Role of sorption energy and chemisorption in batch methylene blue and Cu2+ adsorption by novel thuja cone carbon in binary component system: linear and nonlinear modeling

Abstract

Functionalized thuja cone carbon (FTCC) was synthesized thermochemically. It was carried out by carbonization (250 °C) and activation (320 °C), followed by surface functionalization in 0.5 M HAN (HNO and HCl) mixture and subsequent heating in HSO (95%) at 90 °C. This was used for methylene blue (MB) adsorption in single component system (SCS) and binary component system (BCS) with Cu. Maximum adsorption capacity of MB (83.4 mg/g) was achieved at pH 10 at 100 mg/L of adsorbate solution. MB and Cu adsorption onto FTCC obeyed pseudo-second-order model kinetics. Spontaneous and endothermic MB adsorption was noticed with negative Gibbs free energy change (- 6.34, - 9.20, and - 13.78 kJ/mol) and positive enthalpy change (133.91 kJ/mol). At low concentrations, Cu adsorption increased by 14 mg/g with least reduction of MB adsorption (< 4 mg/g) in BCS. Isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) support the increase in Cu adsorption in BCS. The sorption heat of MB shifted from 165.16 kJ/mol (SCS) to 150.85 kJ/mol in BCS (Temkin) and from 57.74 kJ/mol (SCS) to 50.50 kJ/mol in BCS (D-R), which supports the lower MB uptake in BCS due to decrease in sorption energy. The sorption heat of Cu is increased (148.43 kJ/mol) in the BCS than SCS (155.36 kJ/mol), which makes the equal distribution of increased bonding energies; therefore, FTCC surface sites increased the Cu uptake in the BCS. Desorption studies concluded the reusability of FTCC by 75% and 79% for MB and Cu adsorption respectively. This study recommends to determine the best fit of isotherm and kinetic models to adsorption data by linear as well as nonlinear regression fit.

Phosphoric Acid Activated Carbon from Melia azedarach Waste Sawdust for Adsorptive Removal of Reactive Orange 16: Equilibrium Modelling and Thermodynamic Analysis

“…For pH at point of zero charge (pH pzc ) determination [ 22 ], the surface charge distribution was analyzed by addition of 25 mg MA-AC400 adsorbent to 50 mL of 0.1 M NaCl solution and the pH was adjusted between 3–10 by addition of 0.1 M HCl and NaOH solutions. These mixtures were sealed and agitated at 150 rpm for 24 h under 30 °C.…”

“…The thermodynamic equilibrium constant was calculated using Equation (6). To make it dimensionless, this equilibrium constant was multiplied by solution (water) density (ρw ≈ 1000 g L −1 ) [ 22 , 70 , 71 ]. Changes in enthalpy ΔH (kJ mol −1 ) and entropy ΔS (J mol −1 K −1 ) were obtained via intercept and slope of Van’t Hoff plot lnKd(ρw) against 1/T (Equation (7)) and finally the Gibb’s free energy ΔG (kJ mol −1 ) was determined using Equation (8): …”

“…Numerous research studies have revealed that the error range of experimental data is generally altered throughout the conversion of adsorption isotherms into forms after linearization [ 75 ]. In our current work, five different error functions including coefficient of determination (R 2 ) [ 22 ], chi-square error (χ 2 ) [ 76 ], sum of absolute error (SAE) [ 77 ], Marquardt’s percent standard deviation (MPSD) [ 78 ] and HYBRID functional error (HYBRID) [ 79 ] were calculated and the goodness of fit for Langmuir and Freundlich was suggested. All error functions are represented by Equations (12)–(16): …”

“…Adsorption appears to be an economical, effective and eco-friendly technology for the elimination of reactive dyes from effluents when compared with other methods due to its numerous advantages, which include low cost, ease of design at a large scale, facile manipulations, resistance to contaminants, higher efficiency rate, and an aptitude to cope with dilute as well as concentrated dye effluents [17]. Generally, a wide range of adsorbents obtained from variety of sources such as clay [18], nanoparticles [19], nanotubes [20], agricultural-and forest-derived wastes [21,22], activated carbon [23], graphene composites [24], zeolites [25], chitosan [26], and a number of polymeric adsorbents [27] have been employed for the removal of reactive dyes. The high surface area, good adsorption capacity, mechanical and chemical stability of activated carbon (AC) ranks it as a promising substitute for existing dye removal techniques.…”

Equilibrium, kinetics and thermodynamic study of the adsorptive removal of methylene blue from industrial wastewater by white cedar sawdust

“…(14)) is based on the assumption that the rate-limiting step may be the chemisorption involving valence forces through sharing or exchange of electrons between sorbent and sorbate. It has been successfully applied to the adsorption of metal ions, dyes, herbicides, oils, and organic substances from aqueous solutions [23][24][25]. The pseudo-second-order has the following advantages: it does not have the problem of assigning an effective adsorption capacity, i.e., the adsorption capacity, the pseudo-second order rate constant , and the initial adsorption rate all can be determined from the equation without knowing any parameter beforehand.…”