Batch experiment studies on bio-sorption of Pb(II) and Cu(II) metal ions using low cost adsorbents from Prosopis Juliflora Bark and leaves.

                                                              ABSTRACT

Different heavy metals such as Lead (Pb), Cadmium (Cd), Copper (Cu), Chromium (Cr), Mercury (Hg), Zinc (Zn) and Arsenic (As) are the core elements used as colour pigments in textile industries. This is widely effecting the aquatic environment causing high increase of metallic substances in water resources, which is a threat for the environment and human health. Among different processes adsorption by activated carbon is an efficient process to remove heavy metals from waste water.  Research is being done on inventing different low cost adsorbents from different agricultural wastes that can be used effectively to remove different heavy metals from textile waste water.  My work discuss about the efficiency of removing heavy metals such as copper and lead by using activated carbon from Prosopis Juliflora bark and leaves. Prosopis Juliflora is widely known for the extensive property of absorbing water and certain heavy metals.  Activated carbon was formed from Prosopis juliflora bark and Prosopis Juliflora leaves through Physical and chemical treatment separately. Stock solution for lead and copper was prepared in the laboratory. Batch experiments were conducted to study Effect of adsorption by varying adsorbent dosage, pH and contact time of the adsorbent with the solution. It was concluded that capacity of adsorption of the modified activated carbon from Prosopis Juliflora bark and leaves for heavy metals such as copper and lead was more efficient. This activated carbon can be used as a promising bio-adsorbent for removing Heavy metals from Textile effluent.

Key words : Activated carbon, Adsorption, Prosopis Juliflora leaves and Bark,  Heavy metals

1. INTRODUCTION

Textile waste water has contributed the maximum to the pollution of the water and the environment in recent times. Textile industries use gallons of water for different processes imposed in textile production. The dying and washing process in textile production is condemned as a leading offender in polluting the water bodies in the environment [2]. The input of textile waste water to the surface water bodies not only have negative impact on aquatic, plants and animals and human [1], but also decreases the self purification of water bodies ,which again is an environment constrain. Textile effluent have high load of pollutants in terms of heavy metals, dyes, organic & inorganic materials [2]. This further increases the COD, BOD, pH, turbidity, salinity, suspended solids, etc. which is beyond the acceptable limit of the environment. Textile effluent contains more amounts of dyes and heavy metals. Textile industries use a large quantity of water for the production process. The waste water from the washing and drying units of textile industries are main source of heavy metals disposed to environment.

Heavy metals in large amount increase the toxicity of the water and which has tremendous risk effect to the ecosystem.   As the effluent treatment plants are energy consuming, expensive, includes different complicated process, so many industries discharge the effluent water without any proper treatment. This increases the concentration of heavy metals in the surface and as well under ground water in specific areas which is of great concern for the researches. Different treatment methods are being used for the reduction of heavy metals from the water bodies [3-4]. Among the techniques the most efficient process are ion exchange [8], reverse osmosis [8], adsorption on activated carbon [10]. But these techniques are very expensive and required skilled person. This is why many industries are reluctant to use these techniques for the heavy metal removal.

Recently adsorption has become one of the most effective technique and use of low cost adsorbent[4] to remove heavy metals have reduce the cost of the effluent treatment to a greater extent. Low cost adsorbents are derived mainly from cheap agro waste like coir pith, pine tree bark, neem bark powder, tea waste ,Wheat husk[8] Rice paddy[9]etc which is available locally [5].These adsorbents are mainly used as adsorbent for dye removal and heavy metal removal[11].Different heavy metals found in textile effluent are lead, arsenic, nickel, mercury, chromium, copper, zinc, etc. These heavy metals are found to be toxic and hazardous for the environment and human health. When heavy metals surpass its permissible limit causes serious impact and develop different disorders in human health [7]. Low cost adsorbents are found to be more efficient in removing different dyes like reactive yellow [10], direct dyes [11], acid blue 40 [12], reactive dyes [13] etc. Even different natural adsorbents are used for removal of heavy metals like fluoride [14], Nickel [1-14], chromium etc.

The aim of this experiment is to study the adsorption of heavy metals like copper and lead on activated prosopis juliflora bark and prosopis juliflora leaves. Despite the usefulness of copper in many essential processes in our day to day life but prolonged and over exposure to the metal can result in intense complexities in plants, animals as well as human beings. Further study has been done on the affect of adsorption variables like adsorbent dosage, pH, contact time on adsorption of copper and lead.

2. Method and Materials

2.1 Stock solution preparation:

Stock solution of 0.1 mole of Cu ions are prepared by  dissolving Copper sulphate penta hydrate (CuSO4.5H2O) to distilled water and similarly 0.1 mole of Pb ions was prepared by dissolving Lead Nitrate heptahydrate (PbNO₃.7H2O) in distilled water.  This solution was used as sample solution for adsorption studies. Adsorption experiment was carried out on these samples using activated Prosopis juliflora bark and leaves in proportion of 2:1.

2.2  Prosopis juliflora bark and Prosopis juliflora leaves

Prosopis juliflora bark was collected from local area in Chennai. The collected PJB materials were sun dried for 5 days and then finely powdered with grinding machine in local mill. The powered materials were subjected to intensive washing with distilled water to remove all the dirt particles. The powdered PJC (Prosopis Juliflora carbon) was oven dried at 130°C for 20 hrs to remove excess moisture and was sieved to get uniform particle size of 150 mesh size.  Then the powder was treated with concentrated sulphuric acid for 10 hours then washed with water to get rid of excess acid. The product was dried in a muffle furnace for about 3 hours at the temperature of 800°C. The resulting powder was used for adsorption experiment.

The Prosopis juliflora leaves were collected from various places in Chennai, Tamil Nadu,India. The leaves were boiled in water for 5 mins to take out the green color and dirt present in leaves. Then they were sun dried for 5 days and oven dried at 100°C for 20hrs to extract the moisture content present in the leaves. The dried leaves were grinded in a mixer. The powdered leaves were sieved to get uniform particle size of 150 meshes. The chemical treatment of the leaves were done by soaking 30gm of prosopis juliflora in 50ml of ortho-phosphoric acid(30%) for 24hrs.  Then it was washed in distilled water to extract the acid content from the leaves and was activated in Muffle furnace. The process of converting Prosopis Juliflora bark and leaves into activated carbon had been shown in the flow diagram 1.

3. Result and Discussion

          Adsorption experiment was conducted by taking the sample solution in conical flask and required amount of adsorbents were added to it. It was stirred using mechanical stirrer and the effect was observed by changing the adsorption parameters like pH, adsorbent dosage and contact time.

3.1   Effect of pH

The pH of the solution influences the properties of PJB, affects the adsorption mechanisms to a great extent.  As shown in Fig.3 the variation of Pb(II) and Cu(II) adsorption on Prosopis juliflora bark. For Cu (II), adsorption increases with pH and is maximum at 5. The results indicated that Cu (II) removal was increased to maximum and then decreased with pH variation from 4 to 9 .The maximum % removal of Cu (II) was about 89% at pH 5 and 91% for Pb(II).

        Table 1: Effect of pH on adsorption

Fig. 2 Effect of pH on adsorption of Cu and Pb

3.2 Effect of adsorbent dosage

Adsorption efficiency of Cu (II) and Pb(II) was studied by varying the amount of adsorbents from 50 to 200 mg keeping other parameters (pH, and contact time) constant. As shown in fig.3 that removal efficiency of the copper usually improved on increasing adsorbent doses.  There is no further increase in adsorption after 200 mg of adsorbent.  The maximum % removal of Cu (II) was about 94.27% at the dosage of 200 mg. Similar properties was shown by Pb(II) adsorptions. Within the dosage of 150mg to 250 mg the variation of Pb adsorption was almost constant. The maximum Average adsorption for Lead was 93.67% at adsorbent dosage of 200mg.

Table 2: Effect of adsorbent dosage on adsorption

Fig. 3 Comparison of Adsorption of Cu and lead with Adsorbent dose

 3.5   Comparison of effect of contact time on Cu(II) And Pb(II)

Fig. 4 shows that adsorption efficiency was increased when contact time of the adsorbents and the sample was increased. It was observed that after a period of contact time the adsorption remained constant. The results indicated that Cu (II) removal was increased from 15 to 94% with the contact time variation from 10 to 240minutes. From 210 to 240 minutes, the percentage removal of Cu (II) remains constant (91%), which showed that equilibrium was reached at 210 minutes itself. Thus the results illustrated that the optimum contact time for maximum removal (91%) of Cu (II) was 210 minutes. The optimum contact time for lead adsorption was 180 min with 89% removal.

Table 3: Effect of contact time on adsorption

Fig. 4 Comparison of Adsorption of Cu and lead with Time

4. CONCLUSION

Based on the results of this study following conclusions could be drawn that prosopis juliflora bark and leaves can be effectively used for adsorption of Heavy metals like Copper and Lead. This method is economical compared to other conventional methods for removal of Heavy metals. By removing the heavy metals the textile effluent can be reused for industrial and agricultural purposes.

REFERENCES

1.      AE Ghaly, R Ananthashankar, M Alhattab and VV Ramakrishnan, “Production,  characterization and treatment of textile effluents”: A Critical Review Journal of Chemical Engineering & Process Technology ISSN: 2157-7048 January 03, 2014.

2.      M Mirjalili, Mb Tabatabai, L Karimi “Novel herbal adsorbent based on wheat husk for reactive dye removal from aqueous solutions” African Journal of Biotechnology ISSN 1684–5315 Vol. 10(65), pp. 14478-14484, 24 October, 2011

3.      Sushmita Banerjee, Uma Sharma, Mahesh Chattopadhyaya, “Adsorption Characteristics of Modified Wheat Husk” Article (PDF Available)  in  “Journal of Hazardous Toxic and Radioactive Waste” DOI: 10.1061/(ASCE)HZ.2153-5515.0000191,2014.

4. A.Patil, Prof.J.K.Shinde, A.L.Jadhavand, S.R.Deshpande, Humbarde, K.Krishnakumar “Adsorption of Methylene Blue in waste water by low cost adsorbent Rice husk and wheat shell” International Journal of Engineering Research and Technology. ISSN 0974-3154 Volume 10, Number 1 (2017)

5. Shashi V. Ranga1 , Lopa K. Sanghavi Research Development Cell, Government College of Engineering, Jalagon (M. S), India “Dye waste water treatment using agro waste: Green Adsorption” International Journal of Innovative Research in Science, Engineering and Technology. Volume 6, Special Issue 1, January 2017.

6. Kumar, R. Tamilarasan “Removal of Victoria Blue using Prosopis juliflora bark carbon: Kinetics and Thermodynamic modeling Studies” J. Mater. Environ. Sci. 5 (2) (2014) 510-519 Kumar and Tamilarasan ISSN : 2028-2508 CODEN: JMESCN Nov 2013

7. Gopal and M. Asaithambi, “Adsorption of Acid Blue- 40 (A Textile Dye) using Prosopis Juliflora activated carbon embedded in polyaniline matrix ” PG and Research Department of Chemistry, Erode Arts and Science College (Atonomous), ISSN 0974-1496, Vol. 8 , No. 3 |279 – 286 | July – September 2015

8. Nasir Akhtar, Hajira Tahir, Muhammad Sultan, Ghazala Yasmeen and and Uzma Hameed “Application of chitosan padded rice and wheat husk for the removal of reactive dye from aqueous solution” African Journal of Biotechnology, Vol. 11(64), pp. 12756-12765, 9 August 2014.

9. Muthulakshmi andal and K. S. Thangamani  “Removal of direct dye using activated carbon prepared from Prosopis Juliflora Leaf: isothermal, thermodynamic and kinetic Studies” Chemical Science Review and Letters , ISSN 2278-6783
10. MuthaiyanThilagavathi,Shanmugam Arivoli and Vaithilingam Vijayakumaran, Adsorption of malachite green from waste water using Prosopis Juliflora Bark Carbon,  Kuwait J. Sci. 42 (3) pp. 120-133, 2015.

11.  Khalid M Mousa, Alla Hussein Taha, Ghazala Yasmeen and and Uzma Hameed,   Adsorption of reactive blue dye onto natural and modified wheat straw, Journal of Chemical Engineering & Process Technology. Novmber 25, 2015

12. Mohammad Mirjalili, Marjan Mirjalili, Decolorisation Treatment of wastewater Containing Reactive Yellow 15 using Herbal Absorbent of Wheat Husk, 3rd International Conference on Biological, Chemical & Environmental Sciences (BCES-2015) Sept. 21-22, 2015 Kuala Lumpur (Malaysia)
13. Sri Ram1 , M.Tamilmani1 and T.Sonia, Treatment of textile dyeing effluent by natural adsorbents using Prosopis Juliflora, SSRG International Journal of Civil Engineering- (ICRTCETM-2017) – Special Issue – April 2017 .
14. Sivakumar , D. Shankar , T. Sri Akash , G.S. Vetri Thirumagan, Experimental investigations on removal of fluoride in groundwater using Prosopis Juliflora, International Journal of Advanced Research in Basic Engineering Sciences and Technology (IJARBEST).