New complexes of [5,10,15,20-(tetraphenylporphyrin)] and dichloride (5,10,15,20-tetraphenylporphyrinato) antimony(V) hexachloridoantimonate(V) functionalized with polyethyleneimine: Synthesis, characterization, and application in Eriochrome Black T adsorption from water

Abstract

In the current work, new complexes namely [5,10,15,20 (tetraphenylporphyrin)] /Polyethyleneimine (H₂TPP-PEI) and Dichlorido(5,10,15,20-tetraphenylporphyrinato)antimony(V) hexachloridoantimonate(V)/Polyethyleneimine ([Sb(TPP)Cl₂][SbCl₆]-PEI) were successfully prepared and characterized. The prepared compounds were thoroughly analysed using ¹H NMR, UV, XRD, XRF, TGA-DTA, SEM, and EDAX. SEM analysis showed that the addition of polyethyleneimine to the porphyrin core clearly changed the morphological properties. The optical gap values were calculated using the tauc plot method and were equal to 1.877, 2.030, 1.862, and 2.017 eV for H₂TPP, [Sb(TPP)Cl₂] [SbCl₆], H₂TPP-PEI and ([Sb(TPP)Cl₂][SbCl₆]-PEI), respectively. The existence of sharp peaks at 2θ between 16° and 80° displayed the crystalline nature of the prepared porphyrinic compounds. The change in thermal decompositions for H₂TPP, [Sb(TPP)Cl₂][SbCl₆], H₂TPP-PEI and ([Sb(TPP)Cl₂][SbCl₆]-PEI) revealed that the addition of polyethyleneimine to porphyrin affected the thermal characteristics. The prepared complexes were, further, investigated for the adsorption of Eriochrome Black T (an anionic dye) from water. Highest adsorption capacities were accomplished using [Sb(TPP)(Cl₂)]-PEI (164 mg/g) and H₂TPP-PEI (82 mg/g) under the following experimental conditions (pH = 5, temperature = 19 °C, time = 60 min). However, the adsorption capacities remains poor for H₂TPP and Sn(TPP)(Cl₂). The adsorption data complied well with pseudo second order, Freundlich, and Temkin equations. Overall, the adsorption results had confirmed that polyethyleneimine functionalized porphyrins could be used as a proficient adsorbent of anionic dyes from water.