Preparation of Hematite Nano Particles from Galvanizing Effluents for the Applications in Heavy Metal Removal

Abstract

Due to climate change on earth, governments are pursuing the policy of gradually reducing Greenhouse Effects. For example, country like Germany has The demand for safe drinking water grows day by day together with the increasing world population. Meanwhile water resources become increasingly scarce, and quality of natural water decreases due to a combination of natural and anthropogenic factors. Industry and agriculture have become a premiere source of hazardous constituents, along with natural processes such as rock weathering and volcanic eruptions. The ability to remove hazardous components, particularly heavy metals from water depends on the selected technology and nature of pollutant. Water purification technologies, mostly involved with sorption and ion-exchange processes, often uses natural iron oxides as ion-exchangers for removal of harmful contaminants from water. These technologies are based on the unique cation-exchange behavior of iron oxides, thus making this sorbent limited to cation removal. Arsenic, copper and nickel are commonly found in water supplies and, therefore, are selected for this study to represent heavy metals in water systems. In this work, hematite nanomaterials were synthesized from the galvanizing effluent collected from the LTL Galvanizers at Makola, Sri Lanka. The industry generates approximately 50 m3 of galvanizing effluent per month and it composes both iron and zinc chlorides. To synthesize pure iron oxide materials, we used the effluents from none re-galvanized chemical baths, which does not contain any zinc chlorides. The synthesized materials were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Sorption behaviors of As(III), Cu(II) and Ni(II) were examined batch-wise as a function of pH, temperature, contact time, adsorbent dosage and initial metal ion concentration. Residual concentrations of As(III), Cu(II) and Ni(II) in the solution were determined by the inductively coupled plasma mass spectroscopy (ICP-MS). The adsorption studies were performed by changing one of the conditions while keeping all others fixed. According to the results, maximum percent removals (%) for all metal ions tested were reached within a short period of 30 minutes. For a given parameter the maximum percent removal (%) of both Cu(II) and As(III) reached more than 95%, while the Ni(II) had percent removal between 35% and 65%.