New insights about reactive red 141 adsorption onto multi–walled carbon nanotubes using statistical physics coupled with Van der Waals equation

Co3O4/Bi4O5I2/Bi5O7I C-Scheme Heterojunction for Degradation of Organic Pollutants by Light-Emitting Diode Irradiation

“…ΔH* values (9.67 and 16.99 kJ mol –1 ) were positive and suggested that adsorption of PNP and BB was endothermic while the negative Δ S * values (−0.048 and – 0.08 kJ mol –1 K –1 ) supported the hypothesized interaction between the adsorbant and pollutants that occurred. Moreover, the fact of positively charged catalytic active sites having high affinity toward the pollutants at pH values above a point of zero charge of 4.5 (Figure d) was confirmed and it could also be inferred that no significant changes occurred to the internal structure of the adsorbing catalyst during adsorption as reported elsewhere. − The point of zero charge shows that, below pH 4.5, the catalytic surface is negatively charged and becomes positively charged when the pH of pollutant solution is above 4.5. The isoelectric point of zero charge has been used successfully to predict the charges of different catalysts with respect to pH changes. − Lastly, the positive Δ G * (27.68 kJ mol –1 ) obtained demonstrated the non-spontaneous nature of the adsorption process that could be pioneered by external energy sources such as (mechanical stirring) to enhance the efficiency of the process as it has been proven that Δ G * = 0, Δ G * < 0, and Δ G * > 0 for equilibrium, exergonic, and endergonic processes, respectively .…”

“…Moreover, the fact of positively charged catalytic active sites having high affinity toward the pollutants at pH values above a point of zero charge of 4.5 ( Figure 11 d) was confirmed and it could also be inferred that no significant changes occurred to the internal structure of the adsorbing catalyst during adsorption as reported elsewhere. 67 − 69 The point of zero charge shows that, below pH 4.5, the catalytic surface is negatively charged and becomes positively charged when the pH of pollutant solution is above 4.5. The isoelectric point of zero charge has been used successfully to predict the charges of different catalysts with respect to pH changes.…”

Activated Bentonite: Low Cost Adsorbent to Reduce Phosphor in Waste Palm Oil

“…In both natural and activated bentonite, at minute 30 the amount of P adsorbed slightly due to the interaction time between P ions with the active site on the adsorbent relatively But in the 60th minute the amount of P absorbed actually decreased, this is because in this condition P ion has not entered all the pores into bentonite because it is possible there are still obstructed to enter. Thus, it is possible that P-ions already bonded to the active site of bentonite exist apart from the pores of bentonite during the adsorption process because the bonds that occur in the P ions with the active site on bentonite are the bonds of Van der Walls (Rodrigues et al, 2019). While in the 90th minute, the number of P-ions adsorbed at most compared to the other time.…”

New insights into glyphosate adsorption on modified carbon nanotubes via green synthesis: Statistical physical modeling and steric and energetic interpretations

“…Recently, with the advances in nanotechnology, carbon nanotubes (CNTs) have emerged as promising adsorbents, especially multi-walled carbon nanotubes (MWCNTs), due to their properties, such as a high specific surface area with high molecular capture capacity of pollutants, porous and layered structure [27,28]. The use of CNTs has already been proposed in the adsorption of drugs [29,30], dyes [31,32], metal ions [33,34], formic acid [35], phenolic compounds [36], and sulfur dioxide [37].…”

“…Regardless of the adsorbent adopted and the contaminant in question, it is essential to determine the interactions that occur at the solid/ liquid interface, which depend on the characteristics of the adsorbent, the adsorbate, and the solution. The interpretation of process equilibrium through the construction and modeling of adsorption isotherms is a way to infer interactions between adsorbate-adsorbent [27]. In modeling, adsorption processes are generally elucidated by applying Langmuir, Freundlich, and Sips models.…”