A polyepoxysuccinic acid derivative (LCY-PESA) was synthesized from polyepoxysuccinic acid (PESA) and L-cysteine (LCY) as well as characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy. The new LCY-PESA polymer was evaluated on inhibition of static and dynamic scale deposition

static corrosion inhibition

iron oxide dispersion

and biodegradation. The mechanism of corrosion inhibition was further explored theoretically by quantum chemistry modeling on molecular orbitals of the LCY-PESA polymer. In a medium containing Ca2+ at 400 mg·L-1 and HCO3- at 800 mg·L-1

the inhibition on static scale deposition reached up to 94.6% with addition of LCY-PESA at 6 mg·L-1. The minimum light transmittance was 61.5% when 15 mg·L-1 LCY-PESA was introduced to a clear medium of Ca2+ at 150 mg·L-1 and Fe2+ at 10 mg·L-1. The heat resistance of dynamic scale deposition decreased upon LCY-PESA addition to medium. At concentration of 1.0 mg·L-1

LCY-PESA had about 15% higher inhibition on dynamic scale deposition than PESA. Analysis on crystal structure of calcium carbonate scale deposits by infrared spectroscopy (IR)

X-ray diffraction (XRD)

and scanning electron microscopy (SEM) indicated that LCY-PESA could significantly distort calcium carbonate crystals such that the steady calcite was transformed to vaterite. Further experimental results showed that the new polymer had good scale dispersion and biodegradability. Molecular simulation showed that the sulfur and nitrogen atoms of LCY moiety strongly alter electron density of the highest occupied molecular orbital (HOMO) of the LCY-PESA molecule so that the energy gap (ΔE) between HOMO and LUMO (the lowest unoccupied molecular orbital) of LCY-PESA is less than that of PESA

which could improve corrosion inhibition of LCY-PESA polymer.