**Glossary**

Brief explanations of few terms are mentioned in the state-of–the-art in this short glossary.

**NORM**: Naturally occurring radioactive material.

**TE-NORM**: Technologically enhanced naturally occurring radioactive materials.

**by-product**: Any product from an (industrial) process that is not the intended primary product, but inevitable given the process implemented.

**Product**: The intended output from an (industrial) process.

**REE**: Rare earth elements (or lanthanides), comprising 16 chemical elements, including those with atomic numbers 57 (lanthanum) through 71 (lutetium), as well as yttrium (atomic number 39).

**Waste**: Any material that is:

There is usually a synergy effect for the CMC of surfactant mixtures (mixture of nonionic and ionic surfactant) [69]. Mixture of TX100 and CTAB surfactants showed synergistic interactions, which can be manifested as enhanced surface properties, spreading, and many other phe‐ nomena, as shown in Figure 5. The synergistic behavior of mixed surfactant systems can be exploited to reduce the total amount of surfactant used in a particular application resulting in the reduction of cost [70]. It was observed that the removal values of radium isotopes of mixed systems of both surfactants are higher than their corresponding values without mixing, which indicate synergistic interaction in mixed CTAB-TX100 as a chemical extraction system. Removal of 84% and 80% for 226Ra and 228Ra, respectively, are obtained using synergistic effect of 1% aqueous solution containing 1:1 of the two surfactants investigated. In other words, mixed micelle formation in aqueous solution can be greater than that of the individual surfactant, and explained by non-ideal solution theory [70]. Also, it was observed that combined extraction of cationic and nonionic surfactants was effective in removal of both 226Ra and 228Ra. Experiments indicated that removal efficiency was optimized (80–84%) when a mixture of 1% CTAB and 1% TX100 was employed at the ratio 1:1. The theoretical justification for this surfactants solution is based upon two hypotheses, first that surfactant micelles may sequester radium radionuclides which are sorbed to the TE-NORM sludge waste, and second that the surfactant micelles may increase the concentration of radium radionuclides in the aqueous phase. The developed chemical treatment process would enable to design an

**Table 11.** Effect of temperature on the removal efficiency (R, %) of 226Ra and 228Ra using surfactants solutions

25 25.0 ± 1.7 27.0 ± 2.2 26.0 ± 1.9 22.0 ± 1.3

35 30.0 ± 1.9 39.5 ± 2.2 28.6 ± 2.2 35.9 ± 2.8

45 53.0 ± 1.7 45.3 ± 2.0 43.5 ± 2.7 46.2 ± 3.4

60 58.6 ± 2.1 54.3 ± 3.3 49.8 ± 3.8 50.7 ± 4.2

**TX100 solution CTAB solution**

**226Ra (R, %) 228Ra (R, %) 226Ra (R, %) 228Ra (R, %)**

Brief explanations of few terms are mentioned in the state-of–the-art in this short glossary.

**by-product**: Any product from an (industrial) process that is not the intended primary product,

**TE-NORM**: Technologically enhanced naturally occurring radioactive materials.

appropriate TE-NORM sludge washing strategy.

**NORM**: Naturally occurring radioactive material.

but inevitable given the process implemented.

**Glossary**

**Temperature** °**C**

106 Advances in Petrochemicals

(a) The unwanted/substandard output from an (industrial) process that cannot be utilized under given circumstances (technological/economic perspective);

(b) Declared as unwanted and/or unusable (regulatory perspective).

**Scale**: Solid deposit of low-solubility sulfates or carbonates on the inside of components of gas and oil production installations.

**Sludge**: Mixture of organic and mineral solids in water and liquid hydrocarbons separated from oil or gas at production facilities.

**Radioactive material**: Material designated in national law or by a regulatory body as being subject to regulatory control because of its radioactivity.

**Half-life**: For a radionuclide, the time required for the activity to decrease, by a radioactive decay process, by half. i.e., lose 50% of its activity.

**Secular equilibrium**: is a steady-state condition in which the rate of formation of the radio‐ active daughter products is just equal to the rate of decay; that is, the activity of radioactive parent and daughter are the same.

**Separator**: A pressure vessel used for separating well fluids produced from oil and gas wells into gaseous and liquid components.

**Industrial process**: This term is used very broadly in the present report to denote any human activity involving the application of technology, for example, the mining, processing, and drinking water treatment industries.

**EPA**: Environmental Protection Agency

**UNSCEAR**: United Nations Scientific Committee on the Effects of Atomic Radiation

**TBP**: Tri butyl phosphate

**DEHPA**: Bis (2-ethylhexyl phosphoric acid)

**TOPO**: Tri octyl phosphine oxide

**TBPO**: Tri Butyl phosphine oxide

**TPAsO**: Tri phenyl arsine oxide

**TPPO**: Tri phenyl phosphine oxide
