Rapid elimination of copper (II), nickel (II) and chromium (VI) ions from aqueous solutions by charcoal modified with phosphoric acid used as a green biosorbent

Abstract

Activated carbon modified by phosphoric acid noted CAa was successfully used as a new low‐cost adsorbent for removing Cu2+, Ni2+ and Cr6+ metal ions from artificially contaminated aqueous solutions. Experiments were performed in batches for adsorption kinetics and isotherms. Scanning electron microscope (SEM) observations as well as a nitrogen adsorption–desorption BET surface area measurement showed the formation of mesoporous CAa with an average pore size of 3.1 nm and a surface area of ABET = 678.74 m2 g−1. The adsorption data for Cu2+, Ni2+ and Cr6+ fitted well with Langmuir adsorption model with maximum adsorbed amount of 238.10 mg g−1 for Cu(II), 80.64 mg g−1 for Ni(II) and 125 mg g−1 of Cr(VI) with the maximal amount measured by N2 adsorption of 231.5337 cm3 g−1 STP. The experimental variables studied were pH, temperature, amount of biomass and initial ion concentration. Maximum biosorption was observed for pH = 2. The adsorption capacity seems to be optimized by increasing the temperature, the amount of biosorbent and the initial concentration. Isotherm adsorptions are in agreement with Langmuir models. The calculated changes in adsorption free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) confirm that the present adsorption process is a favorable, endothermic and spontaneous phenomenon.

pH‐sensitive folic acid/poly(vinyl pyrrolidone) functionalized MnFe2O4/single‐walled carbon nanotubes for release of a natural anticancer agent: Chlorogenic acid

“…The positive ΔH 0 value (6.088 kJ/mol) verified the endothermic nature of CGA uptake. 45 The positive value of ΔS 0 (136.740 J/mol K) implied that the randomness of the solid-solution interface increased during the adsorption procedure (Table S3).…”

Sodium Alginate/β-Cyclodextrin Reinforced Carbon Nanotubes Hydrogel as Alternative Adsorbent for Nickel(II) Metal Ion Removal

“…Moreover, such conditions might be because the rich surface oxygen-containing functional groups such as hydroxyl and carbonyl increase the electrostatic interaction and improve interactions with Ni(II), which then promotes Ni(II) adsorption on the SA-β-CD/CNTs. Nevertheless, when the initial concentration increased, the percentage removal slope slowly dropped, showing that the penetration sites on the SA-β-CD/CNTs surface had been filled by Ni(II) metal ions [76]. Therefore, 100 mg/L of Ni(II) solution was used as an optimum concentration for further adsorption study.…”

“…The n value indicates the degree of nonlinearity between solution concentration and adsorption as follows: if n = 1, then adsorption is linear; if n < 1, then adsorption is a chemical process; if n > 1, then adsorption is a physical process. The n value in the Freundlich equation was found to be 1.1528 and 0.08675 L/mg on SA-β-CD and SA-β-CD/CNTs, respectively, showing the physical and chemical adsorption conditions involved during adsorption of Ni(II) [76,78]. A Dubinin-Radushkevich (D-R) isotherm was used to study the pseudo-energy of adsorbed adsorbates on the adsorbent surface.…”

Efficient Removal of Eriochrome Black T Dye Using Activated Carbon of Waste Hemp (Cannabis sativa L.) Grown in Northern Morocco Enhanced by New Mathematical Models

“…The method of preparation applied for the WHAC has two steps: carbonization and activation, as already described in our previous works [26,27]. After impregnation, to remove any excess of phosphoric acid, the solid was filtered under a vacuum.…”