Abstract
Introduction
Within the contemporary sustainability paradigm, national security is increasingly defined by environmental resilience rather than conventional military-political metrics. Transboundary particulate matter (PM₁₀) transport intensified by persistent droughts, land degradation, and climate change epitomizes this non-traditional security threat. Elevated PM concentrations severely impair public health, disrupt macroeconomic stability across agriculture, industry, and tourism, and exacerbate regional geopolitical friction. Although conventional petroleum-based mulches offer immediate soil stabilization, their substantial carbon footprint, prohibitive costs, and potential for secondary soil and groundwater contamination constrain their long-term viability. In response, circular economy principles provide a strategic imperative through industrial symbiosis and waste valorization. A compelling opportunity involves synthesizing calcium chloride (CaCl₂) ​mineral mulch from byproduct hydrochloric acid (HCl) a hazardous petrochemical effluent exceeding 320,000 metric tons annually in Iran thereby transforming a critical industrial liability into an eco-efficient soil-stabilizing resource.
Objective
This study evaluates the technical and strategic feasibility of synthesizing high-purity CaCl₂​ mulch from industrial byproduct HCl and locally sourced limestone. By coupling petrochemical waste management with sustainable soil stabilization, this research develops an integrative framework aligning industrial resource efficiency with national environmental security.
Research Method and Materials
The synthesis of CaCl₂ ​was conducted using industrial-grade limestone (97% CaCO₃ purity) and 32 wt% hydrochloric acid obtained from the Karun Petrochemical Company. The batch reaction was performed with a stoichiometric excess of limestone, designating HCl as the limiting reactant. Given the highly exothermic profile of the reaction and the associated evolution of CO₂ and acidic vapors, specialized containment and ventilation protocols were maintained. Following a 12-hour reaction period, the cessation of effervescence indicated reaction completion, after which the pH was neutralized. The resultant supernatant was separated and quantified via classical acid-base titration (0.1 N NaOH), while X-ray fluorescence (XRF) spectroscopy was performed on the thermally dried precipitate to determine elemental composition and structural purity.
Results and Discussion
Analytical characterization confirmed the successful synthesis of a 32 wt% CaCl₂ aqueous solution. XRF spectroscopy of the dried crystalline product demonstrated an exceptionally high purity of 99.36%, with only minor trace impurities of iron (Fe), magnesium (Mg), and potassium (K). Upcycling this hazardous byproduct into a high-value commodity simultaneously resolves the environmental liabilities of HCl disposal and generates a multifunctional agent suitable for fugitive dust suppression, de-icing, and oilfield operations. This closed-loop valorization pathway curtails dependency on imported chemical stabilizers, mitigates the compounding economic losses of dust storms, and offers a scalable framework for regional environmental diplomacy and cooperative transboundary dust abatement.
Conclusion and Policy Recommendations
Mitigating dust emissions across Iran’s 15 million hectares of vulnerable terrain necessitates a paradigm shift from fragmented end-of-pipe interventions toward integrated circular economy frameworks:
I. Industrial Symbiosis: Policymakers must establish regulatory and fiscal frameworks that mandate and incentivize petrochemical complexes to channel hazardous acidic effluents into environmental remediation value chains.
II. Strategic Diversification: The dual functionality of CaCl₂ across dust suppression and oil-gas operations should be strategically harnessed to bolster macroeconomic resilience and advance industrial import substitution.
III. Resilience Governance: Dust abatement strategies must be institutionalized within national security frameworks and transboundary diplomatic agendas, fostering regional environmental cooperation and community-based watershed restoration to safeguard socio-ecological integrity.