Adsorption of anti-inflammatory and analgesic drugs traces in water on clay minerals

The aim of this study was to assess the adsorption of four non-steroidal anti-inflammatory drugs (NSAIDs), namely Paracetamol (PRC), Diclofenac (DIC), Ibuprofen (IBU), and Ketoprofen (KET), using both batch and continuous experiments with clay. Various analytical techniques, including XRD, FTIR, SEM coupled to EDX, and Zeta potential, were employed to characterize both raw and calcined clay. XRD and FTIR analyses confirmed the kaolinite nature of the clay. SEM data revealed a lamellar structure formed in the clay after calcination at 550 °C. Adsorption tests were conducted to determine the optimal adsorption conditions. Batch kinetics of adsorption demonstrated rapid adsorption of all four NSAIDs, with the highest adsorption occurring at pH 4 (DIC, IBU, and KET) and pH 6 for PRC, using a concentration of 20 mg L-1 of calcined clay. Additionally, the pseudo-second-order model provided the best fit for all NSAIDs adsorption processes. Maximum adsorption capacities, as determined by the Langmuir model, were 80 mg g-1 for PRC, 238 mg -1g for DIC, 138 mg g-1 for IBU, and 245 mg g-1 for KET. In fixed bed column studies, three dynamic models (Thomas, Adams-Bohart, and Yoon-Nelson) were utilized to describe the breakthrough curves, with linear regression used to identify key characteristics for process design. The fixed bed column adsorption study revealed that DIC exhibited the highest removal efficiency at 98%, while KET, IBU, and PRC were more persistent, with removal efficiencies of 77.1%, 76.7%, and 67.1%, respectively. The Thomas model was deemed appropriate for describing the breakthrough curve. These findings offer valuable insights into the interactions between clay and pharmaceuticals with varying physicochemical properties. They also provide information on the adsorption models, saturation, and adsorption capacities of various pharmaceuticals on natural clays, which can be crucial for further research and environmental remediation efforts.

A systematic study on sustainable low carbon cement - Superplasticizer interaction: Fresh, mechanical, microstructural and durability characteristics

As governments around the world take on ambitious construction projects, from housing to infrastructure to transportation, the demand for cement is set to rise. It is anticipated that global cement production is set to achieve a compound annual growth rate of ∼5.1% for the years 2022-2025. The negative impact of cement production on the environment, such as carbon emissions and energy consumption, is also well known. This instigates the need to look for alternative and sustainable supplementary cementitious materials (SCMs) such as Fly ash (FA), Limestone (LS), Metakaolin (MK), Ground granulated blast furnace slag (GGBFS) and Silica fume (SF) which when blended with Portland clinker result in lower carbon emissions and better end products. With expanding cement demand, the need for chemical admixtures has also increased. This comprehensive study focuses on the compatibility of commercially available superplasticizers with SCMs blended low carbon cement and their influence on fresh and hardened properties along with microstructural and durability aspects. The chemistry of superplasticizers and how it effects the hydration mechanism of blended cement are also highlighted in detail. Moreover, the effect of different types of superplasticizers, their dosage, water binder ratio, and details of experiments used by other authors are also discussed and listed. As cementitious matrix containing any kind of SCM such as FA showed better environmental performance on the basis of life cycle assessment which was due to carbon emission factor (ξi). For cement, ξi was 311.27 kg CO2-eq/t, whereas for FA it was much lower (8.70 kg CO2-eq/t). Based on this comprehensive literature review, current challenges for the utilisation of waste SCMs incorporating superplasticizers along with research gap have been identified. Apart from this, the ongoing research work on the effect of chemical and mineral admixture on Limestone-calcined clay cement (LC3) using statistical modelling to optimize the mix is also discussed. It was observed that the use of a specific type of mineral admixture with a superplasticizer inversely affected the mechanical properties like compressive strength and modulus of rupture but improved the water-binder ratio, porosity, and water absorption.

Effect of calcined clay on the improvement of compaction, swell and microstructural characteristics of expansive soil

Expansive soil is problematic soil because its alternate swell shrink behaviour depends on the presence of water. Soil stabilization technique was widely adopted to alter the characteristics of the expansive soil which is suitable for construction. Among the various soil stabilization techniques, chemical stabilization was found to be more suitable method of sustainable stabilizing the soil due to its effective and timely reaction with the chemical compound. Calcined form of clay material is used as an admixture to study the effects on the improvement of soil properties. Calcined Clay (CC) is added into the virgin soil with different percentages of 2%,4%,6%,8% and 10% under varying 1,3,7,14,28 and 60 days of curing by conducting experiments such as standard proctor test, Free Swell test to analyse the compaction characteristics and swelling behaviour of the soil. In addition to that the X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) on virgin and treated soil were studied by varying 2% incremental of CC up to 10% at 28 days of curing. From the test results it shows the variation in the compaction characteristics by rising in Maximum Dry Density (MDD) and reduction in Optimum Moisture Content (OMC) that merges at 8% as an optimum to develop the soil behaviour and from the free swell test, it was found that the Free Swell Index (FSI) of the soil decrease from 210 to 80 at 10% calcined clay added soil and the Mineralogical studies also show the variation in the compounds. Thus, this naturally available calcined clay was used to improve the soil Compaction and swell characteristics that influences the reduction in deformation and increase in shear strength of soil which helped to minimize the environmental problem as well as one of the effective admixtures to improve the expansive soil characteristics.

Utilisation of persistent chemical pollutant incorporating with nanoparticles to modify the properties of geopolymer and cement concrete

The majority of industrial products are identified as persistent organic pollutants after their date of expiry, which is highly harmful to the ecosystem and human health and also going to be banned around the world. Paint latex is one of those pollutants which become a hazardous waste material after stocking for a long time. Approximately 20% of color paints do not get used for their desired purpose after getting sold out and end up in a landfill. Now a day's construction industry is inclining towards the various types of geo-polymer concrete since it does not require cement. But that geo-polymer concrete has too much less workability as compared to the same grade of control cement concrete. To achieve the desired workability as well as other properties of geo-polymer concrete by using waste paint latex as performance improving admixture is the main motive of the present research. Fourteen different mixes of control and calcined clay-based geo-polymer concrete have been prepared by adding up to 3% waste paint latex of weight of cementitious materials and a detailed study has been done on various properties such as workability, rheology, shrinkage, strength and its microstructure. The presence of nanoparticles of TiO₂ in waste paint latex has helped to produce extra hydration products, by which the mechanical properties, durability and microstructure of both traditional and geo-polymer concrete have increased. It has been concluded that a higher dose of waste paint latex improves the workability but the strength and durability properties of traditional and geo-polymer concrete improve up to 2-2.5% of waste paint latex replaced to water.

Characterization data of reference materials used for phase II of the priority program DFG SPP 2005 "Opus Fluidum Futurum - Rheology of reactive, multiscale, multiphase construction materials"

A thorough characterization of base materials is the prerequisite for further research. In this paper, the characterization data of the reference materials (CEM I 42.5 R, limestone powder, calcined clay and a mixture of these three components) used in the second funding phase of the priority program 2005 of the German Research Foundation (DFG SPP 2005) are presented under the aspects of chemical and mineralogical composition as well as physical and chemical properties. The data were collected based on tests performed by up to eleven research groups involved in this cooperative program.

Ternary and quaternary blends as partial replacement of cement to produce hollow sandcrete blocks

Hollow sandcrete blocks constitute more than 90% of residential building construction in developing countries especially in West Africa. Over-reliance on dredged river sands and conventional ordinary Portland cement (OPC) contributes to environmental degradation and post-construction problems such as swelling and shrinkage-induced cracks prevalent in construction projects. The study investigates potential utilization of locally available materials such as laterite, calcite and calcined clay as ternary and quaternary blends to replace cement and quarry dust as 100% replacement of river sand with the aid of Taguchi-Response surface methodology approach. Optimum ternary blend of 24% calcined clay +1% calcite +75% OPC is recommended to achieve volume stability, higher compressive strength and higher flexural load capacity. Alternatively, ternary blends of 24% calcite +4% calcined clay +72% OPC can also be utilized. The improved mechanical properties were attributed to the Na- and Ca-rich aluminosilicates provided by the blended cements. Successful utilization of ternary and quaternary blended cements to produce stronger, durable and eco-friendly sandcrete blocks depends on utilization of high binder-to-aggregate ratio, optimal combination of the constituents, appropriate water-cement ratio and curing/production method. Partial and 100% replacement of river sand with granite dust is possible and contributes to reduction of environmental problems caused by river dredging as well as cleaner, ecofriendly construction. Ternary and quaternary blended cements is recommended to avert post-construction problems such as swelling and shrinkage-induced cracks prevalent in construction projects.

Green remediation of As and Pb contaminated soil using cement-free clay-based stabilization/solidification

Stabilization/solidification (S/S) is a low-cost and high-efficiency remediation method for contaminated soils, however, conventional cement-based S/S method has environmental constraints and sustainability concerns. This study proposes a low-carbon, cement-free, clay-based approach for simultaneous S/S of As and Pb in the contaminated soil, and accordingly elucidates the chemical interactions between alkali-activated clay binders and potentially toxic elements. Quantitative X-ray diffraction and ²⁷Al nuclear magnetic resonance analyses indicated that the addition of lime effectively activated the hydration of kaolinite clay, and the presence of limestone further enhanced the polymerization of hydrates. X-ray photoelectron spectroscopy showed that approximately 19% of As^[III] was oxidized to As^[V] in the alkali-activated clay system, which reduced toxicity and facilitated immobilization of As. During the cement-free S/S process, As and Pb consumed Ca(OH)₂ and precipitated as Ca₃(AsO₄)₂·4H₂O and Pb₃(NO₃)(OH)₅, respectively, accounting for the low leachability of As (7.0%) and Pb (5.4%). However, the reduced amount of Ca(OH)₂ decreased the degree of hydration of clay minerals, and the pH buffering capacity of the contaminated soil hindered the pH increase. Sufficient dosage of lime was required for ensuring satisfactory solidification and contaminant immobilization of the clay-based S/S products. The leachability of As and Pb in high-Ca S/S treated soil samples was reduced by 96.2% and 98.8%, respectively. This is the first study developing a green and cement-free S/S of As- and Pb-contaminated soil using clay minerals as an environmentally compatible binding material.