Role of cationic surfactant in the removal of chromium( <scp>VI</scp> ) by sodium borohydride
Bibliographic record
Abstract
Abstract Sodium borohydride (NaBH 4 ) is one of the most effective reductants for chromium(VI), a severely toxic natural water and soil contaminant. Spectroscopic investigations of oxidative degradation of potassium dichromate (Cr(VI)) by NaBH 4 have been studied in aqueous media. At lower concentrations of oxidant, researchers observed the formation of a coordination complex between chitosan, Cr(VI), and borohydride (BH 4 − ) prior to the rate‐determining step. Removal efficiency decreases from 87.1% to 17.5% with increasing the pH from 3.0 to 8.0 of the reaction mixtures. Activation parameters (activation energy = 59.5 kJ/mol, enthalpy of activation = 57.2 kJ/mol and entropy of activation = −67.8 JK −1 mol −1 ) were determined for Cr(VI) removal and compared with the literature values. Post‐micellar effect was negligible due to the strong coordination between the cetyltrimethylammonium bromide (CTAB) aggregates and reactants. CTAB is an effective inhibitor (removal efficiency decreases sharply from 80.2% to 18.1% with CTAB concentration, from 0.0 to 3.0 mM) and environmentally friendly, and this research showed that the use of CTAB can be a promising approach for the inhibition of the fast removal of water contaminants and resistant compounds.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".