Synthesis and Characterization of Biochar from Peel and Seed of Jackfruit plant waste for the adsorption of Copper Metal Ion from water

 

Mohammed Kadhem Abid¹, Husni Bin Ibrahim² , Syaizwan Zahmir Zulkifli³

 

ABSTRACT:

In this work, jackfruit peel and seeds are utilized to synthesized the biochar for the removal of copper metal ions from water. The synthesized jackfruit peel and seeds were carbonized at 500oC for 2 h under air atmosphere flow. The JPB and JSB were characterized by the use of different characterization techniques such as XRD, BET, FTIR, SEM and CHNS to study it’s physic-chemical properties. The synthesized biochar samples were tested for the removal of Cu metals ion from water and recorded excellent adsorption capacity of 99.84% by JPB adsorbent at optimize adsorption conditions of 45 oC adsorption temperature, 7 pH, 24 hours  contact time and 100 ppm of metal solution concentration. The lowest adsorption capacity of 79.60% was recorded by JSB adsorbent under the optimized parameters of 25 oC temperature, 7 pH, 24 hours  contact time and 40 ppm metal ion concentration. The results demonstrated that, jackfruit based biochar would be an excellent adsorbent for heavy metals from water.

 

 

 

INTRODUCTION:

Environmental pollution through heavy metals is one of the major global concern today. This is due to its toxic nature that causes various degrees of diseases and illnesses. Most of the heavy metal pollution is caused by various human activities such as mining, urbanization, steel industries, tanneries and pharmaceutics¹. Although these activities are vital to human life, but uncontrollable release of chemicals mechanized agriculture and non-treated industrial effluents into the environment, particularly water body can cause sustained series of diseases and illness to human beings. The common heavy metals found in water and soil include lead, chromium, arsenic, zinc and cadmium².

 

These heavy metals when ingested at high quantity can cause health issues such as kidney problem, liver and central nervous system problems. Such heavy metals can equally lead to some diseases such as hepatitis, nephritic syndrome, anemia and encephalopathy³.

 

Heavy metal contamination in water has become widespread in the major cities and industrial areas around the world. Considering the toxic and other health effects of such pollutants, it is necessary to device a feasible means of removing them from waste water to avoid further contamination of natural water bodies by untreated industrial effluents around the world. Several techniques that are reported to be used for the removal of heavy metals and ions from waste water are centrifugation, coagulation, crystallization, distillation, electro-dialysis, evaporation, electrolysis, floatation, gravitation separation, oxidation, ion exchange, precipitation, reverse osmosis and adsorption⁴. A part from adsorption technique, most of the aforementioned techniques are either expensive or technically difficult to operate. The sustainable way for water treatment against heavy metals contamination is through the utilization of low cost and easy operational technique⁵. Adsorption technique is regarded as one of the most promising method for the removal of heavy metals from contaminated⁶. This is due to its ability to be regenerated after use. Adsorption method is also economically feasible and technically easier. The technique is reported to employs several number materials as adsorbents. The most prominent adsorbent is commercial activated carbon. Activated carbon is regarded as the most popular adsorbent for the removal of heavy metals and other ions from contaminated water⁷. This is due to its excellent porosity, high mechanical strength and large internal surface area, which allow it adsorb high quantity of metal ions from the waste water^8,9. In spite of its popular application for water treatment against heavy metals in the industries, activated carbon is found to be expensive material to be used as adsorbent for waste water treatment. For this reason, it is necessary to devise low cost carbon based materials for the adsorption of heavy metals from water. Characterizing the surface functional groups of biochar is imperative to understand the mechanisms that occur during pyrolysis. Moreover, understanding the surface functional groups of biochar is important for the application of biochar for reducing greenhouse gas (GHG) emissions and contaminants in soil and water¹⁰. Biochar has a large specific surface area, is porous, and contains hydroxyl, carboxyl, carbonyl, and other functional groups. It can be used to remove or reduce organic and inorganic contaminants in water, such as toxic heavy metals, dyes, and antibiotics ¹¹. Biochars, with excellent capacity to remove several contaminants from aqueous solutions, constitute an untapped technology for drinking water treatment¹². Biochars have co-benefits including provision of clean energy for household heating and cooking, and soil application of spent biochar improves soil quality and crop yields. Integrating ¹². Biochars have been successfully used to treat wastewater and contaminated soils¹³.

 

In this work, biochar was successfully synthesized from jackfruit seed and peel using carbonization method and chemically activated using acid activation. The synthesized biochar was characterized using various characterization techniques to study its physico-chemical properties. The synthesized biochar was applied for the adsorption of heavy metals from waste water and recorded excellent adsorption capacity on the removal of copper metal ions from water.

 

MATERIAL AND METHODS:

Materials:

The jackfruit seed and peel were obtained from Tanjung Malim, Malaysia. The concentrated H₃PO₄ (98%) and Acetone (99.0%) were obtained from Merck company Malaysia. Copper (II) nitrate Cu (NO3)2 were obtained from Merck Germany. The deionized water was prepared in the chemistry laboratory in Universiti Pendidikan Sultan Idris (UPSI). The carbonization of the prepared jackfruit seeds and peel was performed using 2 Zone Tube furnace, 2ZTF-1100-2035). The adsorption of heavy metals in water was determined by the use of Atomic Absorption Spectroscopy (AAS). All solvents and reagents were used without further treatment.

 

Synthesis of Biochar:

The Biochar was synthesized from plant biomass, specifically jackfruit peel and seeds, which was obtained from Tanjung Malim, Malaysia (local store). The obtained jackfruit seeds and peel were cleaned with deionized water several times to remove any contaminants (dirt) and subsequently dried in an oven at the temperature of 80 ^oC for 48 hours in an oven. The dried jackfruit seed and peel were crushed and made into powder using miller. The obtained powdered jackfruit seeds and peel were impregnated with concentrated H₃PO₄,. The dried activated powder was carbonized in a furnace (2 Zone Tube furnace, 2ZTF-1100-2035) under the air atmosphere flow at the temperature of 500 ^oC for 2 hours. The carbonized material was allowed to cool down before taking it out from the furnace. The biochar was washed with deionized water several times until its pH became neutral and filtered for subsequent use. The obtained jackfruit seeds and peel based biochar was dried in an oven at 80 ^oC for 24 hours before subsequent use.

 

Physic-chemical Characterizations of biochar:

Brunauer-Emmett-Teller total surface area analysis:

The total surface area and the porosity of the synthesized jackfruit based biochar samples were determined by the use of Brunauer Emmett Teller technique (BET) micrometric ASAP 2020 3Flex version 1.02. The analysis was performed by the corresponding nitrogen adsorption-desorption isotherms at a temperature of -196 ^oC. Before the surface area analysis, the biochar samples were degassed at the temperature of 150 ^oC to remove the impurities such as moisture and carbon dioxide.

 

Scanning electron microscopy (SEM):

The surface morphology of the synthesized jackfruit based biochar samples were investigated by the use of Scanning Electron Microscope (SEM) (Hitachi S-3400 Japan model). The biochar samples were coated with gold using a Sputter Coater before analysis.

 

X-ray diffraction analysis:

The structure and crystallography of the synthesized jackfruit based biochar was investigated by the use of X-ray Diffraction (XRD) technique. The analysis was performed using Shimadzu XRD 6000 power X-ray diffractometer. During the samples analysis, the Cu, Kα radiation electrons were accelerated at 27.7 kW and 30 mA in an evacuated X-ray tube with Ni filter over a range of 0° to 80° with a step of 0.04° at screening speed of 2θ min⁻¹.

 

Fourier transform infrared:

The relative surface functional groups of the synthesized jackfruit based biochar were determined by the use of Fourier transform infrared spectroscopy (FTIR) (Thermo Scientific Nicolet TM iS10), recorded within the wavenumber range of 400–4000 cm^-1. Before the analysis, the pellet of the biochar was made by mixing the biochar sample (0.1 mg each) with KBr (100 mg) in a mortar pestle and resultant mixtures pressed in the hydraulic pump. The pellet was scanned under infrared light and the corresponding spectra were recorded.

 

CHNS Analysis:

The Carbon, Hydrogen, Nitrogen and Sulphur (CHNS) composition determination of the jackfruit based biochar was performed by elemental (CHNS) analysis using elemental analyzer (Elementa, Germany). The CHNS analysis was carried out using the in house test method.

 

Adsorption equilibrium of copper from water:

The adsorption experiment was carried out using batch sorption process. The experiment was performed using 100 ML test solution. The initial concentration of the metal solution is 100 mg/L. The Cu solution was placed into 250 ml closed bottles. A specific quantity of 0.05g jackfruit based biochar was placed in the Cu solutions. The two bottles containing copper solutions were added jackfruit seed biochar (JSB) and jackfruit peel biochar (JPB), respectively. The solutions in the bottles were shaking vigorously for 24 hours at room temperature (25 ^oC). At the end of each stirring period, the JSD and JPB were removed from the Cu solution by the means of filtration and the final concentration of the Cu ²⁺ was determined using atomic absorption spectroscopy (AAS). The metal adsorption was performed at constant room temperature and pH of 7.

 

Atomic Adsorption Spectroscopy Analysis:

The amount of adsorbed Cu metal ions was determined using a thermo scientific Atomic Absorption Spectrometer (AAS). The metal ions determination was carried out using flame atomization, and deuterium lamp, which is used as background correction. The resonance lines of hollow cathode lamps (HCl, Analytic Jena, Germany) were adopted for the study of the elements presents in the solution.

 

RESULTS AND DISCUSSION:

Brunauer-Emmett-Teller total surface area analysis

The total surface area analysis for peel and seed jackfruit based biochar was conducted using Brunauer-Emmett-Teller technique and the results are depicted in table 1. The nitrogen adsorption – desorption isotherms of the synthesized jackfruit based biochar at 500 ^oC carbonization temperature are presented in Fig 1 and Fig 2. The jackfruit seed biochar (JSB) has recorded the high surface area of 4.2501 m²/g while the jackfruit peel biochar (JPB) recorded the surface area of 3.6461 m²/g. The pore sizes and pore volumes of JSB and JPB are 32.5009, 37.8662 Å and 0.003453, 0.003452 cm³/g, respectively as presented in Table 1.

 

Table 1: BET surface area, pore size and pore volume of JSB and JPB

Sample	Surface area (m²/g)	Pore Size A	Pore Volume cm³/g
JSB	4.2501	32.5009	0.003453
JPB	3.6461	37.8662	0.003452

 

The adsorption and desorption of nitrogen isotherms of JPB and JSB are depicted in Fig 1 and Fig 2. Both isotherms are representing the type iv isotherms, which indicate the presence of mesoporous and microporous mixture of materials. The relative pressures of these isotherms are of type IV adsorption-desorption related to monolayer-multilayer adsorption, which exhibited capillary condensation similar to narrow silt-like pores ¹⁴. In both cases the hysteresis loop is not well pronounced, this might be due to the deterioration of the porous structure through the destruction of the walls during acid activation¹⁴.

 

However, based on the adsorption desorption isotherms of both biochar samples, there are more enlarged pores, which made the samples to become populated with mesoporous materials and therefore high surface area. The synthesized JPB and JSB contained the combination of microporous and mesoporous materials similar what was previously reported by^15,16.

 

 

Fig 1. The Nitrogen adsorption-desorption isotherm of JPB

 

Fig 2. The Nitrogen adsorption-desorption isotherm of JSB

 

Scanning electron microscopy (SEM):

The surface morphology of the synthesized jackfruit based biochar was investigated by the use of scanning electron microscopy. The images of jackfruit peel biochar (JPB) and jackfruit seed bio-char (JSB) are depicted in Fig. 3 and Fig. 4, respectively. Both images represent some distinctive features that defines the external surface topographies of the synthesized biochars. The jackfruit based biochar samples were carbonized at 500^oC, this allows the formation of dense and smooth structures present in both seed and peel biochar. Further activation with concentrated H₃PO₄ enables the formation of larger surface area and pore sizes manifested in both peel and seed jackfruit based biochar. The larger surface areas possessed by these samples as signified by the BET results were due to well-developed pores. The formation of the pores was as a result of evaporation of the concentrated phosphoric acid during the carbonation at temperature (500^oC) that was previously occupied the spaces thereby leading to the formation of larger pores and subsequently high surface area^17,18.  These features demonstrated the high adsorption capacity of the synthesized biochars.

 

 

Fig 3. SEM image of the synthesized JPB at the temperature of 500 ^oC

 

 

Fig 4. SEM image of the synthesized JSB at the temperature of 500 ^oC

 

X-ray diffraction analysis:

The X-ray diffraction analysis was performed on the synthesized JPB and JSB biochar samples using Shimadzu XRD 6000 power X-ray diffractometer. The spectra of the analyzed biochar samples are depicted in Fig 5 and Fig 6, which represent JPB and JSB, respectively. In both cases, the XRD demonstrated the presence of major hump between the 2ɵ = 10 to 2ɵ =30. The hump in these region of the XRD spectra, which is assigned to C(002) and C(101) indicates the presence of amorphous carbon material composed of aromatic carbon sheets in and oriented random fashion¹⁹ . The obtained XRD spectra of JPB and JSB are in accordance with many published biochar and activated carbon XRD characterizations such as those published by²⁰.

 

 

Fig. 5. X-ray diffraction spectra for jackfruit peel based biochar

 

 

Fig. 6. X-ray diffraction spectra for jackfruit seed based biochar

 

Fourier transform infrared:

The prepared jackfruit based biochar was analyzed by Fourier transform infrared (FTIR) to investigate the functional groups of all the elemental compositions contained in the synthesized biochar. The biochar does not contain of carbon matrix alone but also other heteroatoms such as oxygen, Sulphur, nitrogen, phosphorous and hydrogen. Generally, the biochar surface chemistry is controlled by the composition of different heteroatoms attached to the carbon layers of the bio-char²¹. The FTIR spectra of the synthesized JSB and JPB with excellent surface area is depicted in Fig 7. Both the JSB and JPB show a broad band around 3500 cm^-1, which indicate the presence of OH stretching from hydroxyl group compounds. The hydroxyl groups could be phenols, carboxylic acid, alcohol or water^22,23. The stretching bonds at 2917.34 cm-1 and 2927.31 cm-1 in JPB and JSB, respectively identifies the presence of asymmetric CAH representing the methyl and methylene groups²². The bands from 1784 to 1383 in both spectra are assigned to C-C aromatic ring stretching influenced by the presence of polar functional groups²⁴ . The band region between 1300 cm-1 to 800 cm-1 are assigned to carbon aromatic oxygen stretching C-A-O group representing esters, phenols, alcohols and ethers. Nevertheless, the region could also represent the presence of phosphoric acid group if the activation was done with phosphoric acid²³. The bands at the region of 629.15 and 500 cm1 are assigned to indicate the presence of aromatics substituted by aliphatic groups²⁵. The FTIR results of the synthesized JPB and JSB are all in accordance with the previous published FTIR characterizations of biochar.

 

Fig 7. The synthesized FTIR spectra of JPB and JSB bio-char samples

 

CHNS Analysis:

The elemental analysis of carbon, hydrogen, nitrogen and Sulphur was performed on jackfruit peel and seed based biochar at a constant temperature and the results are tabulated in table 2. There are variations found between the JSB and JPB samples. All the samples were analyzed using the same in house test method. The carbon composition of seed is found to be 59.88%, which is higher when compared to 56.99% that of peel. The hydrogen content for JSB is 2.06% which is higher than the JPB’s 1.79%.  Nevertheless, the nitrogen and Sulphur composition of JPB is much higher when compared to that of JSB. JPB recorded the nitrogen and Sulphur content of 15.43% and 6.36% while JSB recorded 12.02% and 4.57% for the nitrogen and Sulphur, respectively. Temperature variation during the biochar preparation may lead to the variation in major elemental composition, particularly carbon as reported by^26,27. Since the preparation of both JSB and JPB samples was performed under the same condition of temperature, the variation in elemental composition might be as a result of difference in biological composition of the two different parts of the tree. The seeds and the peel biological content might be different and thereby making the elemental composition different as well

 

Table 2. CHNS elemental analysis results for JSB and JPB

S. No.	Parameter	Test	Results (%)
			Seed	Peel
1	Carbon	In House Method	59.88	56.39
2	Hydrogen	In House Method	2.06	1.79
3	Nitrogen	In House Method	12.02	15.43
4	Sulphur	In House Method	4.57	6.36

 

Adsorption equilibrium of copper from water :

The adsorption equilibrium of the synthesized JPB and JSB was performed by preparing different copper (Cu) metal concentrations from 100 ppm to 10 ppm. All other parameters including time were optimized. The adsorption capacity of the two adsorbents were measured by determining the final concentrations of the Cu using atomic absorption spectroscopy (AAS) and the percentage of removal was determined and tabulated in table 3. There was variation in the adsorption capacity of the two adsorbents. In JSB there was increase in adsorption capacity of Cu as the concentration reduces from 100 ppm to 60 ppm and the lowest adsorption capacity (79.60 %) was recorded by 40 ppm. All other concentration recorded more than 96% at optimized adsorption parameters. While in JPB, the adsorption capacity of Cu metal ion slightly decreases as the concentration of Cu ions decreases from 100 ppm to 10 ppm, recording highest adsorption of 99.86% at 100 ppm and the lowest adsorption of 94% at 10 ppm. Both adsorbents are good for the removal of heavy metals from water, but JPB recorded the highest adsorption capacity of Cu metal ion from water. From the obtained results presented in table 2, 100 ppm concentration of Cu is the best concentration for the removal of Cu from water under the optimized adsorption parameters of temperature 25^oC, pH 7 and time 24 hours.

 

Table 3. The adsorption capacity of JPB and JSB adsorbents on Cu metal ion

Jackfruit Seed Bio-char (JSB)
Name of element	Temperature (oC)	pH	Time (Min)	Initial Concentration (ppm)	Final Concentration (ppm)	Percentage of removal (%)
Cu	25	7	24	100	3.80	96.20
Cu	25	7	24	80	0.13	99.84
Cu	25	7	24	60	0.51	99.15
Cu	25	7	24	40	8.16	79.60
Cu	25	7	24	20	0.95	95.25
Cu	25	7	24	10	0.36	96.40
Jackfruit Peel Bio-char (JPB)
Cu	45	7	24	100	0.14	99.86
Cu	45	7	24	80	0.37	99.54
Cu	45	7	24	60	0.27	99.55
Cu	45	7	24	40	0.30	99.25
Cu	45	7	24	20	0.21	98.95
Cu	45	7	24	10	0.60	94.00

 

CONCLUSION:

The jackfruit based biochar was successfully synthesized from jackfruit peel and seed biomass. The synthesized biochar samples designated as JPB for jackfruit peel biochar and JSB for jackfruit seed biochar were characterized using different characterization techniques to investigate their physical and chemical properties. The two synthesized biochar samples were tested for the adsorption of cupper metal ion from water and recorded excellent adsorption capacity under optimized adsorption parameters. The JPB sample recorded the highest adsorption of 99.86% of Cu ion from water under the temperature of 45 ^oC, pH 7 and 24-hours contact time. The best metal ion concentration for this adsorption is 100 ppm.

 

 

While the lowest adsorption capacity of 79.60% was recorded by JSD at the optimized adsorption parameters of 25 ^oC adsorption temperature, pH of 7, contact time of 24-hours and metal ion concentration of 40 ppm. Based on the findings of this work, JPB under the adsorption conditions of 45 ^oC, pH 7, 24-hours contact time and 100 ppm metal ion concentration is more appropriate for adsorption of metal ion from water having adsorbed 99.86% of Cu ions.

 

ACKNOWLEDGEMENT:

The author is grateful to the Department of biology / University Pendidikan Sultan and University Putra Malaysia to provide all facilities for the success of this work

 

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

 

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Accepted on 21.05.2019          © RJPT All right reserved

Research J. Pharm. and Tech 2019; 12(9):4182-4188.