Enhanced methylene blue adsorption from aqueous solution by corn stalk/diatomite gel porous materials

Abstract

Corn stalk and diatomite were cross-linked by N,N'-Methylenebisacrylamide (MBA) to obtain gel porous materials for methylene blue adsorption, which improved the multi-element pores effect. The process solved the difficult recovery problem of powder adsorbents as well. Results showed that the optimal preparation conditions of corn stalk/diatomite gel porous materials were: 1 mL of glutaraldehyde, 6 g of acrylic acid, 150 mg of MBA and 100 mg of potassium persulfate. The adsorption process conditions were optimized: At the pH = 8, 8 mg of gel porous material was adsorbed for 1 hour. Under the optimal conditions, the removal percentage was 93.65% and the adsorption capacity reached 288.43 mg/g. The characterization results indicated that the corn stalk was successfully combined with diatomite. Corn stalk/diatomite gel porous materials had a three-dimensional network structure with more active sites. The adsorption isotherms fit the Langmuir model. Furthermore, the adsorption kinetics fit the pseudo-second-order model. The adsorbent surface is uniform and the adsorption process is mostly monolayer adsorption. The adsorption process includes chemical and physical adsorption. The maximum saturated adsorption capacity was 657.89 mg/g. Corn stalk/diatomite gel porous materials maintained good adsorption performance after cyclic adsorption. The adsorbent prepared in this study has a good regeneration cycle and methylene blue removal capacity.

Graphical Abstract

Keywords:

• Corn stalk/diatomite
• porous material
• methylene blue
• isotherm
• kinetics

Author contributions

Ying Zhang: Data curation, Writing- Original draft preparation. Xueru Sheng, Na Li, Qingwei Ping and Peng Lu: Supervision. Jian Zhang: Funding acquisition, Writing- Reviewing and Editing.

Disclosure statement

The authors declare no competing financial interest.

Figure 1. CDGM flowchart.

Figure 2. Effects of (a) glutaraldehyde, (b) acrylic acid, (c) MBA, and (d) potassium persulfate (KPS) dosage. (Adsorption condition: 50 mL of 50 mg/L MB @25 °C.).

Figure 3. SEM images of (a) diatomite, (b) corn stalk, and (c) CDGM.

Figure 4. FTIR of corn stalk, diatomite, and CDGM.

Figure 5. X-ray diffraction spectra for corn stalk, diatomite, and CDGM.

Figure 6. Zeta potential of corn stalk, diatomite, CDGM, and after adsorption @ pH = 7.

Figure 7. Effect of pH on the adsorption of MB. (Adsorption condition: adsorbent dosage = 8 mg, adsorption time = 60 minutes, 50 mL of 50 mg/L MB @25 °C.).

Figure 8. Effect of adsorbent dosage on the adsorption of MB. (Adsorption condition: pH = 8, adsorption time = 60 minutes, 50 mL of 50 mg/L MB @25 °C.).

Additional information

Funding

We are very grateful funded by the Opening Project of Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control (No. 2019KF20), Liaoning Revitalization Talents Program XLYC1802025 and Fundamental scientific research project of higher education institutions of Liaoning Provincial Department of Education (J202133).