Eco-friendly polyvinylpyrrolidone/alginate incorporating calcium carbonate modified biosorbent waste beads for methylene blue removal: Comprehension of physio-chemical and adsorption optimization

In this particular investigation, zinc chloride ZnCl 2 was utilized as activating agent in the process to produce activated carbon from vegetable waste of okra. The AC was further incorporated into calcium carbonate and polyvinylpyrrolidone/sodium alginate polymer to prepare modified activated carbon based composite hydrogel beads adsorbent (Ca-ACHB). This adsorbent was utilized to remove methylene blue (MB) from water. The (Ca-ACHB) adsorbent was characterized used different analytical instrument like Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric (TGA), Brunauer-Emmett-Teller (BET) and X-ray photoelectron spectroscopy (XPS). The batch adsorption test was utilized in order to ascertain the removal of MB. The BET specific surface area of (Ca-ACHB) was 3.21 mg 2 /g and total pore volume of 0.015 m 3 /g. A sequence of adsorption assessments was conducted at a range of different conditions, including pH (2–11), dosage (0.0025–0.020 g), time (5–360 min), initial concentration (25–150 mg/L) as well as temperature (298–318 K). Whereas kinetic study is well-defined by pseudo-2nd order (R 2  = 0.884). This shows that chemisorption process take place on (Ca-ACHB) adsorbent surface. The Freundlich isotherm (R 2  = 0.987) was better followed by the equilibrium data which specified that multilayer adsorption occurred on (Ca-ACHB) adsorbent. The maximum absorption capacity of adsorbent was 119.92 mg/g using 100 mg/L of MB concentration. The acknowledged outcomes from Gibbs free energy (ΔGᴼ) and enthalpy (ΔHᴼ) constants was −1.83 to −2.17 and 4.98 kJ/mol respectively. These outcomes indicated that adsorption process was endothermic and spontaneous. The reusability of the (Ca-ACHB) adsorbent was examined across various regeneration cycles.