In the present study, nano-scale Zero Valent Iron (NZVI) was synthesized in ethanol medium by the method of ferric iron reduction using sodium borohydride as a reducing agent under atmospheric conditions. The obtained iron nanoparticles are mainly in zero valent oxidation state and remain without significant oxidation for hours. A systematic characterization of NZVI was performed using XRD, SEM and TEM studies. The obtained iron nanoparticles consist of a zero valent core surrounding a rest oxide shell. The diameter of iron nanoparticles was predominantly within the range 20-110 nm. Refractory azo-dye compounds used in the textile industry are commonly detected in many industrial waste water. In this study the removal efficiency of three azo dyes, namely, methyl orange, sunset yellow and acid blue a, with laboratory synthesized NZVI particles in relation to the NZVI dosage, dye concentration and pH was determined. Increasing the dose of NZVI particles enhanced the decolonization of the dyes. The degradation decreased with increasing solution pH and concentration of dyes. These findings demonstrated the fast removal of azo dye compounds with NZVI and the advantage of the synthesized NZVI particles to treat azo dye contaminated wastewater.

Bangladesh is one of the top garment exporting countries of the world. In FY 2014-2015, 81.69% of Bangladesh's export industries was comprised of ready-made garments. Dyeing industries are an integral part of most of these garment industries. Unfortunately, majority of the effluents from these dyeing industries are responsible for severe water pollution and environmental degradation as they are often discharged with no or minimal treatment. This has dire consequences as Bangladesh is a densely populated country with a soaring figure of 1252 per km2 as of 2016, based on the latest United Nations estimates. Additionally, it is a chiefly rural and river centric country and 66 % of its population are directly dependent on its rivers for either their livelihood (e.g. fishermen, oarsman) or other household activities such as washing, bathing, cooking and sometimes even drinking. This has led to an outburst of diseases like cholera, dysentery, diarrhea, hepatitis A, lead poisoning, malaria, etc prevailing for the last few years, creating a catastrophic impact on public health. This has made it imperative for wastewater to be treated properly before its release into the water bodies. Although there are a number of techniques available, most of them are expensive and so the local industries are reluctant to use these methods. In this study, it has been attempted to find a cheap and suitable method for removing dyes from these effluents. NZVI (Nano-scale Zero Valent Iron) seems to have a great potential in this aspect. It is cheap, easy to make and has a high efficiency in degrading dyes. Furthermore, only a small amount is sufficient to remove a relatively large amount of dyes, which makes it an attractive treatment method for Bangladesh.