X-ray diffraction (XRD) is an important and widely used material characterization technique. With the recent development in material science technology and understanding, various new materials are being developed, which requires upgrading the existing analytical techniques such that emerging intricate problems can be solved. Although XRD is a well-established non-destructive technique, it still requires further improvements in its characterization capabilities, especially when dealing with complex mineral structures. The present review conducts comprehensive discussions on atomic crystal structure, XRD principle, its applications, uncertainty during XRD analysis, and required safety precautions. The future research directions, especially the use of artificial intelligence and machine learning tools, for improving the effectiveness and accuracy of the XRD technique, are discussed for mineral characterization. The topics covered include how XRD patterns can be utilized for a thorough understanding of the crystalline structure, size, and orientation, dislocation density, phase identification, quantification, and transformation, information about lattice parameters, residual stress, and strain, and thermal expansion coefficient of materials. All these important discussions on XRD analysis for mineral characterization are compiled in this comprehensive review, so that it can benefit specialists and engineers in the chemical, mining, iron, metallurgy, and steel industries.

To lock atmospheric CO₂ at anthropogenic timescale, fast weathering silicates can be applied to soil to speed up natural CO₂ sequestration via enhanced weathering. Agricultural lands offer large area for silicate application, but expected weathering rates as a function of soil and crop type, and potential impacts on the crops, are not well known. This study investigated the role of plants on enhanced weathering of wollastonite (CaSiO₃) in soils. Using rooftop pot experiments with leguminous beans (Phaseolus vulgaris L.) and nonleguminous corn (Zea mays L.), CO₂ sequestration was inferred from total inorganic carbon (TIC) accumulation in the soil and thermogravimetric analysis, and mineral weathering rate was inferred from alkalinity of soil porewater. Soil amendment with wollastonite promoted enhanced plant growth: beans showed a 177% greater dry biomass weight and corn showed a 59% greater plant height and a 90% greater dry biomass weight. Wollastonite-amended soil cultivated with beans showed a higher TIC accumulation of 0.606 ± 0.086%, as compared to that with corn (0.124 ± 0.053%). This demonstrates that using wollastonite as a soil amendment, along with legume cultivation, not only buffers the soil against acidification (due to microbial nitrogen fixation) but also sequesters carbon dioxide (12.04 kg of CO₂/tonne soil/month, 9 times higher than the soil without wollastonite amendment).

Inherently formed iron-based water treatment residuals (WTRs) were tested as alternative sorbents for multi-heavy metal removal from synthetic solutions, contaminated sediments, and surface waters. The WTRs were mainly composed of iron (hydr)oxides and had a high BET surface area (170.7 m2/g), due to the presence of micro- and mesopores. The sorption capacity of WTRs for As(V), Cd2+, Pb2+ and Zn2+ from synthetic solutions surpassed that of a commercially available goethite by 100-400% for single contaminant tests, and by 240% for total sorption in multi contaminant tests. The maximum sorption capacity of WTRs towards As(V), Pb2+ and Zn2+ was estimated by Langmuir equation fitting to range between 0.5 to 0.6 mmol/g, and their maximum sorption capacity for Cd was 0.19 mmol/g. WTRs performed significantly better than goethite for adsorption of cationic contaminants (Cd, Co, Ni, Pb, Zn) in the sediment tests, independent of the dosage or sediment sample. At the highest WTRs dosage (250 mg/g), concentrations of the cationic contaminants decreased by at least 80%, while approximately 40% removal was obtained with 50 mg/g dosage. Sorbent mixtures composed of WTRs with goethite, and with a clinoptilolite natural zeolite were used to reduce As leaching. The sorbent mixtures delivered the desired performance, with the natural zeolite performing better than the goethite as an amendment to WTRs. In addition, up to 90% removal of surface water contaminants was achieved with both fresh WTRs and the WTRs regenerated using 0.01 M EDTA.status: publishe

Carbon dioxide (CO₂) is a major greenhouse gas, and its concentration in the atmosphere is increasing continuously, hence there is an urgent need to reduce its level in the atmosphere. Soils offer a large natural sink to store CO₂. This study focuses on sequestering CO₂ in the agricultural soils as inorganic carbon, which can be accomplished by adding alkaline-earth silicates. Wollastonite is used in this study as a soil amendment, to sequester CO₂ via the geochemical route of mineral carbonation. The first objective of the present study was to evaluate the effect of mixing a wide range of dosages of wollastonite, as a soil amendment, on the growth performance of two leguminous plants frequently used in agricultural sector: soybean and alfalfa. The plants were grown with different wollastonite dosages (3–20 kg·m⁻² for soybean and 3–40 kg·m⁻² for alfalfa), for a duration of 14 weeks in a microplot experiment in Ontario, Canada. The second objective was to find evidence of enhanced weathering of wollastonite in soil, in addition to the augmentation of inorganic carbon content in soil. For this, mineralogical assessment of the soils was performed using XRD and SEM-EDS analyses. Wollastonite increased the soybean yield by two-fold in the plot amended with 10 kg·m⁻². At all dosages, wollastonite increased the alfalfa growth in terms of height and above-ground biomass dry weight, as well as root biomass. The rate of CO₂ sequestration, at optimum wollastonite dosage, reached 0.08 kg CO₂·m⁻²·month⁻¹. XRD and SEM-EDS analyses indicated accumulation of calcite in wollastonite-amended soil and formation of other weathering products. The results obtained from this study help to understand the impact of wollastonite soil amendment on agronomy, and will aid in implementing such negative emissions technology by informing farmers and industry alike that the use of wollastonite contributes toward global climate change mitigation while supporting crop yield. The findings of this study add to the existing body of knowledge on enhanced weathering as an atmospheric CO₂ removal technology, providing further evidence that wollastonite weathering in agricultural soils can lead to significant capacity for CO₂ sequestration as inorganic carbon, while concurrently promoting plant growth.