Adsorption of Methyl Orange on Coffee grounds Activated Carbon

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2017 International Conference on Alternative Energy in Developing Countries and Emerging Economies 2017 AEDCEE, 25‐26Energy May 2017, Bangkok,Countries Thailand and Emerging Economies 2017 International Conference on Alternative in Developing 2017 AEDCEE, 25‐26 May 2017, Bangkok, Thailand

International Symposium on District Heating Activated and Cooling Carbon AdsorptionThe of15th Methyl Orange on Coffee grounds Adsorption of Methyl Orange on Coffee grounds Activated Carbon a a Supapornthe Rattanapan , Jiraporn Srikram and Panita Kongsunea* Assessing feasibility of using the heat demand-outdoor a a Supaporn Rattanapan , Jiraporn Srikram and Panita Kongsunea* Chemistry Research Unit for Bioresourcefor and Waste Utilization, Department of Chemistry,heat Faculty ofdemand Science, Thaksinforecast University temperature function a long-term district (Phatthalung Campus), Thailand a a

Chemistry Research Unit for Bioresource and Waste Utilization, Department of Chemistry, Faculty of Science, Thaksin University (Phatthalung a,b,c a a Campus), Thailand b c c

I. Andrić

*, A. Pina , P. Ferrão , J. Fournier ., B. Lacarrière , O. Le Corre

Abstract a IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal Abstract b Veolia of Recherche & Innovation, 291 Avenue Dreyfous Daniel, Limay, Franceas an adsorbent for methyl This work reports on the potential waste material of coffee grounds to produce an78520 activated carbon c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France 500 °C of conventional process. The orange (MO) adsorption. The coffee material activated 3 andan This work reports on the potential of grounds waste material of was coffee groundsbytoHNO produce activated carbon as an thermal adsorbent for methyl coffee grounds activeatedThe carbon characterized by SEM, FT-IR properties. Batches tests were 500pHzpc °C of conventional thermalofprocess. The orange (MO) adsorption. coffee(CGAC) groundswas material was activated by HNO 3 andand conducted to investigate MO (CGAC) molecule was removal efficiencybyatSEM, different pH and values, contact time, adsorbent and coffee grounds activeatedthe carbon characterized FT-IR pHzpc properties. Batches ofdosage, tests were temperatures. concentrations MO wereremoval analyzed using anatUV-Vis spectroscopy. maximum adsorptiondosage, capacityand at conducted investigate the MOofmolecule efficiency different pH values, The contact time, adsorbent Abstract to The equilibrium of concentrations MO was 658 mg/g when pH,analyzed initial concentration, contact time and temperature of MO solution capacity are 3, 300 temperatures.(q)The of MO were using an UV-Vis spectroscopy. The maximum adsorption at mg/L, 90 min and 30 ºC, respectively and the dose of CGAC was 0.05 g. The Langmuir, Freundlich and Dubinin–Radushkevich equilibrium (q) of MO was 658 mg/g when pH, initial concentration, contact time and temperature of MO solution are 3, 300 District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the isotherms were used the building experimental data. The best fit investments of the experimental data was obtained by heat the mg/L, 90 min and 30 to ºC,analyze respectively and the sector. dose equilibrium ofThese CGAC was 0.05 g. The Langmuir, Freundlich and Dubinin–Radushkevich greenhouse gas emissions from the systems require high which are returned through the 2 value of 0.9536, indicating the heterogeneity of the CGAC and multi-layer coverage of MO Freundlich isotherm, having an Rthe isotherms usedchanged to analyze experimental equilibrium The best fit of the datafuture was obtained by the sales. Duewere to the climate conditions and building data. renovation policies, heatexperimental demand in the could decrease, onto the CGAC adsorbent. TheR2period. reaction exothermic andthethe ∆G values of were thecoverage feasibility and value of was 0.9536, indicating heterogeneity the negative, CGAC andindicating multi-layer of MO Freundlich isotherm, havingreturn an prolonging the investment spontaneous nature of adsorption. onto the CGAC adsorbent. The reaction was exothermic and the ∆G values were negative, indicating the feasibility and The main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand ©forecast. 2017 The Authors. Published by Elsevier Ltd. spontaneous nature of adsorption. The districtPublished of Alvalade, locatedLtd. in Lisbon (Portugal), was used as a case study. The district is consisted of 665 © 2017 Authors. by Peer-review under responsibility ofElsevier the Organizing Committee of 2017 AEDCEE. © 2017 The Thethat Authors. Published by Elsevier Ltd. and buildings vary in both construction period typology. scenarios (low, medium, high) Energy and three Peer-review under responsibility of the scientific committee of theThree 2017 weather International Conference on Alternative in district Peer-review under responsibility of the Organizing Committee of 2017 To AEDCEE. scenarios and wereEmerging developed (shallow, intermediate, deep). estimate the error, obtained heat demand values were ­Drenovation eveloping Countries Economies. Keywords: Methyl orange, Coffee ground, Activated carbon, Isotherm compared with results from a dynamic heat demand model, previously developed and validated by the authors. Keywords: Methyl orange, Activated carbon,isIsotherm The results showed thatCoffee whenground, only weather change considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation 1.scenarios, Introduction the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). 1.The Introduction value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the Methylinorange (MO), anionic dyeofand the most commonly substance in the process, was chosenand as decrease the number of an heating hours 22-139h during the heatingused season (depending on dying the combination of weather the adsorbate in (MO), this study due its potential risk for environmental pollution. The removal of MO from Methyl orange an anionic dye and the most commonly used substance in the dying process,(depending was chosen as renovation scenarios considered). On to the other hand, function intercept increased for 7.8-12.7% per decade on the coupled scenarios). The values suggested be used to modify the functionadsorption parameters the scenarios considered, and contaminated water hasstudy been attempted bypotential several techniques. However, more preferable technique the adsorbate in this due to itscould risk for environmental pollution.isforaThe removal of MO from improve accuracy of heat demand estimations. due to itsthe ease of operation and cost-effectiveness 2]. contaminated water has been attempted by several[1,techniques. However, adsorption is a more preferable technique

due to its ease of operation and cost-effectiveness [1, 2].

© 2017 The Authors. Published by Elsevier Ltd. Peer-review underauthor. responsibility the 7154; Scientific Committee of The 15th International Symposium on District Heating and * Corresponding Tel.: +668of9870 fax: +66 76 60 9634 Cooling. E-mail address: [email protected], [email protected]

* Corresponding author. Tel.: +668 9870 7154; fax: +66 76 60 9634 E-mail address: [email protected], [email protected] Keywords: Heat demand; Forecast; Climate change 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review the Organizing Committee 1876-6102 ©under 2017responsibility The Authors. of Published by Elsevier Ltd. of 2017 AEDCEE. Peer-review under responsibility of the Organizing Committee of 2017 AEDCEE.

1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling. 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 2017 International Conference on Alternative Energy in ­Developing Countries and Emerging Economies. 10.1016/j.egypro.2017.10.064

950 2

Supaporn Rattanapan et al. / Energy Procedia 138 (2017) 949–954 Author name / Energy Procedia 00 (2017) 000–000

Activated carbon is widely used as an adsorbent due to its high adsorption capacity in the process of adsorption. Commercial activated carbons are mostly prepared from coal, wood, peat and coconut shells. However, demand for novel and more efficient adsorbents has initiated research on low-cost, locally available and renewable materials as potential alternative precursors in activated carbon production. For this purpose, activated carbon was prepared from various agricultural wastes. It was revealed that the adsorption capacity of AC depends on many factors [3]. Types of precursors used for AC preparation are also main factors [4]. Among biomass and agricultural wastes, a coffee ground (CG) is one of the best alternative low-cost materials for AC preparation. This is because CG has a high amount of organic content [5, 6], is locally available and there is a high amount of waste material from coffee shops that can be transformed to be a value-added product. In addition, only small sample sizes of coffee grounds are needed for preparing the activation process. Furthermore, no information of coffee grounds activated carbon (CGAC) was used for MO adsorption. The objective of this research work was to investigate the MO removal efficiency by CGAC. The effects of pH on the MO solution, adsorbent dosage, temperature of MO, and contact time were examined. The CGAC adsorbents were characterized by SEM, pHzpc and FT-IR techniques. 2. Experimental 2.1 Adsorbate Methyl orange (MO), an anionic pollutant in which the chemical formula of C14H14N3NaO3S, MW of 327.33 g/mol and λmax of 464 nm, was selected as the adsorbate in this research work [1]. The 3D structure is shown in Fig. 1A.

Fig. 1, (A) 3D structure of methyl orange dye; (B) SEM micrograph of CGAC and (C) pHzpc of CGAC.

2.2. Preparation of CGAC An amount of coffee ground (CG) was taken from Café Amazon coffee shop at a PTT petrol station, Khunkanun district, Phatthalung province. The coffee ground was put in an oven at 105 °C for 24 hours. Afterward, it was impregnated with 25%V/V HNO3 with a ratio of 1:1 and put into a furnace at 500 °C for 20 min to become activated carbon (CGAC). The CGAC was repeatedly washed with distilled water until its filtrate was neutral. 2.3. Adsorption experiments The adsorption capacity of CGAC was tested for the removal of MO from the aqueous solution. The effects of pH on the MO solution, absorbent dosage, contact time and temperature of MO solution on absorption equilibrium were studied and optimized, respectively. The effect of pH on the MO solution was observed at a pH level that ranged from 3.0 – 12.0. In each pH, the CGAC 0.2 g in 150 mL of 300 mg/L of MO solution at 30 °C in a shaker bath at 240 rpm/min for 180 min were carried out. The initial and final concentrations of MO were analyzed using the UV-Vis technique. Experiments were performed in triplicate and the results were averaged. Controls were obtained by mixing distilled water with each sample. The adsorption capacity at equilibrium qe in mg/g unit of MO was calculated using the equation (1):



Supaporn Rattanapan et al. / Energy Procedia 138 (2017) 949–954 Author name / Energy Procedia 00 (2017) 000–000

 C - Ce = qe  0  w

 V 

951 3

(1)

Where C0 and Ce are the initial and equilibrium concentration (mg/L), respectively, W, and V are the mass of CGAC (g) and volume of the solution (L), respectively. The effect of absorbent dosage, contact time and temperature were done in the same way as the study of the effect, of pH on the MO solution. The CGAC was assigned to be varied from 0.005-0.4 g. The contact time was assigned to be varied from 0-180 min. The effect of temperature was assigned to be varied from 30-50ºC with optimum condition of pH of solution, adsorbent dosage and contact time. 3. Results and discussion 3.1 Characterization analysis The porous structure examination of CGAC can be seen from the SEM photographs, displayed in Fig.1B. It can be clearly seen that the surface texture of CGAC shows a pronounced porosity around the surface. The FT-IR spectrum of precursor CG and CGAC adsorbent are shown in Table 1. For CP, the presence of band at 3260, 3050, 2925, 1741, 1638, 1455, 1240, 1151, 1055, 871,807 cm−1were assigned to functional groups such as hydroxyls, phenols, olefins, esters and ethers [7]. The FT-IR spectrum of CGAC was found that many functional groups disappeared after modification during the thermal-chemical treatment process [3]. It should be noted that when HNO3 was used as activation together with heating in the preparation process of decomposed volatile compounds on the carbon surface, and resulted in an efficient surface modification. Table 1. FT-IR assignation of functional groups on CG precursor and CGAC adsorbent. Reference 3600-3400 3100-3000 3000-2800 2260-2100 1740-1730 1650-1600 1465-1375 1300-1000 1000-675

Wave number (cm-1) CG 3260 3050 2925,2855 1741 1638 1455 1240,1151,1055 871,807

CGAC

2115

1210,1068 875

Functional groups O-H Stretching of alcohol, carboxylic =C-H Stretching of alkene, benzene C-H Stretching of alkane C=C Stretching of alkyne C=O stretching C=C Stretching of alkene C-H bending C-O Stretching of ether, ester C=C-H bending

3.2 Adsorption activity The adsorption capacity of the developed CGAC was tested for the removal of MO from water. Several parameters; like effect of pH, adsorbent dosage, contact time, and temperature, were investigated and optimized. Effect of pH is considered to be one of the key parameters in the adsorption process of metal ions from aqueous solution because it affects the surface charge of the adsorbent and also the chemical speciation of the adsorbate [8]. The effects of pH were conducted in the pH range from 3-12 at fixed times (120 min), adsorbent dosage (0.1 g), temperatures (30 ºC), and initial concentrations (300 mg/L). The removal of MO from an aqueous solution is dependent on pH (Fig.2A) and can be explained by pHzpc (Fig. 1C). The pHzpc of a solid is the pH at which the charge on the surface of the solid is zero [9]. Plot between initial pH and final pH of the solution intersected at the point which is called pHzpc [9] and is found to be 8 for CGAC (Fig. 1C). The surface of the CGAC is positively below pHzpc and negatively charged above pHzpc. In this study, the maximum adsorption capacity of CGAC was obtained at pH 3. This can explain that in the pH 3, the CGAC surface is positive so that it can interact well with the anionic MO dye. The adsorption capacity is decreased at high pH. This is due to weak electrostatic interaction. The effects of adsorbent dosage were conducted by varying the adsorbent amount from 0.05 to 0.4g for CGAC at fixed times (120 min), pH of MO solution (3), temperatures (30 ºC), and initial concentrations (300 mg/L) and shown in Fig. 2B. It was observed that the amount of MO adsorbed per unit weight of CGAC adsorbent (q) decreased when the adsorbent dose increased. This can be attributed to an increase in the adsorbent surface area and the availability of more adsorption sites with the increasing dosage of the adsorbent. Further increment of CGAC adsorbent did not have much affect due to a limited availability of MO adsorbate around the adsorbent.

Supaporn Rattanapan et al. / Energy Procedia 138 (2017) 949–954 Author name / Energy Procedia 00 (2017) 000–000

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The results of contact time effect on the adsorption capacity of CGAC are depicted in Figure 3C. As illustrated in Fig. 2C, the apparent adsorption equilibrium is established within 90 min. Equilibrium being basically due to the saturation of the active site and slow pore diffusion, at which time further adsorption cannot take place. The increase in adsorption capacity at equilibrium (qe) values at low temperature indicates that the adsorption process is more favourable towards lower temperature (Fig. 2D). From the results, the maximum qe of MO was 658 mg/g when pH, initial concentration, contact time and temperature of MO solution was 3, 300 mg/L, 90 min and 30 ºC, respectively and the dose of CGAC was 0.05 g.

A

C

B

D

Fig. 2, (A) effect of pH; (B) effect of adsorbent dosage; (C) effect of contact time; (D) effect of temperature of MO adsorption capacity on CGAC.

3.3 Adsorption isotherms Adsorption isotherms provide information about the capacity of the adsorbent and the nature of solute–sorbent interaction. Moreover, the isotherm constant values are essential to predict the maximum adsorption capacity and describe the affinity and surface properties of the adsorbent. In the present work, the Langmuir [10], Freundlich [11], and Dubinin–Radushkevich [12] isotherms were used to analyze the experimental equilibrium data. Fig. 3 shows the linear plot of, (A) Langmuir; (B) Freundlich; (C) Dubinin–Radushkevich isotherms and isotherm parameters shows in Table2. The Langmuir model is based on the assumption that there is monolayer coverage of adsorbate on a homogenous adsorbent surface [10]. The Langmuir isotherm equation is: Ce C 1 = + e (2) qe qm K L qm where qm represents the maximum monolayer capacity of adsorbent (mg/g), and KL represents the Langmuir adsorption constant (L/mg). The values of isotherm constants are shown in Table 2. The applicability of isotherm equation is compared on the basis of correlation coefficients R2. However, the R2 was lower than that of Freundlich isotherm, indicating that the adsorption of MO onto CGAC adsorbent is not monolayer adsorption. Freundlich isotherm model expresses the heterogeneity of the adsorbent material and multi-layer coverage of adsorbate [11]. The Freundlich isotherm equation can be expressed as follows



Supaporn Rattanapan et al. / Energy Procedia 138 (2017) 949–954 Author name / Energy Procedia 00 (2017) 000–000

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1 lnq e = lnK F + lnCe n

(3)

In this equation KF and n are the Freundlich constants. The higher value of k indicates higher adsorption capacity and higher value of n indicates the stronger adsorption bond between adsorbate and adsorbent. The values of the Freundlich constants are calculated from the slope and intercept of the line and shown in Table 2. The best fit of the experimental data was obtained by the Freundlich isotherm, having R2 value of 0.9536. The qm, KF and n values of MO sorption on MPAC are 558 mg/g, 3.12x10-4 L/mg and 0.4, respectively. Dubinin–Radushkevich (D–R) isotherm was used for understanding the type of bonding between MO and CGAC i.e. physical or chemical. D–R isotherm is presented as follows [12]: 2 lnq e = lnq m - K D ε (4) where KD is a constant which is related to the mean free energy of adsorption per mole of the adsorbate (mol2/J2 ) and ε is the Polanyi potential that is logarithmic function of adsorbate concentration, which is given by the following relationship ε= RTln(1+1/Ce). The slope and intercept of the straight line plot lnqe vs ε2 were used for the calculation of KD and qm (Table 2). KD and qm were found to be 0.0063 L/mg and 1017 (mg/g), respectively. The mean free energy of adsorption (E) was calculated from KD values using the relationship E=1/(2KD1/2). The energy (E) for MO are 39.68 kJ/mol therefore, MO adsorption on CGAC was chemical adsorption process [9].

Fig. 3, The linear plot of, (A) Langmuir; (B) Freundlich; (C) Dubinin–Radushkevich isotherms; (D) adsorption thermodynamic parameters of MO adsorption on CGAC adsorbent. Table 2. Parameters of the Langmuir, Freundlich, and Dubinin–Radushkevich isotherms. Isotherms

Langmuir

Freundlich

parameters

KL (L/mg)

R

values

-0.003

0.6194

2

KF (L/mg)

n

qm (mg/g)

3.12x10-5

0.4

558

Dubinin–Radushkevich R

0.9536

2

KD (L/mg)

E Kj/mol

qm (mg/g)

R2

0.0063

39.68

1017

0.8628

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3.4 Adsorption thermodynamics The adsorption thermodynamic was shown in Fig.3D and parameters were calculated using the following equation and: q e ΔS° ΔH° (5) ln = Ce R RT where R is the universal gas constant (8.314 J mol−1 K−1) and T is the temperature (K). The calculated thermodynamic parameters are listed in Table 3. The Gibbs free energy (ΔG) was calculated from ∆G = ∆H-T∆S. The negative ΔG values confirm the spontaneous nature and feasibility of the adsorption process. The decrease in ΔG° values at low temperature indicates that the adsorption process is more favourable towards lower temperature. The ΔH° value is -43.32 kJ/mol, suggesting that the adsorption might be chemical adsorption type and exothermic nature of adsorption of MO onto CGAC. The negative value of ΔS° indicated decrease in the degree of freedom (or disorder) of the adsorbed species or show the affinity of CGAC for MO in aqueous solution [4, 9]. Table 3. Thermodynamic parameters of MO adsorption on CGAC adsorbent. ∆H° (kJ/mol)

∆S° (kJ/mol.K)

-43.30

-0.114.82

303 -3.1040

∆G°(kJ/mol) 313 -2.3081

323 -1.5123

4. Conclusion The maximum adsorption capacity at equilibrium (q) of MO was 737 mg/g when pH, initial concentration, contact time and temperature of MO solution were 3, 300 mg/L, 90 min and 30 ºC, respectively and the dose of CGAC was 0.05 g. The best fit of the experimental data was obtained by the Freundlich isotherm, having an R2 value of 0.9536, indicating the heterogeneity of the CGAC and multi-layer coverage of MO onto the CGAC adsorbent. The negative ΔG values confirm the spontaneous nature and feasibility of the adsorption process. The adsorption process is more favourable towards a lower temperature. The ΔH° value was -43.32 kJ/mol, which suggests that the adsorption might be a chemical adsorption type and an exothermic nature of adsorption of MO onto CGAC. Acknowledgements This work was supported by the Thaksin University Research Fund and the Graduate School at Thaksin University. References [1]

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