The rapidly increasing population, depleting water resources, and climate change resulting in prolonged droughts and floods have rendered drinking water a competitive resource in many parts of the world. The development of cost-effective and stable materials and methods for providing the fresh water in adequate amounts is the need of the water industry. Traditional water/wastewater treatment technologies remain ineffective for providing adequate safe water due to increasing demand of water coupled with stringent health guidelines and emerging contaminants. Nanotechnology-based multifunctional and highly efficient processes are providing affordable solutions to water/wastewater treatments that do not rely on large infrastructures or centralized systems. The aim of the present study is to review the possible applications of the nanoparticles/fibers for the removal of pollutants from water/wastewater. The paper will briefly overview the availability and practice of different nanomaterials (particles or fibers) for removal of viruses, inorganic solutes, heavy metals, metal ions, complex organic compounds, natural organic matter, nitrate, and other pollutants present in surface water, ground water, and/or industrial water. Finally, recommendations are made based on the current practices of nanotechnology applications in water industry for a stand-alone water purification unit for removing all types of contaminants from wastewater.

Nanocomposites have a great potential to work as efficient, multifunctional materials for energy conversion and photoelectrochemical reactions. Nanocomposites may reveal more improved photocatalysis by implying the improvements of their electronic and structural properties than pure photocatalyst. This paper presents the recent work carried out on photoelectrochemical reactions using the composite materials of ZnO with CdS, ZnO with SnO 2 , ZnO with TiO 2 , ZnO with Ag 2 S, and ZnO with graphene and graphene oxide. The photocatalytic efficiency mainly depends upon the light harvesting span of a material, lifetime of photogenerated electron-hole pair, and reactive sites available in the photocatalyst. We reviewed the UV-Vis absorption spectrum of nanocomposite and photodegradation reported by the same material and how photodegradation depends upon the factors described above. Finally the improvement in the absorption band edge of nanocomposite material is discussed.

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The present work studied the effect of temperature on the corrosion behavior of API X120 steel in a saline solution saturated with co 2 in absence and presence of polyethyleneimine (pei) as an environmentally safe green inhibitor. The effect of PEI on the corrosion behavior of API X120 steel was investigated using destructive and non-destructive electrochemical techniques. The overall results revealed that PEI significantly decreases the corrosion rate of API X120 steel with inhibition efficiency of 94% at a concentration of 100 μmol L −1. The adsorption isotherm, activation energy and the thermodynamic parameters were deduced from the electrochemical results. It is revealed that the adsorption of PEI on API X120 steel surface follows Langmuir adsorption isotherm adopting a Physichemisorption mechanism. Finally, the samples were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques to elucidate the effect of aggressiveness of corrosive media on the surface morphology and the corrosion performance of API X120 steel. The surface topography result indicates that the API X120 steel interface in PEI presence is smoother than co 2 with cl − ions or cl − ions only. This is attributed to the compact protective film limits the aggressive ions transfer towards the metallic surface and reduces the corrosion rate. Moreover, PEI inhibition mechanism is based on its co 2 capturing ability and the PEI adsorption on the steel surface beside the siderite layer which give the PEI molecules the ability to reduce the scale formation and increase the corrosion protection due to capturing the CO 2 from the brine solution. High strength low alloy (HSLA) steels are widely finding its applications in oil & gas industry, thermal power plants and in aerospace industry etc. due to its improved mechanical properties, superior corrosion resistance and weldability when compared with plain carbon steel 1-4. Series of comparative studies have been focused on HSLA pipelines steels in order to understand the effect of alloying elements, heat treatments and other changeable factors on their mechanical properties and microstructure 5-8. it has been reported that the yield strength of the API X120 steel is in range 780-951 MPa based on the shape of the specimen. Moreover, the tensile strength is varied from 940 to 1023 MPa and the strength is more than X120 ksi and reaches to X120 grade according to the API standards 9-11. Corrosion is the major problem that compact the API X120 steel pipelines in the transportation of oil, gas. There are a myriad number of studies that investigate the influence of carbon dioxide with saline solution on the corrosion mechanism of different grades of steel pipelines employed in the pipeline applications 12,13. Additionally, it has been reported that the presence of carbonate ions in oilfield brine solution increases the corrosion rate of the pipelines 14-16. Several parameters have been noted for the corrosion of steel in CO 2 environment such as PH, temperature, CO 2 pres...