Electrospun CS/PCL/HA nanofiber membranes incorporating bimetallic La/Cu-MOF for Ni(ii) adsorption:...

This study describes the production of a new multifunctional membrane made of electrospun nanofiber (LCMCPH) composed of chitosan (CS), polycaprolactone (PCL), and hyaluronic acid (HA) with a bimetallic lanthanum/copper metal-organic framework (La/Cu-MOF) for actual elimination of Ni(ii) ions from water. The LCMCPH nanofiber membrane was prepared through electrospinning and then thoroughly characterized by means of XRD, SEM, BET, FT-IR, EDX, and advanced 2D correlation spectroscopy. It confirmed that the MOF had been successfully introduced into the polymeric matrix without losing its fibrous structure in the mesoporous region. Batch adsorption tests indicated high uptake capacity under optimized conditions up to 354.59 mg g^-1. The adsorption process was optimized systematically with the Box-Behnken design (BBD) and response surface methodology (RSM), where interaction time and adsorbent dose were found to be the two most significant factors. The quadratic model developed was validated statistically through ANOVA with R ² = 0.9669, showing a very good fit between predicted and experimental results. Isotherm studies indicated that adsorption is best fitted by the Langmuir model, which implies monolayer adsorption by a maximum capacity of 345.08 mg g^-1; kinetic studies revealed that the process follows a pseudo-second-order model, meaning chemisorption is the predominant mechanism. Thermodynamic limits indicated that adsorption is endothermic and spontaneous in nature. Further mechanistic studies revealed that adsorption takes place via coordination, electrostatic interaction, and pore diffusion. The optimized conditions (pH ≈ 6, interaction time ≈ 100 min, dose ≈ 0.02 g) gave rise to a high attractiveness value (0.992), thus confirming the efficiency of the optimization approach. Good selectivity and performance in real water matrices highlight its potentiality as a promising scalable adsorbent for wastewater treatment applications.