Chistie Syeda Minnat, Naik Sneha Ullhas, Rajendra Pragathi, Mishra Ranjeet Kumar, Albasher Gadah, Chinnam Sampath, Jeppu Gautham P, Arif Zeenat, Hameed Javaria
Department of Chemical Engineering, Ramaiah Institute of Technology Bangalore, Karnataka, 560054, India.
Department of Chemical Engineering, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, 576104, Karnataka, India.
Sci Rep. 2025 Jul 2;15(1):23209. doi: 10.1038/s41598-025-03359-z.
The textile industry causes lots of pollution due to its discharge of untreated coloured effluents into water bodies, impacting the environment. The present study includes a slow pyrolysis technique to produce magnetic biochar derived from waste areca nut husk (ANH)) biomass to adsorb methylene blue dye. The biochar and biomass were characterised via proximate analysis, ultimate analysis, bulk density, heating value, extractive content, biochemical analysis, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), SEM, BET surface area, pH, water holding capacity (WHC) and X-ray diffraction (XRD). A semi-batch reactor was used to produce biochar (ANHB) at 600 and 800 C at 10 C min heating rate and 45 min holding time in an inert atmosphere. The produced biochar was magnetised by blending aqueous biochar suspensions with aqueous Fe/Fe solutions. Further, magnetised biochar is employed to eliminate methylene blue (MB) dyes at different pHs, contact times, temperatures, dosages and concentrations. Biochar derived at 800 C (ANHB800) gave increased carbon content (62.93%), heating value (33.02 MJ/kg), and BET surface area (112 m/g) over biochar derived at 600 C. The results of the acid treatment biochar (ANHBA800) demonstrated that 5M HSO causes a BET surface area increase (265 m/g) and a ash content decrease (9.96%). However, when magnetic biochar was produced at 800 C it shows an additional increase in BET surface area upto 385 m/g. The MB dye absorption analysis confirmed 85.47% adsorption at 0.3 g/l dosage, 100 ppm concentration, 30 C, 60 min contact time, and pH 7. The adsorption capacity was 785.34 mg/g when fit by the Langmuir isotherm model. Magnetic nanoparticles enhance active sites, electrostatic interactions, and recovery, improving efficiency, cost-effectiveness, and sustainability in dye removal. The adsorption kinetics results suggested that the pseudo-second-order model best explains the experimental data with an R value of 0.994. Additionally, the adsorption isotherm studies were best fitted by the Langmuir model adsorption conforming monolayer adsorption of MB on biochar surface.
纺织工业因其将未经处理的有色废水排放到水体中而造成大量污染，对环境产生影响。本研究采用慢速热解技术，以废弃槟榔壳（ANH）生物质为原料制备磁性生物炭，用于吸附亚甲基蓝染料。通过近似分析、元素分析、堆积密度、热值、萃取物含量、生化分析、热重分析（TGA）、傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）、BET比表面积、pH值、持水能力（WHC）和X射线衍射（XRD）对生物炭和生物质进行了表征。在惰性气氛中，使用半间歇式反应器在600℃和800℃、加热速率为10℃/min、保温时间为45分钟的条件下制备生物炭（ANHB）。通过将生物炭水悬浮液与铁/铁水溶液混合，对制备的生物炭进行磁化处理。此外，采用磁化生物炭在不同pH值、接触时间、温度、剂量和浓度下去除亚甲基蓝（MB）染料。与在600℃制备的生物炭相比，在800℃制备的生物炭（ANHB800）的碳含量（62.93%）、热值（33.02 MJ/kg）和BET比表面积（112 m²/g）有所增加。酸处理生物炭（ANHBA800）的结果表明，5M H₂SO₄使BET比表面积增加（265 m²/g），灰分含量降低（9.96%）。然而，当在800℃制备磁性生物炭时，其BET比表面积进一步增加至385 m²/g。MB染料吸附分析证实，在剂量为0.3 g/L、浓度为100 ppm、温度为30℃、接触时间为60分钟、pH值为7的条件下，吸附率为85.47%。当用朗缪尔等温线模型拟合时，吸附容量为785.34 mg/g。磁性纳米颗粒增强了活性位点、静电相互作用和回收率，提高了染料去除的效率、成本效益和可持续性。吸附动力学结果表明，伪二级模型能最好地解释实验数据，R值为0.994。此外，吸附等温线研究最适合用朗缪尔模型，该模型表明MB在生物炭表面的吸附符合单层吸附。
