Photocatalysis Kinetics Analysis Platform

ChemFitX provides an online photocatalysis kinetics analysis workflow for researchers studying photocatalytic degradation, pollutant removal and light-driven reaction performance. The platform converts time-dependent absorbance, transmittance, concentration or concentration-proportional signals into normalized degradation data and apparent pseudo-first-order kinetic parameters in one browser-based workspace.

Upload one or more experimental files or enter points manually, define the monitoring wavelength and time information, choose how C₀ is selected, and process multiple samples using a common analysis time unit. The platform generates C/C₀ degradation curves, −ln(C/C₀) kinetic plots, apparent rate constants, half-lives, fit statistics, final degradation percentages and condition-comparison plots when the required experimental metadata are available.

The analysis is performed locally in your web browser by this application. Your experimental files are read and processed in the browser and are not uploaded to ChemFitX servers during the analysis.

What the Photocatalysis Kinetics Analysis Platform Can Do

Analyze photocatalytic degradation data from XLSX, XLS, CSV, TSV and TXT files.
Accept multiple experimental files in one analysis session.
Extract time-dependent signals from repeated wavelength/signal column pairs in spectral datasets.
Allow manual entry of time and signal values when a prepared data file is not available.
Work with absorbance, transmittance, concentration, concentration-proportional signal/intensity or already normalized C/C₀ data.
Convert percent transmittance to absorbance before normalization when transmittance is selected.
Normalize experimental signals to C/C₀ using a selected C₀ reference point.
Calculate degradation percentage for each valid time point.
Fit apparent pseudo-first-order kinetics using −ln(C/C₀) versus elapsed irradiation time.
Report apparent rate constant k, intercept, R², RMSE, number of fitted points and half-life.
Compare final degradation percentages and apparent rate constants across samples.
Generate descriptive comparisons against light intensity and irradiation wavelength when suitable metadata are supplied.
Interact with plots using pan, box zoom, zoom in, zoom out and reset controls.
Export processed results as Excel, CSV or JSON and export all generated plots together as a ZIP archive.

Supported Files and Experimental Data

Supported file formats

The platform accepts XLSX, XLS, CSV, TSV and TXT files. Spreadsheet files are read from the first worksheet, while delimited text files are parsed directly in the browser. Multiple files can be added to the experiment queue before processing.

Spectral wavelength/signal pairs

For spectral datasets, the platform interprets repeated pairs of columns as wavelength and signal data for successive time points. It extracts the signal nearest the selected monitoring wavelength (λmonitor) from each pair. Time values may be detected from column headers when they contain recognizable time information, or they can be assigned manually.

Manual data entry

Individual time and signal points can also be entered manually. Repeated points that use the same sample name are grouped into one time series, which is useful for simple kinetic datasets or for adding values without preparing a separate spreadsheet.

Signal types

Each sample can be analyzed as absorbance, transmittance, concentration, a generic signal or intensity proportional to concentration, or an already normalized C/C₀ ratio. One signal type should be used consistently for a given sample.

Experimental condition fields

The platform can store the monitoring wavelength, input time unit, optional light intensity and optional irradiation wavelength for each experiment. Monitoring wavelength and irradiation wavelength are different quantities: λmonitor is the wavelength used to obtain the analytical signal, whereas λirr describes the light used to drive the photocatalytic reaction.

From Experimental Signal to C/C₀

Photocatalytic degradation is commonly followed by comparing a concentration-related signal at each irradiation time with its initial value. ChemFitX converts the selected signal into a concentration proxy and then calculates the normalized ratio C/C₀.

Absorbance and concentration-proportional signals

When absorbance, concentration or a signal/intensity proportional to concentration is selected, the uploaded value is used directly as the concentration proxy. For absorbance-based analysis, this interpretation assumes that the monitored absorbance remains proportional to concentration over the analyzed range and that changing spectral interferences do not invalidate that relationship.

Transmittance data

When percent transmittance is selected, ChemFitX converts %T to absorbance using A = −log₁₀(T), with T expressed as a fraction. The resulting absorbance is then treated as the concentration proxy for normalization.

Already normalized data

If the uploaded values are already C/C₀, select the normalized-ratio option. In this mode, the platform uses the supplied ratio directly rather than dividing it by another starting signal.

Choosing C₀

You can instruct the platform to use the t = 0 point when present, otherwise the first suitable point, or to use the first chronological point explicitly. Elapsed irradiation time is referenced to the selected C₀ point. Negative time values can be retained for pre-irradiation or dark-equilibration records, but the kinetic fit uses non-negative elapsed times.

Degradation percentage

For each valid normalized point, degradation is calculated from the remaining fraction as (1 − C/C₀) × 100. This provides a direct percentage representation of the decrease in the monitored concentration proxy relative to C₀.

Pseudo-First-Order Photocatalysis Kinetics

The platform evaluates apparent pseudo-first-order behavior by fitting −ln(C/C₀) as a function of elapsed irradiation time. For a linear pseudo-first-order relationship, the fitted slope is reported as the apparent rate constant k in the selected analysis time unit, such as min⁻¹, h⁻¹ or s⁻¹.

Fit interval

Optional fit-start and fit-end controls let you restrict the kinetic regression to a selected portion of the experiment. This is useful when only part of the degradation curve is scientifically appropriate for a linear pseudo-first-order approximation.

Intercept and forced-origin fitting

By default, the regression includes an intercept. A separate option can force the fit through the origin, but the platform explicitly advises leaving this option off unless there is a scientific reason to impose that constraint.

Fit diagnostics

For each fitted sample, ChemFitX reports the apparent rate constant k, regression intercept, coefficient of determination R², root-mean-square error (RMSE), and the number of points included in the fit. At least three valid kinetic points are required for the linear regression.

Half-life

When the fitted apparent rate constant is positive, the platform estimates a pseudo-first-order half-life using t₁/₂ = ln(2)/k and reports it in the selected analysis time unit.

Comparing Photocatalytic Samples and Experimental Conditions

ChemFitX is designed to analyze several samples in the same session so that normalized degradation behavior and apparent kinetic parameters can be viewed side by side. The platform generates both time-dependent plots and summary comparisons.

C/C₀ versus irradiation time

The degradation plot shows the normalized concentration ratio for each sample after the selected C₀ reference point. This allows users to compare how quickly the monitored concentration proxy decreases with irradiation time.

Final degradation comparison

A bar chart compares the final calculated degradation percentage for each processed sample. The final point is taken from the non-negative elapsed-time portion of each dataset.

Apparent rate constant comparison

A separate bar chart compares valid positive apparent k values after all rate constants have been converted to the same selected analysis time unit.

Condition-aware descriptive plots

When light-intensity or irradiation-wavelength information is supplied for multiple experiments, the platform can generate descriptive scatter plots of k versus light intensity, k versus irradiation wavelength, degradation versus light intensity, and half-life versus light intensity. These plots should be interpreted only when the experiments are otherwise sufficiently comparable.

Comparison at a common irradiation time

For degradation-versus-light-intensity comparisons, users may select the final point of each sample or a common elapsed time available within the analyzed datasets. When a common time is selected, the platform interpolates the normalized data where appropriate before calculating the degradation value for that comparison.

Interactive Photocatalysis Plots

Generated charts include interactive controls for panning, box zoom, zooming in and out, returning to the full view, and exporting an individual plot as a PNG image. Mouse-wheel and pinch zoom are also supported by the charting interface.

The main visualization set includes C/C₀ versus elapsed irradiation time, pseudo-first-order kinetic plots, final degradation comparison, apparent rate constant comparison, and condition-dependent scatter plots when the required experimental information is present.

How to Use the Photocatalysis Kinetics Analysis Platform

Upload one or more XLSX, XLS, CSV, TSV or TXT files, or open Manual Data and enter time/signal points directly.
Choose the correct uploaded signal type: absorbance, transmittance, concentration, concentration-proportional signal/intensity, or already normalized C/C₀.
For spectral files, enter the monitoring wavelength λmonitor used to extract the analytical signal.
Confirm the input time unit and optionally provide light intensity and irradiation wavelength for condition comparisons.
Review the Experiment Queue. Edit sample names, signal types, time units and experimental condition values if necessary.
For spectral files, check the detected time assignments. Use the Assign control to enter or auto-fill missing time values.
Choose how C₀ should be selected and select the common analysis time unit for kinetic comparison.
If required, define a kinetic fit start and/or end time. Enable forced-origin fitting only when scientifically justified.
Click Process Analysis to calculate normalized degradation data, pseudo-first-order fits and comparison plots.
Review the kinetic fit table, processed-data table and interactive plots before interpreting apparent rate constants.
Export the results as an Excel workbook, CSV, JSON, individual plot images or a ZIP archive containing all available plots.

Understanding the Analysis Results

C/C₀

C/C₀ is the normalized concentration or concentration-proxy ratio relative to the selected initial reference. A value of 1 corresponds to the selected C₀ level, while lower positive values represent a decrease in the monitored signal relative to that reference.

Degradation (%)

Degradation percentage is calculated as (1 − C/C₀) × 100. It is a normalized response derived from the selected analytical signal and should be interpreted in the context of the underlying measurement method.

Apparent rate constant k

The reported k is the slope of the fitted −ln(C/C₀) versus elapsed-time relationship. It is an apparent pseudo-first-order constant for the supplied dataset and experimental conditions, not a universal intrinsic constant of the photocatalyst.

R² and RMSE

R² describes how much of the variation in the transformed kinetic data is represented by the fitted straight line, while RMSE summarizes the typical residual magnitude in the fitted −ln(C/C₀) space. These statistics should be considered together with the plotted data, the fit interval, the number of points and the scientific suitability of the kinetic model.

Half-life

The reported half-life is derived from the apparent pseudo-first-order rate constant when k is positive. It represents the time predicted by that fitted model for the normalized concentration proxy to reach one half of its initial value.

Fit assessment

The platform provides an automated qualitative fit label based mainly on the sign of k and the reported R². This label is a quick diagnostic rather than a substitute for scientific review of the underlying experiment, residual behavior and model assumptions.

Data Processing and Privacy

The photocatalysis analysis is implemented in the browser. Uploaded experimental files are read locally by the application for data extraction, normalization, fitting, plotting and export. The platform states that these experimental files are not uploaded to ChemFitX servers during the analysis.

Because the analysis is browser based, closing or refreshing the page can end the current working session unless the user has already exported the desired results. Keep original experimental files as the primary research record.

Scientific Scope and Important Limitations

The platform is intended to support transparent processing and comparison of photocatalytic degradation datasets. The numerical outputs remain dependent on the quality of the experimental data, the validity of the concentration proxy, the selected normalization point and the suitability of pseudo-first-order kinetics for the system being studied.

Absorbance-based C/C₀ analysis assumes that the monitored absorbance remains proportional to concentration under the experimental conditions.
Changes in scattering, background absorption, overlapping species, intermediates or spectral shape can affect the validity of a single-wavelength concentration proxy.
The monitoring wavelength λmonitor is used to extract the analytical signal and must not be confused with the photocatalytic irradiation wavelength λirr.
Apparent pseudo-first-order behavior should be judged from the transformed data and fit quality rather than assumed automatically for every photocatalytic system.
Forcing a kinetic regression through the origin can change the fitted rate constant and should only be used when scientifically justified.
Apparent k values should be compared across experiments only when relevant conditions such as catalyst loading, pollutant concentration, reactor geometry, irradiation conditions, sampling procedure and analytical method are sufficiently comparable.
Condition-dependent scatter plots are descriptive comparisons. They do not by themselves establish a mechanistic relationship between light intensity, wavelength and photocatalytic performance.
Time zero should normally represent the start of irradiation after any intended dark adsorption equilibration. Negative times can be retained as pre-irradiation records when needed.

Exporting Photocatalysis Results

ChemFitX provides several export routes for documenting or continuing the analysis. The Excel workbook contains a kinetics summary, processed data and key analysis settings. CSV export provides the processed point-by-point dataset, while JSON export stores settings, summary values and processed data in a structured format.

Each chart can be exported individually as a PNG image. The “All plots ZIP” option packages the available plot images into one ZIP archive for convenient download and later use in reports, presentations or further analysis.

Applications

Photocatalytic dye and pollutant degradation studies.
Comparing catalyst or photocatalyst formulations under matched conditions.
Evaluating normalized degradation curves from UV–Vis monitoring data.
Calculating and comparing apparent pseudo-first-order rate constants.
Examining how degradation performance changes across controlled light-intensity conditions.
Organizing multiple photocatalysis datasets into one consistent analysis workflow.
Preparing processed tables and plots for laboratory records, reports, manuscripts and presentations.

Frequently Asked Questions

What file formats can I upload?

The platform accepts XLSX, XLS, CSV, TSV and TXT files. You can also enter time and signal values manually without uploading a file.

Can I analyze several photocatalyst samples together?

Yes. Multiple files and manual datasets can be added to the experiment queue and processed in one session. Samples with the same sample name are grouped into a common time series where appropriate.

Can the platform analyze UV–Vis spectra collected at several irradiation times?

Yes. A spectral file may contain repeated wavelength/signal column pairs for successive time points. The platform extracts the signal nearest the selected monitoring wavelength from each pair.

What is the difference between monitoring wavelength and irradiation wavelength?

The monitoring wavelength is the analytical wavelength used to obtain the concentration-related signal, while the irradiation wavelength describes the light used to drive the photocatalytic reaction.

Does ChemFitX calculate degradation percentage?

Yes. After normalization, degradation is calculated as (1 − C/C₀) × 100 for valid points.

Does the platform calculate a pseudo-first-order rate constant?

Yes. It fits −ln(C/C₀) against elapsed irradiation time and reports the fitted slope as the apparent pseudo-first-order rate constant k when a usable regression can be calculated.

Can I choose only part of the experiment for kinetic fitting?

Yes. Optional fit-start and fit-end values can restrict the pseudo-first-order regression to a selected elapsed-time interval.

Should I force the kinetic fit through the origin?

Only when there is a clear scientific justification. The platform leaves this option off by default and explicitly warns users not to impose it automatically.

Can I compare rate constants measured in different time units?

The analysis converts times to a common selected analysis unit before rate constants are compared. This keeps displayed k values on the same time basis.

Can I compare photocatalytic performance versus light intensity or irradiation wavelength?

The platform can generate descriptive scatter plots when the required condition data are supplied for multiple experiments. These comparisons are meaningful only when the other experimental conditions are sufficiently comparable.

Are my experimental files uploaded to ChemFitX?

According to the platform design, uploaded files are read and analyzed locally in the browser and are not uploaded to ChemFitX servers by this application.

What can I export after analysis?

You can export an Excel workbook, processed CSV data, a structured JSON file, individual plot images, and a ZIP archive containing all available plots.