Flocculation kinetics of precipitated calcium carbonate induced by functional nanocellulose
Bibliographic record
Abstract
ABSTRACTThe interactions between precipitated calcium carbonate (PCC) and electrosterically stabilized nanocrystalline cellulose (ENCC) and dissolved carboxylated cellulose (DCC) have been studied in this thesis. ENCC and DCC usually have a high carboxylate content (3.5 mmol/g or higher) and can be produced by periodate, chlorite and TEMPO oxidations. ENCC/DCC showed a high flocculation efficiency with PCC particles and induced PCC flocculation by a combination of electrostatic and bridging forces. ENCC/DCC induces the maximum PCC flocculation when PCC particles reach to isoelectric point. Novel nanocellulose particles were prepared by periodate oxidation in this study. For partial oxidation (degree of substitution (DS)<2), three products were generated: fibrous cellulose, rod-like dialdehyde cellulose (DAC) nanofibers, which we refer to as sterically stabilized nanocrystalline cellulose (SNCC), and dissolved DAC which we refer to as dialdehyde modified cellulose (DAMC). SNCC has similar dimension (100–200 nm in length and 5–8 nm in width) as conventional nanocrystalline cellulose (NCC) made by sulfuric acid hydrolysis. SNCC was characterized and its properties were compared to NCC. In addition, morphological features and size distributions of three SNCCs prepared by different degrees of oxidation were measured by transmission electron microscopy and dynamic light scattering (DLS). It shows that the three SNCCs have similar diameters (5-10 nm). However, the average length of SNCC decreases with aldehyde content: from approximately 590 nm after 26 hrs of oxidation to 100 nm for an oxidation period of 84 hrs. It indicates that the morphology of SNCC can be well controlled by the degree of periodate oxidation, which depends on the amount of periodate and the reaction time. Based on this observation, we propose that periodate reacts preferentially with the amorphous region of cellulose, followed by proceeding at the boundary of amorphous and crystalline regions. The steric stability of SNCC is proved by DLS when adding cosolvents into aqueous SNCC suspensions. The flocculation of PCC induced by SNCC was also studied. SNCC particles can bridge PCC to induce flocculation at low dosage (above 1mg/g). SNCC induced the maximum flocculation when its fractional coverage was more than half coverage because SNCC particles become unstable after deposition on PCC. Adsorption isotherms of three SNCCs and dialdehyde modified cellulose (DAMC) on PCC particles were measured. It was found that DAMC had a higher affinity than three SNCCs with different aldehyde contents, and the affinity of SNCC increased with reaction time. This indicates DAMC chains adsorb stronger than nanocrystalline parts of SNCC on PCC.
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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".