Abstract
In the present article we have demonstrated a swift and low-cost method to design hydrophobic paper and its potential applications for the determination of Ni2+ ions in wastewater. Styrofoam was used as a precursor to fabricate pristine filter paper into a low wetting substrate. The water contact angle (theta) of the modified paper was similar to 111 degrees whereas atomic force microscopy analysis ensured a uniform coating of the polymer onto cellulose fibers. Metal specific reagent 1-(2-mercaptophenyl) iminomethyl naphthalen-2-ol (MPMN) was manually arrayed and one-step assay for the determination of Ni2+ was demonstrated on the aforementioned substrates. The end-result was observed in the form of a distinct color change which was easily readable via the naked eye. We also quantitated the concentration of Ni2+ ions through flatbed scanning and scoring their pixel gray volume using image analysis software. On Styrofoam modified paper, the limit of detection was improved to 10(-2) mu g mL(-1), which was 3-orders of magnitude lower than that observed on pristine filter paper. The MPMN reagent was highly selective towards Ni2+ in the presence of a high concentration of commonly diverse heavy metals (Ag+, Al3+, As3+, Ba2+, Cd2+, Cr3+, Fe3+, Pb2+ and Mn2+) and some other ions (Na+, Ca2+, K+ and Cl-) in water. Our developed method successfully demonstrated the semi-quantitative determination of Ni2+ ions in tap and municipal wastewater samples. Due to good specificity as well as accuracy towards Ni2+ ions, our low-cost sensor will be useful in point-of-use applications.