Effect of temperature and fly ash content on the catalytically pyrolyzed rice straw biochar–fly ash composites for methylene blue adsorption

Abstract

Rice straw and fly ash are the wastes produced in abundance which need immediate attention for their management. In the present study, the in situ pyrolysis of rice straw in presence of fly ash was carried out and the resultant composites were studied for adsorption of methylene blue (MB). Slow pyrolysis of rice straw in presence of fly ash is evaluated using thermogravimetric analysis (TGA) and Coats-Redfern equation for pseudo-first-order reaction kinetics, respectively. The activation energy (E a ) for the pyrolysis of rice straw was 41.75 kJ/mol which was lowered to 37.39 kJ/mol in presence of fly ash. Biochar fly ash composites BFA4 1-3 , BFA5 1-3 , and BFA6 1-3 were prepared at three 400 C, 500 C, and 600 C pyrolysis temperature, respectively, the subscript indicating three different ratios of rice straw and fly ash (1:3, 1:1, and 3:1 w/w ratio). The composites BF4-6 1-3 were neutral to alkaline in pH, due to the presence of basic oxide and carbonates minerals. BFA4-6 1-3 was studied for batch adsorption of MB and optimized for pH, dose, and initial concentration of adsorbate. The maximum MB adsorption capacity of 25.91 mg/g was reported for the composite BFA4 1 . MB adsorption efficiency (q e ) followed the trend BFA4 1-3 > BFA5 1-3 > BFA6 1-3 , which indicates a strong influence of biochar surface functional groups on dye adsorption, as reiterated by the multiple linear regression (MLR) analysis. Stripping of MB was achieved using methanol as a stripping agent for MB-adsorbed BFA4-6 1-3 with desorption efficiency of 7% to 11% in the first cycle and 23% to 100% in the second cycle.Thus, the biochar fly ash composite with optimum ion exchangeable functional organic moieties would be suitable for dye remediation and waste generated in the process could find application in soil amelioration. K E Y W O R D S adsorption-desorption, composite biochar, dye, thermogravimetric analysis Akanksha Bhardwaj and Shilpa Nag have equal contributions to the paper.

Conservation of waste melon shell and fly ash utilized as reinforcements for aluminum alloy matrix in terrestrial ecosystem acquired green hybrid composites

“…The minor improvement (2.9%) of the green hybrid composite is due to the presence of lightweight waste ash particles in the Al6061 matrix. A similar identification was obtained during the evaluation of AZ91E alloy/waste bagasse ash composite (Anandaram et al, 2022;Bhardwaj et al, 2022;Chandra Pandey et al, 2009;Venkatesh & Manivannan, 2022).…”

Nitrogen‐doped biochar as an efficient sensing material for the electrochemical detection of heavy metal ion Pb2+ and Cd2+

“…Biochar is a multifunctional environmental material that undergoes cracking under high‐temperature and anaerobic conditions and can be converted into long‐term stable carbon biochar from organic wastes such as agricultural wastes, animal wastes, and municipal wastes. The use of biochar has shown outstanding results in outstanding improvements in soil quality and the adsorption of environmental pollutants 11 . Biochar has also been applied in electrochemical research as an electrocatalyst, supercapacitor, and electrochemical sensor 12–15 .…”

“…The use of biochar has shown outstanding results in outstanding improvements in soil quality and the adsorption of environmental pollutants. 11 Biochar has also been applied in electrochemical research as an electrocatalyst, supercapacitor, and electrochemical sensor. [12][13][14][15] Xiang et al 9 established an Au-NPs/BC nanocomposite electrode for the simultaneous detection of hydroquinone and catechol.…”

Copper Selenide (CuSe) Monolith Fabricated by Facile Copper Foam Selenization for Efficient Photocatalytic Degradation of Methylene Blue

“…Methylene blue (MB), as an extremely carcinogenic thiazine pollutant that has been widely used in various industries for diferent purposes (e.g., dyeing of cotton, wool, and fabrics; coloring of paper, as a hair coloring agent and redox reaction indicator in outer space, etc. ), has received special attention during the technical development process [6,7].…”