The adsorption of bixin in aprotic solvents onto acid- and alkali-treated kaolinite was investigated. Kaolinite was treated three times, for 6 h each, with 8 M HCl or 5 M KOH. The adsorbents were characterized by XRD, FT-IR, EDS, and BET-N₂. The effects of contact time and dye concentration on adsorption capacity and kinetics, electronic transition of bixin before and after adsorption, and also mechanism of bixin-kaolinite adsorption were investigated. Dye adsorption followed pseudo-second order kinetics and was faster in acetone than in dimethyl carbonate. The best adsorption results were obtained for KOH-treated kaolinite. In both of the solvents, the adsorption isotherm followed the Langmuir model and adsorption capacity was higher in dimethyl carbonate (q_m = 0.43 mg/g) than in acetone (0.29 mg/g). The adsorption capacity and kinetics of KOH-treated kaolinite (q_m = 0.43 mg/g, k₂ = 3.27 g/mg·min) were better than those of HCl-treated kaolinite (q_m = 0.21 mg/g, k₂ = 0.25 g/mg·min) and natural kaolinite (q_m = 0.18 mg/g, k₂ = 0.32 g/mg·min). There are shift in the band position of maximum intensity of bixin after adsorption on this adsorbent. Adsorption in this system seemed to be based essentially on chemisorption due to the electrostatic interaction of bixin with the strong basic and reducing sites of kaolinite.

中文翻译：

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联苯在酸和碱处理的高岭土在非质子溶剂中的吸附特性。

研究了质子惰性溶剂中联鑫在酸和碱处理的高岭石上的吸附。高岭石用8 M HCl或5 M KOH处理3次，每次6 h。通过XRD，FT-IR，EDS和BET-N ₂表征吸附剂。研究了接触时间和染料浓度对吸附能力和动力学，吸附前后Bixin电子跃迁以及Bixin-高岭石吸附机理的影响。染料吸附遵循拟二级动力学，并且在丙酮中的吸附速度快于碳酸二甲酯。KOH处理的高岭石获得了最佳的吸附结果。在这两种溶剂中，吸附等温线均遵循Langmuir模型，并且在碳酸二甲酯（q _m ＝ 0.43mg / g），而不是丙酮（0.29mg / g）。KOH处理的高岭石（q _m  = 0.43 mg / g，k ₂  = 3.27 g / mg·min）的吸附容量和动力学优于HCl处理的高岭石（q _m  = 0.21 mg / g，k ₂  = 0.25 g / mg·min）和天然高岭石（q _m  = 0.18 mg / g，k ₂  = 0.32 g / mg·min）。在此吸附剂上吸附后，联鑫最大强度的能带位置发生了变化。该系统中的吸附似乎主要基于化学吸附，这是由于联鑫与高岭土的强碱性和还原性位点之间的静电相互作用。