Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 28 Suhad Shaker Mohammed Dhafir T.A. Al-Heetimi Abstract Natural bentonite (B) mineral clay was modified by anionic surfactant sodium dodecyl sulfate (SDS) and characterized using different techniques such as: FTIR spectroscopy, scanning electron microscopy (SEM) and X-Ray diffraction (XRD). The bentonite and modified bentonite were used as adsorbents for the adsorption of methyl violet (MV) from aqueous solutions. The adsorption study was carried out at different conditions such as: contact time, pH value and adsorbent weight. The adsorption kinetic described by pseudo– first order and pseudo – second order equilibrium experimental data described by Langmuir, Freundlich and Temkin isotherm models. The thermodynamic parameters standard free energy (∆G°), standard entropy (∆S°) standard enthalpy (∆H°) were investigated and determined. Keywords: Adsorption, Natural Bentonite, anionic surfactant, Methyl Violet, Isotherm, Thermodynamic. 1. Introduction Environmental pollution has been become a large problem [1]. A large number of dyes flow into the rivers by many industries such as plastics, paper, rubber, cosmetics, pharmaceutical and food- stuff [2]. 12% of synthetic textile dyes used each year is lost during manufacturing process and 20% of these dyes go into the environment through effluents [3]. Methyl violet is popular dye due to its various purposes such as biological stain, dermatological agent, and veterinary industrial products [4]. Methyl violet is a mutagen and mitotic poison which may cause cancer and can cause severe eye irritation through ingestion or skin contact [5]. There are different physical and chemical techniques to remove methyl violet from their aqueous solution such as oxidation [6]. adsorption [7]. and ion exchange [8]. Adsorption is one of the most active treatment processes to remove methyl violet from waste water by using different kinds of adsorbents such as zeolite [9]. Carbon nanotubes [10]. Ibn Al Haitham Journal for Pure and Applied Science Journal homepage: http://jih.uobaghdad.edu.iq/index.php/j/index . Department of Chemistry, College of Education for Pure Science Ibn Al- Haitham, University of Baghdad, Baghdad, Iraq. Article history: Received 22 January 2019, Accepted 24 February 2019, Publish September 2019. Doi:10.30526/32.3.2278 dhafir1973@gmail.com Adsorption of Methyl Violet Dye from Aqueous Solution by Iraqi Bentonite and Surfactant – Modified Iraqi Bentonite mailto:dhafir1973@gmail.com Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 29 sepiolite [11]. and bentonite [12]. Modified bentonite also shows efficient to remove of methyl violet from aqueous solution. Al-Dujaili et al., [13]. used surfactant – modified bentonite and kaolinite clays to remove and appear to be more efficient than unmodified samples. Bentonite is yellow solid clay mineral, very hard and high porosity [14]. It consists of aluminum oxide and silica with small amounts of impurities such as CaO, MgO, Fe2O3 , SO3 and Na2O . The chemical structure of bentonite is Al2O3 . 4SiO2 . H2O Minerals clays have low content of organic carbon and hydrophilic character due to the nature of the interlayer spaces of the minerals [15]. The ion – exchange with surfactant due to the mineral’s clays can convert from organophilic to organphobic and increases the minerals clays interlayer [16]. In this study, a negative surfactant sodium dodecyl sulfate (SDS) was used to modify the bentonite clay. Isotherm, dynamics and thermodynamic functions to removal the methyl violet dye from its aqueous solution on the surface of bentonite clay and on the modified bentonite surface were studied. The modified clay was diagnosed by (FTIR), (XRD) and (SEM). 2. Material and Methods 2.1 Adsorbate and Adsorbent The adsorbate methyl violet (MV) used in this research was obtained by Sigma-Aldrich ≥ 98%, C24H28N3Cl, M.Wt = 393.5 g/mol and the used surface was bentonite clay obtained by general Company for Geological Survey. The chemical analysis of the clay is listed in Table1. The anionic surfactant sodium dodecyl sulfate (SDS > 98%) was purchased from the Romil company. A stock solution (1000 mg/L) was prepared by dissolving of 1g of methyl violet in 1L of deionized water. Table1. The chemical analysis of Bentonite (B). SiO2 Al2O3 CaO MgO Fe2O3 SO3 Na2O L.O.I Total% 54.66 14.65 4.77 6.00 4.88 1.20 0.65 12.56 99.37 2.2 Preparation of Surfactant Impregnated Mineral Clay The clay, which is in the form of powder was washed several times with deionized water and then dried the clay at 90°C for 6 hours and then left to cool at room temperature. The B- SDS was attended by dissolving 3.5g of SDS in 1L of deionized water and mixed with 50g of bentonite with stirring for 24 hours. The suspension washed several times by deionized water, then dried at 100°c for 7 hours. The B and B-SDS used in this research were sieved (≤ 75𝜇𝑚). 2.3 Characterization of the Modified Adsorbent The minerals analysis of B and B-SDS were characterized by using x-ray diffraction (XRD) technique (Shimadzu 6000) powder diffractometer (Japan) using Cuk ∝ radiation, λ = 1.5418A° at 40KV, 30mA and 2θ range from 10-80°. The Fourier-transform infrared spectroscopy (FTIR) (Shimadzu 8400, Japan) in the wave number range of (4000-600cm−1) was used to identify the modification of B. Scanning electron microscope (SEM) type –T- Scan, Vega -111 (Czech) was used to identify the surface morphology of the clays. Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 30 2.4 Adsorption Isotherm Studies Adsorption experiments were performed with the addition of 0.1g of B and 0.1g of B-SDS (separately) with 10ml of methyl violet into conical flasks (100mL) at different initial concentrations of (100,150,200,250,300,350 and 400) mg/L. Equilibrium of adsorption, surface weight, acid function, kinetics, temperature effect of various degrees (25,35 and 45)℃ and thermodynamics studied. The concentration of the dye methyl violet was determined by the adsorption measurement using UV-VIS spectrophotometer BG (T80) at 580 nm. The amount of the adsorbent of methyl violet (qe, mg/g) was calculated by equation (1). qe = (𝐶𝑜 − 𝐶𝑒 ) × 𝑉 𝑤 (1) Where V is the volume (L), W is the adsorbent weight (g), 𝐶𝑜 is the initial concentration (mg/L) and 𝐶𝑒 is the residual concentration at the equilibrium (mg/L). The percentage of methyl violet removal was calculated by using equation (2). % Removal (R%) = (𝐶𝑜−𝐶𝑒) 𝐶𝑜 × 100 (2) 3. Result and Discussion 3.1 FTIR Spectra The FTIR spectra for B and (B-SDS) are shown in Figures 1a,1b. respectively. The bands in Figure 1a. at 3612.67cm−1 and 3541.31cm−1 can be attributed to the vibrations for the structural hydroxyl group (OH stretching) and the band at 1647.21cm−1 attributed to the group OH deformation. The bands at 1006.84cm−1 , 914.26cm−1 , 877.61cm−1 and 796.60cm−1 attributed to Si-O, Al-OH, Fe-O and Mg-O stretching bands respectively. After modification with surfactant SDS Figure 1b. The bands at (3612.67, 3541.31, 1006.84, 914.26, 877.61 and 796.60) cm−1 were shifted and change in the intensity of all bands. The bands at 2924.09cm−1 and 2852.72cm−1 in modified B can be attributed to the symmetric and asymmetric stretching vibrations of CH3 and CH2 groups of the SDS surfactant respectively [17,18]. Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 31 Figure 1. FTIR spectra of (a) B and (b) B-SDS. (b) Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 32 3.2 SEM Analysis The scanning electron microscopic analysis shows crystalline structure, surface texture and porosity of the surface material. The SEM micrograph of B and B-SDS are shown in Figure 2. With a magnification force of (5kx). The micrograph in Figure 2a. Shows that the B outer shape contains a number of similar conglomerates and hillside or plateau forms containing a number of pores. In Figure 2b. Shows that the outer shape of the B-SDS was covered with a thin layer of surface-active material and filled with pores on the surface [19]. Figure 2. SEM Photomicrographs for B(a) and B-SDS (b). 3.3 XRD Analysis The XRD analysis of B and B-SDS are shown in Figure 3a, b. The difference between B and B-SDS is only in the intensity of the XRD peak, while there is no change in the B metal clay. This indicates that the crystalline structure of the B remains intact and has not been destroyed after the surface has been modified by the surface-active materials as noted in the Figure 3. This is corresponding with that mentioned in the literature [20, 21]. (a) (b) Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 33 Figure 3. XRD analysis of the B(a) and B-SDS (b). 3.4 Adsorbent Weight Effect The effect of the weight of B and B-SDS to remove of the MV dye were studied at 25℃ and an initial concentration of 250 mg/L is shown in Figure 4. The increasing in the extent of the removal ratio (R %) of the dye MV on the B after 0.1g of the surface was not removed and the adsorption proves approximately (99%). On the other hand, the removal ratio of the dye MV increases by increasing in the weight of B-SDS, and this increase can be explained by the abundance of adsorption sites free and insert the high concentration between the solution and the surface of the solid surface [22]. In addition, increasing of removal ratio (99.59%) can be attributed to the high surface area of the B-SDS because of the increase in the particle space of the B-SDS, which increases the removal capacity of the surface [23]. Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 34 Figure 4. Effect of adsorbent dosage on the removal of MV onto B and B-SDS at 25℃. 3.5 Effect of Contact Time The effect of contact time on dye adsorption on both B and B-SDS was studied at an initial concentration 250 mg/L, 25℃ , pH=4.45 and 0.1g of B and 0.1 g B-SDS respectively. The capacitance of the MV increased over time and reach affixed value at a specified time. It found that the time needed to reach equilibrium is 8min and 1.5min for B and B-SDS respectively, Figure 5. The adsorption speed in the primary stage was high because of the availability of vacant positions on the surfaces of the mezza and after a certain period of time, the adsorption capacity remains constant due to the lack of effective adsorption sites available. The MV dye absorbed on the surface of B-SDS was faster than the surface of B due to the higher affinity on the B-SDS surface [24]. In addition, the surface of B changed from hydrophilic to hydrophobic after modification of SDS [25,26]. Figure 5. Effect of contact time on adsorption of MV onto (a) B and (b) B-SDS at 25 o C. 24.7 24.72 24.74 24.76 24.78 24.8 24.82 24.84 24.86 24.88 0 5 10 15 q e m g /g t (min.) (a) 97 97.5 98 98.5 99 99.5 100 0 0.2 0.4 0.6 0.8 R % Wt (g) B B-SDS 24.1 24.2 24.3 24.4 24.5 24.6 24.7 24.8 0 1 2 3 q e m g /g t (min.) (b) Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 35 3.6 Influence of pH The effect of pH on the removal of (MV) on B and B-SDS was studied using concentration of 250mg/L at 25℃ and absorbent weight of 0.1g for both B and B-SDS. The results are explained in Figure 6. The removal of (MV) onto B and B-SDS decreased with increasing the pH of a solution. Cationic dye produces molecular cations (𝑁+) dissolution in water and depends on the water pH. At low pH, the surface of the adsorbent become protonated results at lower adsorption of the protonated dye [27]. Figure 6. Influence the pH of solution on the removal of (MV) onto B and B-SDS at 25 o C. 3.7 Adsorption Isotherm The adsorption of the (MV) dye from its aqueous solution on the surfaces of B and B-SDS was studied by using three adsorption models: Langmuir, Freundlich and Temkin [28]. The Langmuir isotherm is represented in the following equation [29]. Ce qe = 1 KLqmax + ( 1 qmax ) Ce (3) Where the 𝐶𝑒 and 𝑞𝑒 are the concentration at equilibrium (mg/L) and the quantity of (MV) adsorbed onto B and B-SDS (mg/g), respectively 𝑞𝑚𝑎𝑥 (mg/g) is the maximum adsorption capacity and K𝐿 is the Langmuir constant in (L/mg). The intercept 1 𝐾𝐿𝑞𝑚𝑎𝑥 and the slope 1 𝑞𝑚𝑎𝑥 can find them graphically by drawing 𝐶𝑒 𝑞𝑒 against 𝐶𝑒 [30]. The second isotherm model was Freundlich which used for the purpose of description the adsorption of heterogenerous system [31]. The Freundlich isotherm is represented in the following equation: log qe = log KF + 1 n log Ce (4) Where KF (slope, mg/g) represented adsorption capacity and n (intercept, unit less) represented adsorption intensity. The Freundlich constant (KF,n) calculated by drawing log qe against log Ce . The latest model is the Temkin isotherm can be calculated using the following equation: qe = B ln KT + B ln Ce (5) Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 36 By drawing ge vs.ln Ce we can determine Temkin constants (KTand B) [32]. By observing the correlation coefficient 𝑅2 values in Table 2. The Langmuir model is not applicable. while observe the applicability Freundlich and Temkin isotherms at all temperatures, it shows the Temkin and Freundlich isotherms are the good fit of experimental date compared that of Langmuir model [33]. On the other hand, KFvalues increased by increasing the temperature of all MV adsorption systems on the B and B-SDS surfaces. Temkin isotherm is the good fit of experimental data compared to Freundlich and Langmuir models. Table 2. Listed the Langmuir, Freundlich and Temkin isotherms parameters. 3.8 Thermodynamic Parameters The thermodynamic parameters such as Gibbs free energy (∆𝐺°), standard entropy changes (∆𝑆°) and standard enthalpy (∆H°) were calculated by using the following equations: ∆𝐺° = −𝑅𝑇 ln 𝐾𝑒𝑞 (6) 𝐾𝑒𝑞 = ( 𝑞𝑒 𝑐𝑒⁄ ) ∗ ( 𝑤 𝑉⁄ ) (7) ∆G° = ∆H° − T∆S° (8) Where (R) is the universal gas constant, (T) is the absolute temperature. 𝐾𝑒𝑞 is the equilibrium constant for the adsorption process , 𝑞𝑒 (mg/g) is the amount of (MV) adsorbed at equilibrium , 𝐶𝑒 (mg/L) is the equilibrium dye concentration in solution , w(g) is the weight of (Band B- SDS) used and V(L) is the volume of (MV) solution used. ∆H° and ∆S° are standard enthalpy and standard entropy respectively can be calculated by using vent's Hoff equation: ln Keq = ∆S° R⁄ − ∆H° RT⁄ (9) The ∆H° and ∆S° can be obtained by drawing ln Keq against 1 T⁄ as the slope and intercept values respectively as shown in Figure 7. Table 3. Shows the thermodynamic parameters values at different temperatures. The negative values of (∆G°) at all temperatures, which became more negative when the temperature increases. This indicated that the process was more spontaneous at higher temperature. While the positive (∆H°) and (∆S°) an indication that (MV) adsorption on B and B-SDS is a endothermic and randomized process [34]. Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 37 Table 2. Langmuir, Freundlich and Temkin Isotherm Parameters for the Adsorption of (MV) onto B and B- SDS. Isotherm Adsorbent 298K 308K 318K 𝑲𝑳 (L/mg) 𝒒𝒎𝒂𝒙 (mg/g) 𝑹𝟐 𝑲𝑳 (L/mg) 𝒒𝒎𝒂𝒙 (mg/g) 𝑹𝟐 𝑲𝑳 (L/mg) 𝒒𝒎𝒂𝒙 (mg/g) 𝑹𝟐 Langmuir B 0.6430 52.3560 0.9562 0.2253 125.0000 0.1841 0.0810 333.3330 0.0252 B-SDS -0.2530 -36.7647 0.2976 -0.2892 -32.8947 0.2538 0.0984 256.4102 0.0340 Freundlich 𝐾𝐹 (mg/g) n 𝑅2 𝐾𝐹 (mg/g) n 𝑅2 𝐾𝐹 (mg/g) n 𝑅2 B 19.2663 1.8663 0.9047 23.0727 1.2362 0.7791 25.3454 1.0900 0.7936 B-SDS 12.4680 0.6269 0.7906 13.7943 0.6142 0.7020 23.3991 1.1534 0.7308 Temkin 𝐾𝑇 (L/mg) B (KJ/mol) 𝑅2 𝐾𝑇 (L/mg) B (KJ/mol) 𝑅2 𝐾𝑇 (L/mg) B (KJ/mol) 𝑅2 B 5.8048 12.0680 0.9702 3.9804 18.3240 0.8394 3.6494 21.2410 0.8929 B-SDS 1.3438 37.1860 0.9070 1.4099 38.4310 0.8249 3.5240 20.3730 0.8479 Figure 7. The relationship between ln keq and 1/T (a) B and (b) B-SDS. y = -1943.9x + 11.558 R² = 0.873 5 5.1 5.2 5.3 5.4 5.5 5.6 0.0031 0.0032 0.0033 0.0034 ln k e q 1/T (K-1) (b) y = -1760.6x + 11.134 R² = 0.9347 5.15 5.2 5.25 5.3 5.35 5.4 5.45 5.5 5.55 5.6 5.65 0.0031 0.0032 0.0033 0.0034 L n K e q 1/T (K-1) 38 Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 Table 3. Thermodynamic parameters for the adsorption of (MV) on B and B-SDS. Adsorbent T(K) ∆𝐆° (kJ.𝒎𝒐𝒍−𝟏) ∆𝐇° (kJ.𝒎𝒐𝒍−𝟏) ∆𝐒° (J.𝑲−𝟏.𝒎𝒐𝒍−𝟏) B 298 -12.8781 0.0002 +3.0986 308 -14.0168 318 -14.7194 B-SDS 298 -12.5802 16.1615 +96.0932 308 -13.2018 318 -14.5169 3.9 Adsorption Kinetics In order to find the mechanism for the adsorption of (MV) on B and B-SDS two models were applied to study the adsorption kinetics which is the pseudo-first order known as equation (Lagergren) and pseudo – second order known as equation (Ho and Mckay). The adsorption process was carried out at 25,35and 45℃ on different times, pH=4.45 and an initial concentration of (MV) of 250mg/L. The linear formula of the pseudo –first order can be represented by the following formula [35]. ln(𝑞𝑒 − 𝑞𝑡 ) = ln 𝑞𝑒 − 𝐾1. 𝑡 (10) Where 𝑞𝑒 and 𝑞𝑡 (mg/g) the amounts of (MV) adsorbed at equilibrium, at t time, 𝐾1(𝑚𝑖𝑛 −1) is the rate constant of first order. The amount of 𝐾1 was determined by drawing ln(𝑞𝑒 − 𝑞𝑡 ) against t as explain in Figure 8. The linear formula of the pseudo – second order can be represented by the following equation: 𝑡 𝑞𝑡 = 1 𝐾2𝑞 2 𝑒 + 𝑡 𝑞𝑒 (11) Where 𝐾2 (𝑔. 𝑚𝑔 −1. 𝑚𝑖𝑛−1) is the rate constant of pseudo – second order calculated from the slope of drawing t/𝑞𝑡 versus time as explain in Figure 9. Table 4. listed the pseudo – first and second order kinetic parameters. On the other hand, the values of correlation coefficient (𝑅2) indicate that the adsorption mechanism of (MV) in the B and B-SDS system were more fitted to the pseudo – second order. Figure 8. Pseudo-first order plot of (MV) adsorption onto (a) B and (b) B-SDS. -6 -5 -4 -3 -2 -1 0 0 2 4 6 L n ( q e -q t) t (min.) 298 K 308 K 318 K (a) -2.5 -2 -1.5 -1 -0.5 0 0 0.5 1 1.5 ln (q e -q t) t (min.) 298 K 308 K 318 K (b) 39 Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 Figure 9. Pseudo-second order plot of (MV) adsorption onto (a) B and (b) B-SDS. Table 4. kinetic parameters for the adsorption of (MV) on to B and B-SDS. Adsorbent T(K) Pseudo – first order 𝑲𝟏(𝒎𝒊𝒏 −𝟏) 𝑹𝟐 Pseudo – second order 𝑲𝟐(𝒈. 𝒎𝒈 −𝟏. 𝒎𝒊𝒏−𝟏) 𝑹𝟐 B 298 0.7456 0.9930 4.0402 1 308 0.2473 0.9465 8.0808 1 318 0.4026 0.9109 20.1005 1 B-SDS 298 1.8438 0.9977 8.0000 1 308 2.2597 0.9781 5.4138 1 318 1.5939 0.9823 5.4406 1 4. Conclusion In this study bentonite and modified bentonite were used to remove the (MV) dye from aqueous solutions. The results indicate high adsorption of this dye using both surfaces. Adsorption models have been applied the results showed that model Temkin was the most effective of models Langmuir and Freundlich the adsorption mechanism was studied and the pseudo – second order was the most suitable for both surfaces. The thermodynamic functions of ∆G o , ∆H o and ∆S o were calculated and the process of adsorption of (MV) on both surfaces was found endothermic, spontaneous and randomness. References 1. Paul, J.; Rawat, K.P.; Sarma, K.S.S.; Sabharwal, S. Decoloration and degradation of Reactive Red-120 dye by electron beam irradiation in aqueous solution. Applied Radiation and Isotopes.2011, 69, 7, 982-987. 2. Stolte, M.; Vieth, M. Fondement histopathologique des modifications de la muqueuse œsophagienne. Ce que l’endoscopiste peut (et doit) voirPathologic basis of mucosal changes in the esophagus. What the Endoscopist can (and must) see. Acta endoscopica. 2001, 31, 2, 125-129. 3. Alizadeh, N.; Mahjoub, M. Removal of crystal violet dye from aqueous solution using surfactant modified NiFe2O4 as nanoadsorbent; isotherms, thermodynamics and kinetics studies. Journal of Nanoanalysis.2017, 4, 1, 8-19. 0 0.05 0.1 0.15 0.2 0.25 0 2 4 6 t/ q t t (min.) 298 K 308 K 318 K (a) 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0 0.5 1 1.5 t/ q t t (min.) 298 K 308 K 318 K (b) 40 Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 4. Adak, A.; Bandyopadhyay, M.; Pal, A. Fixed bed column study for the removal of crystal violet (CI Basic Violet 3) dye from aquatic environment by surfactant-modified alumina. Dyes and Pigments.2006, 69, 3, 245-251. 5. Jirekar, D.B.; Pramila, G.; Farooqui, M. Kinetics and Isotherm Studies on Crystal Violet Dye Adsorption onto Black Gram Seed Husk. International Journal of ChemTech Research.2014, 15, 427-434. 6. Pera-Titus, M.; Garcı́a-Molina, V.; Baños, M. A.; Giménez, J.; Esplugas, S. Degradation of chlorophenols by means of advanced oxidation processes: a general review. Applied Catalysis B: Environmental.2004, 47, 4, 219-256. 7. Diaz-Nava, M.C.; Olguin, M.T.; Solache-Rios, M. Adsorption of phenol onto surfactants modified bentonite. Journal of Inclusion Phenomena and Macrocyclic Chemistry.2012, 74, 1-4, 67-75. 8. Park, Y.; Ayoko, G.A.; Horváth, E.; Kurdi, R.; Kristof, J.; Frost, R.L. Structural characterisation and environmental application of organoclays for the removal of phenolic compounds. Journal of colloid and interface science. 2013, 393, 319-334. 9. Apreutesei, R.E.; Catrinescu, C.; Ungureanu, A.; Teodosiu, C. Removal of 4- chlorophenol by surfactant modified zeolites and surfactant modified alkali-treated natural zeolites. Environmental Engineering and Management Journal.2009, 8, 5, 1053- 1060. 10. Ding, H.; Li, X.; Wang, J.; Zhang, X.; Chen, C. Adsorption of chlorophenols from aqueous solutions by pristine and surface functionalized single-walled carbon nanotubes. Journal of Environmental Sciences.2016, 43, 187-198. 11. Yildiz, A.; Gür, A. Adsorption of phenol and chlorophenols on pure and modified sepiolite. Journal of the Serbian Chemical Society.2007, 72, 5, 467-474. 12. Yu, J.Y.; Shin, M.Y.; Noh, J.H.; Seo, J.J. Adsorption of phenol and chlorophenols on hexadecyltrimethylammonium-and tetramethylammonium-montmorillonite from aqueous solutions. Geosciences Journal.2004, 8, 2, 191-198. 13. Al-Dujaili, A.H.; Alkaram, U.F.; Mukhlis, A.A. The removal of phenol from aqueous solutions by adsorption using surfactant-modified bentonite and kaolinite. Journal of Hazardous Materials.2009, 169, 1, 324-332. 14. Goldschmidt, V.M. The principles of distribution of chemical elements in minerals and rocks. The seventh Hugo Müller Lecture, delivered before the Chemical Society on March 17 th 1937. Journal of the Chemical Society (Resumed).1937, 655-673. 15. Grim, R. Clay Mineralogy, 2 ed Mc Graw-Hill, NewYork,1968. 16. Ngulube, T.; Gumbo, J.R.; Masindi, V.; Maity, A. An update on synthetic dyes adsorption onto clay-based minerals: A state-of-art review. Journal of Environmental Management.2017, 191, 35-57. 17. Karadag, D.; Turan, M.; Akgul, E.; Tok, S.; Faki, A. Adsorption equilibrium and kinetics of reactive black 5 and reactive red 239 in aqueous solution onto surfactant- modified zeolite. Journal of Chemical & Engineering Data.2007, 52, 5, 1615-1620. 18. Ma, Y.; Zhu, J.; He, H.; Yuan, P.; Shen, W.; Liu, D. Infrared investigation of organo- montmorillonites prepared from different surfactants. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy.2010, 76, 2, 122-129. 19. Biglari, H.; RodríguezíCouto, S.; Khaniabadi, Y.O.; Nourmoradi, H.; Khoshgoftar, M.; Amrane, A.; Vosoughi, M.; Esmaeili, S.; Heydari, R.; Mohammadi, M.J.; Rashidi, R. 41 Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 Cationic surfactant-modified clay as an adsorbent for the removal of synthetic dyes from aqueous solutions. International journal of chemical reactor engineering.2018, 16, 5, 1- 14. 20. Hussein, M.M.; Khader, K.M.; Musleh, S.M. Characterization of raw zeolite and surfactant-modified zeolite and their use in removal of selected organic pollutants from water. International Journal of Chemical Sciences.2014, 12, 3, 815-844. 21. Mao, H.; Li, B.; Li, X.; Yue, L.; Liu, Z.; Ma, W. Novel one-step synthesis route to ordered mesoporous silica-pillared clay using cationic− anionic mixed-gallery templates. Industrial and Engineering Chemistry Research.2009, 49, 2, 583-591. 22. Zhang, L.; Zhang, B.; Wu, T.; Sun, D.; Li, Y. Adsorption behavior and mechanism of chlorophenols onto organoclays in aqueous solution. Colloids and Surfaces A: Physicochemical and Engineering Aspects.2015, 484, 118-129. 23. El-Dars, F.M.; Hussien, M.Y.M.; Kandil, A.H.T. TOC Reduction in Drinking Water using Anionic Surfactant Modified Bentonite. International Journal of Scientific and Engineering Research.2015, 6, 3, 584-594. 24. Luo, P.; Zhao, Y.; Zhang, B.; Liu, J.; Yang, Y.; Liu, J. Study on the adsorption of Neutral Red from aqueous solution onto halloysite nanotubes. Water research.2010, 44, 5, 1489-1497. 25. Nourmoradi, H.; Avazpour, M.; Ghasemian, N.; Heidari, M.; Moradnejadi, K.; Khodarahmi, F.; Moghadam, F.M. Surfactant modified montmorillonite as a low-cost adsorbent for 4-chlorophenol: Equilibrium, kinetic and thermodynamic study. Journal of the Taiwan Institute of Chemical Engineers.2016, 59, 244-251. 26. Songül Uçar, Atilla Evcin, Mustafa Uçar, Rafiğ Alibeyli and Marek Majdan. Removal of Phenol and Chlorophenols from Aquatic System Using Activated Clinoptilolite. Journal Biology and Chemistry.2015, 43, 3, 235-249. 27. Ullah, H.; Nafees, M.; Iqbal, F.; Awan, S.; Shah, A.; Wassem, A. Adsorption Kinetics of Malachite green and Methylene blue from aqueous solutions using surfactant-modified Organoclays. Acta Chimica Slovenica.2017, 64, 2, 449-460. 28. Mahmoud, M.E.; Nabil, G.M.; El-Mallah, N.M.; Karar, S.B. Assessment of the adsorptive color removal of methylene blue dye from water by activated carbon sorbent- immobilized-sodium decyl sulfate surfactant. Desalination and Water Treatment.2016, 57, 18, 8389-8405. 29. Lee, C.K.; Low, K.S.; Gan, P.Y. Removal of some organic dyes by acid-treated spent bleaching earth. Environmental Technology.1999, 20, 1, 99-104. 30. Xie, J.; Meng, W.; Wu, D.; Zhang, Z.; Kong, H. Removal of organic pollutants by surfactant modified zeolite: Comparison between ionizable phenolic compounds and non-ionizable organic compounds. Journal of hazardous materials.2012, 231, 57-63. 31. Maderova, Z.; Baldikova, E.; pospiskova, K.; Safarik, I.; Safarikova, M. removal of dyes by adsorption on magnetically modified activated sludge. International journal of Environmental science and technology.2016, 13, 7, 1653-1664. 32. Kuleyin, A. Removal of phenol and 4-chlorophenol by surfactant-modified natural zeolite. Journal of Hazardous Materials.2007, 144, 1, 307-315. 33. Mahdavinia, G.R.; Zhalebaghy, R. Removal kinetic of cationic dye using poly (sodium acrylate)-carrageenan/Na-montmorillonite nanocomposite superabsorbents. Journal of Materials and Environmental Science.2012, 3, 5, 895-906. 42 Ibn Al-Haitham Jour. for Pure & Appl. Sci. 32 (3) 2019 34. Wang, S.; Qiao, N.; Yu, J.; Huang, X.; Hu, M.; Ma, H. Effect of ionic strength on the adsorption behavior of phenol over modified activated clay. Desalination and Water Treatment.2016, 57, 9, 4174-4182. 35. Doğan, M.; Alkan, M.; Demirbaş, Ö.; Özdemir, Y.; Özmetin, C. Adsorption kinetics of maxilon blue GRL onto sepiolite from aqueous solutions. Chemical Engineering Journal.2006, 124, 1, 89-101.