Date of Award

2-2014

Document Type

Thesis

Degree Name

Master of Science in Chemical Engineering (MSChE)

Department

Chemical Engineering

First Advisor

Muftah El- Naas

Second Advisor

Dr. Sulaiman AI - Zuhair

Third Advisor

Dr. Yaser Greish

Abstract

Electrocoagulation (EC) has been evaluated for the removal of Cr (VI) from brackish groundwater using three different bench-scale EC reactors, namely batch stirred tank reactor (BSTR), continuous stirred tank reactor (CSTR) and a continuous electrocoagulation column (ECC). Batch EC process was experimentally examined at room temperature and the results indicated that Fe-Fe electrode pair was the most efficient arrangement and was able to achieve 100 % Cr removal at an electrocoagulation time of 5 minutes, a current density of 7.94 mA/cm2, and pH of 8. A kinetic study of batch EC was then performed using both pseudo-first-order and pseudo-second-order models. It was confirmed that removal of chromium by EC follows pseudo-first-order models. In all conditions SSE was minimized below 3.696. The generated sludge was characterized using EDS, X-ray fluorescence (XRF) and FE-SEM. The analysis confirmed the formation and precipitation of Fe(OH)3 and Cr(OH)3 as solids. The efficiency of different inlet flow rate was also assessed for both continuous CSTR and ECC, and indicated that 90 mL/min was the most efficient flow rate when continuous stirred EC (CSTR) reactor is used, and 30 mL/min using continuous column EC (ECC), at Fe/Fe pairs and room temperature 25 °C. The study affirmed that the new innovative ECC process improves the removal efficiency of chromium with lowest estimated energy consumption of 0.75 kWh/m3 and dissolved iron of 0.185 mg/l with an electrical cost of 0.030 US $/m3 of treated groundwater. Overall, the study affirmed that electrocoagulation is a reliable, environmentally compatible technique for the purification of groundwater.

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