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Toxic and hazardous metals such as cadmium (Cd) and Lead (Pb) can cause cancer in humans; hence, reducing their bioavailability in the soil is crucial for human health and environmental safety. In this study, biochar modified with nanoscale zero-valent iron (nZVI-BC) was synthesized from low-cost adsorbent waste materials and iron (iii) oxide (Fe2O3) via carbothermal reduction process for stabilization of Pb and Cd in the soil. Furthermore, an evaluation of treatment efficiency on exposure health hazards for both carcinogenic and non-carcinogenic risks was done. The results revealed that nZVI-modified eggshell biochar was able to reduce the concentration bioavailable of Pb and Cd in soil by (69–75%) and (62–65%), and reduce the toxicity leaching of Pb and Cd by (53–66%) and (68–75%), respectively. The treatments reduced carcinogenic risk (CR) and hazard index (HI) in children and adults by 35–47% for Pb and 25–36% for Cd, respectively. Hence, this study proposes a new way to reduce and modify environmental wastes to make nZVI-supported biochar that can remediate toxic metals from the soil, improve soil nutrients, reduce human exposure health risks, and enhance the environment's health. [ABSTRACT FROM AUTHOR]

On the basis of H 2 O 2 -mediated growth of gold nanoparticle (AuNPs), a novel plasmonic enzyme-linked immunosorbent assay (pELISA) was developed with a polyclonal antibody for the ultrasensitive simultaneous naked-eye detection of tetrabromobisphenol A bis(2-hydroxyetyl) ether (TBBPA DHEE) and tetrabromobisphenol A mono(hydroxyethyl) ether (TBBPA MHEE), one of the major derivatives and byproducts of tetrabromobisphenol A (TBBPA), respectively. In this modified indirect competitive pELISA, glucose oxidase (GOx) played an important role leading to the growth of AuNPs through a reaction between GOx and glucose to produce hydrogen peroxide (H 2 O 2 ). In addition, further signal amplification was achieved via a large number of GOx molecules, which were immobilized on silica nanoparticles carrying poly brushes (SiO 2 @PAA) to increase the enzyme load, and the whole complex was conjugated on the second antibody. Under the optimized conditions, 10 -3 μg/L TBBPA DHEE can be distinguished via the observation of a colored solution, and the limit of detection (LOD) of the method using a microplate reader reaches 3.3 × 10 -4 μg/L. In contrast, the sensitivity of the method was 3 orders of magnitude higher than that using conventional colorimetric ELISA with the same antibody. Furthermore, the proposed approach showed good repeatability and reliability after a recovery test fortified with a variety of targets was performed (recoveries, 78.00-102.79%; coefficient of variation (CV), 4.38-9.87%). To our knowledge, this is the first case in which pELISA was applied for the detection of small molecules via the production of H 2 O 2 from GOx and glucose. The method will be widely used for the investigation of TBBPA DHEE and TBBPA MHEE in real environments.