# Bi-Langmuir q-profiles **URL:** \ **Category:** Chromatography Modeling\ **Created:** [March 6, 2026, 4:25pm UTC](https://forum.cadet-web.de/t/bi-langmuir-q-profiles/1406 "2026-03-06T16:25:23Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![ollie\_p](https://forum.cadet-web.de/letter_avatar_proxy/v4/letter/o/858c86/32.png) [@ollie\_p](https://forum.cadet-web.de/u/ollie_p)\ **Post date:** [March 6, 2026, 4:25pm UTC](https://forum.cadet-web.de/t/bi-langmuir-q-profiles/1406/1 "2026-03-06T16:25:23Z")
Hello, I am trying to capture the data on the solid phase concentrations for a case with A and B under various inlet conditions. I can produce plots for outlet concentration but I cannot work out how to get the data of q. My working code is: ```auto #%% (A) import numpy as np import matplotlib.pyplot as plt from CADETProcess.processModel import ComponentSystem from CADETProcess.processModel import BiLangmuir from CADETProcess.processModel import ( Inlet, LumpedRateModelWithoutPores, Outlet ) from CADETProcess.processModel import FlowSheet, Process C_in = [[7.5, 7.5], [10, 10], [15, 15]] c_store = [] q_store = [] for i in range(len(C_in)): component_system = ComponentSystem() component_system.add_component('A') component_system.add_component('B') # -------------------------------------------------------- # Bi-Langmuir binding model # -------------------------------------------------------- binding_model = BiLangmuir(component_system, n_binding_sites=2, name='langmuir') binding_model.is_kinetic = True binding_model.adsorption_rate = [0.015, 0.03, 0.02, 0.035] binding_model.desorption_rate = [1, 1, 1, 1] binding_model.capacity = [100, 100, 100, 100] print('hi 1') # -------------------------------------------------------- # Column system # -------------------------------------------------------- feed = Inlet(component_system, name='feed') feed.c = C_in[i] eluent = Inlet(component_system, name='eluent') eluent.c = [0, 0] column = LumpedRateModelWithoutPores(component_system, name='column') column.binding_model = binding_model column.length = 0.6 column.diameter = 0.024 column.axial_dispersion = 4.7e-6 column.total_porosity = 0.65 column.solution_recorder.write_solution_bulk = True outlet = Outlet(component_system, name='outlet') flow_sheet = FlowSheet(component_system) flow_sheet.add_unit(feed, feed_inlet=True) flow_sheet.add_unit(eluent, eluent_inlet=True) flow_sheet.add_unit(column) flow_sheet.add_unit(outlet, product_outlet=True) flow_sheet.add_connection(feed, column) flow_sheet.add_connection(eluent, column) flow_sheet.add_connection(column, outlet) process = Process(flow_sheet, 'batch elution') print('hi 2') # -------------------------------------------------------- # Events # -------------------------------------------------------- Q = 60 / (60 * 1e6) process.add_event('feed_on', 'flow_sheet.feed.flow_rate', Q) process.add_event('feed_off', 'flow_sheet.feed.flow_rate', 0.0) process.add_event('eluent_on', 'flow_sheet.eluent.flow_rate', Q) process.add_event('eluent_off', 'flow_sheet.eluent.flow_rate', 0.0) process.add_duration('feed_duration') process.add_event_dependency('eluent_on', ['feed_off']) process.add_event_dependency('eluent_off', ['feed_on']) process.add_event_dependency('feed_off', ['feed_on','feed_duration'], [1,1]) process.cycle_time = 750 process.feed_duration.time = 60 print('hi 3') # -------------------------------------------------------- # Run CADET # -------------------------------------------------------- print(binding_model.n_binding_sites) print(binding_model.n_bound_states) if __name__ == " __main__": from CADETProcess.simulator import Cadet print('hi 4') process_simulator = Cadet() print('hi 5') simulation_results = process_simulator.simulate(process) print('hi 6') # -------------------------------------------------------- # Extract outlet solution # -------------------------------------------------------- outlet_solution = simulation_results.solution.column.outlet solid_solution = simulation_results.solution.column.solid t_full = outlet_solution.time c = outlet_solution.solution c_store.append(c) solid_solution = simulation_results.solution.column.solid q_store.append(solid_solution.solution) c_store = np.array(c_store) #q_store = np.array(q_store) print("DATA GENERATED\n") plt.figure(figsize=(8,6)) for i in range(len(C_in)): c = c_store[i] cA = c[:,0] cB = c[:,1] plt.plot(t_full, cA, label=f"A dataset {i}") plt.plot(t_full, cB, '--', label=f"B dataset {i}") plt.xlabel("Time (s)") plt.ylabel("Outlet concentration") plt.title("Outlet Chromatograms (Bi-Langmuir)") plt.legend() plt.grid() plt.show() ``` When I add the line: ```auto column.solution_recorder.write_solution_solid = True ``` I get the error: ```auto ValueError: Expected size (751, 100, 2) ``` Which comes after (during the first iteration of the loop): ```auto hi 1 hi 2 hi 3 2 4 hi 4 hi 5 ``` I have also tried using (to the same result): ```auto column.solution_recorder.write_solution_bound ``` I put all the print(‘hi n’) in to indicate where the code reaches. Note: hi 6 is never printed when i get the error. Any ideas? Thanks! ---
**Author:** ![j.schmoelder](https://forum.cadet-web.de/user_avatar/forum.cadet-web.de/j.schmoelder/32/93_2.png) [@j.schmoelder](https://forum.cadet-web.de/u/j.schmoelder)\ **Post date:** [March 8, 2026, 5:22pm UTC](https://forum.cadet-web.de/t/bi-langmuir-q-profiles/1406/2 "2026-03-08T17:22:58Z")
Hi Ollie, thanks for reaching out. Your issue seems to have been fixed in [this PR](https://github.com/fau-advanced-separations/CADET-Process/pull/289), so if you use our `dev` branch, your script should run. To install it, run the following: ```auto pip install git+https://github.com/fau-advanced-separations/CADET-Process.git@dev ``` Note, I hope that we can soon make a new release which includes this fix. Cheers, Jo ---
**Author:** ![ollie\_p](https://forum.cadet-web.de/letter_avatar_proxy/v4/letter/o/858c86/32.png) [@ollie\_p](https://forum.cadet-web.de/u/ollie_p)\ **Post date:** [March 9, 2026, 12:05pm UTC](https://forum.cadet-web.de/t/bi-langmuir-q-profiles/1406/3 "2026-03-09T12:05:46Z")
Hi Jo, Ok thank you for the response! I have installed this but the code still does not record any solids. What lines in my code do I actually need to change? Kind regards, Ollie ---
**Author:** ![j.schmoelder](https://forum.cadet-web.de/user_avatar/forum.cadet-web.de/j.schmoelder/32/93_2.png) [@j.schmoelder](https://forum.cadet-web.de/u/j.schmoelder)\ **Post date:** [March 9, 2026, 12:07pm UTC](https://forum.cadet-web.de/t/bi-langmuir-q-profiles/1406/4 "2026-03-09T12:07:47Z")
Hi, if you add ```auto column.solution_recorder.write_solution_solid = True ``` then ```auto simulation_results.solution.column.solid ``` will contain the solid solution. ---
**Author:** ![ollie\_p](https://forum.cadet-web.de/letter_avatar_proxy/v4/letter/o/858c86/32.png) [@ollie\_p](https://forum.cadet-web.de/u/ollie_p)\ **Post date:** [March 23, 2026, 12:47pm UTC](https://forum.cadet-web.de/t/bi-langmuir-q-profiles/1406/5 "2026-03-23T12:47:19Z")
Sorry this still does not work but it is not of high importance for me to fix right now it was more curiosity, I will try again when the bug is patched 🙂