DNA from Plant leaf Extracts: A Review for Emerging and Promising Novel Green Corrosion Inhibitors.

With growing global awareness and concern for environmental protection through the use of less hazardous and environmentally-friendly extracts of plant origin, there has been a plethora of green corrosion inhibitors research with far reaching contributions to the science of corrosion prevention and control. Attention has increasingly turned towards green corrosion inhibitors, compounds of natural origin with anti-oxidant activity towards metals and their alloys. Green inhibitors have been investigated for their corrosion and adsorption properties with good results. The findings from these research works provide evidence of the adsorption behavior of green inhibitors which was confirmed by the adsorption isotherms that were proposed. Adsorption is the first step of any surface reaction and since corrosion is a surface phenomenon the effectiveness of green corrosion inhibitors is related to their ability to adsorb on metal surfaces. This review proposes the potential of plant dna as an emerging and promising novel inhibitor for mild steel. It begins with a list of plants that have been used in studies to determine corrosion inhibition properties and moves on to establish the adsorption behavior of bio macromolecules; protein, polysaccharides (chitosan) and dna. It reviews studies and investigation of dna interaction and adsorption on inorganic surfaces before focusing on the use of salmon (fish) sperm dna and calf thymus gland dna as green corrosion inhibitors for mild steel. It concludes that plant dna is a promising candidate for green corrosion inhibitor given the similarity between the plant and animal dna structure and function, and the fact that the use of plant is more environmentally sustainable than animal-based produc

Recent Natural Corrosion Inhibitors for Mild Steel: An Overview

Traditionally, reduction of corrosion has been managed by various methods including cathodic protection, process control, reduction of the metal impurity content, and application of surface treatment techniques, as well as incorporation of suitable alloys. However, the use of corrosion inhibitors has proven to be the easiest and cheapest method for corrosion protection and prevention in acidic media. These inhibitors slow down the corrosion rate and thus prevent monetary losses due to metallic corrosion on industrial vessels, equipment, or surfaces. Inorganic and organic inhibitors are toxic and costly and thus recent focus has been turned to develop environmentally benign methods for corrosion retardation. Many researchers have recently focused on corrosion prevention methods using green inhibitors for mild steel in acidic solutions to mimic industrial processes. This paper provides an overview of types of corrosion, corrosion process, and mainly recent work done on the application of natural plant extracts as corrosion inhibitors for mild steel

Mixed-metal oxide conducting polymer nanocomposites for the removal of fluoride and chromium(VI) from aqueous solution

Abstract: Water is an indispensable natural resource for sustaining life which is undoubtedly not free in all places. The chemical composition of surface or underground waters is one of the principal aspects upon which the relevancy of water for domestic, industrial or agricultural purposes hinges upon. Inorganic anions are commonly in existence in water; nonetheless, some of these including oxy-anions, are undesirable and continually accountable for the grave environmental and health problems. Such ions like arsenic (As(V)), hexavalent chromium(Cr(VI)), fluoride (F‒) phosphate (PO43‒) and nitrate (NO3‒) when in exceeding maximum limits, constitute some of the most hazardous water pollutants. Fluoride, at low a concentration of 0.8-1.5 mg/L as recommended by World Health Organisation (WHO) can prevent tooth decay and contribute to the development of strong bones, especially in young children. However, at higher concentrations it has catastrophic health effects ranging from dental related problems to debilitating skeletal fluorosis as well as affecting body parts like the muscles, brain, lungs, kidneys, thyroid, reproduction and enzymes. Its high concentration in ground water is primarily owing to the weathering of fluoride rich minerals, high ash volcanic eruptions and many anthropogenic activities. On the other hand, industrial activities such as electroplating, leather tanning, dye production, ferrochrome production, wood preservation, mining and paints manufacture have indirectly led to the discharge of Cr(VI) ions into environmental water. Cr(VI) is one of the most toxic, highly soluble and mobile anions in the environment which causes health problems in the form of dermatitis, damage to the liver, lung and skin cancer, skin irritation and internal haemorrhage. The WHO recommended level of Cr(VI) is 0.1 mg/L in surface waters and 0.05 mg/L in drinking water. Consequently, sustainable technologies have been developed to remove fluoride and Cr(VI) ions from water ranging from chemical precipitation, reverse osmosis, electrochemical methods, adsorption, membrane processes, ion exchange and phytoremediation. Among these techniques, adsorption has shown superiority, attributed to its simplicity in design, low operating costs, efficiency and reversibility. Several adsorbents have been utilised for adsorption successfully. However, some drawbacks such as high cost, low selectivity, narrow pH ranges, low adsorption capacity, slow adsorption and poor mechanical strength have been encountered with some of the adsorbent materials. Nano-metal oxides (NMOs) and conduction polymers have a better potential as adsorbents physical and chemical properties. However they have problems of agglomeration, hence low adsorption capacity and difficult to separate from aqueous media. More studies on modification and...Ph.D. (Chemistry

Synthesis and characterisation of Zeolites from Coal Fly Ash (CFA)

In this study, disposed coal fly ash samples from Zimbabwe were used in synthesis of zeolites. The method of direct hydrothermal treatment with sodium hydroxide at different concentrations (2, 2.5, 3.5 and 4.5 moldm-3) at a constant temperature of 100°C and activation time of 24 h was applied. Characterisation of coal fly ash and confirmation of occurrence of the zeolite material was done using XRF, XRD, FTIR, and BET techniques. The zeolite materials formed were a mixture of zeolite Na-X (NaAlSi1.1O4.2225H2O), zeolite Na-A (Na2Al2Si3.3O8.867H2O), zeolite NaP1 Na6Al6Si10O32H2O) and zeolite hydroxysodalite (Na1.08Al2Si1.68O7.441.8H2O). The variety and yield of zeolites formed depend on the concentration of sodium hydroxide used

Synthesis of zeolites and their applications in heavy metals removal: a review

Over 800 million tonnes of coal fly ash are produced worldwide every year posing an environmental threat due to disposal problems. Nowadays the increasing interest in the synthesis of zeolites from low cost materials has prompted extensive studies on their conversion into zeolites as one of promising coal fly ash utilization methods. Zeolite synthesized from coal fly ash is a minor but interesting product, with a number of environmental applications. This paper provides an overview on the methodologies for zeolite synthesis from coal fly ash, and a description of conventional alkaline conversion processes, of synthesis of different zeolitic products and their methods of characterisation.The examination of the studies presented by different authors reveal that one of the main potential applications of zeolite materials is the uptake of heavy metals and organic pollutants such as dyes from polluted waste waters and nearly all zeolite synthesis have been driven by environmental concerns