Solidification/stabilization of tannery sludge with iron-based nanoparticles and nano-biocomposites

Abstract

This paper presents leaching behavior of chromium from the stabilized/solidified (S/S) matrixes of tannery sludge. S/S matrixes were formed using cement, and nanoparticles and nano-biocomposites. The chromium in tannery sludge was immobilized by ZVIN (zero-valent iron nanoparticles), MIN (magnetic iron oxide nanoparticles), ZVIN–SB (zero-valent iron nanoparticles/sugarcane bagasse composite) and MIN–SB (magnetic iron oxide nanoparticles/sugarcane bagasse composite). The semi-dynamic leachate tests such as ANS 16.1 and ASTM C 1308 were performed to evaluate the efficacy of S/S matrixes. The parameters such as leaching rate, cumulative fraction leached, effective diffusivity, leachability index and leaching mechanism were calculated for the S/S matrixes containing sludge stabilized by nanoparticles and nano-biocomposites and unstabilized sludge. The leaching rate of chromium from the test specimens showed the effectiveness of nanoparticles and nano-biocomposites. Diffusion studies from the S/S matrixes indicated immobility of chromium. The mean leachability index was found to be higher than 13 for all the test specimens which shows that the S/S matrixes can be effectively utilized for ‘controlled applications.’ Further, nanoparticles and nano-biocomposites increased compressive strength of the S/S matrixes. XRD, SEM/EDX and FTIR revealed that chromium could be chemically fixed into cement matrixes.