Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
Environ Pollut. 2020 Nov;266(Pt 2):115102. doi: 10.1016/j.envpol.2020.115102. Epub 2020 Jul 4.
Current study deals with the surface modification of acid activated carbon (prepared from Pongamia pinnata shells) with Cetyltrimethylammonium bromide (CTAB) and its role as an adsorbent in eliminating anionic azo dyes viz. Congo red (CR) and Direct blue 6 (DB) from single and binary adsorptive systems. Binary adsorptive system involved the synergistic and antagonistic influence of one dye over the adsorption of other dye. Physico-chemical alterations due to surfactant modification and post adsorption were studied using atomic force microscopy (AFM), Zeta Potential, scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), surface area analysis and Fourier-transformed infrared spectroscopy (FTIR). Process parameters influencing efficient adsorption of CR and DB species viz. initial pH of dye solution, adsorbent dosage, incubation temperature and initial concentration of dye species were optimised. Sorbate-sorbent interaction studies for single adsorptive system revealed sorbate's monolayer formation over adsorbent's surface and the involvement of chemisorption, as verified by Langmuir isotherm model and pseudo-second order model, respectively. Langmuir maximum adsorption capacity of the adsorbent was 555.56 mg/g for CR and 625.00 mg/g for DB. Meanwhile, for binary adsorptive system, competitive Langmuir model verified both CR and DB had antagonistic/competitive effect over each other's adsorption. Thermodynamic analysis revealed the adsorptive process as exothermic, spontaneous and thermodynamically favourable with an elevated degree of dis-orderedness. Co-existing cations and anions has nominal effect on the adsorption capacity of dyes. Recyclability studies verified a modest efficiency of 62.52% for CR and 50.47% for DB species after the end of 4th adsorption-desorption cycle; thus affirming its recyclability potential. Phytotoxic assay affirmed the effectivity of the adsorbent in adsorbing dye species from aqueous solutions using Vigna mungo seeds as the model.
本研究对从麻疯树（Pongamia pinnata）壳中制备的酸活化炭进行了十六烷基三甲基溴化铵（CTAB）表面改性，并将其作为吸附剂，用于从单一组分和双组分吸附体系中去除阴离子偶氮染料刚果红（CR）和直接蓝 6（DB）。双组分吸附体系涉及一种染料对另一种染料吸附的协同和拮抗影响。通过原子力显微镜（AFM）、Zeta 电位、扫描电子显微镜（SEM）、能量色散 X 射线光谱（EDS）、表面积分析和傅里叶变换红外光谱（FTIR）研究了表面活性剂改性和吸附后的物理化学变化。优化了影响 CR 和 DB 物种有效吸附的工艺参数，如染料溶液的初始 pH 值、吸附剂用量、孵育温度和染料初始浓度。单一组分吸附体系的吸附剂-吸附质相互作用研究表明，吸附质在吸附剂表面形成单层，且涉及化学吸附，这分别由 Langmuir 等温线模型和准二级动力学模型验证。吸附剂对 CR 的最大吸附容量为 555.56mg/g，对 DB 的最大吸附容量为 625.00mg/g。同时，对于双组分吸附体系，竞争 Langmuir 模型验证了 CR 和 DB 对彼此吸附的拮抗/竞争效应。热力学分析表明，吸附过程是放热、自发和热力学有利的，无序度增加。共存的阳离子和阴离子对染料的吸附容量有一定的影响。在第 4 次吸附-解吸循环结束后，CR 和 DB 的回收效率分别为 62.52%和 50.47%，这证明了其具有一定的可回收性。利用豇豆种子作为模型，植物毒性试验证实了吸附剂从水溶液中吸附染料的有效性。
