Competitive adsorption and molecular interaction study of sulfamethoxazole and trimethoprim on biomass-based activated carbon
Bibliographic record
Abstract
This study investigated the adsorption of sulfamethoxazole and trimethoprim onto activated carbon from reed canary grass in single- and binary-solute systems. Trimethoprim showed higher adsorption capacity than sulfamethoxazole. Single solute adsorption isotherms were modeled using Nitta model to assess equilibrium and site energy. The adsorption of trimethoprim and sulfamethoxazole followed a monolayer pattern, with trimethoprim exhibiting a higher maximum adsorption capacity (0.69 mmol/g) compared to sulfamethoxazole (0.55 mmol/g). Trimethoprim also demonstrated a significantly greater adsorption affinity (521.89 L/mmol) than sulfamethoxazole (70.92 L/mmol). The ratio of adsorption sites occupied to adsorbed molecules was 0.81. Weighted mean of site energy was 11.5 kJ/mol for sulfamethoxazole and 16.7 kJ/mol for trimethoprim, suggesting stronger trimethoprim interactions. Competitive adsorption experiments showed that trimethoprim significantly reduced sulfamethoxazole adsorption due to its stronger interaction with the adsorbent and its larger molecular size, which blocked small pores and shielded the adsorbent surface, restricting sulfamethoxazole access to adsorption sites. In the binary-solute system, the maximum adsorption capacity increased to 0.93 mmol/g, surpassing the individual maximum capacities of sulfamethoxazole and trimethoprim in their single-solute systems. However, the adsorption affinities of sulfamethoxazole and trimethoprim during competitive adsorption, at 9.29 and 267.69 L/mmol respectively, were lower than their corresponding values in single-solute solutions. Scanning transmission X-ray microscopy combined with X-ray absorption near-edge structure spectroscopy revealed adsorption mechanisms of sulfamethoxazole on activated carbon. The aromatic CC peak shifted from 285.7 to 285.2 eV, indicating π-π electron donor-acceptor interaction. The carboxylic carbon peak at 288.1 eV increased in intensity, suggesting n-π interaction.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".