Targeting surface modification of nano calcium carbonate and its high proportion filling performance of ABS copolymer

Integrated recovery of calcium salts and collagen-derived fractions from eggshell waste using ultrasound-assisted acid treatment.

Utilisation of calcium carbonate derived from pilot-scale indirect CO2 mineral carbonation of waste concrete: Impacts on mechanical and microstructural properties of mortar

Heterogenous catalysts for transesterification from snail, crustacean and mollusc shells

Flexible and porous sponges with high osteoconductivity have a wide range of bone healing applications. Although polymer/ceramic composite materials can serve as soft bone grafts, osteogenesis can be compromised when the ceramic surface is covered by the polymer. This study aimed to fabricate a bone-graft sponge with high elasticity and osteoconductivity by integrating carbonate apatite (CAp) particles inside and on the surface of poly(l-lactide-co-ε-caprolactone) (PLCL). A slurry comprising PLCL and a calcium carbonate (CaCO3) precursor was freeze-dried to obtain a PLCL/CaCO3 sponge, which was then phosphatized into a PLCL/CAp sponge using a mildly alkaline sodium phosphate solution. This sodium phosphate solution not only converted CaCO3 into CAp but also partially degraded the PLCL matrix to expose CAp on the surface, which improved the hydrophilicity of the surface. Interconnected macropores with diameters of 500-600 μm were also introduced by embedding and subsequently leaching sodium chloride (NaCl) crystals from the PLCL/CaCO3 sponge. Invitro cell experiments demonstrated that CAp and the macroporous structure significantly enhanced osteoblast adhesion and differentiation. Invivo evaluations using a rabbit femoral defect model revealed that CAp endowed the PLCL sponge with osteoconductivity, facilitating bone ingrowth from the defect margins in 4 weeks. The macroporous structure enabled bone regeneration throughout the sponge. These findings suggest that the developed PLCL/CAp sponge is a promising biomaterial for bone regenerative applications.

Experimental study on impermeability of concrete panels repaired by Enzyme-Induced Calcium Carbonate Precipitation (EICP)

Engineering porous vaterite CaCO₃ nanostructures via alcohol-surfactant coordination in co-precipitation: A facile route to tunable drug-carrier platforms.

This study aimed to examine the association between pulmonary function and serum biomarkers among Egyptian workers occupationally exposed to ultrafine calcium carbonate (CaCO 3 ) particles, which can penetrate biological membranes and accumulate in the lungs. A cross-sectional study was conducted on 80 nonsmoking males: 40 CaCO 3 -exposed workers and 40 matched controls. Participants underwent medical and occupational history taking, clinical examination, spirometry, and serum biomarker measurement (Clara cell protein 16 [CC16], matrix metalloproteinase-9 [MMP-9], and tissue inhibitor of metalloproteinase-1 [TIMP-1]). Exposed workers demonstrated a significantly higher prevalence of respiratory symptoms along with significantly reduced pulmonary function indices. They also showed decreased CC16 and elevated MMP-9 and TIMP-1 levels. Biomarkers correlated with lung function decline and exposure duration. Chronic CaCO 3 exposure was associated with increased respiratory risk, necessitating protective workplace measures.

Strain-hardening cementitious composites (SHCC) develop multiple microcracks under tensile or flexural loading, which accelerates the ingress of aggressive agents. Microbially induced calcium carbonate precipitation (MICP) offers a promising route to enhance the self-healing of such crack networks. This study innovates by systematically coupling key MICP parameters, such as bacterial suspension-to-cementation solution ratio, calcium source, and Ca²⁺ concentration, and directly translating the optimized mineralization condition into a practical spray-based crack-healing protocol for SHCC. The mineralization products were characterized using SEM, EDS, XRD, and elemental mapping. The results show that mixing ratio and Ca²⁺ concentration strongly govern CaCO₃ quantity and morphology. At 1.5 mol/L, calcium acetate produces higher mineralization performance than calcium chloride and calcium nitrate under the tested conditions. In SHCC specimens, five spray treatments with 1.5 mol/L cementation solution achieved complete surface crack closure (100% healing rate) and markedly reduced capillary absorption. This study provides insights into the key factors affecting MICP mineralization in cementitious systems and offers practical guidance for optimizing microbial self-healing agents in construction materials.

Low-carbon concrete crack repair strategies based on soybean urease induced calcium carbonate precipitation technology

Optimizing compressive strength in eco-friendly cement composites using CO₂-sequestered precipitated calcium carbonate by particle size and replacement ratio

Recycling solid waste into artificial aggregates represents a promising approach for large-scale solid waste management and alleviating the shortage of natural construction materials. However, the preparation and curing processes play a decisive role in the performance of aggregates. To meet the requirements of early-age strength of aggregates and synergistic load-bearing behavior with hardened cement matrices, this study developed a novel solid waste-based artificial aggregate using steel slag(SS) and recycled concrete fines (RCF). Polypropylene fibers (PPF) were incorporated, and a combined process of compaction granulation and CO 2 curing was employed. The results show that the optimal performance was achieved with a mix proportion of RCF:SS = 60:40, 1% PPF content, and a compaction pressure of 89 MPa, which increased compressive and splitting tensile strengths by 152.68% and 81.81%, respectively. Energy evolution analysis further revealed that this mix proportion enhanced the total energy, elastic strain energy, and dissipated energy by 157.30%, 135.93%, and 203.72%, respectively. These improvements are attributed to the synergistic effect of fiber bridging and compaction-induced densification, which together enhance material toughness and energy dissipation capacity. Additionally, calcium carbonate crystals formed during CO 2 curing effectively filled internal pores and strengthened the fiber-matrix interface. In summary, This study introduces the incorporation of polypropylene fibers into steel slag-recycled concrete fines-based artificial aggregates, achieving synergistic regulation of their microstructure and mechanical properties through combined compaction and CO 2 curing. In perspective, this approach enables the high value integral utilization of solid wastes and provides an eco-friendly technical strategy and theoretical guidance for the production of high-performance, low-carbon artificial aggregates. • Solid wastes are integrally recycled into artificial aggregates by compact granulation and CO 2 curing. • Fibre addition into artificial aggregates improves the stress-strain properties of aggregates. • Reinforced artificial aggregates modify the stress-strain properties of cement matrix. • Energy evolution characteristics of cement specimens with reinforced aggregates are improved.

Mineralization regeneration of NH3–CO2 absorption solution and crystalline phase transition pathways of calcium carbonate

EPS-mediated mineralization drives granule densification and enhances denitratation-anammox coupling under alkaline conditions.

Interfacial interactions between oil and porous calcium carbonate in brine: Insights for enhanced oil recovery and spill remediation.

ABSTRACT The presence of oil in water can have a devastating impact on the environment, harming wildlife, ecosystems, and water quality. The oil content in industrial wastewater typically varies from 100 to 1000 mg/L, necessitating a reduction to 5 mg/L before discharge. To address the treatment of these oil-water emulsions, tubular membranes were produced using a horizontal extrusion method. The membranes comprised fly ash, quartz, calcium carbonate, and α-alumina in a weight ratio of 70%, 20%, 5%, and 5%, respectively. A solution of 2 wt.% carboxymethylcellulose (CMC) sodium salt in water is used as a binder for the ceramic precursors. The sintered membranes at 1100°C (FA_1100) and 1200°C (FA_1200) were found to have average pore diameters of 0.15 and 0.11 μm, porosity of 37.31 and 36.67%, and mechanical stability of 31.65 and 38.53 MPa, respectively. The pure water permeability of FA_1100 and FA_1200 was estimated to be 9.89 × 10−8 and 3.79 × 10−8 m3 /m2.kPa.s, respectively. The separation efficiency of these membranes was evaluated through cross-flow filtration at five different pressure levels, ranging from 69 kPa to 345 kPa for an oil-water emulsion of concentration 100 mg/L. The oil removal efficiency of the membranes increased progressively with increasing pressure, and complete oil removal was observed at a pressure of 345 kPa. The membrane FA_1100 showed the best permeate flux and rejection combination. The permeate produced from these ceramic membranes is fully reusable in the oil industry, which can contribute to addressing the current water scarcity issue. Research highlights A cost-effective tubular ceramic membrane for treating oil-water emulsions has been developed domestically. Increasing the sintering temperature reduces the porosity and pore size of the prepared membrane. Membranes displayed superior compressive strength compared to other clay-based membranes. Complete removal of oil was achieved using the membrane under crossflow mode.

Inflammatory bowel disease (IBD) involves oxidative stress, chronic inflammation, and gut microbiota dysbiosis, complicating therapeutic intervention. Herein, we engineer a robust living therapeutic platform via a biomimetic nanoarmoring strategy. A uniform FDA-approved calcium carbonate (CaCO3) nanocoating is in situ mineralized on the surface of the probiotic Escherichia coli Nissle 1917 (EcN) preassembled with the flavonoid luteolin (Lut), creating the nanocomposite EcN-Lut/CaCO3. This nanoarmoring strategy enhances bacterial viability under simulated gastrointestinal conditions (a 100-fold survival increase) and enables colon-specific delivery. The composite demonstrates potent reactive oxygen species scavenging (∼100%) and immunomodulatory capacity in vitro, downregulating pro-inflammatory cytokines (TNF-α, IL-6, IL-1β, IL-17A) while elevating anti-inflammatory IL-10. In a DSS-induced murine colitis model, EcN-Lut/CaCO3 significantly attenuated disease severity, restoring colon length (a 57.30% recovery compared to healthy control), reducing the disease activity index by 72.73% relative to the DSS group, and improving histopathology. Transcriptomic analysis reveals dual regulation of host signaling pathways with activation of cAMP/cGMP-PKG metabolic cascades and suppression of IL-17/TNF inflammatory pathways. Concurrently, 16S rRNA sequencing shows that the nanoarmored platform effectively reverses dysbiosis, selectively enriching beneficial genera such as Lactobacillus and Muribaculaceae while suppressing proteobacterial pathobionts. This work presents a generalizable nanoarmoring strategy that transforms fragile probiotics into intelligent, multifunctional living therapeutics, offering a powerful approach for the targeted treatment of IBD and other complex inflammatory disorders.

The Bay of Bengal is a large but relatively shallow embayment of the northeastern Indian Ocean. It receives a significant amount of freshwater and sediment, approximately 2000 million tonnes annually, from the Himalayan and the Indian peninsular rivers during the North East (NE) and the South West (SW) monsoons, respectively. The sediment flux to the bay is among the highest globally due to its size, location, and the catastrophic deposition of sediments. Long paleo-synoptic reconstructions and paleomonsoon interpretations from sediment cores in the Bay of Bengal are limited. This is largely because the enormous sediment load that enters the Bay through river discharge occurs under high-energy conditions, making it challenging to retrieve turbidity-free and undisturbed sediment cores. However, some recent reports (Ponton et al., 2012; Tripathy et al., 2014) have documented variations in paleoclimate and geochemical cycles from the Last Glacial Maximum to the late Holocene period in the Bay of Bengal. Sedimentological and geochronological studies conducted on the eastern Bengal shelf studied by Kuehl et al. (1989) revealed that the highest sediment accumulation from the Ganges-Brahmaputra river system occurs near the head of the Swatch of No Ground, which is located west of the present river mouths of Ganges-Brahmaputra. Additionally, Kolla and Rao (1990) analyzed sediment sources from the Bay of Bengal and reported high quartz and low calcium carbonate percentages adjacent to the Indian subcontinent, likely due to a substantial influx of terrigenous clastics. Furthermore, investigations on the mineralogy and heavy minerals in sands suggest that sediments of the western Bengal Fan, characterized by high levels of smectite, sillimanite, and garnet, are derived from peninsular Indian rivers.

To develop bone grafts with superior osteoconductivity, we have fabricated unidirectionally connected porous carbonate apatite (CAp) via gelatin gelation combined with freeze-drying. A composite of calcium carbonate (CaCO3) and gelatin was first gelled at low temperature and then subjected to directional freeze-drying to create well-aligned macroporous channels. The samples were then sintered to remove the organic components and subsequently phosphatized to convert the composition into CAp. The resulting material exhibited a porosity exceeding 80% with fully interconnected unidirectional pores favorable for cell migration and vascular infiltration. Bone regeneration was evaluated by implanting the material into rabbit femoral bone defects; a comparison was also made with nonoriented porous controls. Histological and radiographical analyses demonstrated that the unidirectional porous structure significantly enhanced directional ingrowth of new bone tissue and accelerated early-stage bone formation relative to the control. This study demonstrates that unidirectional porous CAp fabricated via a gelatin-based freeze-casting method is promising for bone regeneration, particularly in clinical applications requiring guided bone formation.

ABSTRACT We present a hybrid stochastic-continuum model to study the sulphation of calcium carbonate and the consequent formation of gypsum, a key phenomenon driving marble deterioration. While calcium carbonate and gypsum are continuous random fields evolving according to random ordinary differential equations, the dynamics of sulfuric acid particles follow Itô-type stochastic differential equations. The particle evolution incorporates both strong repulsion between particles via the Lennard‒Jones potential and non-local interactions with the continuum environment. The particle–continuum coupling is also achieved through a chemical reaction, which is modelled as a Poisson counting process. We simulate the spatiotemporal evolution of this corrosion process using the Euler‒Maruyama algorithm with varying initial data combined with finite elements to address spatial discretization. Despite symmetric initial data, our simulations highlight an uneven progression of corrosion due to stochastic influences in the model.