Display omitted •Poly(ethylenimine)-functionalized pyroxene nanoparticles (PEI-PNPs) embedded into Diatomite has been prepared.•High removal efficiency of dye from real textile wastewater was achieved.•Breakthrough curves were described by convection-dispersion transport equation.•The breakthrough data was also analyzed using the equivalent length of unused bed approach. In this study, polyethylenimine-functionalized pyroxene nanoparticles (PEI-PNPs) were embedded into Diatomite (D4500), a commonly used filter aid, at <5wt% to remove a dissolved commercial textile red dye (CRD) from wastewater in batch and continuous flow column experiments. An array of characterization techniques, such as XRD, BET, HRTEM, and SEM was carried out for the Diatomite embedded nanoparticles. The filter aid was mainly composed of macroporous diatomaceous earth, its adsorption surface area and capacity for the CRD were improved significantly via embedding more PEI-PNPs. The adsorption isotherms in the batch studies were fairly explained by the Sips model. The adsorption performance of the fixed-bed column was tested for D4500, before and after embedding it with virgin and PEI-functionalized pyroxene nanoparticles, to determine the breakthrough curves under different operational conditions (e.g., inlet concentration of CRD, inlet flow rate, bed height, and nanoparticle concentration in Diatomite, %nps). The convection-dispersion transport equation was used to describe the obtained breakthrough curves, which enabled the determination of the axial dispersion coefficient (DL) and the Peclet number (Pe). Additionally, the breakthrough data was analyzed using the equivalent length of unused bed (HUNB) approach. In this approach Pe was correlated with HUNB with a good accuracy with the correlation: HUNB=0.013Pe+1.25 when Q and Co are the operational control parameters, while the correlation: HUNB=4.08e−0.002Pe when Z and %nps are the operational control parameters. These correlations can be helpful and useful for scaling up our proposed process for real industrial applications.