Industrial Crops and Products 41 (2013) 319–323
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Optimisation of a method to extract the active coagulant agent from Jatropha curcas seeds for use in turbidity removal Zurina Z. Abidin a,b,∗ , Nur S. Mohd Shamsudin a , Norhafizah Madehi a , Shafreeza Sobri a a b
Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
a r t i c l e
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Article history: Received 30 January 2012 Received in revised form 2 May 2012 Accepted 5 May 2012 Keywords: Coagulation Coagulant Jatropha curcas Turbidity Extraction Wastewater
a b s t r a c t An improved and alternative method for the extraction of the active coagulant agent from Jatropha curcas seeds was developed and compared with the conventional water extraction method (JCSC-DW). In the new method, the seeds were extracted using different solvents in different concentrations, using NaCl (JCSC-NaCl) and NaOH (JCSC-NaOH) to extract the active coagulant agent from the Jatropha. In addition, ultrasound was investigated as a potential method to assist the extraction process. Batch coagulation experiments were conducted to evaluate the performance of the extracted coagulant achieved through various schemes. The effects of the dosage, pH and concentration of solvents were investigated for optimum turbidity removal at different values of initial synthetic wastewater turbidity from 50 to 500 NTU. JCSC-NaCl at 0.5 M was found to provide a high turbidity removal of >99% compared to JCSC-DW and JCSC-NaOH at pH 3 using 120 mg/l of the coagulant agent. Among these three solvents, NaOH demonstrated the lowest performance in turbidity removal. The conventional extraction method of the active coagulant agent by blending the seeds in solvents for 2 min alone sufficiently extracts most of the coagulant component from the Jatropha seed and provides up to 99.4% turbidity removal. Blending assisted by ultrasound demonstrated comparable turbidity removal in a shorter period of time and thus showed a potential to be used on a larger scale. Analysis was undertaken to determine the protein content as this is believed to be the coagulating agent. It was found that extraction of the coagulant agent using NaCl yielded more protein compared to when using water and NaOH. © 2012 Elsevier B.V. All rights reserved.
1. Introduction The application of a coagulation/flocculation process is applied in water and wastewater treatment to remove turbidity, colour and natural organic matter (Aboulhassan et al., 2006; Chang et al., 2009). Inorganic coagulants (e.g. aluminium sulphate, ferric chloride and calcium carbonate) and synthetic organic polymers (e.g. polyaluminium chloride (PACI) and polyethylene imine) are common coagulants used in this treatment. Among all the available coagulants, including other inorganic and organic chemicals, aluminium salts are the most widely used worldwide because of their effectiveness and competitive cost (Okuda et al., 1999). However, the sludge obtained from treatments using aluminium salts leads to disposal, problems, such as aluminium accumulation in the environment (Pillai and Divakaran, 2002). Moreover, some studies have reported that residual aluminium sulphate (alum) and polyaluminium chloride may induce Alzheimer’s disease (Flaten, 2001; Martyn et al., 1989), whereas the synthetic organic polymers, such
∗ Corresponding author. Tel.: +60 3 8946 4371; fax: +60 3 8656 7120. E-mail address:
[email protected] (Z.Z. Abidin). 0926-6690/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.indcrop.2012.05.003
as acrylamide have neurotoxic and carcinogenic effects (Mallevialle et al., 1987). One possible solution to these problems may be in the development of new coagulants which are preferably extracted from natural and renewable sources, such as microorganisms, animals or plants. These coagulants must be safe for human health and biodegradable. In recent years, numerous studies on a variety of plant materials which can be used as sources of natural coagulants have been reported. For example, natural coagulants from Calostropis procera (Okonku and Shittu, 2007), Nirmali seed and maize (Raghuwanshi et al., 2002), mesquite bean and Cactus latifaria (Diaz et al., 1999), Cassia angustifolia seed (Sanghi et al., 2002), different leguminous species (Antov et al., 2010) and chestnut (Sciban et al., 2009) have been investigated. The material which has received the greatest degree of attention is the seed of Moringa oleifera (Antov et al., 2010; Ndabigengesere et al., 1995; Madrona et al., 2011; Okuda et al., 1999; Nkurunziza et al., 2009). Jatropha curcas is a shrub or tree belonging to the Euphorbiaceae family. The seed and presscake (waste after oil extraction) are believed to contain an active coagulant agent which can be used in wastewater treatment (Abidin et al., 2011; Makkar et al., 1997). This same coagulant agent derived from Jatropha carcas seed and presscake has been reported to exhibit a strong coagulative as well
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as a disinfectant effect, comparable to alum (Abidin et al., 2011; Pritchard et al., 2009). Previous study reported a 99% turbidity removal in synthetic wastewater when using J. curcas seed dissolved in distilled water at pH 3 at a dosage of 120 mg/l (Abidin et al., 2011). These results support the ability of J. curcas as a potential coagulant agent. In this study, the aim is to improve the extraction process of the coagulant agent from J. curcas. Since the active coagulant agent in the J. curcas seed is believed to be a soluble cationic protein (Abidin et al., 2011), it is of interest to investigate coagulant agent extraction using different types of solvents, such as NaCl, NaOH and water. In addition, previous research has also make use of ultrasound treatment in order to improve the extraction process (Sayyar et al., 2011). Thus, the use of ultrasound-assisted extraction was also employed in this study to improve the extraction efficiency.
in an ultrasonic cleaning bath (Model: Branson 1510) and simultaneously blended using a hand mixer (Moulinex) for 1 min, 2 min, 5 min, 10 min and 15 min. This experiment was conducted at 28 ◦ C using an ultrasonic wavelength of 42 kHz. The resulting suspension was collected at each time point (1, 2, 5, 10 and 15 min) and filtered through muslin cloth. Again the filtrate was used in a subsequent jar floc test. 2.4. Coagulation experiments
In this study, samples of synthetic turbid water were prepared by adding a stock kaolin suspension to tap water for all coagulation experiments. The stock kaolin suspension was prepared by dissolving 10 g of kaolin powder in 1 L of distilled water. The suspension was stirred slowly at 20 rpm for 1 h to achieve uniform dispersion of the kaolin particles. The suspension was then permitted to stand for 24 h to allow for complete hydration of the kaolin. This suspension was used as a stock solution for the preparation of water samples of varying turbidity for the coagulation tests. Three groups of turbidity were considered, namely; low turbidity (50 NTU), medium turbidity (100 and 200 NTU) and high turbidity (500 NTU). The stock kaolin suspension was diluted using tap water and the initial pH was adjusted with 1 M sodium hydroxide (NaOH) or 1 M hydrochloric acid (HCl) to obtain the desired values of turbidity and pH for the synthetic turbid water.
The jar test was performed to evaluate the performance of the coagulant agent extracted from the various processes as described above based on standard methods (Okuda et al., 1999; Ndabigengesere et al., 1995; Abidin et al., 2011). Six 1 l beakers were filled with 500 ml of kaolin suspension and placed in the slots of a jar tester which was equipped with an illuminator. Various dosages of J. curcas seed extract were added to each beaker and agitated for 4 min at 100 rpm for rapid mixing. The mixing speed was reduced to 40 rpm for another 25 min. All the suspensions were then left for sedimentation. After 30 min of sedimentation, the clarified samples were collected from the top of the beaker and filtered using muslin cloth to remove any remaining sediment. The turbidity of each clarified sample was then measured using a turbidimeter (HachTurbidimeter Model 2100 N). The coagulation experiments were investigated with respect to the effect of pH, dosage, types of solvent used for extraction, initial turbidity and also the use of ultrasound. The pH was varied from pH 1 to 12 while the dosages of Jatropha seed were studied from 20 to 160 mg/l. The initial turbidity was investigated from 50 to 500 NTU and three types of solvent namely NaOH, NaCl and distilled water were employed. The ultrasound treatment was varied from 1 to 15 min at a fixed wavelength of 42 kHz. These parameters were varied one at a time to identify the optimum conditions for each parameter. All the experiments were repeated at least twice for consistency, and the results averaged.
2.2. Preparation of J. curcas seed powder
2.5. Determination of protein content in coagulant extractant
The husk of the J. curcas seeds was removed manually. Good quality seeds were selected and the kernels were ground to a fine powder (63–500 m) using an ordinary food processor. The J. curcas powder was then used in each experiment.
The active coagulant agent was believed to be protein (Abidin et al., 2011). Here, the active component was purified using the method by Sevag and dialysis as described by Okuda et al. (1999). 5 ml of chloroform and butanol mixture (5:1) were added to 1 ml of the extractant solution (obtained after blending and filtering with muslin cloth). This mixture was shaken in a rotary shaker for 30 min. This was followed by centrifugation to separate the aqueous layer from the gel and organic solvents. This process was repeated until no gel was formed. Next the sample was subjected to a dialysis process using cellulose tubing with a MW cutoff 12–14 kDa to remove low MW impurities. Distilled water was used for the external solution of the tube and changed during the dialysis period. The protein content of the extract was estimated by the method of Bradford using bovine serum albumin as a standard (Bradford, 1976).
2. Materials and methods 2.1. Preparation of kaolin synthetic wastewater
2.3. Preparation of J. curcas seed coagulant 2.3.1. Conventional blending extraction method 5000 mg of J. curcas powder was blended with 100 ml of solvent using an ordinary food processor (Model BL 333, Khind) for 2 min to extract the active coagulation agent from the J. curcas seeds. The solvents used were distilled water (DW), sodium chloride (NaCl) at concentrations of 0.01 M, 0.05 M, 0.1 M, 0.5 M and 1.0 M and sodium hydroxide (NaOH) at concentrations of 0.005 M, 0.01 M, 0.05 M and 0.1 M. The solvent concentration selection was based on preliminary laboratory results. The suspension was filtered through muslin cloth and the filtrate solution was used in a subsequent jar floc test. To prevent any ageing effects, such as changes in pH, viscosity and coagulation activity due to microbial decomposition of organic compounds during storage, fresh coagulant agent was prepared and used immediately for each sequence of experiments. 2.3.2. Ultrasound-assisted extraction method Similarly, 5000 mg of J. curcas powder was mixed with 100 ml of solvent in a 250 ml beaker. These experiments were only performed at the optimum concentration of the solvent (0.5 M NaCl, 0.05 M NaOH and distilled water) which was determined in the earlier part of the study. The powder and solvent mixture was immersed
3. Results and discussion 3.1. Effects of using different solvents as the extracting agent of the coagulant from J. curcas seeds In order to study the improvement of the extraction process and hence the amount of coagulant agent extracted from the seeds, different molar concentrations of NaCl and NaOH were used. Fig. 1 shows the effects of using different NaCl concentrations on the turbidity percentage removal of synthetic wastewater. The investigation was conducted at pH 3 and a dosage of 120 mg/l, as determined in previous work (Abidin et al., 2011).
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Fig. 1. Effects of using different concentrations of NaCl for extracting the coagulant agent from Jatropha seeds against the percentage turbidity removal of synthetic wastewater at turbidity values of 50–500 NTU.
Turbidity removal was found to increase as the salt concentration increased until up to 0.5 M. Similar trends were also observed for all other initial turbidity values of the synthetic wastewater studied. This meant that as the concentration of NaCl increased, more coagulant agent was extracted from the seed and thus dissolved in the extracting solvent. This phenomenon is known as the salting-in effect (Nelson and Cox, 2008; Voet and Voet, 1990). Since the coagulant agent is a protein, when the salt concentration increased the solubility of the coagulant agent and hence its concentration in the solution also increased. More coagulant agent in solution means more coagulation activity can occur, thus leading to a higher percentage removal of turbidity. Above 0.5 M, the percentage turbidity removal started to decrease as the NaCl concentration increased. This was attributed to the salting-out effect whereby the solubility of proteins decreases with salt concentration (Nelson and Cox, 2008; Voet and Voet, 1990). The percentage removal increased as the initial turbidity increased. JCSC-0.5 M NaCl showed a greater percentage reduction in turbidity (99.4%) at a higher initial turbidity (500 NTU) of the wastewater. For a lower turbidity (50 NTU) and in the medium range of 100 and 200 NTU, at 0.5 M, the percentage turbidity removal was approximately 96.8%, 97.9% and 98.9%, respectively. The ability of the coagulant to work at higher turbidity ranges reflected its versatility to treat various wastewaters. The optimum concentration to enhance the solubility of the coagulation agent from the J. curcas seeds was 0.5 M and this lead to an improved coagulation activity. Fig. 2 shows the percentage turbidity removal using different concentrations of NaOH for extracting the coagulant agent from seeds at different initial turbidity values of the synthetic wastewater. Here, the range of NaOH concentrations used was 0.005–0.1 M. When the concentration of NaOH solution increased, the
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Fig. 3. Effects of Jatropha curcas seed coagulant (JCSC) extracted with 0.5 M NaCl (JCSC-0.5 M NaCl), 0.05 M NaOH (JCSC-0.05 M NaOH) and distilled water (JCSC-DW).
coagulation efficiency of the wastewater also increased until it reached an optimum level at 0.05 M. After that, the percentage removal started to decrease. A similar behaviour was observed for all turbidity values of wastewater studied. The decrease in coagulation activity upon reaching the optimum level suggested that some protein may be denatured at NaOH concentrations higher than 0.1 M and hence this reduced the protein solubility in the crude extract solution (Lestari et al., 2010). These results were similar to those obtained when using NaCl as the extracting solvent. Fig. 2 also shows that higher initial turbidity values gave better percentages of turbidity removal. This again indicates its compatibility with a higher range of turbidity levels. Under the conditions of JCSC-0.05 M NaOH, for an initial turbidity value of 500 NTU, the percentage reduction was approximately 91.4%. However, at 50, 100 and 200 NTU, the percentage of maximum turbidity removal decreased to 67.0%, 74.9% and 81.4%, respectively, using JCSC0.05 M NaOH. In this case, 0.05 M NaOH solution can be considered as the optimum concentration to enhance the solubility of the active coagulation agent from the J. curcas seeds for an improved coagulation performance. In the determination of the best solvent to be used for the extraction of the active coagulant agent from J. curcas seeds, the effects of JCSC-0.5 M NaCl and JCSC-0.05 M NaOH were compared with JCSCDW. Fig. 3 shows the turbidity removal of synthetic wastewater using these three types of coagulants. At 500 NTU, JCSC-DW and JCSC-0.5 M NaCl could effectively coagulate more than 99% of the initial turbidity, while the JCSC-0.05 M NaOH provided 91.4% turbidity removal. Seeds extracted using NaCl demonstrated a greater performance compared to the other solvents. 3.2. Effects of pH and coagulant dosage on JCSC-0.5 M NaCl and JCSC-0.05 M NaOH
Fig. 2. Effects of using different concentrations of NaOH for extracting the coagulant agent from Jatropha seeds against the percentage turbidity removal of synthetic wastewater at turbidity values of 50–500 NTU.
Fig. 4 illustrates the effects of pH on turbidity removal using JCSC-0.5 M NaCl and JCSC-0.05 M NaOH in comparison to JCSC-DW. As the pH increased, the percentage turbidity removal decreased. The highest turbidity removal using JCSC-0.5 M NaCl, JCSC-0.05 M NaOH and JCSC-DW was observed to occur at pH 3 with a percentage of turbidity removal of approximately 99.4%, 91.4% and 99%, respectively. This is in agreement with a previous study (Abidin et al., 2011) in which it was found that Jatropha coagulant agent is efficient under acidic conditions, especially at pH 3. A significant reduction in turbidity removal (
