Environmental Engineering Department at the College of Engineering, University of Baghdad, held PhD dissertation examination titled:

“Competitive removed of Fe(III), Cr(III) Cu(II) from aqueous solutions using adsorption and eletroco-agulation proceses in batch and continuous systems”

    By the student Amjed Sabah Kamil and supervised Assist.Prof.Dr. Haider Mohammed Abd-AlHameed on Wednesday 27/8/2025, in the Environmental Engineering discussion hall. The examination committee consisted of Prof. Shahla Ismail Ibrahim as Chairman, and the membership of Prof.Dr. Mohanned Jasim Mohammed Ridha, Prof.Dr. Khalid Khazaal Hamadi, Prof.Dr. Zainab Bahaa Mohammed, and Assist.Prof.Dr. Hussein Majeed Faleeh. After conducting the public discussion and listening to the student’s defense, the dissertation was accepted. It was summarized as follows:

In the present study, adsorption of Cu (II), Fe (III), and Cr (III) from aqueous solution onto free-floating plant Water hyacinth (WH) biomass by using Flash graphene was investigated through a series of batch and continuous experiments. Also utilized to remove Cu (II), Fe (III) and Cr (III) ions from aqueous solution employing electrocoagulation methods in two-scale levels in batch and continuous mode. The characterizations of Water hyacinth before and after flash graphene were performed using various techniques including Brunauer, Emmett and Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM). The surface areas of water hyacinth raw, before flash graphene and water hyacinth after flash graphene were found to be (6.38, 23.9 and 101.9 m2/g) respectively. The optimum batch conditions for interaction of water hyacinth and aqueous solution laden with Cu (II), Fe (III), and Cr (III)  have values of pH 7, sorbent dosage 1 gram per 100 milliliters, contact time 1hr. for 50 mg/L metal concentration agitation speed 300 rpm, the higher removal efficiency achieved was 98% for Fe (III) ions in single. The best fit is in Pseudo-Second-Order kineticand and Freundlich isotherm models with coefficient of determination (0.998, 0.941) respectively. Expanded bed reactor was adopted for the continuous removal of Cu (II), Fe (III), Cr (III), the influences of operating factors including: bed height, particles size and flow rates were investigated. For WHAFG, different liquid influent rates  (0.1, 0.2, 0.3) L/min and bed heights (1, 2, and 3 cm) were employed, along with particle sizes of 1 mm, 600 µm, and 250 µm. Investigating the impact of the most crucial operational process parameters on the removal of Cu (II), Fe (III), Cr (III), TDS, EC, and other parameters at two-scale levels in batch and continuous mode without the addition of chemical reagents is the main goal of electrocoagulation. Different variables that affecting the removal efficiencies were evaluated such as electrodes distance (2, 3, 4) cm, hydraulic retention time (10 – 90) minutes, applied Voltage (10, 30, 50 V), influent rates 0.1, 0.2, 0.3 L/min., using (Iron and Graphite) and (Graphite and Graphite) electrodes that depend on the self-electrode potential. In addition, one of the most sustainable and useful by products is found to be producing H2 gas as a clean energy fuel, The optimum H2 products in Single Component System Cr (III) (Iron + graphite) were Energy (0.076 KW), achieved at (50 V, 3 cm electrodes distance and 90 minutes). As a result, in the batch electrocoagulation system the optimum removal efficiencies of single Cr (III) using (Iron and Graphite) and (Graphite and Graphite) electrodes are 94.1 %, 72.4 % respectively, were achieved at (50 V, 3 cm electrodes distance and 90 minutes). Other parameters optimum values of single Cr (III) using (Iron and Graphite) and (Graphite and Graphite) electrodes are TDS (131 ppm, 263 ppm), EC (262 µs/cm, 526 µs/cm), Current (7.72 A, 15.70 A), pH (4.51 and 4.33), Temp. (28.1 C°,36.4 C°) respectively. Also, in the continuous electrocoagulation system the optimum removal efficiencies of single Cr (III) using (Iron and Graphite) and (Graphite and Graphite) electrodes are 91.98 %,68.88 % respectively, were achieved at (50 V, 3 cm electrodes distance and 0.3 L/min. flow rates, 90 minutes). Other parameters optimum values of Single Cr (III) using (Iron and Graphite) and (Graphite and Graphite) electrodes are TDS (148 ppm, 260 pmm), EC (296 µs/cm, 520 µs/cm), Current (5.64 A, 15.46 A), pH (4.17 and 4.37), Temp. (21.9 °C, 30.4 °C) respectively.

The recommendations of this dissertation:

1. Study the capability of using prepared WHAFG for removing other Heavy metals and organic pollutants such as antibiotics, dyes, phenolic compounds and furfural from aqueous solutions in batch and continuous flow system.
2. Compare the biosorption efficiency of using another biomass.
3. Investigate adsorbent disposal after saturation.
4. Investigate the effect of rotating electrodes on the removal of efficiency.