Comparison of Cation Anion Dye Removal Characteristics between Kelp-based Magnetic Biochar and Pine-based Magnetic Biochar

• Published in: Daehan hwan'gyeong gonghag hoeji Vol. 42; no. 6; pp. 308 - 318
• Main Authors: Oh, Hee So, Chang, Jae-Soo
• Format: Journal Article
• Language: English
• Published: Korean Society of Environmental Engineers 01-06-2020
• Subjects: adsorption; congo red; crystal violet; kelp; magnetic biochar
• ISSN: 1225-5025; 2383-7810
• DOI: 10.4491/KSEE.2020.42.6.308

Objectives:This study investigates the adsorption capacity of magnetic biochar (KB-Fe) derived from kelp for two dyes, Congo red (CR) and crystal violet (CV), which have different charge characteristics. The adsorption capacities were compared to magnetic biochar (PB-Fe) derived from pine.Methods:Pristine biochars (KB, PB) were produced through the pyrolysis of kelp and pine sawdust at 500℃. Magnetic biochars (KB-Fe, PB-Fe) were produced by treatment of 60 g of biomass in 1 L of 0.1 M FeCl3･6H2O and pyrolysis of the raw materials at 500℃. The fundamental characteristics of the biochars were analyzed, and the adsorption capacities of the biochars for the CR and CV dyes were evaluated based on two adsorption isotherm models, two adsorption kinetics models, and adsorption characteristics based on changes to the pH between 5 and 11.Results and discussion:CR adsorption by all biochars decreased with an increase in pH. When KB and PB were surface-modified with magnetic iron oxides, their adsorption capacity for CR increased. CV adsorption by all biochars increased with pH. When KB and PB were surface-modified with magnetic iron oxides, their adsorption capacity for CV considerably decreased. According to the Langmuir isotherm model, the adsorption capacity for CR was in the order of KB-Fe, KB, PB-Fe, and PB, and the adsorption capacity for CV was in the order of KB, PB, PB-Fe, and KB-Fe. The CR adsorption was better described by the pseudo-second order kinetics model for all biochars, with the exception of KB-Fe. CV adsorption was also better described by the pseudo-second order kinetics model for all biochars, with the exception of KB.Conclusions:The results show that kelp biochar has great potential for the adsorptive removal of CR and CV compared to pine-based biochar. In addition, it was demonstrated that surface modification of kelp biochar with magnetic iron oxides can significantly improve its adsorptive capacity for anionic dyes; however, its adsorptive capacity for cationic dyes decreases.