Adsorption of 4-Chlorophenol from Simulated Industrial Effluents Using Cuscuta Seeds ( Batch and Column Study )

This study investigates the possibility of using cuscuta seeds to remove 4-chlorophenol from industrial aqueous effluents. The removal of4-chlorophenol was studied using both batch and fixed bed processes.Batch adsorption studies were performed by changing parameters as contacttime, initial pollutant concentration, degree of agitation and mass of adsorbent. Fixed bedadsorption runs were performed by varying many column parameters aspollutant initial concentration,solution flow rate, and bed height. The amount of 4-chloro phenol removed was increase as the contact time increases; pollutant initial concentration increases; degree of agitation increases; the amount of adsorbent increases; column bed height increases and solution flow rate decreases. Theequilibrium adsorption data were fitted well to bothLangmuir and Freundlich isotherm equations and the isotherm parameters were calculated and Freundlich isotherm fits the data better. The kinetic data were fitted well to the pseudo second order kinetic model than the first order model. The results shows that cuscuta seeds can be used as efficient adsorbent for the removal of 4-chlorophenol from industrial effluents using both batch and continues operation moods. Index Term-Cuscuta seeds, adsorption, 4-chlorophenol, kinetics, isotherm, fixed bed. INTRODUCTION In recent years organic contaminants from industrial effluentswhich is seriously affects the human health and the environment has been recognized as an issue of great importance.4-chlorophenol is a serious problem in many countries. The main sources of this contaminant are petrochemical, petroleum refineries, leather and textile, steel plants, plastic, pesticides, paper, pharmaceuticals and paints industries. It has a high solubility in aquatic environment. The most common used techniques for the removal of 4chlorophenol are catalytic and photo-catalytic decompositions, chemical precipitation, ion exchange, membrane processes, reverseosmosis, chemical oxidation, precipitation, electrochemical conversion, gas-stripping, solvent extraction and adsorption. Activated carbon adsorption has been found to be from the best available technologies in the removal of organic compounds, but it is highly expensive especially for developing countries as Egypt.In recentyears, there has been a continuous search for locallyavailable and cheaper adsorbents for the replacement ofactivated carbon for removal of a variety of organic compoundssuch as phenol and its derivatives (1). Cuscuta plant considered one of the most parasitic plant evolution and it was found in huge quantities in most countries especially Egypt (2). 2EXPERIMENTAL PROCEDURE 2.1. Adsorbate (4-chlorophenol) Analytical grade 4-chlorophenol from J.T. Baker was used in theexperiments. A stock solution of adsorbate was prepared using double distilled water. 2.2. Adsorbentpreparation Cuscuta seeds was provided from Delta, (Egypt).The adsorbent preparation was as follows, (10 Kg) were washed severaltimes with distilled water, dried at 85C overnight, crushed, sieved. The resulting adsorbent was used without any further treatment in the adsorption process 2.3. Analysis of 4-chlorophenol The concentration of 4-chlorophenol in solution was determined using direct photometric method. After adsorption process andsample preparation and according to the standard methods, the residual 4chlorophenol concentrations were measured using (spectrophotometer DR-2010, HACH) by chloroform extraction method. The absorbanceof the colored complex of 4-chloro phenol with 4-amino-antipyrine was measured at 460 nm [3]. 2.4. Determination of equilibrium time needed for adsorption In order to determine the time needed practically to reach equilibrium, a preliminary kinetic investigation was made at certain operating conditions. A large number of conical flasks containing the same composition of adsorption mixture (20 ml solution with 0.1gm adsorbent) were well shaken at 250 r.p.m. and temperature 25 Cto be representative ofenvironmentally relevant conditions then samples were separately withdrawn at different time intervals. The withdrawn samples were filtered and analyzed. Samples were repeatedly withdrawn until equilibrium state is reached. International Journal of Engineering & Technology IJET-IJENS Vol:18 No:03 11 181103-7575-IJET-IJENS © June 2018 IJENS I J E N S 2.5. Adsorption studies The sorption studies were conductedin a routine manner by both batch and continuous techniques. 2.5.1 Batch adsorption process For batch experiments a certain amount (0.1 gm) of cuscuta seeds were placed into a 250-mL flasks containing 20 mL solution with different initial 4-chlorophenol concentrations (40 900 mg/L).The flasks were agitated on a shaker with a constant shaking speed for the time needed to reach equilibrium from the preliminary kinetic investigation then the samples was filtered and the 4-chlorophenol concentration was measured. All experiments were carried out in duplicates and theaverage value was used for further calculations. The effects of adsorbent dosage, the initial 4-chlorophenol concentration, contact time and the agitation speed were investigated. The amount of 4-chlorophenol adsorbed using cuscuta seeds will be determined by the difference between the initial concentration (Co) and the equilibrium pollutant concentration (Ce). The amount of 4-chloro phenol adsorbed at equilibrium qe (mg/g) was calculated from the following equation: qe = (Co Ce)V /m (1) Where Co and Ce represent the initial and equilibrium 4-chloro phenol concentrations (mg/L), respectively; V is the volume of 4-chloro phenol solution (mL) and m is the amount of cuscuta seeds (mg). The adsorbent mass was changed in the range of 0.05 0.2 gm. The 4-chloro phenol initial concentrations were varied from 40 to 900 ppm. 2.5.2 Fixed bed adsorption process Fixed-bed column studies were applied in order to observe the adsorptive tendency of the adsorbent. The fixed-bed columns appears to have a distinct advantage over batch-type operations due to the fact that in batch operations the efficiency of the adsorbent material for removing solute from solution decreases as the adsorption proceeds, whereas in column operations the adsorbent is continuously in contact with solution of fixed concentration. As a result the exhaustion capacity of the column is relatively greater than that of batch capacity (4). Column experiments were conducted at room temperature. The column was fabricated from byrex with 3.5 cm internal diameter and 130 cm height. The solution was fed to the top of the column using a pump different volumetric flow rates (0.3, 0.5 and 0.7 cm/sec), different bed heights (20, 40 and 60 cm) and different initial 4-chlorophenol concentrations (100, 200 and 300 mg/L). Effluent from the column was collected at regular interval and was analysed for all used operating conditions. 2.6. Adsorption isotherms models As the sorption process reaches equilibrium,it is important to study of adsorption isotherms in order to explain the distribution of 4-chloro phenol molecules between liquid and adsorbent phases. Moreover, the isotherms will provide dataexplains the heterogeneity and homogeneity of the adsorbent surface, the type of coverage, and possibility of interaction between the adsorbate species (5). It also provides a panorama of the course taken by the system under study in a concise form, indicating how efficiently an adsorbent will adsorb and allows an estimate of the economic viability of the adsorbent commercial applications for the specified pollutant (5).Tow isotherms equation have been tested in this study to identify the equilibrium data of the adsorbent, Langmuir [4], and Freundlich [14]. The Langmuir isotherm assumes that monolayer uptake occurs at binding sites with homogenous energy levels (6). Langmuir isotherm model determines the maximum sorption capacity of 4-chlorophenol on the homogenous surface of cuscuta seeds waste. The Langmuir isotherm can be linearized using Ce/qe = (1/qLKL) + (1/qL) Ce (2) Where qe is the mono-layer adsorption capacity of adsorbent (mg/g), KL is the Langmuir adsorption constant (L/mg) and qL is the mono-layer adsorption capacity of adsorbent (mg/g). Therefore, a plot of Ce/qe versus Ce gives a straight line of slope 1/qL and intercepts 1/(qLKL). To determine if adsorption process was favorable or unfavorable for Langmuir type adsorption process, Langmuir isotherm is then classified using a dimensionless constant separation factor (RL), which can be defined as: RL = 1 / (1+KLCmax) (3) Where Cmax is the large (initial) solution concentration (mg/L). If the value of RL< 1, it indicates a favorable adsorption and if RL> 1 then, an unfavorable adsorption. The RL values for the adsorption of 4-chloro phenol onto cuscuta seeds waste was in the range 0 < RL<1, indicating that Langmuir adsorption is favorable. The Freundlich isotherm model can be applied for non-ideal adsorption on aheterogeneous surface of sorbent (7). The Freundlish model can be expressed as: Log qe = log KF + (1/n) log Ce (4) Where KF and n are the Freundlich adsorption constants,which can be determined by the linear plot of log qe versus log Ce. International Journal of Engineering & Technology IJET-IJENS Vol:18 No:03 12 181103-7575-IJET-IJENS © June 2018 IJENS I J E N S 2.7. Kinetic Modeling The kinetics of 4-chlorophenol adsorption can be modeled by various equations. The pseudo-first-order Lagergren equation is given as (7) Log (qe-qt) = log qe – (k1/2.303) t (5) Where qt and qe are the amounts of ion adsorbed at time t and at equilibrium (mg/g), respectively, and k1 is the rate constant of pseudo-first-order adsorption process (h). The slope and intercept of plots of log (qe−qt) versus t were used to determine the first-order rate constant k1 and equilibrium adsorption capacity qe. The pseudo-second-order kinetic model by Ho and McKay (8), with the linear form: t/qt=1/(k2qe)+(1/qe)t (6) Where k2 is the equilibrium ra