Over the last century, classical thermodynamics has been used as the most important tool to describe equilibrium properties of environmental chemical processes. However, thermodynamics has its limitations, which are most often apparent in biological and phase boundary systems. Metastable Equilibrium Adsorption (MEA) Theory proposes a fundamental deficiency in the existing theoretical foundation of adsorption thermodynamics that adsorption density Г (mole/m2) has been incorrectly used as a state variable in the past. When Г is not treated as a state variable, classical thermodynamic adsorption principles will have to be re-examined so that equilibrium adsorption constants will be fundamentally affected by the kinetics/reversibility of adsorption processes (Pan et al., 1998, J. Colloid Interface Sci., 201, 71；J. Colloid Interface Sci., 201, 77). This implies that previously measured equilibrium adsorption data may show a lack of consistency, thereby making the use/comparison of the data problematic. This theory therefore has broad and fundamental implications in many adsorption related fields such as colloid and interface sciences, chemistry and chemical engineering, environmental sciences, catalysis and material sciences.

Recently we have further developed the MEA theory in the following 6 aspects. 1) Set up the technique of XAFS that made the measurement of the microscopic structures of adsorbed pollutants at particle-water interfaces possible (Pan et al., 2004,J. Colloid Interface Sci., 271,28; J. Colloid Interface Sci., 271,35). 2) Developed 2 novel techniques (i.e. Circulative Temperature Scanning Adsorption-desorption technique and Assemble-disassemble Initial Concentration technique) to quantitatively measure the irreversible kinetics of adsorption reactions. The latter has never been possible before in the whole area of sciences and so the 2 novel techniques may be a revolutionary breakthrough in the development of non-linear non-equilibrium adsorption theories. 3) Developed a technique of plasmid DNA assay to measure the toxicity of environmental pollutants at different MEA states (Chang and Pan, 2004, Environmental Science). 4) Developed quantum chemical calculation methods that can obtain mechanistic information from molecular level on the microstructure and reactivity of environmental pollutants at particle-water interfaces (Zhu and Pan, 2004, J. Physical Chemistry; Pan and Zhu, 2004, 228th ACS meetings). 5) Found the control of MEA states on the mechanistic pathway of photocatalytical degradation of organic pollutants. 6). Developed new principles in phosphorus biogeochemistry based on the MEA theory that imposed new understandings in phosphorus limitation in the East Mediterranean, which may contribute to a more accurate modeling of global environmental change (Pan et al, 2002, Environ. Sci. & Technol., 36:3519).

The above-mentioned techniques triggered by the development of MEA theory, such as XAFS, quantum chemical calculation and plasmid DNA assay of environmental pollutants, are also significant in promoting studies in Molecular Environmental Science in China.