"Clay minerals are particularly important because they have a relatively high surface area. For example, montmorillonite, which I used several times as a research sample, has a specific surface area of 83.9 m2 g -1. This means that 1.1 gram (1 / 4 teaspoons) of clay mineral samples from the soil have a surface area of 100 m2, which is the same as the area of a football field. This indicates that although physically the clay mineral is very small, it has a very large substance for life. "Indonesian soil binds various minerals and elements needed by plants. The bound nutrients and minerals can be released back according to their speed or kinetics, so they are absorbed with the right concentration by plants," said Prof. Jaslin Ikhsan, M.App., Sc., Ph.D as he delivered Inaugural Speech at the UNY Auditorum (21/11) entitled Model of Complexation and Modification of Clay Mineral Surfaces as New Materials and Their Benefits. Jaslin Ikhsan who is a lecturer in the Chemistry Education Study Program of the Faculty of Mathematics and Science (FMIPA), YSU, was inaugurated as the 165th UNY Professor.

Jaslin stated that although the benefits of clay minerals have been known and the practice of using clay minerals has been used for a long time, however, there is not much research that explains the reaction mechanism that occurs on the surface of clay minerals. "The surface reactivity of the solid phase in the soil comes from chemical properties or functional groups on the surface of the clay minerals. When a functional group on the surface reacts with a dissolved molecule to form a surface complex, a reaction called surface complexation occurs, "he explained.

Jaslin concluded the contents of his speech as follows: First, Indonesian clay contains aluminosilicate, philosilicate or clay minerals which have a) active sites with a charge; b) large specific surface area; c) surface capacitance; d) cation / anion exchange capacity; e) the interlayer and shaft areas, which make the soil play an important role in binding chemical compounds and releasing them. The principle of binding or the adsorption process by clay minerals is used by various groups and industries for health, waste handling, environmental management and catalysts.

Our research shows that computer software aided surface complexation models are excellent for explaining the processes or reactions that occur on the surface of clay minerals. This model is simple and has been widely used by researchers in the world and has produced quality publications in various reputable international journals. In addition, this model is considered to be effective and efficient in terms of finance, security and work safety in the laboratory. Third, the surface of clay minerals can be modified into new, more functional materials, as needed. "Our research is able to change a surface that is charged and polar, into a surface that is hydrophobic and very important to reduce PAH waste which damages soil quality and the environment," said Jaslin, he continued. Anions or cation exchangers can increase the capacity of silica to bind anions / cations, this result means for the handling of environmental wastes such as toxic heavy metal waste from the environment.

The complexation model can also be used by students as a good chemistry learning medium, especially in determining various reactions, and determining the equilibrium constant, so that students can carry out free exploration of reactions and reaction balance constants based on potentiometric titrations or acid-base titrations. (rew, Tj.lak)

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