Purpose – This work focused on the sulphonation modification research of highly crosslinking non-polarity macroporous adsorption resin (MAR) LX1180; the adsorption behaviour of LX1180 and its chloromethylation- and sulphonation-modified products (LX1180-Cl and LX1180-SO₃₋); and the influence of the structure parameters matching degree of MAR and flavonoids on the adsorption feature and adsorption kinetics.
Design/methodology/approach – LX1180-SO₃₋ was obtained by the processes of chloromethylation first and then sulphonation. LX1180-Cl and LX1180-SO₃₋ were prepared through the principle of substitution reaction from LX1180 and LX1180-Cl, respectively. First, Monochloromethyl ether (ME), pre-treated ZnCl₂, NaCl and iron powder were added into the swollen LX1180 to obtain the chloromethylated LX1180. Thereafter, NaCl, NaOH and SAA were added into the swollen LX1180-Cl to obtain the sulphonation modification LX1180. The conditions were investigated and optimised; the structures of LX1180-Cl and LX1180-SO₃₋ were characterised by Fourier transform infrared chromatography (FTIR) and a specific surface area instrument. Finally, the adsorption kinetics and adsorption isotherm were used to evaluate the adsorption capacity of LX1180-Cl and LX1180-SO₃₋ for flavonoids, and the adsorptions and desorptions of LX1180-SO₃₋ with different sulphonation degree on different flavonoids were investigated systemically.
Findings – Results showed that LX1180-Cl and LX1180-SO₃₋ had been prepared successfully, and that after the sulphonation, the adsorption capacity tended to increase with the increase of adsorption time, and the equilibrium adsorption capacity of LX1180-SO₃₋ was also higher than that of LX1180.
Research limitations/implications – The research only investigated the adsorption and desorption properties for only one kind of functional group, and other functional groups should also be studied in future work.
Practical implications – This contribution can provide a further base for the research of separation and purification of natural products with the aim to improve food additive removal or isolation and purification of flavonoids used for healthcare applications. Originality/value – The adsorptions and desorptions of LX1180-SO₃₋ with different sulphonation degree on different flavonoids were investigated. The relationship between sulphonation degree and the adsorption and desorption capacities of flavonoids were also explored, and the results showed that with the increase of sulphonation degree, the adsorption of LX1180-SO₃₋ to rutin and cyanidin was maximum, while the desorption ratio was minimum at the same sulphonation degree; this phenomenon could be ascribed to the variation in the polarity matching degree.