Traceable green antiscalants for membrane desalination and high-recovery water treatment: Fluorescent platforms, mechanism-guided design, and engineering translation

Mineral scaling remains a major constraint in membrane desalination, high-recovery reverse osmosis, brine concentration, and industrial water reuse. Conventional antiscalants have enabled practical scale control for decades, but their performance is still commonly evaluated by static inhibition efficiency, residual ion concentration, crystal morphology, or endpoint precipitation tests. These metrics provide limited information on where the antiscalant acts, how much active inhibitor remains, and whether the proposed mechanism is supported under realistic water-treatment conditions. This review discusses traceable antiscalants within an evidence-qualified green-design framework that integrates scale inhibition, fluorescence-based monitoring, mechanistic substantiation, environmental qualification, and engineering translation. We summarize major mineral scales and conventional inhibition strategies, then examine why residual dose is not necessarily equivalent to effective antiscalant concentration in complex water matrices. Fluorescently tagged phosphonates, bisphosphonates, polyacrylates, and other functional polymers are reviewed as probes for tracking inhibitor-associated signals and spatial distribution. Particular attention is given to intrinsically fluorescent carbon, silicon, and sulfur quantum-dot platforms, including polymer-functionalized variants. Mechanistically, antiscalant design should expand beyond, rather than replace, classical metal-ion association and crystal-growth inhibition by adopting a stage-specific framework that considers precursor regulation, heterogeneous nucleation, crystal-surface recognition, and polymer conformation. The coupling of inorganic scaling with organic fouling and biofouling is also discussed. Overall, traceability should be treated as an evidence layer rather than a surrogate for antiscaling activity, and engineering translation requires dynamic membrane validation, real-water calibration, environmental qualification, and process-level assessment.