The Removal of Ibuprofen Drugs Residues from Municipal Wastewater by Moringa Oleifera Seeds

Municipal wastewater may contain residues of different drugs causing severe chemical contamination of water bodies. However, the microbial degradation of Wastewater Treatment Plants (WWTP) may not eliminate such drug residues completely. The current work was designed to remove the Ibuprofen drug residues by using the Moringa Oleifera seeds. Various testing methods such as Brunauer, Emmett and Teller (BET), Transmission Electron Microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) were applied to assess the efficiency of such plant seeds in bioremoval of ibuprofen residues from municipal wastewater The batch reactor was used to find the optimum operating conditions using various parameters with different pH values, duration time, Ibuprofen concentration and various quantities of plant seeds. In the batch reactor, the operation conditions were: pH 7, duration time 150 min, Ibuprofen dose of 1000 mg/l, activated adsorbents and Moringa Oleifera seeds in the amount of 1000 mg/l. Moreover, the packed bed reactor was used to examine different parameters such as initial Ibuprofen concentration, flow rate and bed depth for 6 hours. It was found that the best conditions were 2 cm depth, and 25 l/hr flow rate. Meanwhile, the kinetic constants were studied by adsorption equilibrium with the isothermal Langmuir and Freundlich models. The best results were shown with the Freundlich isotherm, and the first pseudo order was more suitable for the removal of Ibuprofen by adsorbed activation of Moringa Oleifera seeds.


INTRODUCTION
It has been reported that the residues of various pharmaceuticals and xenobiotic compounds were found in drinking and wastewaters are another public health concern (Ippolito et al., 2011; Touraud et al., 2011;Szymonik et al., 2017). Little is known about the potential chronic health effects associated with long-term ingestion of mixtures of these compounds through drinking water (Kümmerer, 2001;Patneedi and Prasadu, 2015). However, the occurrence of such pharmaceuticals drugs residues in water is due to pharmaceutical industry waste, personal hygiene products, hospital waste and therapeutic drugs (Hee-Jong and Seong-Ho, 2011). It has been well documented that such drug residues had a significant impact on both public health and environment (Yao et al., 2010;Proesser and Sibly, 2015;Adegoke et al., 2018).
The residues of pharmaceutically active compounds (PhACs) and related contaminants were investigated thoroughly worldwide (Lin et (Heberer et al., 2002) has examined a new long-term monitoring program of sewage, surface, ground-and drinking water and found that in the course of the monitoring program, PhACs and some other polar compounds were detected at the concentrations up to the micro g/L-level in all compartments of the Berlin water cycle.
On the other hand, M. oleifera seeds were used intensively in water purification (Amagloh and Benang, 2009) The M. Oleifera (Moringaceae) plant belongs to the Moringa genus (Morton, 1991). This plant is now cultivated in all tropical and subtropical regions (Ali et al., 2009). This is due to its resistance to different climates, as well as poor and moderately dry soils (Ali et al., 2009). It reaches 15 m in height, with a diameter of 20-40 cm (Odee, 1998). Many parts of the plant show pharmacological properties, recognized by popular use and corroborated by the scientific community while other parts of the plant (seeds and leaves) are regarded as low cost and environmentally sound biosorbents (Ali et al., 2015).
Ibuprofen drug, a carboxylic acid. Anti-inflammatory drugs or NSAIDs are frequently used to relieve certain pains. The Ibuprofen medicine has a powdery white appearance and is produced in the form of capsules, tablets, or powder (Carlo, 2013;Pehlic et al., 2013). Therefore, the current work was designed to use the Moringa Oleifera seeds as biosorbent for the removal of Ibuprofen drug residues from municipal wastewater.

Preparation of activated carbon
M. Oleifera seed pods were collected and washed thoroughly with distilled water and dried to constant weight under sun light. Thereafter, the seed pods were ground and sieved to a size of 106 μm, left to dry in an air oven at 105 °C for 6 h. Finally, they were stored in vacuum desiccators.
According to the procedure in ASTM, D 4442 for moisture content, the activating carbon of M. Oleifera seed (ACMO) was prepared following the previous work (Abdallah, 2017). After pretreatment, zinc chloride (ZnCl 2 ) was added to the chemical activation method, as follows: The sulfuric acid (H 2 SO 4 ) was used to activate the raw material with ratio 1:10; 60 g of raw material was weighted and impregnated in 600 ml 10% H 2 SO 4 (v/v) and 10% ZnCl 2 (w/v) for 24 hours with continuous mixing then left to dry at 100-105 o C in oven and stored until it was used as shown in Figure 1. (Dahham, 2018).
The experimental work consisted of two parts where the first was performed using a batch reactor to study the operation conditions and the second used a packed bed reactor to study the breakthrough.

Batch Experiments
The different adsorption experiments were carried out in a batch reactor to obtain the best operation conditions, such as Ibuprofen concentration (100, 250, 500, 1000 mg), adsorbent material (100, 250, 500, 1000 mg) and pH (2,5,7,9). The tests were performed in a beaker with the capacity of 1 L with rotation speed of 200 rpm for detention time 3 hour at room temperature of 22°C. Packed bed reactor was designed and constructed to be used for continuous operation. The reactor consists of a glass tube with 60 cm length and internal diameter of 2.1 cm. The Ibuprofen solution was pumped using submersible water pump from feed solution to the bed during the valve that controls the flow rate after passing during flow meter. Different sizes of glass beads were used to provide inert zone as well as to catch any impurities and to assist inflow distribution of the reactants through the bed as stated by (Satterfield, et al., 1996), As shown in Figure 2, the flow pattern used in this experimental was down flow and the effluent was collected in a plastic container.
The operation conditions obtained from batch reactor experiment were used in a continuous system (backed bed reactor). The parameters involved different bed heights (1, 1.5, and 2 cm), different flow rates (25, 30, and 35) l/hr, and different Ibuprofen initial concentrations (100, 400, and 625 mg/l). The experiment was performed at room temperature. The sample was withdrawn from effluent each 30 minutes, filtered and stored to analyze later. The high performance liquid chromatography (HPLC) instrument was used to measure Ibuprofen concentration.

BET Instrument Results
Many factors are important on adsorbent process one of them surface area, Table 1 shows the results of M. oleifera seed activated carbon surface area.
The results of BET instrument show that there was a clear increase in the surface area of activated M. oleifera compared to normal seeds. According to the International Union of Pure and Applied Chemistry (Nicoleta et al., 2013), the mesoporous (20 to 500 nm) was the characteristic of the activated M. oleifera pore size. The chemical composition of the M. oleifera seed, and the activation during Transmission Electron Microscopy (TEM) test are given in Tables 2 and  3, while the results of Energy Dispersive Spectroscopy (EDS) are presented in Figures 3 and 4. It was observed that sulfur, and phosphorus and nitrogen appeared in certain amounts, but these quantities were decreased after the carbonization process where the carbon reduction during carbonization process was due to the oxidation of the organic content.
In the images of the M. oleifera before and after activation during the scanning electron microscopy (SEM) test, which are shown in From Fourier transform infrared spectroscopy (FT-IR), the IR spectrum of natural and activated M. oleifera with function groups are shown in Table 4 and in Figures 7 and 8.
The results of FT-IR spectrum of natural and activated M. oleifera are shown in Figures 7 and 8. A wide function group range was about 3912.50-3282.84 cm -1 but low peaks were attributed to the surface hydroxyl group and chemisorbed water. The narrow peak varied from 2331.92 cm -1 to 2312.65 cm -1 and hydroxyl group from 1905.09 cm -1 to 1789.94 cm -1 that between two groups which         (Munajad et al., 2018).

Results of batch reactor
In order to estimate the Ibuprofen concentration in the experimental work of batch reactor, the Ibuprofen concentration was measured in the wastewater collected from the AL Rustomyia treatment plant -Baghdad city and it was found very high (650 mg/l). The removal efficiency rate in this station was 60% due to the use of drugs in large quantities through medical and non-medical prescriptions. Moreover, an animal skin tanning factory (Syadia), near the treatment plant, discharged industrial wastewater carrying significant quantities of Ibuprofen with diclofenac used in tanning animal skins.

Change in pH
Figures 9 and 10 represent the effect of pH on the adsorption of Ibuprofen by activated Moringa Oleifera. An improved removal of Ibuprofen along with increasing pH up to 7 was observed, where at low pH, the adsorbent surface (activated M. oleifera seed powder) was surrounded by hydronium (H 3 O + ) ions, and this has decreased the interaction of Ibuprofen with the sites of activated M. oleifera seed powder by repulsive forces resulting in low adsorption.

Different Ibuprofen concentration
In this study, the temperature and pH were kept constant at 22°C , and pH 7 while the activation Moringa oleifera equaled to (100 mg/l), and  Figure 11 shows the relation between time (min) with Ibuprofen concentration (mg/l) where the Ibuprofen concentration was decreased with time and the high removal concentration was 250 mg/l. This is due to the available space of activated Moringa Oleifera. However, Figure 12 shows that the Ibuprofen concentration was increased with decreasing the time for all adsorbent tests.

Different mass of Moringa oleifera
The relationship between time and the concentration of activated M. oleifera is shown in Figure 13. The Ibuprofen concentration was decreased with the time causing a clear increase in the removal efficiency, along with the concentration of the adsorbent substance activated M. oleifera, as shown in Figure 14. This was due to the adsorption sites, which were initially opened and the Ibuprofen was interacted easily with the site where the concentration difference between the bulk solution and the solid liquid interface was initially higher and this may lead to higher rate of adsorption observed after 150 minutes. At this time, the reaction has reached the steady state. The best removal efficiency was achieved at the M. oleifera concentration of 1000 mg / liter. Because there was sufficient space for the reaction and the last period, the reaction was completed because the Ibuprofen concentration has become a very small amount. Thus, ensuring uniformed spaces with high interlayer where the Ibuprofen entered to become eliminated (Kurniawan et al., .

The kinetic models
An important step in studying the adsorption processes is the study of kinetics (Wang, 2008). The kinetic equation is reported in the n-th order of absorption as in equation (2): (dc / dt) = -k C n (2) where: k -adsorption rate coefficient, C -Ibuprofen concentration, t -time, and n-th -reaction order.
From the previously equation, the pseudofirst and pseudo-second-order kinetic equation were shown as in Equations (3) (4) (First -order) log (q e -q t ) = log q e -K 1 t (3) where: qt, q e is the adsorbed at time t and equilibrium (mg/g), t is the time of adsorption process (min), and, k 1 , and k 2 is the rate constant for pseudofirst, and pseudo-second-order reaction, respectively. K 1 is a constant (min-1), which is determined by plot ln (q e -q t ) versus t.
(Secondorder) = 1 2 ᴧ2 + (4) The initial sorption rate is defined by the following equation: This kinetic study on different Ibuprofen concentration due to large value of R 2 The result k and R 2 for first and second order were shown in Figures 15, 16 and in Table 5. From the results, it was found that the pseudo-first order was the best result because of the high R 2 .
The results showed that the pseudo-first-order equation has fitted the experimental data well with a correlation coefficient (R 2 ) which was more close to one than the second-order. Table 5 shows the result of first-order and second-order models and also to those observed in Figures 15 and 16. The deviation from the straight line of sorption as in the pseudo-first-and second-order model, and the adsorption in this study was a slow especially in the initial period of the reaction. On the basis of the correlation coefficients, the first-order model was a reaction pathway for sorption of Ibuprofen by activated Moringa oleifera (Kowanga et al., 2016).

Packed bed reactor
The breakthrough was studied in packed bed reactor and the experimental tests were performed with different parameters such as bed height of adsorbent (1, 1.5, 2cm), initial Ibuprofen concentration (100-400-625 mg/l), the flow rate (25-30-35 l/hr), constant pH up to 7 and temperature of 22°C.

Different height bed
The results showed that the breakthrough was increased along with bed height, as shown in Figures 17 and 18 for Ibuprofen removal efficiency with time. Moreover, it was found that the breakthrough observed in bed height 1 cm was not clear because the bed was small and not enough to complete adsorption, but in beds of 1.5, 2 cm, the breakthrough was very clear due to increase in the surface area for adsorption and increase in detention time that referred to high capacity to adsorb the Ibuprofen solution. These results are supported by those of recent study (Al Ani et al., 2019). The breakthrough has begun approximately from the same time, but it was finished at different times.

Different flow rate
In order to study the effect of flow rate, different flow rates (25,30, and 35 l/hr) were applied with constant of bed height at 2 cm, pH at 7, Ibuprofen concentration at 625 mg/l, and temperature at 22°C. The effect of changing flow rate is shown in Figure 19. The results showed that with increasing the flow rate, the breakthrough has become steeper depending on resident time of Ibuprofen passing on adsorbed bed. Thus, the residence time was decreased with increasing the flow rate. Additionally, Figure 20 shows that the Ibuprofen concentration was decreased with increasing operation time of the bed for removal and decreasing flow rate.

Different initial Ibuprofen concentrations
The effect of the initial Ibuprofen concentrations (100, 400, 625mg) on breakthrough with other parameter kept constant is shown in Figure 21, where the bed height was 2 cm, flow rate 25 l/hr, pH 7, and temperature -22°C. It seems that with increasing the initial Ibuprofen concentration, the breakthrough increased too. Figure 22 shows that the Ibuprofen concentration decreased with time.

Kinetic isotherm model
The isotherm analysis was studied through applying a fitting technology for several isotherm models to achieve a suitable model that it is applied for designing objectives. In the Langmuir and Freundlich adsorption models, the constant of Freundlich equation was determined by slope and the linearized was done by using the equation 5. lnqe = ln K + 1 × lnCe (6) where: k, n constant, 1/n range between (0-1) However, the constant of Langmuir equation was determined by slope, interest linearized by using the equation 7, This equation was used to determine the value of q max (mg/g) and b (L/mg) through plot 1/q e versus 1/C e . The activated Moringa oleifera seeds adsorbent through Freundlich adsorption models showed that during R2, the Ibuprofen concentration was more effective on the model, so that the kinetic was adapted to the change in Ibuprofen concentrations.
The activated M. oleifera seeds adsorbent through the Langmuir adsorption models showed that the change in the concentrations of activated M. oleifera seed at 100 mg was more effective on Ibuprofen removal, so that the kinetic was adapted on change in weight of activated M.oleifera seed as shown in Figures 23 and 24. The results of the Freundlich and Langmuir model constant are given in Table 6. It was seen that: • q e which represents the solute obtained in unit mass of local adsorbent was found to be related directly with value of concentration C e that represented the equilibrium concentration • The type of equilibrium isotherm that considers a favorable type and there due to the high weight of adsorbent for Langmuir and Freundlich which can be applied. Both models give approximately the same results, but the Langmuir model gives slightly higher R2 values.

CONCLUSION
The activated M. oleifera seeds were found to be the best adsorbent and a good alternative, being a cheap adsorbent that can be used for the Ibuprofen removal from wastewater. Using a batch reactor, it was found that the operation conditions were as a follows: pH 7, Ibuprofen concentration 1000 mg/l, adsorbents (activated M. oleifera seed -1000 mg/l. From the results, the first order was found the best adsorption kinetic result in batch reactor. The break points of the breakthrough curve for adsorbents (activation of M. oleifera seed) increased along with the bed height and initial flow rate. In the case of a continuous reactor, the Freundlich and Langmuir isotherm models were found to be favorable for activation of M. oleifera seed as adsorbents.