Abstract:
Objective To address the limitations of conventional lithium ion detection methods (e.g., titration, atomic absorption spectrometry)—such as high alkali consumption, substantial energy requirements, and poor anti-ion interference ability—in the analysis of complex brines (e.g., geothermal brines, oil and gas field produced water), this study developed a novel, efficient, and highly selective detection method.
Method A phthalocyanine-based fluorescent probe was synthesized, leveraging steric compatibility between the lithium ion radius and the phthalocyanine macrocyclic cavity. This design enables specific lithium recognition through formation of a stable high-coordination-number complex, with quantification achieved via fluorescence intensity changes upon binding.
Result The probe exhibited exceptional lithium ion selectivity, effectively mitigating interference from common cations (Na+, K+, Mg2+, Ca2+) in complex matrices. A linear relationship (R2 > 0.99) between fluorescence intensity and lithium ion concentration (2×10−5 to 2×10−4 mol/L) enabled construction of a robust calibration curve. Successful on-site quantification of lithium ion in oil and gas field produced water confirmed practical utility.
Conclusion This phthalocyanine fluorescent probe method provides an efficient and precise strategy for lithium ion detection in complex brine environments. It extends lithium carbonate pharmaceutical analysis technology to resource exploration while offering critical technical and theoretical support for sustainable lithium extraction, advancing development of lithium resource utilization technologies.
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