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Biosorption - a green approach for heavy metal removal from water

3 rd International Colloquium Energy and Environmental Protection 14 - 16 November 2018 Ploie s ti , Rom a nia. Biosorption - a green approach for heavy metal removal from water Bondarev Andreea, Gheorghe Cǎtǎlina-Gabriela, Mihai Sonia, Cǎlin Cǎtǎlina

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Biosorption - a green approach for heavy metal removal from water

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  1. 3rd International ColloquiumEnergy and Environmental Protection14 - 16 November 2018 Ploiesti, Romania Biosorption - a green approach for heavy metal removal from water Bondarev Andreea, Gheorghe Cǎtǎlina-Gabriela, Mihai Sonia, Cǎlin Cǎtǎlina a Petroleum-Gas University of Ploieşti, Romania

  2. Outline of Presentation • Introduction • Objectives • Materials and Methods • Results and Discussion • Conclusions

  3. 1. Introduction • Water contamination with heavy metals due to industrial activities generates serious environmental problems because of their high toxicity and non-biodegradability. [1] • The conventional methods for metal ions removal from wastewater are limited by technical and economical barriers, especially when concentration of metals in the wastewater is low (<100 ppm) [2] Fig.1. Conventional Methods for Heavy Metal Removal [2]

  4. Biosorption uses inexpensive biomaterials to sequester environmental pollutants from aqueous solutions by a wide range of mechanisms, including ion exchange, complexation and physical adsorption.[2] • Variouswastematerialsfor biosorptiveremoval of heavy metal ionsfromwastewater: olive leaves, coconuthusk, coffeeground, tea leaves, almondshellresidues, hazelnutshell, groundnuthuskwereselectedbecause of theirlow cost and a higherbiosorptioncapacity. [3-6] • Algae, bacteria, yeast, fungi andwastematerialsfromagriculturalandfoodindustries areused as biosorbent. [3-6]

  5. Biosorption - a green approach for heavy metal removal from water Fig.2. Bioremediation and the factors that influence the biosorption [6]

  6. 2. Objectives • To determine whether low-cost biosorbents: green tea waste and carrot residue would have an acceptable adsorption efficiency for removing Pb(II) and would thus offer an effective and economical alternative to more expensive treatments. • To investigate theeffects of experimental parameters on heavy metal biosorption: initial concentration, pH, adsorbent dose. • The equilibrium data:described by typical Freundlich, Langmuir and Temkin adsorption models for each heavy metal - adsorbent system.

  7. 3.Materials and Methods Preparation of the adsorbent supports Waste materials that are available in large quantities: green tea waste (GTW)andcarrot residues (CR) were used as adsorbents for the removal of Pb (II) from synthetic wastewater. Thesematerialswereselectedbecause of a low cost andtheavailability of functionalgroups. Adsorption mechanism of heavy metals by tea waste seems to be conducted by compound and groups such as the caffeine, catechin, theophylline, tannin, etc. → with metals constitute bond and their absorption. Carrot residue is composed mainly of cellulose and lignin, both with the capacity to bind metal cations due to carboxylic and phenolic groups. [2-6] Fig. 3. Representation of possible adsorption mechanism (binding of functional groups of sorbent) with heavy metal.[7]

  8. Carrot residue (CR) • Carrotresidueis a thefibrousby-product of carrotmillingoperationand it canbeobtainedfrom a carrot-juiceprocessingplant in a large quantity. • This material was washedwithdistilledwatertoremovethesurfaceadheredparticles or othersolubleimpurities,then itwasovendried for 12 h, at 80°C. • In orderto eliminate solublecomponentssuch as tannin, resinsreducingsugars, coloringsubstances, theresiduewaswashedwith 0.1 M HClanddistilledwateruntil a constant pH wasachieved. • The sample was oven dried for 12 h at 80°C. Thisbiosorbentwasgroundandsieved, to get homogenousparticlesized material;the dried sample was stored in a desiccator for further use.

  9. The lignified plant cell wall is a complex material in which cellulose, hemicelluloses and lignin are in tight association.Carrot residue has potential adsorption capacity because of some functional groups in its structure: carboxyl and phenolic hydroxyl groups. (fig.4) Figure4.Structure of lignocellulosicbiomass.[6]

  10. Green tea waste (GTW) • Tea waste is available in cafetarias, beverage chain storesor tea factories. • Waste green tea leaves were used for adsorbent development. Surface impurities, soluble and coloured components from green tea waste (GTW) were removed by washing with boiling distilled water till the wash solution was neutral. • The sample was oven dried for 12 h at 80°C. The dried sample was sieved to obtain homogenous particle sized material and stored in a desiccator for further use. • Tea waste used for this study was not treated chemically or thermally.

  11. The major catechins of green tea may explain the potentialadsorptioncapacity of green tea waste [7]. Figure 5. Chemical structures of catechins [7]

  12. Metal analysis • Atomic absorption spectrophotometry was used for Pb (II) analysis. • A Varian AA 240 FS type atomic absorption spectrometer with an air-acetylene flame and a hollow cathode lamp for Pb was used for metal ion analysis. The absorbance of the samples was read in duplicate.

  13. 4. Results and Discussion Effects of experimental parameters on heavy metal biosorption Fig.5. Effect of initialconcentrationof Pb 2+ on theadsorbentmaterials (GTW and CR) (Concentration in therange 20–80mg/L, pH = 6.5, at room temperature, contact time24h) Fig.6. Effect of adsorbentdose on theadsorption of Pb 2+ usingdifferentmaterials (GTW and CR) (Initial Pb+2concentration:60 mg/L, with varying amounts of sorbent: from 0.10 to 1.00 g, at room temperature).

  14. Effects of experimental parameters on heavy metal biosorption • Observation: • A slightly decrease in Pb2+ ion removal capacity at pH >6.0 may be caused by hydrolysis accompanying by precipitation of metal hydroxide. This effect weakens electrostatic interactions and decreases adsorption. • At a pH higher than the presented optimal values, several hydroxyl low-soluble species may be formed, such as: Pb(OH)+, Pb(OH)2. Fig.7. Effect of pH on theadsorption of Pb2+ usingdifferentmaterials (GTW and CR) (The adsorbentdosage 0.5 g, Initial Pb+2concentration:60 mg/L)

  15. Equilibrium studiesThe adsorption equilibrium data is important to optimize the parameters of an adsorption system and to provide physico-chemical information, to explain the mechanism of adsorption. • The sorption capacity of an adsorbent can also be described by equilibrium adsorption isotherm, which is characterized by definite constants whose values express the surface properties and affinity of an adsorbent support. [6] • The adsorption capacity qe (mg/g) after equilibrium - the amount of lead adsorbed at equilibrium per unit mass of the adsorbent material [6,7]

  16. Isotherm modeling • Langmuir, Freundlich and Temkinisotherm models were selected to fit the experimental data. • The Freundlich model can be applied for non-ideal adsorption on heterogeneous surfaces and multilayer sorption. The Freundlich model is described as follow (Freundlich, 1906): [8] (2) original form (3) linearized form KF (mg g−1) and n (valuebetween 0 and 1) are Freundlichequilibriumconstants; 1/n is an empiricalparameterrelatingtheadsorptionintensity, whichvarieswiththeheterogeneity of the material.

  17. It is well known that the Langmuir equation is intended for a homogeneous surface and a good fit of this equation reflects monolayer adsorption. ►It was determined in accordance with the following equations (Langmuir, 1918): [8] • q (mg g−1)isthe maximumamount of metal ionsadsorbed per specific amount of adsorbent, when all binding sites are occupied; C(mg L−1 or mmol L−1) istheequilibriumconcentration; qm (mg g−1) istheamount of metal ionsrequiredtoform a monolayer; KListhe Langmuir equilibrium constant relatedtotheenergy of sorption (L mg−1 or L mmol−1). (4) original form; (5) linearized form

  18. The Temkin (Aharoni and Ungarish, 1977) isotherm has generally been applied in the following form: [9] (6) original form (7) linearized form KT(L mg−1):Temkinisotherm constant andbT(KJ/mole): constant relatedtotheheat of adsorption. The Temkin isotherm was first developed by Temkin and Pyzhevandand is based on the assumption that the heat of adsorption would decrease linearly with the increase in coverage of the adsorbent. The Temkin isotherm equation has been applied to describe adsorption on heterogeneous surface.[9]

  19. 4. Results and Discussion Adsorption isotherm study ● The equilibrium data were used to determine the maximum capacities of the adsorbents in this experiment. ● The isotherms provide an estimate of the adsorption capacity and also important information about applicability of a potential adsorbent for the adsorption of a pollutant. ● The adsorption intensities and adsorption capacities (qe) were determined from the intercept and slope data, respectively, for each adsorbent support.

  20. Freundlichadsorptionisotherms Figure8. Linear fitting of the Freundlich isotherms models for all samples (adsorbents: GTW and CR)

  21. Langmuir adsorptionisotherms Figure9. Linear fitting of the Langmuir isotherms models for all samples (adsorbents: GTW and CR)

  22. Temkinadsorptionisotherms Figure10. Linear fitting of the Temkin isotherms models for all samples (adsorbents: GTW and CR)

  23. A comparison of the three isotherms reveals that the correlation coefficient for the Freundlich model was the highest and showed better fits for carrot residue (CR). Langmuir isotherm provided a better fit for the other adsorbent, green tea waste (GTW). • The equilibrium data which fitted Langmuir isotherm, with higher coefficients suggest that the adsorption process followed monolayer sorption in this case. Table 1. Parameters of Freundlich, Langmuir and Temkin adsorption isotherm models for lead removal

  24. To confirm the feasibility of the adsorption process followed the Langmuir isotherm, a dimensionless constant - separation factor RL, was calculated by the following equation: • where C0is the initial concentration of sorbate(mg/L) and b (L/mg) is theLangmuir constant. Figure 11. Variation of RL with initial concentration C0 (mg/L) Unfavorable adsorption (RL>1) Linear adsorption (RL=1) Favorable adsorption (0 < RL< 1) Irreversible adsorption (RL= 0) RLvalues: in the range of 0.0580 to 0.0151 for CRand 0.0245 to 0.0062 for GTW, thus indicating that the adsorption of Pb (II) was favorable at 25 ºC.

  25. 5. CONCLUSIONS • Fromthe experimental data it canbeconcludedthatcarrotresidues (CR) andgreen tea waste (GTW)haveconsiderablebiosorptioncapacity. • Their key property is the presence of functional groups that can bind metal ions through complexation. • The adsorption of Pb2+was dependent on thefollowing experimental conditions: pH, initialconcentrationandadsorbentamount.

  26. ●The equilibriumsorption data wereappliedtovarioussorptionisothermmodelsandtheorder of fitness was: Langmuir > Freundlich >Temkin for green tea wasteandFreundlich > Temkin > Langmuir for carrotresidue. • A comparison of the three isotherms reveals that the correlation coefficient for the Freundlich model was the highest and showed better fits for carrot residue (CR). Langmuir isotherm provided a better fit for the other adsorbent, green tea waste (GTW). • The values of ∆G<+10 KJ/mol suggested the feasibility of the present adsorption process and the spontaneous nature of the adsorption of Pb2+ onto GTW and CR.

  27. The resultspresented in table 1 revealthatthevalue of ‘n’ Freundlichparameterwasgreaterthan 1, whichindicatesthattheadsorption of Pb(II) on investigatedmaterials (CR and GTW) wasfavourable. For a good adsorbent thevalue of ‘n’ Freundlichparameter is usually between 1 and 10. • The TemkinparameterbT (KJ/mol)relatedtoheat of sorption, was lessthan 8 for alladsorbents, that indicate weakinteractionbetween metal andsorbent. [5, 8]

  28. ●This study showed that locally available materials such as carrot residue and green tea waste can be used as efficient sorbents for lead ions removal, representing an effective and environmentally clean utilization of waste matter. • There is a ready supply of agricultural wastes worldwide. The use of such materials will not only convert waste materials into low-cost effective adsorbents, but also provide a solution to their disposal. • More studies are needed to optimize the system from the regeneration point of view, to investigate the economic aspects and to confirm the applicability of this sorbents under real conditions, such as in the industrial effluent treatment.

  29. Table 2: Heavy metal removal capacities (mg/g) for various methods [9]

  30. References 1.Gary, H., Handwerk, G.E., Kaiser M.J., Petroleum Refining, 5th Edition, CRC Press NY, 2007, Chapter 13, SupportingProcesses, pp. 290-293 2.Shah, M., Journal of Petroleum andEnvironmentalBiotechnology, 2014, 5:4, pp.1-12 3.Bozbas¸S., Boz, Y., 2016, ProcessSafetyandEnvironmentalProtection, 103, pp. 144–152 4.Ben-Ali, S., Jaouali, I., Souissi-Najar, S., Journal of CleanerProduction, 2017, 142, pp. 3809- 3821 5.Amarasinghe, B.M., Williams, R.A., Chemical Engineering Journal, 2007, 132, pp. 299–309 6.Uhrenholt Jensen,C., Rodriguez Guerrero,J., Karatzos,S., Olofsson,G., BrummerstedtIversen,S., Biomass Conv. Bioref., 2017, 7, pp.495-509 7.Tzeng, J., Weng, Z., Huang, J., Lin,Y., Wei Lai, N., Yao-Tung, L., International Biodeterioration & Biodegradation, 2015, 104,pp. 67-73 8. Bondarev, A., Pantea, O., Mihai,S., Calin, C., Gheorghe,C.G., 2016, Rev.Chim., 67 (4), 728-733 9. Argun, M., Dursun, S., J. Int. Environmental Application & Science, 2006,1 (1-2), pp. 27-40

  31. 3rd International ColloquiumEnergy and Environmental Protection

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