An efficient sonophotocatalytic degradation of reactive blue 19 (RB 19) dye was successfully carried out using sulphur-doped TiO₂ (S-TiO₂) nanoparticles. The effect of various treatment processes that is sonolysis, photolysis, catalysis, sonocatalysis, photocatalysis, and sonophotocatalysis were investigated for RB 19 removal. S-TiO₂ were synthesized in 1, 3 and 5 wt % of sulphur by sol-gel process and characterized by X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX), UV-Visible diffuse reflectance spectra (DRS). The results confirm anatase phase of TiO₂, porous agglomerate structure, and a red shift in the absorbance spectra of S-TiO₂. The dye degradation was studied by using UV-Vis spectrophotometer at λ_max = 594 nm. The reaction parameters such as pH, catalyst dosage, initial dye concentration, ultrasonic power and effect of sulphur doping in different weight percent were studied to find out the optimum degradation conditions. Optimum conditions were found as:S-TiO₂ = 5 wt %, catalyst (S-TiO₂ 5 wt %) = 50 mg, RB 19 solution concentration = 20 mg L^-1, pH =3, ultrasound power = 100 and operating temperature = 25 ^oC.The response of 5 wt % S-TiO₂ was found better than 1 and 3 wt % S-TiO₂ and other forms TiO₂. The sonophotocatalysis process was superior to other methods. During this process the ultrasound cavitation and photocatalysis water splitting takes place which leads to the generation of ^●OH. As reveled by the GC/MS results the reactive Blue 19 (20 mg L^-1) was degraded to 90 % within 120 min. The S-TiO₂ sonophotocatalysis system was studied for the first time for dye degradation and was found practicable, efficient and cost effective for the degradation of complex and resistant dyes such as RB19.

Synthetic azo dyes are economic, cheap and stable to washing and sunlight exposure due to their chemical structure and properties. For such reasons, these dyes are extensively used in coloring of textile, leather, plastic and paint but they can cause quality damage to the water bodies which make it necessary to treat the dyes before discharging into the environment as they have great potential to negatively affect the environment. This research addressed the theory and the effects of operational parameters involved in Sono-Fenton oxidation on the targeted pollutant (Congo red). The effects of varying the concentrations of hydrogen peroxide and iron sulfate, pH, ultrasonic power, dye concentration, temperature and reaction time on the discoloration and degradation efficiencies were investigated. Degradation was carried out with Ultrasonic frequency of 35 kHz at 20, 40, 60 and 80 W acoustic intensity with initial dye concentration of 5, 10, 15, 20, 25, and 50 mg L^-1 and optimized quantities of H₂O₂ and FeSO₄ addition. It was observed that the degradation rate by Ultrasound alone was slow, however, sonication significantly accelerated the Fenton reaction. Alone Fenton process resulted in less removal of the dye from the solution, but Ultrasound assisted Fenton technique maximized the results upto 83 % in 60 min and COD was removed up to 89% from the solution after 60 min of contact time. From the derived results it is concluded that Ultrasound can significantly increase the degradation rate of Congo red dye in a solution through Ultrasound assisted Fenton process as they produce rather more H•  and •OH radicals synergistically which enhances the degradation efficiency.

Under the KSA vision 2030, the non-ferrous metal products industry is growing at a record growth rate of 54%. However, this rapid industrialization has also caused the introduction of highly acidic and heavy metal laden wastewater whose carcinogenic effects are well known. In the proposed work, we will use magnesite (MgCO₃) tailings as a low-cost adsorbent which can be used for both neutralizing the acidic waste as well as removing heavy metals by adsorption from wastewater of non-ferrous metal product industry. First, batch experiments will be done to find out the adsorption mechanism using various adsorption models. Secondly, rapid small scale column tests will be done to understand the dynamics of the contaminant removal so that effluent quality can be further improved. In the end, an economic feasibility for usage of locally manufactured magnesite columns in industry will be done based on the performance.

Our work will help to:

1. Introduce cheaper locally available adsorbents
2. Treat industrial waste at minimum cost
3. Create research interests and job opportunities in this emerging field of adsorbent production

The expected outputs from our work are:

1. Production of cheaper and more efficient adsorbents
2. Removal of industrial waste contaminants using natural material

Keywords : Magnesite, Adsorption, Acid Mine Waste, small scale column test

Mining, mineral processing and metallurgical extraction are the three principal activities of gold mining industries which produce mining wastewater. Large quantity of wastewater is produced during these activities which is release to the environment. Heavy metal pollution like Zn, Ni, Pb, AS, Cu, Cd, Co, Hg and acid mine drainage is a very important environmental concern due to waste materials containing metal rich sulfides from mining activity. These characteristics of gold mining wastewater result in complex stresses for the biological treatment and leads to selection of different treatment technology like physical removal of heavy metals by activated carbon. This study aims to investigate the Rice Husk potential for selected heavy metals removal. The sorption study will be conducted in batch and column reactors. Various parameters like column height, flow rate, adsorbent doze, temperature, time, pH and particle size will be optimized for maximum heavy metals removal. The adsorbent surface characterization will be done by Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscope (SEM). The data will be analyzed using isotherms and kinetic models.

Gold Mine wastewater possesses heterogeneous heavy metals contaminants. Application of adsorption technology has not yet been used for heavy metals in mult-solutes removing using rice husk in natural form and as precursor for functionalized activated carbon in batch and fixed bed column reactors simultaneously.

Objective

To screen the potential of rice husk for treatment of heavy metals from aqueous solution.

To convert the adsorbent into activated carbon form with required sequestration properties for efficient metal removal in batch and column reactors.

To study adsorption mechanism for rice husk and its activated carbon using various isotherms, thermodynamics and kinetic models.