Adsorptive retention of citric acid onto activated carbon prepared from Havea braziliansis sawdust: Kinetic and isotherm overview

Preparation and characterization of raw and carbon from banana peel by microwave activation: Application in citric acid adsorption

“…To understand the adsorption behavior of CA onto RBP and MBPC surface, it is necessary to obtain additional information about pH zpc and CA speciation. In aqueous solutions, CA occurs as CAH 2 2À , CAH 3 , CAH 3À , and CA 4À at different ratios depending on pH [4].…”

“…CA is mildly toxic by ingestion, moderately toxic by subcutaneous and intraperitoneal route, and poisonous by intravenous route. Furthermore, in excess amounts, CA causes problems to flora and fauna and disturbs the esthetic value of drinking water [4][5][6][7].…”

“…Various adsorbents, including activated carbon [17], pseudoboehmite [18], and activated carbon prepared from Pistacia Abbreviations: a, nitial adsorption rate for Elovich model (mg/g/minute); b, desorption constant for the Elovich kinetic model (mg/g); C, intercept for intraparticle diffusion rate constant; C 0 , initial concentration of adsorbate (mg/L); C e , equilibrium concentration of adsorbate in solution (mg/L); COD, chemical oxygen demand; D eff , effective diffusion coefficients (cm 2 /s); k 1 , rate constant of The Lagergren-first-order kinetic model (1/min); k 2 , Rate constant of pseudo-second-order model (g/mg/minute); K F , Freundlich isotherm constant related to adsorption capacity [(mg/g) (L/mg) 1/n ]; k id , intraparticle diffusion rate constant (mg/g/min À1/2 ); K L , langmuir adsorption constant (L/mg); N, Freundlich isotherm constant related to adsorption intensity; q 2 , maximum adsorption capacity for pseudo-second-order model (mg/g); q e , adsorption capacity of adsorbate at equilibrium (mg/g); q m , mono-layer adsorption capacity of adsorbent (mg/g); q max , maximum adsorption at monolayer coverage (mg/g); q t , amounts of adsorbate on the adsorbent at any time t (mg/g); R L , dimensionless separation factor; t, time (hours); T, absolute temperature (K); V, volume of the solution (L); w, amount of adsorbent used (g); DG, change in Gibbs free energy of adsorption (kJ/mol); DH, change in enthalpy of adsorption (kJ/mol); DS, change in entropy of adsorption (J/mol/K). lentiscus leaves [5] and Hevea braziliansis sawdust [4] have been used in this regard.…”

“…CA is mildly toxic by ingestion, moderately toxic by subcutaneous and intraperitoneal route, and poisonous by intravenous route. Furthermore, in excess amounts, CA causes problems to flora and fauna and disturbs the esthetic value of drinking water [4][5][6][7].Removal of CA is accomplished using different methods such as membrane filtration [8], anaerobic treatment [9], electrochemical oxidation [10], biohydrogen production [11], microbial treatment [12], catalytic wet peroxidation [13], and anaerobic and multilevel aerobic digestion [14][15][16]. However, these processes are associated with very high operational costs [7].…”

Adsorption for Dyes on Activation Carbons from Japanese Cedar Wood Prepared by Precarbonization and Two-stage Composite Activations with Wood Ash and Steam

“…-and other ions, the chemical action on the surface, e.g. adsorption, makes the surface potential of the suspended particles neutral, thus, the pH value is called the point of zero charge (pH PZC ) [64]. When pH > pH PZC , the acid functional group is separated, releasing protons, and leaving a negatively charged carbon surface, which is favorable for cation adsorption.…”