We present constraints on the baryonic matter density parameter, Ωb, within the framework of the ΛCDM model. Our analysis utilizes observational data on the effective optical depth from high-redshift quasars. To parameterize the photoionization rate Γ−12, we employ a Bézier polynomial. Additionally, we approximate the Hubble parameter at high redshifts as  km s−1 Mpc−1. Confidence regions are obtained with h = 0.701 ± 0.013 and Ωm = 0.315, optimized by the Planck mission. The best-fit values are  and , corresponding to an old data set and a new data set, respectively. We test the non-parametric form of Γ−12, obtaining . These results are consistent with the findings of Planck at the 1σ confidence level. Our findings underscore the effectiveness of quasar data sets in constraining Ωb, eliminating the need for independent photoionization rate data. This approach provides detailed cosmic information about baryon density and the photoionization history of the intergalactic medium.

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