Waste power banks (a kind of lithium-ion battery) are widely generated along with the growing widespread use of mobile phone. Vacuum carbon reduction is encouraged to recover cobalt and nickel from ...spent lithium-ion battery. However, the mixed nickel and cobalt particles are difficult to be further separated. Recovering cobalt and nickel respectively from the electrode powders is important to improve the recovery value of spent lithium-ion battery. According to the analysis of Gibbs free energy of the reduction process of Ni2+ and Co2+, we proposed a cleaner technology of step-by-step vacuum carbon reduction to recover nickel and cobalt in sequence from the electrode powder of spent lithium-ion batteries. The Ni2+ and Co2+ in the spent lithium-ion battery are reduced into nickel and cobalt in vacuum tubular furnace at the temperatures of 691 °C and 873 °C respectively. Nickel and cobalt can be separated in sequence by magnetic separation at the reduction products of different temperatures. Additionally, for energy saving and accurate reduction, we analyzed the heat transfer in the vacuum reduction process and constructed the models for computing the true temperature of electrode powder in crucible. The models are used to compute the accurate reduction temperatures for Co2+ and Ni2+. It will greatly reduce the energy cost in the reduction process which be attributed to sustainable development. The models also can guide the structure design of vacuum tubular furnace for improving the efficiency of heat transfer.
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•A cleaner technology was developed to recover nickel and cobalt from waste power banks.•Models for the heat transfer during vacuum reduction were constructed to save energy.•Nickel and cobalt were reduced at the optimized temperatures of 691 °C and 873 °C respectively.
•The existing soil remediation technologies were reviewed.•Non-thermal plasma is an attractive and promising technology for soil remediation.•Non-thermal plasmas for organic contaminated soil ...remediation were reviewed.•The influential factors on plasma remediation were discussed.•The remediation mechanisms were elucidated.
There is an increasing focus around the world on soil contamination by organic compounds due to its harmful effect on human health. Significant efforts have been devoted to the remediation of soil contaminated by organics, leading to the development of various remediation strategies, such as physical remediation, bioremediation, and chemical remediation. Recently, an attractive advanced oxidation process (AOP), non-thermal plasma technology, has drawn increasing attention for the remediation of organic contaminated soil due to the low energy consumption, rapid start-up and shutdown of the process, as well as a low requirement for the pretreatment process of soil, etc. In this work, the current situation of soil contamination by organic pollutants and the existing soil remediation methods were introduced. The research progresses of various non-thermal plasmas for organic contaminated soil remediation were presented, such as dielectric barrier discharge (DBD), pulsed corona plasma, and non-thermal gliding arc fluidized bed. The effects of different parameters (e.g., applied voltage, soil properties, type and feed flow rate of the carrier gas, as well as the reactor configuration) on the remediation performance of non-thermal plasmas were discussed. In addition, the possible degradation mechanisms of organic pollutants by non-thermal plasmas were analyzed.
Lead sorption capacity and mechanisms by sludge-derived biochar (SDBC) were investigated to determine if treatment of acid mine drainage (AMD) containing metals with SDBC is feasible. It was found ...that the biochar derived from pyrolysis treatment of sewage sludge could effectively remove Pb²⁺ from acidic solution with the capacities of 16.11, 20.11, 24.80, and 30.88mgg⁻¹ at initial pH 2, 3, 4 and 5, respectively. Lead sorption processes were pseudo-second order kinetic and faster at a higher pH. Furthermore, the relative contribution of both inorganic mineral composition and organic functional groups of SDBC for Pb²⁺ removal mechanisms, was quantitatively studied at pH 2–5. The results showed that Pb sorption primarily involved the coordination with organic hydroxyl and carboxyl functional groups, which was 38.2–42.3% of the total sorbed Pb varying with pH, as well as the coprecipitation or complex on mineral surfaces, which accounted for 57.7–61.8% and led to a bulk of Ca²⁺ and Mg²⁺ release during sorption process. A new precipitate was solely observed on Pb-loaded SDBC as 5PbO·P₂O₅·SiO₂(lead phosphate silicate) at initial pH 5, confirmed by XRD and SEM–EDX. The coordination of Pb²⁺ with carboxyl and hydroxyl functional groups was demonstrated by FT-IR, and the contribution of free carboxyl was significant, ranging from 26.1% to 35.5%. Results from this study may suggest that the application of SDBC is a feasible strategy for removing metal contaminants from acid solutions.
Phytoremediation is the most promising and emerging technology for remediation of metal-contaminated sites. The aim of the current research was to investigate the metals accumulation potential of ...four weed species i.e.,
Parthenium
,
Cannabis
,
Euphorbia
, and
Rumex
species. The endogenous free proline, total phenolic, carotenoids, and chlorophyll contents were assessed under metals stress and correlated with metals accumulation in plants. Plants of each species were allowed to grow in reference (uncontaminated) soil and other group on industrial effluent-contaminated soil under natural environment. Phytoextraction potentials of these plants were evaluated for removal of lead (Pb) and chromium (Cr). The heavy metal concentration in plant parts was analyzed by atomic absorption spectrophotometer. Varied accumulation of metals was found among different weed species. Moreover, metal accumulation was different within plant tissues i.e., roots, leaves, and stem.
Cannabis
and
Parthenium
showed bio-concentration BCF > 1 for Pb, reflecting their high metal accumulation potential and both plants were found superior than
Rumex
and
Euphorbia
for Cr accumulation. The endogenous free proline and phenolic contents showed significantly positive correlation with Pb accumulation in four plants i.e.,
Parthenium
(
R
2 = 0.977,
R
2 = 0.9996),
Cannabis
(
R
2 = 0.9924,
R
2 = 0.9999),
Euporbia
(
R
2 = 0.9992,
R
2 = 0.9832),
Rumex
(
R
2 = 0.6033,
R
2 = 0.8272) respectively. Similarly, Cr accumulation in plants showed significantly positive correlation with proline and phenolic but the BCF ˂ 1.The chlorophyll and carotenoids contents in all plants negatively correlated with Pb and Cr concentration.
•Cr(VI) removal efficiency by TPBC was weakened by pyrolytic temperature increase.•The reduction of Cr(VI) was mainly affect by carboxyl group.•Adsorption-reduction-adsorption process was simulated ...based on apparent kinetics.•Cr(VI) removal was kinetic controlled by Cr(VI) and Cr(III) adsorptions.
Tobacco petiole biochar (TPBC) was prepared via pyrolysis and used for Cr(VI) removal. Cr(VI) removal efficiency was reduced by pyrolytic temperature (PyT) increase which mainly affected by functional groups rather than specific surface area. According to the optimal pseudo second-order kinetic, the initial adsorption rate was decreased with PyT increase from 355.91 mg·g−1·min−1 (PyT = 300 °C) to 3.44 mg·g−1·min−1 (PyT = 700 °C). The isotherm was optimally explained by Temkin model involved physical absorption with heat of 28.73 J/mol. Simulation result of adsorption-reduction-adsorption process showed the Cr(VI) removal was kinetic controlled by Cr(VI) and Cr(III) adsorptions. TPBC300 was the optimal TPBC for chromium removal from electroplating wastewater with efficiencies of: 66.7% (Cr(VI)) and 21.1% (Cr(tot)).
•The sludge derived biochar is an excellent sorbent for Pb(II)/Cr(VI) ions.•400°C for 2h seems the optimal conditions for biochar pyrolysis.•A long-time pyrolysis reinforces the Pb(II)/Cr(VI) ...sorption bond on biochar.•Cr(VI) sorption is highly pH-dependent, and the optimal occurs at pH 2.•Reducing Cr(VI) to Cr(III) is the main sorption mechanism on biochar.
To optimize the pyrolysis process of municipal wastewater sludge for metal sorption, this study investigated the characteristics of the produced biochar under different heating conditions with particular interest in Pb(II) or Cr(VI) sorption. Results indicate that the biochar pyrolyzed at 400°C for 2h obtained the largest BET surface area and was rich of organic functional groups, owning the highest Pb(II) (at pH 5.0) and Cr(VI) (at pH 2.0) sorption capacity. The Pb sorption is dominated by the rate-limited chemical processes, and a longer residence during pyrolysis significantly reinforces its sorption bonds. The Cr(VI) sorption is highly pH-dependent, and the optimal occurs at pH 2, where the transformation of Cr(VI) to Cr(III) makes a significant contribution as confirmed by the XPS spectra. Similarly, a longer residence during pyrolysis also facilitates the Cr(VI) sorption in terms of capacity and affinity, likely due to the greater reducing potential of biochar.
Applications of nanoparticles and plants for efficient restoration of heavy metal-polluted water and soil are an emerging approach and need to be explored. Hydroponic study was performed to find the ...role of zinc oxide nanoparticles (ZnO NPs) in plant growth, antioxidative response, and lead (Pb) accumulation in
Persicaria hydropiper
. Seedlings were grown in Pb-polluted media amended with 5, 10, 15, and 20 mg L
−1
ZnO NPs. Inductively coupled plasma spectroscopy (ICP) was used for Pb analysis in plant tissues. Pb significantly inhibited seedling growth, and ZnO NPs alleviated Pb-induced stress by promoting plant growth, and improved chlorophyll and carotenoid contents. Oxidative stress ameliorated in ZnO NPs exposed seedlings through enhanced production of free proline, phenolics, flavonoids, and activation of antioxidative enzymes. Pb accumulation boosted in ZnO NP treatments, and highly significant increase in Pb accumulation in roots (255.60±4.80 mg kg
−1
), stem (124.07±2.84 mg kg
−1
), and leaves (92.00±3.22 mg kg
−1
) was observed in T3 (15 mg L
−1
ZnO NPs) for
P. hydropiper
. Contrarily, ZnO NPs at 20 mg L
−1
dose suppressed plant growth, Pb accumulation, secondary metabolites, and antioxidative enzyme activities. Moreover, positive correlation was found in Pb accumulation with free proline and secondary metabolite contents in plant tissues. These results suggest that ZnO NPs at optimum concentration may augment efficacy of plants to remove heavy metal from polluted water through nanophytoremediation.
Agromining: Farming for Metals in the Future? van der Ent, Antony; Baker, Alan J. M; Reeves, Roger D ...
Environmental science & technology,
04/2015, Volume:
49, Issue:
8
Journal Article
Peer reviewed
Open access
Phytomining technology employs hyperaccumulator plants to take up metal in harvestable plant biomass. Harvesting, drying and incineration of the biomass generates a high-grade bio-ore. We propose ...that “agromining” (a variant of phytomining) could provide local communities with an alternative type of agriculture on degraded lands; farming not for food crops, but for metals such as nickel (Ni). However, two decades after its inception and numerous successful experiments, commercial phytomining has not yet become a reality. To build the case for the minerals industry, a large-scale demonstration is needed to identify operational risks and provide “real-life” evidence for profitability.
Sewage sludge pyrolysis can effectively dispose of sludge and obtain sludge-derived biochar (SDBC) as an adsorbent for pollutant removal. Recently, persistent free radicals (PFRs), which have also ...been detected in many types of biochar, have attracted considerable attention for organic pollutant degradation. Sludge collected from a sewage treatment plant was pyrolyzed into SDBC, which contained a large amount of PFRs, and the resulting SDBC was then applied for the removal of p-chlorophenol. An SDBC dosage of 5 g L−1 was applied for treating 5 mg L−1 of p-chlorophenol; the highest removal efficiency of 90% was achieved at pH 3, and 22% of the initial p-chlorophenol was degraded by the SDBC. Hydroxyl free radicals were observed and contributed to the degradation of p-chlorophenol. The spent SDBC was reused five times after regeneration through the desorption of adsorbed p-chlorophenol. The p-chlorophenol removal efficiency remained constant, but the degradation decreased with increasing reuse cycles, suggesting that the p-chlorophenol degradation efficiency was positively correlated with the intensity of PFRs on SDBC. Further modification of the SDBC sample in HNO3 or NaOH increased the amount of PFRs, and consequently, the degradation of p-chlorophenol under low oxygen conditions, further confirming the crucial role of PFRs in p-chlorophenol degradation. This study provides insights into the application of SDBC, a promising material, for contaminant abatement.
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•SDBC removed 90% of p-chlorophenol, among which 22% was degraded.•Hydroxyl radicals were confirmed to contribute to the p-chlorophenol degradation.•The p-chlorophenol degradation efficiency was positively correlated to the PFRs intensity.•SDBC modification increased the PFRs amount and the p-chlorophenol degradation if O2 was limited.
Papillary thyroid cancer (PTC) progresses slowly and has a good prognosis, while the prognosis is worse if combined with central neck lymph node metastasis at an early stage. The different endoscope ...approaches may affect the thoroughness of lymph node dissection. This study aimed to compare the clinical efficacy and safety of prophylactic central lymph node dissection(CLND) for cN0 PTC performed via breast and transoral approach versus via breast approach alone.
A retrospective analysis of the surgical data of 136 patients with stage cN0 PTC was performed from August 2020 to December 2022. Among them, 64 underwent the breast and transoral approach (combined approach group), and 72 underwent the breast approach alone (breast approach group). The relevant indexes of surgery, the number of lymph nodes dissected, the occurrence of postoperative complications, and the cosmetic satisfaction of incision were statistically compared between the two groups.
The operation time of the combined approach group was 156.4 ± 29.8 min, significantly longer than that of the breast approach group, 119.6 ± 55.9 min, and the difference was statistically significant (P<0.05). The two groups of patients were compared in terms of intraoperative bleeding, postoperative drainage, hospitalization time, incision cosmetic satisfaction, and the occurrence of postoperative complications, and the differences were not statistically significant (P>0.05). The total number of lymph nodes retrieved in the central area (10.6 ± 7.1) and the number of positive lymph nodes (4.6 ± 4.9) in the combined approach group were significantly more than those in the breast approach group (7.4 ± 4.8, 1.6 ± 2.7), and the difference was statistically significant (P<0.05). The difference between the two groups in terms of the number of negative lymph nodes was not statistically significant (P>0.05).
The study demonstrated that choosing the breast combined transoral approach for prophylactic CLND of cN0 PTC could more thoroughly clear the central area lymph nodes, especially the positive lymph nodes, which could help in the evaluation of the disease and the guidance of the treatment, while not increasing the postoperative complications. It provides a reference for clinicians to choose the appropriate surgical approach and also provides new ideas and methods for prophylactic CLND in patients with cN0 PTC.
