Q2. What is the effect of - EAA interaction on biochar surface?
In addition, according to reaction (equation 9), π-π EAA interaction now may be partially effective as biochar surface was highly negative and sulfonamide molecules also behave as negative species.
Q3. What is the nature of the interaction between functional biochar and sulfonamides?
When π-electron-acceptor is positively charged and this charge lies within or resonates with an arene unit of sulfonamides (e.g. charge in aromatic or heterocyclic aromatic amine) then a stabilized overall interaction is designed as π+-π EDA [16, 36].
Q4. What is the free energy of formation of Go(-)CAHB in water?
The free energy of formation ∆Go(-)CAHB in water can be estimated from gas-phase reaction and the resulting ∆Go(-)CAHB is: firstly, about -56.2 kJ mol -1 for the hydrogen dicarboxylic conjugate pair; and secondly, approximately -50.2 kJ mol-1 for the hydrogen carboxylate-phenolate pair [39].
Q5. What was the effect of temperature on the sorption affinity of the three solutes?
Further increases in temperature from 25 to 30 oC led to a decline in sorption affinity and Kd indicated that adsorption affinity was not strong enough to support homogeneous covering of the surface.
Q6. What is the reason for the higher adsorption affinities of functionalized biochar?
higher adsorption affinities of functionalized biochar may be partly due to the increase in surface area and reduction in pore diameter, accompanied by active adsorption sites facilitating the adsorption of neutral sulfonamide molecules.
Q7. What is the reaction in equation 11?
The reaction in equation 11 shows the proton transfer from biochar surface functional groups (mostly –COOH rather than –OH) to amino N in sulfonamides molecules (-NH+…..-O/-OOC-BC).
Q8. What was the fit for the Langmuir isotherm model?
Competitive removal of sulfonamide antibiotics was found to be better fitted to the Langmuir isotherm model with higher R2 values and the maximum sorption capacities were obtained at 25 oC.
Q9. What was the first sharp increase in Kd values for each single solute?
The second sharp increase in Kd values for each single solute was observed from pH 5 to 6, 5 to 6.3, and 7 to 8, for SMX, STZ and SMT respectively; which coincided with the intersections of neutral and negative species of the three compounds.
Q10. What is the sorption affinity of the three different solutes?
When comparing the single solute sorption capacities, each competitive solute was found to have nearly 2-fold less adsorption capacity for overall individual sorption capacities.