Biopolymer-based fly ash-activated zeolite for the removal of chromium from acid mine drainage

Acid mine drainage (AMD), acid rock drainage, and fly ash from coal burning in power plants both posses widespread environmental and economic problems for many countries. Various biopolymers like chitosan have been used as a low-cost adsorbent for removal of toxic metals from AMD. The present investigation involves the microwave synthesis of low-cost chitosan biopolymer-based fly ash zeolite (CS@FAZ) adsorbent for the removal of chromium (Cr) from the acidic environment. The compositional and surface morphological characterization were conducted using FTIR, XRD, and SEM-EDS analysis. The Synthesized adsorbents were used for the removal of Cr (VI) ion under different experimental conditions, including initial concentration (15 to 60 mg L-1), contact time (0 to 180 minutes), dose (0.25 to 4 g L-1), solution pH (2 to 6). The optimum removal was 67.48% at room temperature 27℃, pH 3, concentration 45 mg L-1 and 0.1 g L-1 dose of CS@FZ adsorbent. The field evaluation parameters such as ionic strength and regeneration capacity show the adsorbent’s potential applicability in the remediation of AMD. The kinetics models and adsorption isotherm were determined to be pseudo-second order (R2 > 0.8952) validated with 27.78 mg g-1maximum adsorption capacity and fitted by Freundlichisotherm (R2 > 0.9264). The present low-cost adsorbent can be used for large scale to eliminate the Cr (VI) from the acid mine drainage.