Makara Journal of Technology Makara Journal of Technology
Volume 23 Number 2 Article 2
8-2-2019
Adsorption of Heavy Metal Ions by Oil Palm Decanter Cake Adsorption of Heavy Metal Ions by Oil Palm Decanter Cake Activated Carbon
Activated Carbon
Mohd. Ezreeza Mohamed Yusoff
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
Juferi Idris
Universiti Teknologi MARA Sarawak, Kampus Kota Samarahan, 94300 Kota Samarahan, Sarawak, Malaysia
Nahrul Hayawin Zainal
Biomass Technology Unit, Engineering and Processing Division, Malaysian Palm Oil Board (MPOB), Ministry of Plantation Industries and Commodities, 6, Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia
Mohamad Faizal Ibrahim
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
Suraini Abd-Aziz
Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia, [email protected]
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Recommended Citation Recommended Citation
Yusoff, Mohd. Ezreeza Mohamed; Idris, Juferi; Zainal, Nahrul Hayawin; Ibrahim, Mohamad Faizal; and Abd- Aziz, Suraini (2019) "Adsorption of Heavy Metal Ions by Oil Palm Decanter Cake Activated Carbon,"
Makara Journal of Technology: Vol. 23 : No. 2 , Article 2.
DOI: 10.7454/mst.v23i2.3760
Available at: https://scholarhub.ui.ac.id/mjt/vol23/iss2/2
This Article is brought to you for free and open access by the Universitas Indonesia at UI Scholars Hub. It has been accepted for inclusion in Makara Journal of Technology by an authorized editor of UI Scholars Hub.
Adsorption of Heavy Metal Ions by Oil Palm Decanter Cake Activated Carbon
Mohd. Ezreeza Mohamed Yusoff
1, Juferi Idris
2, Nahrul Hayawin Zainal
3, Mohamad Faizal Ibrahim
1, and Suraini Abd-Aziz
1*1. Depart ment of Bioprocess Technology, Faculty of Biotechnology and Bio molecu lar Sciences, Universiti Putra Ma laysia, 43400 UPM Serdang, Se langor, Ma laysia
2. Universit i Te knologi MA RA Sara wak, Ka mpus Kota Sa marahan, 94300 Kota Sa marahan, Sa rawa k, Malaysia 3. Bio mass Technology Unit, Engineering and Processing Division, Malaysian Pa lm Oil Board (M POB), M inistry of Plantation Industries and Commodit ies, 6, Pe rsiaran Institusi, Bandar Ba ru Bangi, 43000 Ka jang, Se langor, Ma laysia
*e-mail: [email protected]
Abstract
Adsorption processes are wide ly used for the removal of heavy metals fro m waste streams. Oil pa lm decanter cake (OPDC) is used as a bioadsorbent because of its compositional properties for activated carbon production; moreover, it is a readily available ra w materia l produced in palm o il mills and is thus abundant and cheap. In this study, the OPDC was carbonized at 700 °C and activated using steam at 700 °C to produce oil palm decanter cake activated carbon (AC- OPDC). Batch adsorption experiments were carried out to compare the adsorption capacities of the raw OPDC and the AC-OPDC for heavy meta ls re moval. The ma ximu m adsorption capacities of AC-OPDC on Cu(II), Pb(II), and Zn(II) were found to be 45.01, 128.51, and 39.21 mg/g, respectively, which were higher than those of the raw OPDC. This study demonstrates that the AC-OPDC has the potential to be a bioadsorbent for heavy metal re moval fro m wastewater.
Abstrak
Adsor psi Ion Logam Berat menggunakan Oil Pal m Decanter Cake Acti vate d Car bon. Proses adsorpsi banyak digunakan untuk menghilangkan logam berat dari a liran limbah. Oil palm decanter cak e (OPDC) digunakan sebagai bioadsorben karena sifat komposisinya untuk produksi karbon aktif; selain itu, OPDC me rupakan bahan baku yang ter- sedia berlimpah dan murah pada pabrik minyak ke lapa sawit. Da la m studi in i, OPDC dika rbonisasi pada suhu 700 °C dan diaktivasi menggunakan uap pada suhu 700 °C untuk me mp roduksi oil palm decanter cak e activated carbon (AC- OPDC). Beberapa eksperimen adsorpsi telah dilaku kan untuk me mbandingkan kapasitas adsorpsi atas bahan mentah OPDC dan AC-OPDC untuk menghilangkan logam berat. Kapasitas adsorpsi ma ksimu m dari AC-OPDC pada Cu(II), Pb(II) dan Zn(II) adalah 45,01 mg/g, 128,51 mg/g dan 39,21 mg/g. Kapasitas tersebut lebih tinggi dibanding kapasitas adsorpsi atas bahan mentah OPDC. Studi ini mende monstrasikan bahwa AC-OPDC me mpunyai potensial untuk menja- di bioadsorben untuk menghilangkan loga m berat dari limbah air.
Keywords: activated carbon, bioadsorbent, heavy metal, oil palm decanter cak e, steam activation
1. Introduction
The rapid e xpansion of heavy metal-re lated industries, such as the electroplating, mining, sme lting, battery manufacture, tanneries, paint, pesticides, printing, and photography industries, has caused serious environmen- tal problems due to the incomplete treatment of wastes containing heavy metals [1]. In Peninsular Malaysia, the electronics and semiconductor industries produce a sig- nificant amount of sludge containing heavy metals. It has also been reported that the international port and shipping activities in Malacca Strait have caused water
pollution by contamination with lead, copper, and arsen- ic [2]. Unlike organic wastes, heavy metals are non- biodegradable and can be absorbed by living organisms.
They may accu mulate in the body once they enter the food chain and thus pose a great threat especially to human health. Therefore, before the wastewater is dis- charged to the river stream, adequately treating it to meet the discharge standard is essential [3].
Various treatment processes are utilized for re moving heavy metals from wastewater, and they include adsorption, chemical precipitation, flotation, ion exchange,
60 Yusoff, et al.
me mb rane filtrat ion, coagulation, and flocculation [4],[5]. However, adsorption has proved to be the most efficient because of its simple design, low-cost operation, and easy operation [6]. Activated carbon is the most generally used adsorbent due to its highly effective adsorption capacity for removing heavy metals from the wastewater [7],[8]. However, despite its wide usage in the wastewater treatment industry, the manufacturing cost of comme rcia l activated carbon is notably high.
Thus, to reduce the production cost, new adsorbents are developed from various materia ls, and the existing adsorbents are improved.
Some of the materials that have been used as adsorbents include wood, coal, peat, biomass, and agricultural wastes such as peanut hull, hazelnut shells, lignin, and ma ize cob [9]. Oil palm decanter cake (OPDC), obtained from the palm o il mill operation, has a big potential to be used as an adsorbent. The average value of OPDC generated fro m 1 ton of fresh fruit bunch (FFB) is about 42 kg. In a month, a palm oil mill with a processing capacity of 90 tons of FFB per hour could produce 160–200 tons of OPDC [10]. Th is OPDC has not yet been well utilized and is dumped at the side of the factory. Malaysia is the second leading oil palm producer after Indonesia; its total oil palm-p lanted area increased from 5.74 million to 5.81 million hectares in 2017 [11]. According to this statistic, in 2017, there were about 454 operating palm oil mills in Malaysia with a total FFB processing capacity of 112.19 million tons per year [12], wh ich produced up to 1.17 million tons of OPDC per year. Furthermo re, OPDC contains 76% water (wet basis) and 12% residual oil (dry basis), and the rest is cellulose, lignin, ash, and organic content (nitrogen, phosphorus, and potassium). Studies have been conducted on the use of OPDC for biogas fermentation [12], bio-fert ilizer, biofuel, and cellu lose e xtraction [13],[14]. Due to the generation of a large amount of OPDC and its characteristics, this oil palm biomass waste can be converted to bioadsorbent for various applications.
Bioadsorbent can be produced by carbonization and activation processes. There are ma inly t wo types of activation methods for bioadsorbent production: physical and chemica l. Physical act ivation has been shown to be more environ mentally friendly due to the absence of chemicals involved in the process. Furthermore, the chemical process requires much more e xpensive chemical activating agents as well as an additional washing step to remove the chemical agent after activation. Therefore, in this study, OPDC was subjected to steam activation to produce the activated carbon OPDC (A C-OPDC), and a laboratory tria l was conducted to test the capability of the AC-OPDC as an adsorbent for heavy metals re moval.
2. Experime ntal
Material c ollection. The OPDC was collected fro m a palm oil milling plant, Alaf Palm Oil Mill, in Kota Tinggi, Johor, Malaysia. The OPDC was stored in a cold room at 4 °C before use. Then, it was sundried until the moisture content reached below 4% prior to carbonizat ion and activation processes.
Bioadsor be nt Producti on. The OPDC was first carbonized at 700 °C for 60 min under low-o xygen atmosphere using an electric vertical reactor with a length of 127 c m and an internal dia meter o f 30 c m [15]. After carbonization, the OPDC was activated by applying steam at 700 °C for another 1 h; the steam was produced by a steam generator and had a pressure of 2.50 psi. The AC-OPDC was then washed with distilled water until it reached pH 7 and was then dried at 105 °C for 24 h. Finally, it was ground and sieved to less than 150 µm before being kept in a irtight containers for further analyses.
Characterization of bioadsorbent. The moisture content, volatile matter, fixed carbon, and ash content of the bioadsorbent were analyzed using a thermogravimetric analyzer (Mettle r Toledo, TGA/SDTA 851, USA). The compositions of cellu lose, hemicellulose, and lignin were determined based on the method described by Georing and Van Soest [16]. The specific surface areas of the prepared bioadsorbent were determined through N2 adsorption at −196 °C using a surface area analyzer (Quantachrome, USA). The Brunauer-Emmet -Teller (BET) model was applied to fit a nitrogen adsorption isotherm and evaluate the bioadsorbent surface area.
The morphology of the bioadsorbent was exa mined using scanning electron microscopy (SEM , Le ica S440).
Prior to the SEM observations, the samples were coated with gold using an E-1010 ion sputter. Fourier- transform infrared (FTIR) spectroscopy was used to determine the surface functional groups of the bioadsorbent. The FTIR spectra of the sample we re recorded between 4000 and 400 c m−1 using an FTIR spectrometer (PerkinElme r, USA) by attenuated total reflection method.
He avy me tal adsor ption. Batch experiments were con- ducted to investigate the adsorption of heavy metals ions on the adsorbents. The reagents used were copper sulfate for Cu(II), lead nitrate for Pb(II), cadmiu m chlo- ride for Cd(II), potassium dichro mate for Cr(VI), and zinc sulfate for Zn(II). Heavy metal solutions were pre- pared by dissolving each metal salt at a known concen- tration in distilled water to obtain a stock solution.
Then, each of the metal solutions was dissolved in a separate flask to obtain 100 mg/ L of the in itia l concen- tration for all heavy metal solutions except the Pb(II) solution, which was 200 mg/L. The init ia l pH was ad- justed to 5 except for the Cr(VI) solution, which was
Mak ara J . Technol. August 2019 Vol. 23 No. 2
adjusted to 2 based on the study by Kobya et al. [17].
Then, 100 mL of each solution was placed in a 250 mL conical flask with 0.1 g of adsorbent and was agitated at a speed of 200 rp m at 30 °C for 24 h. The final concen- tration of meta l ions was measured by inductively coupled plasma mass spectrometry (PerkinElmer, USA).
The amount adsorbed and the removal efficiency we re calculated using the following equations:
qe= �Co- Ce�
M ×V (1)
Removal efficiency (%) = �Co-Ce�
Co ×100 (2) where is the amount adsorbed at equilibriu m (mg/g), and are respectively the initial and equilibriu m concentrations (mg/L), V is the volume of the solution (L), and M is the mass of the adsorbent.
3. Results and Discussion
Charac teristics of the OPDC. The n itrogen (N), phos- phorus (P), potassium (K), total solids, and lignocellulosic contents (cellu lose, hemicellulose, and lignin) of the OPDC are presented in Table 1. The results show that the lignocellulosic co mponents of the OPDC consisted of a relatively high lignin content (13.98%). A high lignin content in lignocellu losic bio mass indicates that the biomass can be selected as a substrate source for biochar. The lignin content provides the strength properties for the lignocellulosic bio mass [18], g iving the biomass a tough, rather than fragile, structure.
Car bonizati on and Acti vation of OPDC. After the carbonization and activation processes of OPDC, the fixed carbon content of the AC-OPDC increased, while the volatile matter content decreased (Table 2). Th is is due to the degradation of biomass components such as cellu lose, hemice llu lose, and lignin during the car- bonization and activation processes [21]. At 250–300
°C, the hemice llu lose component degraded, followed by cellu lose at 350–400 °C, wh ile lignin decomposed at temperatures above 400 °C [22]. At the carbonization and activation temperature of 700 °C, almost all these components decomposed from solid to vapor at higher temperatures.
The carbonization and activation processes function to induce the formation of pores in the AC-OPDC. The pores formation is reflected by the surface area measure ment. In this study, for the AC-OPDC, the carbonization and activation processes produced a BET surface area of 153.52 m2/g, which is significantly higher than that of the raw OPDC (Tab le 2). This higher surface area is due to the decomposition of lignocellulosic components, which induced the formation of pores during carbonizat ion [23]. Then, the steam activation
further widened the pores and removed any unorganized materia ls that blocked the pores. Basically, a high surface area is an important characteristic for bioadsorbent as it provides a better sorption site for the meta l ions [24].
The format ion of pores inside the AC-OPDC was observed under a scanning electron microscope as shown in Figure 1. The AC-OPDC shows a rough surface with some crac ks and crevices that lead to the formation of pores, although the pores developed unevenly, and some of them still contained some fine particles. This shows that the decomposition of the volatile co mponents caused the ruptured surface of the AC-OPDC with a la rge nu mber of pores, as has been discussed by Saka [25].
The FTIR spectra of OPDC and AC-OPDC (Figure 2) show the difference in absorption bands between the OPDC and the AC-OPDC. The bands in the OPDC a re similar to those found in the OPDC studied by Sahad et al. [26] and in lignocellulosic bio mass such as oil palm mesocarp fiber [27] and oil pa lm e mpty fruit bunch [28]. The absorption bands at 3290.35 c m−1 and 2916.97 cm−1 indicate the stretching of O-H and C-H groups, respectively. These groups represent the aliphatic moie- ties in cellulose, lignin, and possibly hemicellulose [29].
Table 1. Characteristics of the Raw OPDC in this S tudy Compared with those of Other S tudies
Parame ter This study Lit. sources Reference Nitrogen, N (%) 3.90 2.38– 4.34 [12,19,20]
Phosporus, P (%) 0.54 0.39 [20]
Potassium, K (%) 1.40 2.39 [20]
Total solids (mg/kg)
45,650 22,233–197,670 [12,19]
Ce llu lose (%) 10.43 50.07 [12,19]
Hemicellulose (%) 26.70 30.74 [12,19]
Lignin (% ) 13.98 10.40 [12,19]
Table 2. Characteristics of the Bioadsorbent
Adsor be nt Proxi mate anal ysis (% ) B ET (m2/g)
Mt Vm Fc Ash
OPDC 4.12 63.92 11.15 20.81 2.74 AC-OPDC 1.74 15.46 28.66 54.15 153.52 Mt – M oisture Fc – Fixed carbon
Vm – Volatile matter BET – Surface area
62 Yusoff, et al.
The bands at 1627.92 cm−1 signify aromat ic C=C stretch found in lignin [27], wh ile the bands at 1317.75 c m−1 indicate C-H bending [30]. The bands within the range of 1000 to 1200 c m−1 may imp ly C-O-C and C-O stretches, which are contributed by the cellulose and lignin co mponents [28]. Co mpared to the OPDC, the AC-OPDC showed fewer bands. The loss of bands at 3290.35 c m−1 and 2916.97 c m−1 indicates that the amount of hydrogen was reduced after activation [30].
All of the bands at 1428.64, 983.08, and 752.65 c m−1 indicate C-H bending [30],[31]. The bands at 1428.64 and 983.08 c m−1 show a lower intensity after activation, which is due to the removal of hydrogen and oxygen groups caused by the decomposition of volatile co mpo- nents and the reaction of steam with the precursors that had removed those groups [31].
After the adsorption of heavy metals, the bioadsorbent was also analyzed using FTIR spectroscopy to deter- mine the functional groups that were involved in the adsorption (Figure 3b). The shift of bands position indi- cates that the functional groups related to those bands
(a)
(b)
Figure 1. S EM Micrographs of (a) Raw OPDC and (b) AC-OPDC
played a role in the adsorption of the heavy metals. For Cu(II), Pb(II), and Zn(II) adsorptions, an aromatic C=C stretch of OPDC was involved in the ions adsorption.
The bands at 1317.75 c m−1 showed significant change after Zn(II) adsorption, which indicates the involvement of C-H group. Moreover, O-H bands all shifted after Pb(II), Cd(II), and Cr(VI) adsorptions. Meanwhile, for adsorption by AC-OPDC, C-H bending at 983.08 and 1428.64 c m−1 were involved in all the heavy metals tested. The C-H bending at 752.65 c m−1 shifted signifi- cantly after Pb(II) adsorption.
He avy me tal i ons adsor ption. The heavy metal ions adsorption was conducted using AC-OPDC in co mparison with raw OPDC. The adsorptions of Cu(II), Pb(II), and Zn(II) by AC-OPDC showed higher heavy metal re moval than the adsorptions by raw OPDC (Table 3).
This is due to the formation of pores, which allow mo re area for the sorption of heavy metal ions [24]. However, the AC-OPDC had lower adsorption capacities for Cd(II) (7.14 mg/g) and Cr(VI) (7.64 mg/g), co mpared to raw OPDC, which adsorbed 43.95 mg/g and 29.45 mg/g, respectively.
This might be due to the electrostatic forces and specific chemical interaction of the O-H group that was involved in the Cd(II) pores [32]. Meanwh ile , for the Cr(VI) ad- sorption, the C-O group that was already present in the OPDC might have contributed to it having higher ad- sorption sites than the AC-OPDC. The activation process eliminated the functional groups associated with Cr(VI) adsorption in the AC-OPDC, which subsequent- ly reduced the adsorption capability. A simila r finding was also observed by Periasamy and Na masivayam [33]. In their study, peanut hull carbon, even with a small surface area, removed Cd(II) more effect ively than commerc ial activated carbon.
Figure 2. S EM Micrographs of (a) Raw OPDC and (b) AC-OPDC
Mak ara J . Technol. August 2019 Vol. 23 No. 2
(a) (b)
Figure 3. Fourier-transform Infrared S pectra Before and After Adsorption by (a) OPDC and (b) AC-OPDC
Table 1. Comparison of Adsorption Capacities of OPDC and AC-OPDC with those of the Commercial AC and the ACs of Other S tudies
Acti vate d c ar bon Acti vati on agent He avy metal Adsor ption capaci ty (mg/g)
Re moval efficiency
(% ) Reference
OPDC - Cu(II)
Pb(II) Cd(II) Zn(II) Cr(VI)
18.60 96.17 43.95 22.26 29.45
18.60 48.08 43.95 22.26 29.45
This study
AC-OPDC Steam Cu(II)
Pb(II) Cd(II) Zn(II) Cr(VI)
45.01 128.51 7.14 39.21 7.64
45.01 64.26 7.14 39.21 7.64
This study
Lignite coal (co m- me rcia l A C)
Steam Cu(II)
Pb(II) Cd(II) Zn(II) Cr(VI)
98.22 165.30 95.64 81.74 71.87
98.22 82.65 95.64 81.74 71.87
This study
Oil pa lm e mpty fruit bunch
NaOH Pb(II)
Cu(II)
48.96 0.84
- [34]
Phaseolus aureus hulls
Steam Pb(II)
Zn(II) Cu(II) Cd(II)
21.8 21.2 19.5 15.7
- [35]
Furthermore, the commerc ia l AC showed a high remov- al effic iency for all the metal ions, compared with OPDC and AC-OPDC, due to the high surface area of the comme rcia l AC. However, co mpared with the ACs of other studies, the AC-OPDC still e xh ibited a better adsorption capacity (Table 3).
4. Conclusions
The AC-OPDC produced in this study showed the po- tential to be used as an adsorbent for heavy metal ions re moval, especially for Cu(II), Pb (II), and Zn(II), with adsorption capacities of 45.01, 128.51, and 39.21 mg/g,
64 Yusoff, et al.
respectively; however, it was not suitable for Cd(II) and Cr(VI) adsorptions. The Cd(II) and Cr(VI) could be re moved by using raw OPDC. Although the adsorption capacity of AC-OPDC was lowe r than that of the com- me rcia l AC, the AC-OPDC was still better than some of the ACs reported in the literature. Therefo re, it can be concluded that the AC-OPDC can be used as a bio- adsorbent to remove heavy metal ions.
Acknowledge ments
The authors acknowledge the financial support by Min- istry of Higher Education (MOHE), Ma laysia.
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