Removal of Heavy Metals from Oil Fields Drilling Mud Wastewater Using Zeolite

Abstract

The aim of this research work was to study the potential capability of zeolites and kaolin to remove some, heavy, metals from drilling mud wastewater. Four samples were used, (three zeolites and one kaolin). Two natural zeolites (Stablite and Stellerite) collected from Al Gadaref state (East Sudan), synthesized zeolite from fly ash using sodium hydroxide under hydrothermal conditions. Kaolin sample collected from Elmerkhiat mountain (North-East Omdurman Sudan). X-ray diffraction (XRD) was used to indicate crystal structure and ascertain zeolites and kaolin quality, the result shows that stablite (ZN1), have monoclinic, for stellerite (ZN2) similar to orthorhombic, synthesized zeolite (SZ) attributed to hexagonal and for natural kaolin (ka) triclinic. X-ray fluorescence (XRF), shows that major constituents of sample are SiO2 and Al2O3, in addition some other oxide, such as MgO, CaO, Fe2O3, TiO2 and Na2O were also detected. The main constituents were confirmed by scanning electron microscopy (SEM), and Energy Dispersive (EDX) analysis to be oxygen, silicon and aluminum, and the main function group of samples were determined using, Fourier Transform Infrared (FT-IR) analysis to determine framework of sample (SiO4 and AlO4) from 681cm-1 to 698cm-1. The morphology of samples investigated using (SEM) to show a profound crystalline property of the samples. In addition, specific surface area, pore size and pore volume of samples investigated by N2 (adsorption- desorption) analysis, surface area of ZN1 was 20.44m2/g, ZN2 26.88m2/g, SZ 40.717m2/g and Ka 14.73m2/g, the pore size was 11.8 nm, 12.69nm, 13.8 nm and 18.02nm respectively. Some parameters such as pH, concentration and contact time were optimized for efficiency, from stander solutions of (Cr3+, Co2+, Zn2+ and Fe2+), the optimum condition for removal were 4.5 to 6.0 pH, metal concentration of 200ppm and 80 minutes. These conditions were adopted to minimize the level of targeted heavy metals in wastewater of drilling mud (fluid) collected from oil filed. The experimental data showed that the respective efficiency v percent of those species were 66.6%, 80, 80%, 50% and 77% for ZN1, 83.8%, 96.8%, 38.4%, and 38.3% for ZN2, 99%, 97%, 98% and 80% for SZ and 72.8%, 78.6%,77.9% and 39% for Ka. Synthesized zeolite showed high affinity to remove heavy metals due to increased surface area 40.317m2/g.