THE EFFECTS OF NATURAL ZEOLITE ON HYDROCARBON ENCAPSULATION
The oil and gas industry produce large quantities of synthetic drill cuttings each year. These cuttings typically contain high levels of hydrocarbons, heavy metals, and chlorides. Traditionally, thermal treatment is a process that treats drill cuttings, but studies have found that it does not remove toxic contaminant. In recent years, scientists have looked for alternative treatment products.
A variety of studies (Conner & Hoeffner, 1998; Opete et al., 2010) examined how encapsulation as a waste conversion process produces an entity with structural integrity that is compatible for storage, landfill, or reuse. Challenges to this process involve the interference of high concentrations of organic compounds with the hardening of cement.
Pozzolans and ion exchange resins, both of which describe the properties of natural zeolite, are commonly used binding and solidification agents (Opete et al., 2010). These materials stabilize drill cuttings prior to landfilling and construction applications.
The use of zeolite as a binding material prior to encapsulation is related to its unique ability to absorb, trap, and immobilize contaminants. As a result, contaminant are not free to influence or interfere with the concrete development process (Hogg & Koop, 2010). Stabilization occurs in five ways: volatile organic compounds are captured by molecular sieving; non-volatile organics are adsorbed onto the surface area of zeolite grains; heavy metals are trapped by ion exchange; radioactive cations are trapped by ion exchange; metals are immobilized by the hydrogen bonding of oxyanions (Hogg & Koop, 2001).
Natural zeolite absorbs free hydrocarbons on contact (Hogg & Koop, 2001). The longer the contact between the contaminant and absorbent (i.e. zeolite) the more the contaminant is absorbed. Hogg and Koop (2001) incorporated zeolites into inverted drill cuttings and found that the hydrocarbons were absorbed into the pores of the material due to the affinity that zeolite has for hydrocarbons.