Removal of Congo Red and Methylene Blue from Aqueous Solutions by Vermicompost-Derived Biochars

Abstract

Biochars, produced by pyrolyzing vermicompost at 300, 500, and 700°C were characterized and their ability to adsorb the dyes Congo red (CR) and Methylene blue (MB) in an aqueous solution was investigated. The physical and chemical properties of biochars varied significantly based on the pyrolysis temperatures. Analysis of the data revealed that the aromaticity, polarity, specific surface area, pH, and ash content of the biochars increased gradually with the increase in pyrolysis temperature, while the cation exchange capacity, and carbon, hydrogen, nitrogen and oxygen contents decreased. The adsorption kinetics of CR and MB were described by pseudo-second-order kinetic models. Both of Langmuir and Temkin model could be employed to describe the adsorption behaviors of CR and MB by these biochars. The biochars generated at higher pyrolysis temperature displayed higher CR adsorption capacities and lower MB adsorption capacities than those compared with the biochars generated at lower pyrolysis temperatures. The biochar generated at the higher pyrolytic temperature displayed the higher ability to adsorb CR owing to its promoted aromaticity, and the cation exchange is the key factor that positively affects adsorption of MB.

Surface oxygenation of biochar through ozonization for dramatically enhancing cation exchange capacity

“…Methylene blue is natively positively charged in solution, and therefore is more electrostatically attracted to biochar that has been treated with ozone. An independent study also noticed that the cation exchange is the key factor that positively affects methylene blue adsorption (Yang et al 2016). Since the ozonized biochars showed improvement on adsorption of methylene blue by as much as a factor of about 5 which is significantly greater than the factor of 2 increase in the CEC value, some other property in addition to CEC in the ozonized biochar may also have affected methylene blue adsorption.…”

Superb adsorption capacity of biochar derived from leather shavings for Congo red

“…Feedstock for biochar includes vermicompost, 16 Korean cabbage waste, 4 poplar catkins, 17 durian rind, 18 rice straw, 19 bamboo, 20 palm oil 21 , rice husks, 21 and cattle manure. 22 Moreover, achieving specic surface area and high adsorption capacity is always important in development of an efficient adsorbent.…”

Removal of Methylene Blue From Aqueous Solution Using Activated Rice Husk Biochar: Adsorption Isotherms, Kinetics and Error Analysis

“…Recently, the development and use of various adsorption materials, techniques and technologies for the removal of contaminants from aqueous media have increased [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] . Many researchers [15][16][17][18][19][20][21][22][23][24][25][26][27] have used many agricultural based waste materials such as Retama Raetam plant, saw dust, wheat bran, Jatropha Curcas and Terminalia Catappa and unmodified saw dust as an alternative cheaper and affordable substitute for application as sorbent for adsorption of contaminants from aqueous media. Rice husks are waste materials from rice processing and are usually discarded indiscriminately or burnt sometimes leading to eutrophication and green house aerosols, carbon (IV) oxide, carbon(II)oxide, methane, nitrogen oxides and volatile organics which present serious health and climatic changes [27][28][29][30][31][32][33][34][35][36] Varieties of synthetic anionic and cationic dyes are routinely used by chemical industries such as leather, textile, printing, food, pulp and paper [27] .…”