Efficiency of a Modified Rose-Stem-Based Bioadsorbent for the Removal of Cr (III) from Tannery Wastewater

The removal of Cr(III) from tannery effluents using rose stem waste as a bioadsorbent (BA) was investigated. First, sorption experiments were performed using virgin BA to verify its efficiency. Due to the BA’s low retention capacity, it was chemically modified separately with H2SO4, NaOH, and Na3C6H5O7. The BA was characterized by means of a Fourier transform infrared (FT-IR) spectrometer, and subsequently,employed in sorption studies. Second, the effects of pH (2-6), adsorbent dose (33 –300g/L)and contact time (1–30h) were examined through batch experiments. Synthetic solutions (250ppm) prepared with Cr(OH)SO4 were used to study these variables. Then, an actualtannery effluent was used to verifythe ideal conditions selected for the synthetic solutions. An atomic absorption spectrophotometer was also utilized to determine the Cr(III) concentration. The results showed that the efficiency raised with increasing BA dose (200g/L), contact time (20h), and pH 6. The BA efficiency on Cr (III) removal of the tannery effluent (57%) was lowerthan that of the synthetic samples (72%). The pseudo-second-order kinetic model and equilibrium represented by the Sips isotherm,with a power of 5.1mgCr/g BA,best fit the experimental data.