A novel biogenic waste-derived CHS-DFCW/AC hybrid composite for highly efficient Mn(VII) remediation: Techno-economic assessment, ANOVA, and advanced modeling
Raouf Hassan, Raid Alrowais, Aly A.A. Soliman, Ahmed S. Elshimy
Abstract
A previously unexplored composite material, designated CHS-DFCW/AC, was engineered for the targeted removal of Mn(VII) from aqueous systems. Its fabrication involves the strategic combination of activated carbon (AC) derived from agricultural waste with a matrix of duck feather creatin waste (DFCW), subsequently functionalized with chitosan (CHS) to create a novel hybrid biosorbent. Analytical investigations via FTIR, XRD, BET surface area analysis, TG/DTG, FESEM, EDX, and elemental mapping collectively verified the unique adsorption properties of the CHS-DFCW/AC biosorbent. A statistical modeling approach employing the Box-Behnken design (BBD) was applied to evaluate and refine the effects of three principal adsorption variables: solution pH, adsorbent mass, and reaction duration. BBD analysis and experimental studies established that peak removal efficacy is achieved under the following conditions: a pH of 2, an adsorbent dose of 16 mg, a contact time of 150 min, an initial concentration of 150 mg/L, and a temperature of 328 K. The adsorption kinetics were accurately described by both pseudo-first-order (PFO) and pseudo-second-order (PSO) models, whereas the equilibrium data showed a superior fit with the Langmuir isotherm. Advanced computational modeling reveals the adsorption mechanism to be a temperature-independent, multimolecular phenomenon characterized by a favored vertical molecular alignment. Thermodynamic profiling suggested the process is spontaneous and endothermic, driven by a synergistic mechanism combining physisorption and chemisorption. This mechanism is predominantly governed by electrostatic attraction, alongside complexation and chelation at nitrogen and oxygen donor sites, with associated binding energies between 21.58 and 23.75 kJ/mol. With a production cost of 5.14 USD/kg and excellent reusability (76.59 % efficiency after five cycles), this biosorbent is a cost-effective solution for wastewater treatment. The estimated cost for treating 100 liters of 50 mg/L Mn(VII) solution is almost 0.63 USD, underscoring its strong industrial applicability for advanced tertiary treatment processes.