Adsorption technology and mechanism of As(III) and As(V) in wastewater by iron modified rice husk biochar

Abstract

Arsenic pollution has become a common phenomenon, which seriously endangers the environment and poses a great threat to human health. In this paper, a novel method has been developed for simultaneous removal of composite arsenic pollution based on the modified rice husk biochar as an efficient adsorbent. Iron modified rice husk biochar (MRHB) adsorbent has been prepared using rice husk as raw material, NaHCO₃ as pore expander, FeCl₃·6H₂O as modifier and NaOH as precipitant. The adsorption characteristics of MRHB for As(Ⅲ) and As(V) has been investigated on the basis of batch experiments. X-ray diffraction, scanning electron microscopy, and Fourier Transform Infrared were carried out to characterize the composition and structure of MRHB. The results show that the arsenic concentration of 1.0 mg/L, adsorbent dosage of 1.0 g/L, the maximum removal rates of As(Ⅲ) and As(V) are 99.88% and 99.93% at pH of 5. The adsorption performance of MRHB for As(V) and As(V) fits well to the pseudo-second-order kinetic model, indicating that the chemisorption control plays a dominant role in adsorption process. Results from this study demonstrated the promise of MRHB in application as an efficient and environmentally friendly adsorbent for composite arsenic pollution.