Anita S. Mramba

Bio: Anita S. Mramba is an academic researcher from Tshwane University of Technology. The author has contributed to research in topics: Effluent & Adsorption. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

Biopolymer composites for removal of toxic organic compounds in pharmaceutical effluents – a review

Abstract: The generation of polluted and/or toxic effluents from pharmaceutical companies has emerged as one of today's most pressing environmental challenges. Traditional wastewater treatment methods which have been employed to address such challenges over the years have numerous significant drawbacks. Adsorption is gaining popularity in the scientific community due to its high performance, low cost, ease of handling, and diverse range of adsorbents. This review paper focuses on the application of green, environmentally friendly, cheap or readily available biodegradable biopolymer composite adsorbents as a developed technique in an attempt to completely degrade toxic recalcitrant organic compounds from various environmental matrices. This paper will discuss traditional methods, advanced methods, combination techniques including benefits and drawbacks, as well as by products or any side effects that limit their use.

Organophosphorus Pesticides: Impacts, Detection and Removal Strategies

Abstract: • The toxicities (acute or chronic) of the organophosphorus pesticides on human is a function of exposure concentration. • Organophosphorus pesticides detection methods (conventional methods and advanced techniques) were compared. • Adsorption is comparatively cheaper than various other organophosphorus pesticides removal strategies. • The fates of degradation products of organophosphorous pesticides need to be further explored. Pesticides are applied to enhance the agricultural productivities by controlling the pests. However, enormous amount of the excessively-applied pesticides get into the environmental samples such as soil, water and air where they exert their toxic effects. One of the common pesticides in the environment is a group known as organophosphorus pesticides. Their persistency is low when compared to that of the organochlorine pesticides but their wide usage has raised serious concern among the environmentalists and government agencies. Herein, the toxicities of the organophosphorus pesticides on soil, water, air and man have been discussed. With their toxicities in mind, the conventional methods and the advanced techniques for their detections were discussed in details. The merits and demerits of these methods were highlighted. Finally, various methods of removing the detected organophosphorus pesticides from the environment were comprehensively discussed.

Electrochemical removal of 4-Clorophenol in water using a porous Magnéli-phase (Ti4O7) electrode.

Abstract: Electro-oxidation is a promising technology for removal of refractory organic pollutants. While the appeal of this technology lies in its chemical-free nature, commercially scale-up application may be limited by the availability of electrode materials and mass transport. Here we report the development of a flow-through electro-oxidation system for removal of chlorophenols in water using Magnéli-phase (Ti4O7) tubular anode and a 304 stainless steel (SS) tubular cathode. The key to this system was the porous and conductive Magnéli-phase Ti4O7 anode, the structure and composition of which was confirmed by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. System efficacy was evaluated by using 4-chlorophenol (4-CP) as a typical refractory contaminant and model chlorophenol. Under optimized conditions, a complete removal of 4-CP could be obtained within 120 min in 0.04 mol L-1 Na2SO4 solution. Electro-produced HO• and direct electron transfer were both shown to contribute to the 4-CP electro-oxidation process due to the high selectivity and oxygen evolution potential of the Ti4O7 anode. The intermediates of 4-CP degradation were identified and a pathway for its electro-oxidation was proposed. When challenged with industrial wastewater containing 4-CP, chemical oxygen demand (COD) and total organic carbon removal efficiencies of 67.5% and 63.1% respectively could be obtained, accounting for energy consumption of 85.1 kWh·kg COD-1 for degradation of 1 kg of COD in industrial wastewater. This study provides an effective and robust solution for the removal of refractory emerging contaminants from industrial wastewaters using a continuous-flow electro-oxidation system.

Iron-based materials for the adsorption and photocatalytic degradation of pharmaceutical drugs: A comprehensive review of the mechanism pathway

Abstract: Adsorption and photocatalytic degradation techniques for removing various contaminants have received broad consideration and acceptance due to their advantages over conventional wastewater treatment techniques. Iron-based materials are among several groups of adsorbents, and photocatalysts that have proven to be effective in pharmaceuticals-based pollutants removal from wastewater. Pharmaceutical drug removal is accompanied by several mechanisms, so there is a deep need for a better understanding of the complexity and development of wastewater treatment using iron-based materials. Therefore, this review examined the mechanism of adsorption and photocatalysis degradation of pharmaceuticals in aqueous solutions by iron-based materials. The adsorption of pharmaceutical drugs was found to be influenced by changes in the solution pH. The mechanism of removal of these contaminants by iron-based materials through adsorption occurred via electrostatic, π-π, and hydrogen bond interactions among others. In the case of photocatalysis, the first mechanism occurred through the formation the hydroxyl radicals due to highly reactive species (electrons and holes) that partook in the reaction processes, while the second mechanism is related to the formation of hydrogen peroxide, H2O2, by photogenerated electrons in the conduction band and with the well-known photo dissolution of iron oxide leading to free Fe2+ and Fe3+ ions. The overall idea of this review is to provide useful information on the mechanisms of adsorption and photocatalytic degradation of pharmaceutical contaminants using iron-based materials. The review summarizes the current understanding and the advances in the pharmaceutical-bearing effluent treatment using nanostructured adsorbents and photocatalysts, including future developments for a cleaner and safer environment.