Environmental concerns over traditional chemical coagulants have increased research on plant-based alternatives. The turbidity removal capacity of five leaf-based natural coagulants — Morus alba, Vachellia nilotica, Trigonella foenum-graecum, Melia azedarach and Juglans regia — was comparatively assessed in synthetic kaolin water (500 NTU) at three pH levels (4, 7 and 10), six dosage levels (0–5000 mg L⁻¹) and three settling times (20–60 min). The full dataset (810 measurements) was analysed by four-way factorial ANOVA with Tukey's HSD (α = 0.05) — an empirical full-factorial optimisation approach. Functional group composition was characterised by FTIR spectroscopy. All effects were significant (p < 0.001; adjusted R² = 0.983), pH being dominant (ηp² = 0.97), followed by dosage (0.95), species (0.84) and settling time (0.83). At pH 4, Morus alba achieved 82.5 ± 0.8% turbidity removal at 500 mg L⁻¹ (60 min settling). Optimal removal fell to 42.6–50.1% at neutral pH and 22.6–30.1% under alkaline conditions. However, a persistent 8–13 percentage-point efficiency gap and a 12–25-fold dosage ratio relative to conventional coagulants (alum, FeCl₃, PAC) confirms that leaf-based systems are best positioned as complementary rather than substitutive technologies. pH-adjusted leaf-based coagulants are promising candidates warranting validation with natural water matrices and techno-economic assessment