Synthesis of Green Magnetite/Carbonized Coffee Composite from Natural Pyrite for Effective Decontamination of Congo Red Dye: Steric, Synergetic, Oxidation, and Ecotoxicity Studies

Abstract

Green magnetite/carbonized spent coffee (MG/CFC) composite was synthesized from natural pyrite and characterized as an adsorbent and catalyst in photo-Fenton’s oxidation system of Congo red dye (C.R). The absorption behavior was illustrated based on the steric and energetic parameters of the advanced Monolayer equilibrium model of one energetic site (R2 > 0.99). The structure exhibits 855 mg/g as effective site density which induces its C.R saturation adsorption capacity to 436.1 mg/g. The change in the number of absorbed C.R per site with temperature (n = 1.53 (293) to 0.51 (313 K)) suggests changes in the mechanism from multimolecular (up to 2 molecules per site) to multianchorage (one molecule per more than one site) processes. The energetic studies (ΔE = 6.2–8.2 kJ/mol) validate the physical uptake of C.R by MG/CFC which might be included van der Waals forces, electrostatic attractions, and hydrogen bonding. As a catalyst, MG/CFC exhibits significant activity during the photo-Fenton’s oxidation of C.R under visible light. The complete oxidation of C.R was detected after 105 min (5 mg/L), 120 min (10 mg/L), 135 min (15 mg/L), 180 min (20 mg/L), and 240 min (25 mg/L) using MG/CFC at 0.2 g/L dosage and 0.1 mL of H2O2. Increasing the dosage up to 0.5 g/L reduce the complete oxidation interval of C.R (5 mg/L) down to 30 min while the complete mineralization was detected after 120 min. The acute and chronic toxicities of the treated samples demonstrate significant safe products of no toxic effects on aquatic organisms as compared to the parent C.R solution.

Enhancing the photocatalytic elimination of acephate residues using Ni0 doped and diatomite-supported NiO: optimization, pathway, and toxicity

“…The apparent quantum yields were determined by computing the ratio of used charge carriers to the entire quantity of photons that accessed the experimental setting (eqn (3)). 56,57 The values of ϕ may be derived using eqn (4), which depends on the estimated kinetic rate constants obtained from first-order modeling: 56,57 where variables K 1 (S −1 ), ελ (cm −1 M −1 ), I 0, λ (Einstein I −1 S −1 ), and (cm) represent the kinetic rate constants, molar absorbing, the strength of incoming light having a certain wavelength λ , and the diameter of the quartz cell utilized, respectively. The ϕ values obtained from the conducted experiments using varying dosages of NiO/D and Ni@NiO/D, as well as varied AC levels, are shown in Table 1.…”

“…41 Additionally, the electron–hole pair (h + ) has a splitting impact on the water molecules, causing the release of hydroxyl oxidation radicals. 57 Subsequently, the oxidizing radicals produced, particularly the OH˙ type, promptly interact with the dissolved AC chemicals, resulting in the oxidation and destruction of their organic frameworks. The ongoing interactions led to a series of degrading reactions, resulting in the formation of intermediates.…”

“…The apparent quantum yields were determined by computing the ratio of used charge carriers to the entire quantity of photons that accessed the experimental setting (eqn (3)). 56,57 The values of f may be derived using eqn (4), which depends on the estimated kinetic rate constants obtained from first-order modeling: 56,57 f ¼ Number of LVOX molecules Number of absorbed photons ;…”

Synthesis and Characterization of Iron-Rich Glauconite Nanorods by a Facile Sonochemical Method for Instantaneous and Eco-friendly Elimination of Malachite Green Dye from Aquatic Environments

“…Additionally, the temperature has an impact on the dominant condition of the sites that are filled. , The application of high-temperature conditions has been found to have a positive impact on the activation of uptake sites for GNRs. This effect can be attributed to the exposure of further active sites as well as the presence of new energetic site groups. , There is a direct relationship between the increase in adsorption temperature and the decrease in the viscosity level of the MG solutions . Consequently, the mobility and diffusion activity of water-soluble MG molecules exhibit a significant increase upon interaction with additional reactive sites.…”

“…Furthermore, the conspicuous reductions in the reported entropy suggest a noteworthy decrease in the quantity of accessible sites accompanied by a major loss in the degrees of freedom and diffusion characteristics of the MG ions. 66,67 Internal Energy and Free Enthalpy Characteristics The present study assessed the internal energy (E int ) associated with the sequestration of MG via GNRs as well as the changes in free enthalpy (G) resulting from variances in dye concentration as well as operational temperature. These evaluations were conducted using values obtained from eqs 3 and 4, which were computed using previously established parameters including Nm (MG) , n (MG) , C 1/2 , and the translation partition (Z v ).…”