An efficient p-tetranitrocalix[4]arene based adsorbent for the removal of carbofuran from aqueous media
作者:Shahabuddin Memon、Sibghatullah Memon、Najma Memon
DOI:10.1007/s13738-014-0432-8
日期:2014.12
Present study describes the adsorption of carbofuran (CF) from aqueous solutions using p-tetranitrocalix[4]arene based modified silica through batch and column methods. Various parameters were optimized including initial pesticide concentrations (5 mg L−1), pH (2–10), contact time (60 min) and adsorbent dosage (30 mg). Modified silica was characterized by FT-IR and scanning electron microscope. The adsorption was further explained by Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models. Moreover, adsorption kinetics and adsorption thermodynamics were also investigated. Adsorption in dynamic mode was evaluated by breakthrough volumes and the Thomas model, applying batch conditions using 30 mg of modified silica at pH 5. It has been noticed that CF removal efficiency of modified silica was 98 % as compared to bare silica (48 %). Adsorption of CF on modified silica was found to be multilayer and physical in nature. Consequently, adsorption obeys pseudo-second-order kinetic equation following external mass transfer diffusion process as the rate-limiting step. Thermodynamic parameter (ΔG, ΔS, ΔH) values suggest that the adsorption of CF is spontaneous and exothermic in nature. Thomas model rate constant k TH (cm3 mg−1 min−1) and maximum solid phase concentration (q o mg g−1) was found to be 0.52 and 12.3, respectively, in dynamic mode.
本研究通过分批法和柱法,描述了使用对四硝基杯[4]芳烃基改性二氧化硅从水溶液中吸附呋喃(CF)的过程。优化了各种参数,包括初始农药浓度(5 mg L−1)、pH值(2–10)、接触时间(60 min)和吸附剂用量(30 mg)。通过FT-IR和扫描电子显微镜对改性二氧化硅进行了表征。通过Langmuir、Freundlich和Dubinin–Radushkevich(D–R)模型进一步解释了吸附过程。此外,还研究了吸附动力学和吸附热力学。通过突破体积和Thomas模型评估了动态吸附,在pH值为5时,使用30 mg改性二氧化硅,应用分批条件。与未改性二氧化硅(48 %)相比,改性二氧化硅的CF去除效率为98 %。研究发现,CF在改性二氧化硅上的吸附是多层的,并且是物理性质的。因此,吸附服从伪二级