Yuhong Fu,Can Wu,Qin Liu,Shanshan Li,Sen Li,Shuai Zhang,Quan Wan
Gold recovery from wastewater should be cost-effective, efficient, and environmentally friendly. In this study, adsorbents containing Fe(II,III) systems were prepared via thermal modification of pyrite. The effects of thermal modification temperature, the source of pyrite, pH, ionic strength, adsorbent solid–liquid ratio, and coexisting metal ions on adsorption were investigated. Further, the removability of iron ions was explored, and multiple adsorption–desorption experiments were conducted to verify the stability and recyclability of the adsorbent. The adsorption law and mechanisms were analyzed using adsorption isotherms, thermodynamics, kinetics, and spectroscopy. The results revealed that the natural pyrite modified at 300°C ( N-Py-300) was a more suitable gold adsorbent with a maximum adsorption of 1055.2 mg/g at 25 °C. When coexisting with other metal ions, N-Py-300 exhibited highly selective adsorption of Au(III). Using a mixture of 10 % thiourea and 2 % HCl as a desorbent facilitated the desorption of almost all Au from N-Py-300, resulting in the recovery of Au and the reuse of N-Py-300. The Fe ions released from the adsorbent were effectively reduced by the addition of Ca(OH) 2 . The adsorption kinetics and isotherm data were in strong agreement with the pseudo-secondary and Langmuir models, indicating that Au(III) was chemisorbed on N-Py-300 as a monolayer and that Au(III) was reduced to Au(0) and Au(Ⅰ). The pH and IS also affected the adsorption behavior, implying that an electrostatic effect exists. Our findings provide that the thermally modified pyrite can be used to recover precious metals from wastewater efficiently, and provides an experimental basis for the resourceful use of pyrite.
Yuhong Fu,Shanshan Zhang,Qin Liu,Shanshan Li,Shuai Zhang,Sen Li,Can Wu,Meimei Ran
The environmental effects of nanoparticles have attracted widespread attention. The removal and recycling of nanoparticles are crucial for both environmental protection and resource reuse. However, current removal and recycling methods are not yet mature, and there is a need to explore inexpensive materials for the efficient removal and recycling of nanoparticles. This study investigates the effects of pyrite species, thermal modification temperature, pH and ionic strength on the adsorption of gold nanoparticles (AuNPs) by pyrite. The experimental results demonstrate that the adsorption rate of artificially thermally modified pyrite is slightly faster than that of naturally thermally modified pyrite. However, the concentration of Fe ions dissolved from the artificially thermally modified pyrite is higher. Natural pyrite, when thermally modified at 400°C and 500°C, adsorbs 100% of AuNPs within 10 min. The lower the acidity of the system, the faster the adsorption rate. Conversely, an increase in ionic strength decreases the adsorption rate. Artificially thermally modified pyrite primarily adsorbs AuNPs through electrostatic gravitational attraction, which is supplemented by a significant amount of chemisorption. After four recycling cycles, the adsorption and desorption rates of AuNPs using artificially thermally modified pyrite were 92.1% and 94.2%, respectively, indicating excellent adsorption and recovery performance. The results of this study provide a new method for the recycling of nanoparticles and an experimental basis for the further application of thermally modified pyrite in environmental treatments.
Sediment (SM) is composed of multiple components and exhibits a complex surface morphology, enabling it to adsorb water pollutants and result in sediment pollution. It is noted that SM can convert into material for reuse after calcination to decompose the adsorbed organic pollutants, which remains efficient photocatalytic performance. Our research demonstrates that SM-raw degrades 61.4 % of tetracycline (TC) within 240 min, and after adding Peroxysulphate (PDS) and hydrogen peroxide (H 2 O 2 ), the SM-350 (calcined at 350 °C) and the SM-250 (calcined at 250 °C) could remove 94.7 % and 95.7 %. Quenching experiments reveal that •O 2 − , 1 O 2 , and h + primarily contribute to TC degradation in SM-350/PDS and SM-250/H 2 O 2 systems. In addition, the SM samples maintained good degradation performance after five consecutive cycles. Additionally, the possible pathway of TC degradation and its product risk assessment was established to verify the toxicity of the intermediate products gradually decreased. In conclusion, this study offers a novel insight into the potential of SM as a cost-effective photocatalyst for the effective remediation of sediment and water pollution, but also plays an important role in environmental governance as a new strategy of “waste to treat waste”.
危险品化学品经营许可证（带存储）