本文针对含砷废渣处理技术现状,提出了一种铜砷滤饼控铜浸砷处理工艺。试验结果表明,在保证砷铼浸出率的情况下可控制铜浸出率小于15%,浸出的铜可以通过硫化砷置换法将铜转入渣中以实现铜、砷的分离,铜渣返回熔炼系统回收铜。

The recycling of solid wastes is obligable as it can reduce the environmental pollution and prevent the diffusion of secondary pollution. In this study, a novel cheap adsorbent was prepared by modifying electrolytic manganese residue (EMR) with EDTA. The maximum adsorption capacity of adsorbents for diethyl dithiocarbamate (DDTC) was 133.46 mg/g under initial pH of 7.32 at room temperature. Adsorption kinetics study revealed the DDTC adsorption on EDTA-EMR is mainly controlled by chemisorption and isotherm studies implied the adsorption is a monolayer process. Mechanism exploration found that the DDTC molecules could enter into the holes of EDTAEMR, and the transition metal-based sorption sites were crucial for the target molecule immobilization and chelation. High pH value (> 10) was found to have inhibited the adsorption capacity of adsorbent, which should be due to the fact that the decreasing of functional groups on adsorbents surface and the competition between DDTC and OH?. The ionic strength has negligible effect on the adsorption and the as-synthesized adsorbents showed excellent performance after five cycles. The overall results reveal that EDTA-EMR is a promising adsorbent ascribed by its low cost, good recyclability and excellent adsorption capacity.

Residual flotation reagents (FRs) in mineral processing wastewater (MPW) cause serious organic pollution and difficult to discharge or recycle of MPW. In this study, the degradation of 100 mg/L of FRs (butyl xanthate (BX), diethyl dithiocarbamate (DDTC), ester-200 (Z-200) and butyl amine (BA)) commonly used for metal sulfide ore flotation were investigated by heterogeneous advanced oxidation process (AOPs) adopting peroxymonosulfate (PMS) as oxidants and modified manganese slag as metal-base catalyst (MS-N3H). The results showed MS-N3H/ PMS system had higher degradation capacity than other reports, by which 100% of DDTC and 97.3% of BX could be degraded in 10 min, also 93.2% of Z-200 and 85.6% of BA were degraded in 30 min, respectively. The differential behaviours in degradation of thiol collectors (TCs) were correlated to their molecule structures and affected by their HMO index. However, the good water solubility of BX made it as the most degradable reagents in competitive system. The catalytic reactions of Z-200 and BA were pH-dependent processes which were dominated by the PMS ionization and base activation. Inorganic ions had little effects on reactions except for SiO32 , but the negative effect could be alleviated by the integrated process. Higher mineralization degrees of C, S and N elements indicated that TCs and their by-products were removed by the MS-N3H/PMS with higher degradation rates. Further, the catalyst showed superior regeneration ability and the system could be effectively used in real MPW treatment with relatively high removal efficiency of total organic carbon (TOC).

Efficient removal of Hg2+ from aqueous solution is key for environmental protection and human health. Herein, a novel composite of nano humboldtine decorated almandine was synthesized from almandine for the removal of Hg2+. Results showed that the Hg2+ removal process followed pseudo-second-order kinetic model and Langmuir equation, and the maximum adsorption capacity was 575.17 mg/g. Furthermore, Hg2+ removal by the composite was pH-dependent and low pH value facilitated the removal of Hg2+. SEM and HADDF-STEM results suggested a new rod morphology was generated and the adsorbed mercury was mainly enriched into this structure after reaction with Hg2+ solution. The removal mechanisms of Hg2+ by the composite was pH dependent, and included ion exchange, surface complexation, reduction and oxidation. Our results demonstrated that the composite was an ideal material for Hg2+ removal and the transformation ways of mercury related species could be a significant but currently underestimated pathway in natural and engineered systems. © 2020 Elsevier B.V.

Comprehensive utilization of tailings is not only conducive to ensuring the sustainable use of resources but also can reduce the related environmental pollution. In the present work, a new utilization way of copper tailings was proposed and a novel composite (OMT-6) was prepared by modification of tailings with oxalic acid. The composite had super high Pb2+ adsorption capacity with the maximal Pb2+ removal capacity of 862.07 mg/g. Its Pb2+ removal behaviours followed pseudo-second-order kinetic equation and Langmuir model, suggesting that Pb2+ removal depended on monolayer adsorption. The surface of OMT-6 was rough and a lot of nanospheres were loaded on its surface. The composite had mesoporous structure and a larger specific surface area compared with tailings, the above characteristics of which facilitated Pb2+ removal. The major crystal structures of OMT-6 were transformed to CaC2O4 center dot H2O and FeC2O4 center dot 2H(2)O after oxalic acid modification and Pb2+ could be removed by the ions exchange between Ca2+, Fe2+ and Pb2+. Pb2+ removal mechanisms of OMT-6 involved ion exchange, surface complexation and electrostatic attraction interaction, among which ion exchange played a key role. These results indicated that the prepared OMT-6 composite from copper tailings was an ideal material for Pb2+ removal from aqueous solution. (C) 2020 Elsevier Ltd. All rights reserved.

Preparations of catalysts for sulfate radicals-based advanced oxidation (SR-AOPs) are usually time-consuming and costly. This study developed a short-cut method for preparation of AOPs catalyst (MS-N3H) directly from electrolytic manganese slag. MS-N3H/PMS could effectively remove levofloxacin (LVF) from solution. Phase transformation and active sites exposure after modifications facilitated the adsorption and catalysis capacities. Both radical and non-radical pathway contributed to the degradation of LVF, in which abundant Mn and Fe on MS-N3H surface contributed to the generation of SO4 center dot-, (OH)-O-center dot and O-2(center dot-) radicals, and lattice oxygen played a crucial role in non-radical O-1(2) production. The MS-N3H/PMS was stable for the degradation of LVF in different water matrixes and kept high recyclability even after four recycles. This study brought underlying insights to develop novel high-efficient and easy-preparing catalysts for the degradation of recalcitrant organic pollutes.

Preparing a cost-effective material which can been applied in a wide pH range is very crucial for the remediation of Cr(VI) polluted water. In this study, a novel material, almandine/humboldtine nanospheres (AHN) composites, was synthesized directly from almandine by one-pot method. Characterizations of XRD and SEM/TEM showed that the structure changes of almandine to nano-humboldtine leaded to significant increase of Cr(VI) removal capacities. And 96.45% of Cr(VI) was removed by AHN-24 composite at pH value of 3, initial Cr(VI) concentration of 20 mg/L, temperature of 298.15 K and dosage of 0.6 g/L. Furthermore, Cr(VI) removal capacity was only decreased from 48.23 mg/g to 34.33 mg/g when the initial pH value increased from 3 to 11, which demonstrated that the synthesized composite had a wide pH application range in Cr(VI) removal. The thermodynamic parameters (Delta G(0) < 0, Delta H-0 > 0 and Delta S-0 > 0) illustrated that Cr(VI) removal process was spontaneous and endothermic. FTIR and XPS revealed that the Cr(VI) removal mechanisms included reduction-precipitation and reduction-complexation. Combined with cost analysis, all of results implied that the synthesized composites were a high efficient and low cost material for Cr(VI) pollution remediation in a wide pH range.

The reduction of Cr(VI) by iron-based materials was inhibited under neutral and alkaline conditions due to the production of precipitates. In this work, a novel composite with a wide pH range application in the remediation of Cr(VI) contamination, SiO2/nano-FeC2O4 composite (SNFC), was prepared from natural biotite-containing minerals. Transmission electron microscope (TEM) analysis indicated that nano-FeC2O4 with average particle size of 10.08 nm was uniformly coated on the surface of layered minerals. Batch experiments results showed that Cr(VI) was completely removed in the pH range of 2-10 within 60 min at an initial Cr(VI) concentration of 20 mg/L. The removal rate of Cr(VI) was decreased when the initial pH value increased from 2 to 6 and then kept at constant when the initial pH value increased from 6 to 10. Furthermore, continuous fixed bed column studies showed that simulated permeable reactive barriers (PRB) with SNFC was considerably effective for in situ removal of Cr(VI) from groundwater under alkaline conditions. Characterizations of X-ray diffraction (XRD) and scanning electron microscope (SEM) suggested that the reactive component in the composite for Cr(VI) removal was nano-FeC2O4 rather than biotite itself. The Cr(VI) removal mechanisms of SNFC involved reduction, precipitation and surface complexation. These results plus the preliminary cost analysis indicated that the composite was an efficient, economical, and easy for mass production material with application for remediation of Cr (VI) polluted groundwater in a wide pH range.

Developing a material with high adsorption capacity and selectivity to remove lead from Pb2+ polluted wastewater is of vital importance for environment protection and resources utilization. In this study, a novel composite, SiO2 decorated with nano ferrous oxalate (SDNF), was prepared from natural biotite containing ores to remove Pb2+ . Pseudo-first-order kinetic (R-2 = 0.99) and Langmuir models (R-2 = 0.99) fitted the data well, manifesting that Pb2+ adsorption process was monolayer adsorption. The maximum Pb2+ adsorption capacity was identified as 446.98 mg/g. SEM and TEM images showed that nano ferrous oxalate with average size of 11.51 nm was coated on the surface of ores, and their distributions were uniform. Results of XRD, XPS, FTIR and zeta potential indicated that ion exchange, surface complexation and electrostatic attraction interaction were involved in the remvoal of Pb2+, and the ion exchange between Fe2+ and Pb2+ played a major role. Moreover, both Cd2+ and Zn2+ removal efficiency are less than 2 % in Pb-Cd or Pb-Zn coexisted solution, indicating the composite possessed high selectivity for Pb2+ removal. All above results indicated that the composite was a material with high adsorption capacity and selectivity for Pb2+, which was suitable for remediation of Pb2+ pollution from Pb2+ containing wastewater.

This study firstly reported a novel nano humboldtine/almandine composite (NHLA composite) prepared directly from almandine through one-pot method based on the interaction of almandine and oxalic acid. The formation of humboldtine/almandine binary phase from natural almandine was determined by X-ray diffraction. Analysis of scanning & transmission electron microscope showed that large amount of nano humboldtine with uniform size (average size of 15.59 nm) were loaded on the almandine sheets. Compared with raw minerals, Pb(II) removal capacity of synthesized composite was significantly increased, demonstrating that the main active ingredient for Pb(II) removal was humboldtine phase rather than almandine itself. Pb(II) adsorption capacity was increased with the increasing of initial pH value or temperature. Langmuir isotherm and Pseudo-second order kinetic equation were well fitted with experimental results and the maximum Pb(II) adsorption capacity from Langmuir isotherm was 574.71 mg/g at temperature of 25 degrees C. In addition, heavy metal removal experiments in coexisting systems of multiple heavy metal ions manifested that the composite had a high selectivity for Pb(II) adsorption. Ion exchange, surface complexation and electrostatic interaction have involved in the Pb(II) adsorption. The synthesized composite was considered as a low cost, high efficiency, super selectivity and easy to mass production material for Pb(II) adsorption from solution. (C) 2020 Elsevier Ltd. All rights reserved.