Parameters	Description	Unit
PR (%)	phosphorus removal efficiency	[%]
qe,calc	equilibrium concentration of the adsorbed substance predicted by the isotherm model	[mg P/g]
qe	equilibrium concentration of the adsorbed substance	[mg P/g]
qm	maximum sorption capacity	[mg P/g]
qt	sorption capacity after time t	[mg P/g]
Ce	equilibrium concentration of the sorbed substance	[mg P/L]
K	equilibrium constant	[-]
n, m	heterogeneity parameters of the sorbent surface	[-]
t	time	[s]
Co	initial concentration of phosphorus	[mg P/L]
Ct	concentration of phosphorus after time t	[mg P/L]
V	volume of solution	[L]
M	mass of material	[g]
k1	rate constant	[1/min], [g/(mg P·min)]
R2	coefficient of determination	[-]
Adj R2	adjusted coefficient of determination	[-]
z	corresponding variable	[-]
Abbreviation	Description
SEM	scanning electron microscopy
SEM-EDS	scanning electron microscopy—energy dispersive spectroscopy
BET	Brunauer, Emmett, and Teller (the method of determination of the specific surface area)
FT-IR	Fourier transform infrared spectroscopy
RM	raw marl
HM	heated marl at 1000℃
P	Polonite®