Adsorption characteristics and mechanisms of Cd2+ from aqueous solution by biochar derived from corn stover

Abstract

Corn stover could be pyrolysed to prepare biochar for removing pollutants in water and realizing the resource utilization of biomass. The aims of the present study were to investigate the optimal preparation and adsorption conditions of biochar and to reveal the adsorption characteristics and mechanisms of Cd2+ in water by biochar. For this purpose, with Cd2+ as the target pollutant, the pyrolysis conditions involved in the pyrolysis temperature, retention time, and heating rate were evaluated and optimized. Additionally, the characteristics, mechanisms and optimal adsorption conditions of Cd2+ by biochar were determined. A series of characterization techniques was employed, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and specific surface area analysis (SBET). The optimum pyrolysis parameters were a pyrolysis temperature of 700 °C, a retention time of 2.5 h, and a heating rate of 5 °C/min. Acid/base modification did not improve the adsorption capacity of biochar. The Langmuir and the Elovich model were the most suitable isotherm and kinetic models for equilibrium data, respectively. The maximum adsorption capacity fitted by Langmuir model was 13.4 mg/g. Furthermore, mineral precipitation and π electron interactions were shown to be the main adsorption mechanisms of Cd2+. The optimum adsorption conditions for Cd2+ in water were a CaCl2 electrolyte solution of 0.01 mol/L, a pH level of 6.7, and a biochar dosage of 0.4 g. Our results indicated that corn stover biochar was an appropriate approach for improving the status of water with Cd2+ contamination in the short term and for promoting a new perspective for the rational utilization of corn stover and the low-cost pollution control of heavy metals in water.

From Waste to Green: Water-Based Extraction of Polyphenols from Onion Peel and Their Adsorption on Biochar from Grapevine Pruning Residues

“…This circumstance could have occurred due to the presence of unsaturated adsorption sites during the adsorption process, while the limited adsorption capacity may be due to particle aggregation, resulting from high adsorbent mass [ 85 ]. In the research conducted by Chen et al [ 86 ], the influence of biochar dosage on Cd 2+ adsorption was investigated, among others conditions. The optimum adsorption conditions were obtained using a biochar dosage of 0.4 g which is similar to the results obtained in this work.…”

Detoxification of corn stover prehydrolysate by different biochars and its effect on lactic acid fermentation

“…The surface area of corn stover biochar made by Chen et al under 500 °C for 60 min is 4.56 m 2 g −1 , which is similar to the result in this study. 24 Zhang et al produced biochar from cow manure at 500 °C which has a surface area of 1.77 m 2 g −1 . 25 Among the three biochar samples produced in this study, MB has the largest surface area of 7.03 m 2 g −1 , followed by CSB (5.18 m 2 g −1 ), and CMB (4.08 m 2 g −1 ).…”

Sustainable Technological Applications of Green Carbon Materials

“…Biochar-type materials were prepared from the pyrolysis (700 • C, retention time of 2.5 h, and heating rate of 5 • C/min under nitrogen) of corn stover [51]. This carbon-based material was used to remove cadmium (II) ions from water, with a maximum adsorption capacity of 13.4 mg/g [51].…”

“…Biochar-type materials were prepared from the pyrolysis (700 • C, retention time of 2.5 h, and heating rate of 5 • C/min under nitrogen) of corn stover [51]. This carbon-based material was used to remove cadmium (II) ions from water, with a maximum adsorption capacity of 13.4 mg/g [51]. Biochar has been used to remove heavy metals from aqueous solutions due to its large SSA and the precipitation of metal hydroxides due to the high pH and surface O/C ratio and polarity [52].…”