Treatment of Refinery Industry Wastewater Using Ion Exchange Technology and Studies Kinetics and Thermodynamic Parameters

Dr. Thamer J. Mohammed, Saif I. Habeeb, Zaydoun K.Kreamid, Ali A. Ali Department of Chemical Engineering, University of Technology, Baghdad, Iraq. Petroleum Research and Development Center, Ministry of Oil. Corresponding Author Emailthamer_jasim58@yahoo.com, Abstract A batch system has been used for removal of chloride, sulfate and sodium pollutants from wastewater of Daura refinery. The fine grained resin lewatit was used in this study, batch experiments were performed to examine the effects amount of resin and mixing time on the removal efficiency and residual of pollutants. The kinetics and thermodynamics of adsorption were also analyzed. Various thermodynamic parameters such as enthalpy (ΔH◦), free energy (ΔG◦) and entropy (ΔS◦) showed that the adsorption was endothermic, spontaneous and feasible. The removal efficiency of sulfate, chloride and sodium is (91%, 88%, 82%), respectively. The optimum mixing time is (12min) for sulfate and sodium, and (14 min) for chloride. Sulfate adsorption on lewatit fitted well to the pseudo-second-order kinetic model, but adsorption of chloride and sodium on lewatit behaves to the pseudofirst-order kinetic model.


Introduction
The advances in technology and industry, large amounts of water are used for industrial activities and consequently significant volumes of wastewaters are generated.
Based on the type of industry, various levels of pollutants are deliberately released and discharged into the environment directly (Donald and Herbert, 1979) [6].
Wastewaters released by oil refineries contain large amounts of toxic derivatives such as oil and grease, phenols, sulphides, cyanides, suspended solids, nitrogen compounds as well as heavy metals such as iron, nickel, copper, selenium, zinc, molybdenum, salt (organic and inorganic), etc (Graham, 1959) [8], but Not all salts (contaminants) are toxic or harmful and therefore do not have to be removed to make water safe to drink. Ion exchange is the reversible interchange of ions between a solid ion-exchange medium and a solution. Cations may be exchange for Na + or H + , while anions are exchanged for OH -.
Most exchange media in current use are in a form of soluble synthetic polymer resins, although some naturally occurring minerals such as the green sand and Zeolite are also used (Mat Calf and Eddy, 1981; Hikki, 1999) [11.17]. Hardness, the salts of calcium and magnesium bicarbonate (or chloride & sulfate) may precipitate out on heating coils and in boilers and cause scale to form add to the salts sodium. Yet they are safe to consume in drinking water. For example higher pressures boilers may require very "pure" or demineralized water (water from which the minerals have been removed) (WQA, 1996) [27]. To remove unwanted ions (dissolved salts) from water, a process called "ion exchange" is most often used.
The important characteristics of ion exchange resin are moisture content and particle size. Water is an essential component of ion exchange resins for many purposes. It has an influence on the porosity and selectivity of the resin, as higher moisture content leads to increased porosity and therefore the active exchange sites are spaced further apart No.20 Journal of Petroleum Research & Studies (JPR&S) (DeSilva, 1999) [5]. The water content of a resin is inversely related to the degree of cross linking. Therefore, a drastic increase in water content is indicative of a reduction in cross linking (Harland and Clive, 1994) [10].
Particle size has two influences on ion exchange processes. The rate of exchange for a resin decreases with increasing particle size due to the lower surface area available for exchange. Head loss through ion exchange beds increases as a result of decreasing particle size. As a result, smaller beads are more likely to fracture (Crittenden. et al, 2005) [4]. The bead size of conventional resins is 300 to 1200 μm.
On the basis of origin, there are two general types of ion exchange materials, that is, organic and minerallic; the former majority is synthetic polymers available in cationic and anionic forms whereas the latter exists in cation-exchange form only (e.g., zeolites and betonites). Thus, organic ion exchange materials can be cationic, anionic, and combined cationic/anionic (amphoteric) exchangers considering the nature of fixed ion exchange sites (functional groups). Since ion exchangers act in a similar way to conventional acids and bases, the main classes of these materials, that is, cation and anion exchangers, can be further classified depending on the type of the functional group into several types: strongly acidic, strongly basic, weakly acidic, and weakly basic materials (Inamuddin and Mohammad , 2012) [13].
The aim of the present work was to investigate that treatment of wastewater (in Daura refinery) by ion exchange (resin) to removal pollutant ion of sulfate, chloride, sodium and during this treatment, also will be calculating best weight of resin, mixing time, study the effect of temperature on removal efficiency of pollutant, study kinetic of reaction and thermodynamic parameter of ion exchange method.

Ion Exchange Capacity
Generally, the ion exchange capacity is expressed in terms of total exchange capacity; the capacity is expressed in terms of a wet-volume capacity. The wet-volume capacity depends upon the moisture content of the resin which is dependent upon the functional form of the resin and will vary for a given type of resin. The wet-volume capacity is commonly expressed in milliequivalents per milliliter of resin bed (meq/mL), although it may also be expressed in terms of kilograins as CaC per cubic foot (kg/ )

No.20 Journal of Petroleum Research & Studies (JPR&S)
100 of resin which depends on the quantity of functional groups in the resin bead.

Selectivity
The selectivity of an ion exchange resin indicates the affinity or preference towards certain anions in terms of anion exchange and cations for cation exchange. . where a higher atomic number is more selective (DeSilva, 1999; Harland and Clive, 1994) [5,10]. The selectivity typically increases with increasing charge on the exchanging cation in the order: For anions, a typical series of selectivity is as follows:

Distribution Coefficient
The distribution coefficient is the concentration of an ion in the exchanger q e = the amount of ion adsorbed at saturation (mg/g).
Plot of ln (q eq t ) versus t allows calculation of the rate constant k 1 and q e .
Similar to pseudo-first order reaction kinetic, q e and k 2 can be determined from the slope and intercepts of plot t/q t versus t.
One of studies of water and wastewater treatment is (Brown et al ,2002) [2] use of a novel ion exchange process ,it has made it possible to utilize either strong or weak acid cation resin to soften produced waters at TDS levels up to 7000mg/L to levels of residual hardness below 0.1 mg/L. By utilizing large dosages of high purity brine it is possible to eliminate the use of acid and caustic, even for regeneration of WAC resins.

Materials
In this study, ion exchange technical used chemicals material resin [strong basic anion Lewatit (mp 500) and strong acid cation Lewatit (S108)].

Effect of Weight Resin on Removal Efficiency of Chloride, Sulfate and Sodium
The resin amount is one of the important parameters used to obtain the quantitative

Effect of Mix Time on Removal Efficiency of Chloride, Sulfate and Sodium
The effect of contact time on the ion exchange of , by strong basic anion Lewatit (mp 500) and strong acid cation Lewatit (S108) exchange resin was The results show that the removal of chloride is greater than the sulfate and sodium. The sequence of removal is therefore Cl < SO4 < Na.

Ion Exchange Kinetic
Kinetics of adsorption describing the solute uptake rate, which in turn governs the
The values of enthalpy and entropy were obtained from the slope and intercept of lnK d versus 1000/T (Fig. 10).  ………………………………………. (5) The values of the thermodynamic parameters for the sorption of ions on lewatit are given in Table (

Conclusions
1. When the amount of resin was increasing the final concentration was decreasing and the removal of efficiency was increasing.
2. The highest efficiency was 91 % when anion resin was used and the mix time is 12 min at neutral pH.
3. The selectivity increases generally with higher valence charge.
4. The actual capacity of resin was in safety lime of the theoretical capacity.

5.
The adsorption process was endothermic, spontaneous and feasible.