.Ram Mohan Rao, Adsorption of Cadmium and Zinc Ions from Aqueous solution using Low cost adsorbents, Journal of applied Sciences, Vol No 14, No.7, SP, Mohamad hajar, Biosorption of Cadmium from Aqueous Solution using Dead Biomass Brown Alga Sargassum Conference Proceedings. 5.. Namasivayam C and K.Ranganathan, Removal of Cd(II) from waste water by adsorption on waste Fe(III) Cr(III) hydroxide Water Res.,29: , Taty-Costodes, V. C.,H Fauduet, C. Porte and A Delacrix Removal of Cd(II) and Pb(II) ions from aqueous solutions by adsorption onto sawdust of Pinus sylvestis, J. Hazard. Mater B15,pp: , Suresh Gupta, B.V. Babu, Removal of Toxic Metal Cr(VI)from Industrial Waste water using Sawdust as Adsorbent: Equilibrium, Kinetics and Regeneration Studies Acepted paper R S. Publication (rspublication.com), rspublicationhouse@gmail.com Page 298