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This study aims to examine the potential of natural clay mineral from the southern part of Saudi Arabia as an effective adsorbent material for the removal of heavy metal ions of cadmium (Cd) and nickel (Ni) from aqueous solutions. The SEM analysis showed that clay particles had mixed shapes such as elongated rod-like and rectangular shape having rough corners with larger particles of 2-8 µm in size and smaller particles in the sub-micron size range. X-ray diffraction data revealed that clay particles had a good crystalline structure and composed of a mixture of various minerals including feldspar, illite, quartz, calcite, and gypsum. The BET surface area was found to be 35 ± 1 m²/g and the average pore size and pore volume of 6.5 ± 0.5 nm and 5.7e-02 cc/g, respectively. The X-ray fluorescence analysis of clay showed main compounds of SiO2 (47.33%), Al2O3 (18.14%), Fe2O3 (15.89%) with many others such as CaO, MgO, TiO2, and K2O in minor quantities. It was found that 1.2 g of clay removed up to 99.5% of Ni and 97.5% of Cd from 40 ppm aqueous solutions. The metal removal efficiencies were increased from around 95% up to 99% by increasing the pH of aqueous solutions from 4 to 11. The adsorption of Ni and Cd ions on Saudi clay was relatively fast, and up to 97% of ions were removed from solution within 45 min. The SEM-EDX and BET analysis for recycled clays further confirmed that the metal ions were removed from water through adsorption onto the clay. The experimental data fitted well with Langmuir and Freundlich isotherms. The maximum adsorption capacity of clay for Cd and Ni from isotherms was found to be 3.3 and 2.7 mg/g respectively. The findings of this study confirm the potential role of Saudi natural clay in wastewater treatment processes as a cheap, environment-friendly and safe natural adsorbent material. [ABSTRACT FROM AUTHOR]

This study presents a preliminary assessment of biodiesel production from waste sources available in the Kingdom of Saudi Arabia (KSA) for energy generation and solution for waste disposal issues. A case study was developed under three different scenarios: (S1) KSA population only in 2017, (S2) KSA population and pilgrims in 2017, and (S3) KSA population and pilgrims by 2030 using the fat fraction of the municipal solid waste. It was estimated that S1, S2, and S3 scenarios could produce around 1.08, 1.10 and 1.41 million tons of biodiesel with the energy potential of 43423, 43949 and 56493 TJ respectively. Furthermore, annual savings of US $55.89, 56.56 and 72.71 million can be generated from landfill diversion of food waste and added to the country’s economy. However, there are challenges in commercialization of waste to biodiesel facilities in KSA, including waste collection and separation, impurities, reactor design and biodiesel quality. [ABSTRACT FROM AUTHOR]

Energy consumption in KSA (kingdom of Saudi Arabia) is growing rapidly due to economic development with raised levels of population, urbanization and living standards. Fossil fuels are currently solely used to meet the energy requirements. The KSA government have planned to double its energy generating capacity (upto 120 GW (gigawatts)) by 2032. About half of the electricity capacity of this targeted energy will come from renewable resources such as nuclear, wind, solar, WTE (waste-to-energy) etc. Natural zeolites are found abundantly in KSA at Jabal Shamah occurrence near Jeddah city, whose characteristics have never been investigated in energy related applications. This research aims to study the physical and chemical characteristics of natural zeolite in KSA and to review its potential utilization in selected WTE technologies and solar energy. The standard zeolite group of alumina–silicate minerals were found with the presence of other elements such as Na, Mg and K etc. A highly crystalline structure and thermal stability of natural zeolites together with unique ion exchange, adsorption properties, high surface area and porosity make them suitable in energy applications such as WTE and solar energy as an additive or catalyst. A simple solid–gas absorption system for storing solar energy in natural zeolites will be a cheap alternative method for KSA. In AD (anaerobic digestion), the dual characteristics of natural zeolite like Mordenite will increase the CH 4 production of OFMSW (organic fraction of municipal solid waste). Further investigations are recommended to study the technical, economical, and environmental feasibility of natural zeolite utilization in WTE technologies in KSA. [ABSTRACT FROM AUTHOR]