Feasibility of reduced iron species for promoting Li and Co recovery from spent LiCoO2 batteries using a mixed-culture bioleaching process.

The recovery of metals from spent LiCoO2 batteries (SLBs) is essential to avoid resource wastage and the production of hazardous waste. However, the major challenge in regard to recovering metals from SLBs using traditional bioleaching is the low Co yield. To overcome this issue, a mixed culture of Acidithiobacillus caldus and Sulfobacillus thermosulfidooxidans was designed for use in SLBs leaching in this study. With the assistance of Fe2+ as a reductant, 99% of Co and 100% of Li were leached using the above mixed-culture bioleaching (MCB) process, thus solving the problem of low metal leaching efficiency from SLBs. Analysis of the underlying mechanism revealed that the effective extraction of metals from SLBs by the Fe2+-MCB process relied on Fe2+-releasing electrons to reduce refractory Co(III) to Co(II) that can be easily bioleached. Finally, the hazardous SLBs was transformed into a non-toxic material after treatment utilizing the Fe2+-MCB process. However, effective SLBs leaching was not achieved by the addition of Fe0 to the MCB system. Only 25% Co and 31% Li yields were obtained, as the addition of Fe0 caused acid consumption and bacterial apoptosis. Overall, this study revealed that reductants that cause acid consumption and harm bacteria should be ruled out for use in reductant-assisted bioleaching processes for extracting metals from SLBs.

In situ electrokinetic (EK) remediation of the total and plant available cadmium (Cd) in paddy agricultural soil using low voltage gradients at pilot and full scales.

Electrokinetic (EK) remediation has been widely studied at laboratory scales. However, field-scale research is far less. In this study, a 14-day EK remediation was carried out, in a field pilot (4 m2) test and a full-scale (200 m2) application for the first time, in a cadmium (Cd) contaminated paddy agricultural field near a mining area. A low voltage of 20 V was applied at both scales; voltage gradient was 20 V m-1 and 4 V m-1 at the pilot and full scales, respectively. Samples were taken from near the anode and cathode, and in the middle of the electric field, in the soil layers 0-10 cm, 10-20 cm, and 40-50 cm. After the EK remediation, a significant portion of the total Cd was removed in all the layers at the pilot scale, by 87%, 72%, and 54% from the top down, but only in the 0-10 cm layer at the full scale by 74%. As for the plant available (exchangeable and soluble) Cd, significant removal (64%) was only observed in the 0-10 cm layer at the pilot scale. The percentage reduction of the electrical conductivity and removal efficiency of the total Cd was higher near the anode than the cathode. The soil pH was elevated near the cathode but stayed below pH 6 due to the sufficient supply of lactic acid. After the EK remediation, the concentration of the total Cd dropped below the hazard threshold, i.e. 0.4 mg (kg dry wt soil)-1 for agricultural paddy fields in China. A total energy of 2 kW·h and 0.6 kW·h was consumed at the pilot and full scales, respectively. This study showed a successful in situ EK remediation of Cd contaminated paddy agricultural soil, especially in the surface layer, with low voltage and energy demand.

Decomplexation of heterogeneous catalytic ozonation assisted with heavy metal chelation for advanced treatment of coordination complexes of Ni.

Following the conventional physicochemical treatment of electroless nickel (Ni) plating wastewater (ENPW) in electroplating wastewater treatment plants, highly stable and recalcitrant coordination complexes of Ni (CCN) still remain. This results in various technical problems, leading to the treatment difficulty, poor wastewater biochemistry, and failure to meet effluent standards. Therefore, an efficient decomplexation system involving heterogeneous catalytic ozonation assisted with heavy metal chelation (O3/SAO3II-MDCR) was proposed in this study for the advanced treatment of CCN. The catalyst SAO3II was characterized by various methods, which revealed the mechanism of catalytic ozonation. Hydroxyl radicals (OH) and other reactive oxygen species (ROS) groups were detected, proving that catalytic ozonation was a complicated reaction process and also a foundation process of the entire system. These ROS are vital for decomplexation via heterogeneous catalytic ozonation of the system. During the catalytic decomplexation process via ozonation, CCN first underwent gradual decomposition from a highly stable macromolecular state to a volatile micromolecular state (or even completely mineralized state). Then Ni was chelated to form an insoluble and stable chelate via competitive coordination. The optimum conditions for the O3/SAO3II-MDCR system were determined by single factor static experiments. After treatment with the O3/SAO3II-MDCR system, the effluent concentration of total Ni was found to be <0.1 mg L-1, exhibiting a removal rate of up to 95.6% and achieving effective removal of total Ni from ENPW and stably meeting the discharge standard. O3/SAO3II-MDCR system can easily and hopefully be extended to practical engineering applications.

Hepatic arteriolosclerosis: a small-vessel complication of diabetes and hypertension.

Liver involvement in diabetes is well recognized in the form of steatohepatitis and glycogenic hepatopathy. More recently, sinusoidal fibrosis, even in the absence of steatosis, has also been suggested to be associated with diabetes (diabetic hepatosclerosis); however, case-control studies are lacking. In addition, microangiopathy (hyaline arteriolosclerosis), a well-known complication of diabetes, has not been well studied in liver. Therefore, we undertook a cross-sectional blinded study with the specific aim of evaluating the association between hepatic sinusoidal fibrosis and hepatic arteriolosclerosis (HA) with diabetes. Liver biopsy findings from 89 diabetic patients obtained between January 2006 and December 2009 were compared with those of 89 nondiabetic patients matched by age and hepatitis C virus infection status. Patients with cirrhosis, liver mass, right heart failure, significant alcohol use, or insufficient available clinical information were excluded. Medical records were reviewed for the presence of diabetes, body mass index, diabetes treatment, and comorbidities at the time of biopsy (eg, underlying liver disease, hypertension, dyslipidemia). Liver biopsies were evaluated blinded to all clinical data (including presence or absence of diabetes) for a variety of histologic features, especially patterns of fibrosis and HA. Diabetic patients had a higher average body mass index (33 vs. 30 m/kg, P=0.0039), prevalence of hypertension (78% vs. 33%, P<0.0001), and dyslipidemia (52% vs. 20%, P<0.0001). Among diabetic patients, 87% had type 2 diabetes, and 57% used insulin. Whereas sinusoidal fibrosis, with or without steatosis, was not significantly associated with the presence of diabetes, HA was significantly more prevalent among diabetic patients compared with controls: 45% versus 29% (P=0.0298). The presence of both diabetes and hypertension had a significant odds for HA: with an adjusted odds ratio of 2.632 (95% confidence interval, 1.178-5.878; P=0.0183). Biliary changes were associated with HA in some cases (10.6%).In this study, we describe the histopathologic entity of HA for the first time. It is a small-vessel complication (microangiopathy) of the liver observed mainly in patients with diabetes who also have arterial hypertension. The clinical and prognostic implications of this finding, particularly regarding liver injury, remain to be further investigated.