Rheological Behavior of Xanthan Gum Solution Related to Shear Thinning Fluid Delivery for Subsurface Remediation

Journal Article · Tue Jan 15 04:00:00 EST 2013 · Journal of Hazardous Materials, 244-245:160-170

DOI:https://doi.org/10.1016/j.jhazmat.2012.11.028· OSTI ID:1060647

Zhong, Lirong; Oostrom, Martinus; Truex, Michael J; Vermeul, Vincent R; Szecsody, James E

Xanthan gum, a biopolymer, forms shear thinning fluids which can be used as delivery media to improve the distribution of remedial amendments injected into heterogeneous subsurface environments. The rheological behavior of the shear thinning solution needs to be known to develop an appropriate design for field injection. In this study, the rheological properties of xanthan gum solutions were obtained under various chemical and environmental conditions relevant to delivery of remedial amendments to groundwater. Higher xanthan concentration raised the absolute solution viscosity and increased the degree of shear thinning. Addition of remedial amendments (e.g., phosphate, sodium lactate, ethyl lactate) caused the dynamic viscosity of xanthan gum to decrease, but the solutions maintained shear-thinning properties. Use of simple salt (e.g. Na+, Ca2+) to increase the solution ionic strength also decreased the dynamic viscosity of xanthan and the degree of shear thinning, although the effect is a function of xanthan gum concentration and diminished as the xanthan gum concentration was increased. At high xanthan concentration, addition of salt to the solution increased dynamic viscosity. In the absence of sediments, xanthan gum solutions maintain their viscosity properties for months. However, xanthan gum solutions were shown to lose dynamic viscosity over a period of days to weeks when contacted with saturated site sediment. Loss of viscosity is attributed to physical and biodegradation processes.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1060647
• Report Number(s): PNNL-SA-87185; AA3030100
• Journal Information: Journal of Hazardous Materials, 244-245:160-170, Journal Name: Journal of Hazardous Materials, 244-245:160-170
• Country of Publication: United States
• Language: English