Pistachio shells as remediating agents for uranium in contaminated industrial seawater

Investigation of Chelating Agents for the Removal of Thorium from Human Teeth upon Nuclear Contamination

Thorium-232 (232Th) is a radioactive heavy metal that is of increasing interest as a source of nuclear energy. However, upon nuclear incidents, the ingestion or inhalation of Th in major quantities can contribute to chemical and radiological health problems, including accumulation in the bone tissue and an increased risk of developing pancreatic, lung, and hematopoietic cancers. The major mineral component of the bone is hydroxyapatite (HAP)─also the major mineral component of the teeth. As such, the teeth are the first site of exposure upon oral ingestion of Th-contaminated materials, and Th can pose a potential risk to teeth development. In essence, in the case of human contamination, it is critical to identify effective chelating agents capable of removing Th. Using a batch study methodology, this present work investigates the uptake and the removal of Th from synthetic HAP and from teeth samples by diethylenetriamine pentaacetate (DTPA), ethylenediaminetetraacetic acid (EDTA), and other promising chelating agents. Th uptake over synthetic HAP exceeds 98% at physiological pH with <1 min of contact time and uptake exceeds 90% across the entire pH range. Regarding teeth, over 1 mg Th uptaken per gram of tooth is observed after 24 h. The overall effectiveness of chelating agents for the removal of Th from is as follows: DTPA > EDTA > NaF/mouthwash/3,4,3-LI(1,2-HOPO); this trend was observed both in synthetic HAP and Th-impregnated teeth samples.

Eco-friendly approach for efficient catalytic degradation of organic dyes through peroxymonosulfate activated with pistachio shell-derived biochar and activated carbon

This study introduces a simple method for the preparation of biochar (BCP) and activated carbon using pistachio (ACP) external hull as residual solid waste. Low-cost raw materials, biodegradable, recyclable and organic solid wastes are advantages of this method. Furthermore, complete degradation of methyl orange (MO) and methylene blue (MB) to H₂O and CO₂ as eco-friendly compounds in mild reaction condition occurs at a short time. Also, the effects of crucial parameters (temperature, time, catalyst dosage, initial dye and oxidant concentration, initial reaction pH level and radical scavengers), capability, adaptability, performance and reusability of ACP were also evaluated. The results displayed that dyes could be decomposed effectively by the PMS/ACP-800 system. Furthermore, the sulphate radical (SO4∙-) was a major active role in the degradation process, while hydroxyl radical (^•OH) played a minor role. Overall, ACP had yielded high degradation of MB and MO dyes; therefore, ACP-800 could be effectively and reliably applied in the treatment of industry effluents containing MB and MO dyes.

Uptake and Removal of Uranium by and from Human Teeth

Uranium-238 (²³⁸U), a long-lived radiometal, is widespread in the environment because of both naturally occurring processes and anthropogenic processes. The ingestion or inhalation of large amounts of U is a major threat to humans, and its toxicity is considered mostly chemical rather than radiological. Therefore, a way to remove uranium ingested by humans from uranium-contaminated water or from the air is critically needed. This study investigated the uranium uptake by hydroxyapatite (HAP), a compound found in human bone and teeth. The uptake of U by teeth is a result of U transport as dissolved uranyl (UO₂²⁺) in contaminated water, and U adsorption has been linked to delays in both tooth eruption and development. In this present work, the influence of pH, contact time, initial U concentration, and buffer solution on the uptake and removal of U in synthetic HAP was investigated and modeled. The influence of pH (pH of human saliva, 6.7-7.4) on the uptake of uranyl was negligible. Furthermore, the kinetics were extremely fast; in one second of exposure, 98% of uranyl was uptaken by HAP. The uptake followed pseudo-second-order kinetics and a Freundlich isotherm model. A 0.2 M sodium carbonate solution removed all the uranyl from HAP after 1 h. Another series of in vitro tests were performed with real teeth as targets. We found that, for a 50 mg/L U in PBS solution adjusted to physiological pH, ∼35% of the uranyl was uptaken by the tooth after 1 h, following pseudo-first-order kinetics. Among several washing solutions tested, a commercially available carbonate, as well as a commercially available fluoride solution, enabled removal of all the uranyl taken up by the teeth.