Mohammad Al-Harahsheh

Fly ash-based geopolymer for Pb removal from aqueous solution

The aim of this work was to synthesis highly amorphous geopolymer from waste coal fly ash, to be used as an adsorbent for lead Pb(II) removal from aqueous wastewater. The effect of various parameters including geopolymer dosage, initial concentration, contact time, pH and temperature on lead adsorption were investigated. The major components of the used ash in the current study were SiO(2), Al(2)O(3) and Fe(2)O(3) representing 91.53 wt% of its mass. It was found that the synthesized geopolymer has higher removal capacity for lead ions when compared with that of raw coal fly ash. The removal efficiency increases with increasing geopolymer dosage, contact time, temperature, and the decrease of Pb(2+) initial concentration. The optimum removal efficiency was obtained at pH 5. Adsorption isotherm study indicated that Langmuir isotherm model is the best fit for the experimental data than Freundlich model. It was found also that the adsorption process is endothermic and more favorable at higher temperatures.

Microwave treatment of electric arc furnace dust with PVC: Dielectric characterization and pyrolysis-leaching

Microwave treatment of electric arc furnace dust (EAFD) with poly(vinyl chloride) (PVC) was studied in this work. A comprehensive characterization of the dust as well as assessing the suitability of using the thermal de-chlorination of the common plastic (PVC) under inert atmosphere was carried out to assess the possibility of Zn and other heavy metals extraction (Pb and Cd) from EAFD. The dielectric and thermal properties of EAFD, PVC and their mixtures were measured. Once combined and heated the metal oxides present in the dust reacted with HCl released from PVC during thermal de-chlorination, forming metal chlorides which were subsequently recovered by leaching with water. It was found that zinc chloride could be almost completely recovered in the leaching stage, with the overall recovery of Zn reaching 97% when the EAFD:PVC ratio was 1:2. The investigation highlighted that franklinite, the most refractory mineral to leaching, was completely destroyed. The leaching residue was found to compose mainly of magnetite and hematite.

Microwave-assisted total digestion of sulphide ores for multi-element analysis

A new two-stage microwave-assisted digestion procedure using concentrated HNO(3), HCl, HF and H(3)BO(3) has been developed for the chemical analysis of major and trace elements in sulphide ore samples prior to inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. In the first stage 0.2 g of the certified reference material (CRM) sample was digested with a combination of acids (HNO(3), HCl, and HF) in a closed Teflon vessel and heated in the microwave to 200 degrees C for 30 min. After cooling, H(3)BO(3) was added and the vessel was reheated to 170 degrees C for 15 min. The precision of the method was checked by comparing the results against six certified reference materials. The analytical results obtained were in good agreement with the certified values, in most cases the recoveries were in the range 95-105%. Based on at least 17 replicates of sample preparation and analysis, the precision of the method was found to be < or = 5%.

Pyrolysis of poly(vinyl chloride) and-electric arc furnacedust mixtures.

An investigation into the pyrolysis kinetics of PVC mixed with electric arc furnace dust (EAFD) was performed. Mixtures of both materials with varying PVC ratios (1:1, 1:2, 1:3) were prepared and pyrolyzed in a nitrogen atmosphere under dynamic heating conditions at different heating rates (5, 10, 30 and 50 °C/min). The pyrolysis process proceeded through two main decomposition steps; the first step involved the release of HCl which reacted with the metal oxides present in the dust, subsequently forming metal chlorides and water vapor. Benzene was also found to release as detected by TGA-MS. The remaining hydrocarbons in the polymer backbone decomposed further in the second step releasing further volatile hydrocarbons. Different models were used to fit the kinetic data namely the integral, the Van Krevelen, and Coats and Red fern methods. The presence of EAFD during PVC decomposition resulted in a considerable decrease in the activation energy of the reaction occurring during the first decomposition region. Furthermore, iron oxides were retained in the pyrolysis residue, whilst other valuable metals, including Zn and Pb, were converted to chlorides that are recoverable by leaching in water. It is believed that EAFD can be utilized as an active catalyst to produce energy gases such as propyneas evident from the TGA-MS.

Recycling of stone cutting sludge in formulations of bricks and terrazzo tiles.

This study examines the possibility for enhancing the use of stone cutting sludge waste in the production of building bricks and terrazzo tiles, which would reduce both the environmental impact and the production costs. Stone cutting wastes in the form of sludge is currently generated at several factories in Jordan. At the Samara factory, incorporation of the sludge in the batch formulations of bricks and terrazzo tiles was examined. The physicochemical and mineralogical characteristics of the sludge were analyzed to identify the major components. Results indicated that the sludge generated from stone cutting could be used in producing concrete bricks. Mixtures of aggregates with added amounts of sludge were used successfully to produce non-load bearing bricks. Sludge was also used to produce terrazzo tiles and the results indicate that the transverse strength, water absorption and tile measurements, for all the taken samples, comply with Jordanian standards. The transverse strength decreased while water absorption increased as the sludge ratio increased.

Thermal analysis on the pyrolysis of tetrabromobisphenol A and electric arc furnace dust mixtures

The pyrolysis of Tetrabromobisphenol A (TBBPA) mixed with electric arc furnace dust (EAFD) was studied using thermogravimetric analysis (TGA) and theoretically analyzed using thermodynamic equilibrium calculations. Mixtures of both materials with varying TBBPA loads (1:1 and 1:3) were prepared and pyrolyzed in a nitrogen atmosphere under dynamic heating conditions at heating rates of 5 and 10 °C/min. The mixtures degraded through several steps, including decomposition of TBBPA yielding mainly HBr, bromination of metal oxides, followed by their evaporation in the sequence of CuBr3, ZnBr2, PbBr2, FeBr2, MnBr2, KBr, NaBr, CaBr2, and MgBr2, and finally reduction of the remaining metal oxides by the char formed from decomposition of TBBPA. Thermodynamic calculations suggest the possibility of selective bromination of zinc and lead followed by their evaporation, leaving iron in its oxide form, while the char formed may serve as a reduction agent for iron oxides into metallic iron. However, at higher TBBPA volumes, iron bromide forms, which can also be evaporated at a temperature higher than those of ZnBr2 and PbBr2. Results from this work provide practical insight into selective recovery of valuable metals from EAFD while at the same time recycling the hazardous bromine content in TBBPA.

Olive mills wastewater treatment using local natural Jordanian clay

AbstractIn the Mediterranean area, olives are harvested and sent to mills where olive oil is extracted. These mills produce two types of wastes, namely olive kernel and olive mills wastewater (OMW). This OMW is considered an environmental problem because of its high organic content (COD over 80–200 g/l), high phenolics content (more than 400 mg/l), and low acidic pH (3–6). This study is about investigating the feasibility of using simple naturally occurring local Jordanian clay as a possible adsorbent to decrease the levels of the above negative characteristics of raw OMW as a step in developing a methodology to solve OMW problem without creating new problems to freshwater supply resources. Natural clay was calcined at several temperatures (350–550°C), some of which were further subjected to acid treatment using 1, 3, and 5 M-HCl solutions at 85°C. These treated clays were contacted with OMW in batch experiments to decide on optimum conditions to be used for a continuous packed bed treatment system. COD a...

The effect of reaction conditions on the precipitation of sodium hexafluorosilicate produced from waste hexafluorosilicic acid

The effect of reaction conditions on the precipitation of sodium hexafluorosilicate produced from waste hexafluorosilicic acid The purpose of the study is to investigate the optimum conditions for the precipitation of sodium hexafluorosilicate (Na2SiF6) from waste hexafluorosilicic acid, an effluent from the phosphoric acid industry. Sodium chloride and sodium hydroxide were used as reactants to produce Na2SiF6. The effect of various parameters on the precipitation was investigated and includes; the molar ratio of the reactants, contact time, the temperature and the effect of seeding. The optimum reaction conditions were found to be as follows; excess sodium chloride or sodium hydroxide to hexafluorosilicic acid of 25%, contact time 40 minutes and a reaction temperature of 40°C. The reaction of hexafluorosilicic acid with an aqueous solution of sodium chloride at optimum conditions gave a maximum yield of 94.26% Na2SiF6 while the reaction of hexafluorosilicic acid with the aqueous solution of sodium hydroxide at optimum conditions gave a maximum yield of 97.3% Na2SiF6. The X-Ray diffraction (XRD) analysis reveals that the only crystals present in the precipitate are Na2SiF6. Also, Scanning Electron Microscope (SEM) analysis shows that the different morphology of these crystals depend on the precipitation conditions.

Extracting oil from used auto tires at low temperature after chemical treatment

This study presents an alternative tactic to pyrolysis of auto tires avoiding the use of high temperature and increasing the yield of oil produced. It depends on a simple chemical treatment of auto tires with sodium carbonate at low temperature (50°C) followed by solvent extraction. This treatment produced two folds of the yield that can be obtained using normal solvent extraction. The experimental results suggests that sodium carbonate is responsible for breakage of CS bond in the main structure of auto tires making solvent extraction easier. Additionally, the sulphur content of the extracted oil using the sodium carbonate treatment is reduced significantly (by about 28%) making the product more favorable energy/fuel source. This technique allows about 30wt.% of oil to be extracted from the used auto tires at 50°C under atmospheric pressure resulted from the breakage of the sulphur cross-linking by the sodium carbonate.

Removal of Sulfur Dioxide by a Slurry of Jordanian Oil Shale Ash

Abstract This work presents a study on the capacity of oil shale ash to remove sulphur dioxide from air streams before escaping into the atmosphere. Slurries of different concentrations of this ash showed an uptake capacity of 4 × 10−4 mol SO2/g ash obtained after 250 sec. This value increases with the increase of solution pH, temperature, and ash concentration, and decreases the ash particle size. The process of uptake seems to be coupled with both adsorption of SO3 2− on the surface of metal oxides and reaction with alkali and alkali earth metal hydroxides.