Alaadin A. Bukhari

Effect of Carboxylic Functional Group Functionalized on Carbon Nanotubes Surface on the Removal of Lead from Water

The adsorption mechanism of the removal of lead from water by using carboxylic functional group (COOH) functionalized on the surface of carbon nanotubes was investigated. Four independent variables including pH, CNTs dosage, contact time, and agitation speed were carried out to determine the influence of these parameters on the adsorption capacity of the lead from water. The morphology of the synthesized multiwall carbon nanotubes (MWCNTs) was characterized by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) in order to measure the diameter and the length of the CNTs. The diameters of the carbon nanotubes were varied from 20 to 40 nm with average diameter at 24 nm and 10 micrometer in length. Results of the study showed that 100% of lead was removed by using COOH-MCNTs at pH 7, 150 rpm, and 2 hours. These high removal efficiencies were likely attributed to the strong affinity of lead to the physical and chemical properties of the CNTs. The adsorption isotherms plots were well fitted with experimental data.

Removal of Chromium (III) from water by using modified and nonmodified carbon nanotubes

This study was carried out to evaluate the environmental application of modified and nonmodified carbon nanotubes through the experiment removal of chromium trivalent (III) from water. The aim was to find the optimal condition of the chromium (III) removal from water under different treatment conditions of pH, adsorbent dosage, contact time and agitation speed. Multi wall carbon nanotubes (MW-CNTs) were characterized by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The diameter of the carbon nanotubes produced varied from 20-40 nm with average diameter of 24nm and 10 micrometer in length. Adsorption isotherms were used to model the adsorption behavior and to calculate the adsorption capacity of the absorbents. The results showed that, 18% of chromium (III) removal was achieved using modified carbon nanotubes (M-CNTs) at pH 7, 150 rpm, and 2 hours for a dosage of 150 mg of CNTs. The removal of Cr (III) is mainly attributed to the affinity of chromium (III) to the physical and chemical properties of the CNTs. The adsorption isotherms plots were well fitted with experimental data.

Ground water coagulation using soluble stainless steel electrodes

Abstract This study dealt with colloids separation from ground water in the Eastern Province of Saudi Arabia. The water was found to have a conductivity of 4400 μs/cm and chloride and sulfate concentrations of 834 and 550 mg/l, respectively. The turbidity of the water was increased to 76 nephlometric turbidity unit (NTU) by the addition of bentonite. The efficiency of using soluble stainless steel electrodes for the in-situ formation of ferric hydroxide has been investigated. The electrical current input was found to be inversely proportional to the residual turbidity in the test water. At a contact time of 5 min and a natural chloride content, the highest turbidity removal efficiency of 95% was achieved at a current of 1 A. When the current was reduced to 0.5 A and the contact time was increased to 10 min, the residual turbidity was reduced from 4.0 to 1.6 NTU. Furthermore, similar turbidity removals were achieved at a much shorter contact time (2 min) when 1 g/l sodium chloride was added to the test water. Due to the importance of pH variation with regard to coagulation, the phenomenon of voltage-induced hydrogen evolution was investigated as well. While the solutions final pH increased with the increase in current and contact time, it decreased with the increase in sodium chloride concentration.

Electrochemical Treatment of Nitrite Using Stainless Steel Electrodes

The efficiency of nitrite removal in an electrochemical cell was investigated in this study using stainless steel electrodes. The experiments were designed to study the effects of current input, volume of the solution, initial pH, and number of electrodes on removal of nitrite at a concentration typical to aquaculture system effluents. Current variation causes opposite trends, while an increase in current would increase the oxidizing efficiency of the system, the voltage induced increase in pH due to hydrogen evolution would decrease the efficiency of the oxidizing agent formed. However, the highest nitrite removal was achieved at a current of 2 A and a complete removal was attained after a duration of ten minutes. A first order reaction model was developed to predict the effect of current on nitrite removal. The energy consumption was directly proportional to the initial pH and the solution volume, while it was inversely proportional to the number of electrodes.

Evaluation of micro- and nano-carbon-based adsorbents for the removal of phenol from aqueous solutions

This work reports on the adsorption efficiency of two classes of adsorbents: nano-adsorbents including carbon nanotubes (CNTs) and carbon nanofibers (CNFs); and micro-adsorbents including activated carbon (AC) and fly ash (FA). The materials were characterized by thermogravimetric analysis, transmission electron microscopy, Brunauer–Emmett–Teller (BET) specific surface area, zeta potential, field emission scanning electron microscopy, and UV spectroscopy. The adsorption experimental conditions such as pH of the solution, agitation speed, contact time, initial concentration of phenol, and adsorbent dosage were optimized for their influence on the phenol. The removal efficiency of the studied adsorbents has the following order: AC > CNTs > FA > CNFs. The capacity obtained from Langmuir isotherm was found to be 1.348, 1.098, 1.007, and 0.842 mg/g of AC, CNTs, FA, and CNFs, respectively, at 2 hours of contact time, pH 7, an adsorbent dosage of 50 mg, and a speed of 150 rpm. The higher adsorption of phenol on AC can be attributed to its high surface area and its dispersion in water. The optimum values of these variables for maximum removal of phenol were also determined. The experimental data were fitted well to Langmuir than Freundlich isotherm models.

Coupled electrokinetics-adsorption technique for simultaneous removal of heavy metals and organics from saline-sodic soil.

In situ remediation technologies for contaminated soils are faced with significant technical challenges when the contaminated soil has low permeability. Popular traditional technologies are rendered ineffective due to the difficulty encountered in accessing the contaminants as well as when employed in settings where the soil contains mixed contaminants such as petroleum hydrocarbons, heavy metals, and polar organics. In this study, an integrated in situ remediation technique that couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the efficiency of contaminant removal. For the 21-day period of continuous electrokinetics-adsorption experimental run, efficiency for the removal of Zn, Pb, Cu, Cd, Cr, Hg, phenol, and kerosene was found to reach 26.8, 55.8, 41.0, 34.4, 75.9, 92.49, 100.0, and 49.8%, respectively. The results obtained suggest that integrating adsorption into electrokinetic technology is a promising solution for removal of contaminant mixture from saline-sodic soils.

Removal of bentonite causing turbidity by electro‐coagulation

Abstract The efficiency of electro‐coagulation as a turbidity removal process has been investigated using bentonite as a turbidity source. The influence of certain operational parameters such as current input, contact time, electrolyte concentration, and initial turbidity on the coagulation efficiency were studied. The process was found to achieve excellent turbidity removals. The lowest residual turbidities were 0.5 and 0.75 NTU for the samples with initial turbidities of 112 and 52 NTU, respectively. This was obtained at a current of 0.5 A, a contact time of 5 minutes, and a calculated dissolved iron concentration of 10.8 mg/l. At a constant current of 0.5 A, a reduction in the contact time from 5 to 2 minutes in the case of turbidity level 1 (52 NTU) and from 5 to 1 minute in the case of turbidity level 2 (112 NTU) resulted in better turbidity removals. The optimal operational parameters for turbidity level 1 are a current of 0.5 A, a contact time of 2 minutes and an NaCl concentration of 2 g/l resulti...

Removal efficiencies of indicator micro-organisms in the Al-Khobar wastewater treatment plant

Increasing population and developmental needs of Saudi Arabia underline the need for an increase in the reuse of treated wastewater. However, treated wastewater contains a large number of pathogens that requires proper treatment before reuse. Little information is available on the treatment efficiency of wastewater treatment plants operating in this region. A 1-year study was conducted at the Al-Khobar wastewater treatment plant to investigate the removal efficiency of five indicator micro-organisms, namely, Standard Plate Count, total coliform, fecal coliform, coliphage, and Clostridium perfringens. The raw sewage, secondary effluent, and chlorinated effluent were analyzed weekly for the detection and enumeration of these indicator micro-organisms. High-percent removal of Standard Plate Count, total coliform, and fecal coliform (98 to 99%) was observed after secondary treatment compared to coliphage removal of 83.6% and Clostridium perfringens removal of 55.5%, whereas, after chlorination, Standard Plate...

Seasonal Variations in the Microbial Population Density Present in Biological Sludge

Sludge produced during the treatment of wastewater is being used as fertilizer in several Gulf countries. The Water and Sewage Authority of Saudi Arabia has targeted the reuse of the total amount of sludge in the future. However, these sludges should be properly treated before reuse as they contain a large number of pathogens and parasites. Little information is available on the microbial characteristics of sludge produced in wastewater treatment plants operating in this region. Variations in the population densities measured by Standard Plate Count, total coliform, fecal coliform, coliphage, and Clostridium perfringens present in the sludge, were monitored during a one year study at Al-Khobar wastewater treatment plant so that the effect of seasonal variations on the fate of these five indicator microorganisms could be investigated. This paper covers an evaluation of the fate of indicator microorganisms in the drying sludge. Insight gained in this study will be helpful in establishing guidelines for the use of sludge as fertilizer for agriculture purposes.

Application of Box-Behnken Design to Hybrid Electrokinetic-Adsorption Removal of Mercury from Contaminated Saline-Sodic Clay Soil

A hybrid electrokinetic-adsorption (HEKA) technique using uniform electric field and granular activated carbon (GAC) produced from date palm pits was investigated for the removal of mercury from natural saline-sodic clay heavily contaminated with heavy metals, phenol, and kerosene. Response surface methodology (RSM) was employed to model, optimize, and interpret the results obtained with the aid of Design Expert software. According to the Box-Behnken experimental design, 15 experiments were conducted each with residence time of three weeks. The effects of voltage gradient (0.2–1 V/cm), initial Hg concentration (mg/Kg), and polarity reversal interval (0-48 hours) on Hg removal efficiency and energy consumed for Hg removal were investigated. Respectively, the responses fitted reduced cubic (R2 = 99.3%) and quadratic models (R2 = 92.3%) with the overall relative contributions of the investigated parameters on the responses following the order: voltage gradient > initial Hg concentration > polarity reversal interval based on analysis of variance (ANOVA). The optimal conditions obtained with desirability of 90% aimed at maximizing Hg removal were 24 hours polarity reversal interval, 0.2 V/cm voltage gradient, and 100 mg/kg initial Hg concentration. This optimum operating condition yielded good removal of Hg (99.5%) at reduced energy consumption of 50.1kWh.m−3mg−1. Experimental validation of the models showed good prediction of Hg removal efficiency (0.0368% prediction error). The results presented herein suggest that HEKA technology could be utilized effectively for the removal of Hg from contaminated, low permeable soils under extreme soil and contamination conditions.