Stability of heavy metals in soil washing residue with and without biochar addition under accelerated ageing

Shen, Zhengtao,Hou, Deyi,Zhao, Bin,Xu, Wendi,Ok, Yong Sik,Bolan, Nanthi S.,Alessi, Daniel S. Elsevier 2018 Science of the Total Environment Vol.619 No.-

<P><B>Abstract</B></P> <P>Soil washing residue (SWR), which typically concentrates the washed toxic metals and is comprised of high contents of clay particles, may pose risks to the surrounding environment. This study aims to simulate accelerated ageing to assess the stability of selected metals (Cd<SUP>2+</SUP> (132mg/kg), Cu<SUP>2+</SUP> (248mg/kg) and Pb<SUP>2+</SUP> (3470mg/kg)) in a SWR (89.68% of clay) with and without biochar treatment. The soil was incubated under constant moisture and wet-dry cycles (accelerated ageing), respectively, and the mobility and fractions of heavy metals in the soils with and without biochar treatment were examined. Under the constant moisture condition, biochar addition at 5% w/w reduced the leached Cd<SUP>2+</SUP> (by 1.81%) and Cu<SUP>2+</SUP> (by 8.70%) from SWR at day 1 and the leached Cu<SUP>2+</SUP> (by 51.08%) and Pb<SUP>2+</SUP> (by 25.36%) from SWR at day 14; however, the leached metals in the TCLP solution from the biochar-amended soils still exceed the regulatory limits (1mg/L for Cd<SUP>2+</SUP>, 5mg/L for Pb<SUP>2+</SUP>, no regulatory limits for Cu<SUP>2+</SUP>). Conversely, accelerated ageing (14days) significantly increased the fractions of exchangeable Cd<SUP>2+</SUP> (from 3.63–3.94% to 6.21–6.29%) and Pb<SUP>2+</SUP> (from 0.025–0.027% to 0.034–0.041%) as well as the TCLP leachabilities of Cd<SUP>2+</SUP> (from 2.91–3.28% to 3.46–3.73%), Cu<SUP>2+</SUP> (from 0.08–0.10% to 0.03–0.06%) and Pb<SUP>2+</SUP> (from 0.25–0.35% to 0.52–0.57%) in the soils, as compared with those incubated under constant moisture, regardless of biochar addition. This study reveals challenges associated with stabilising SWR due to the presence of residual fine-grained particles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cd<SUP>2+</SUP> and Pb<SUP>2+</SUP> in soil washing residue (SWR) exceeds TCLP regulation limit. </LI> <LI> Heavy metal mobility in SWR was reduced by biochar addition. </LI> <LI> Accelerated ageing mobilised heavy metals in SWR regardless of biochar addition. </LI> <LI> Accelerated ageing show SWR poses long-term risks to the environment. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Risk evaluation of biochars produced from Cd-contaminated rice straw and optimization of its production for Cd removal

Shen, Zhengtao,Fan, Xiaoliang,Hou, Deyi,Jin, Fei,O'Connor, David,Tsang, Daniel C.W.,Ok, Yong Sik,Alessi, Daniel S. Pergamon Press 2019 Chemosphere Vol. No.

<P><B>Abstract</B></P> <P>Based on the “waste-treat-waste” concept, biochars were produced from cadmium (Cd)-contaminated rice straw (CRSBs) at 300, 500, and 700 °C (CRSB300, CRSB500, and CRSB700). The risks of the Cd remaining in CRSBs were evaluated and the optimal biochar pyrolysis temperature for Cd removal was investigated. It was observed that 41% of the total Cd in the raw rice straw was exchangeable, which may pose significant risks to crops and humans. Pyrolyzing at 300 °C did not significantly alter the Cd fractions, while the exchangeable fraction of Cd greatly dropped to 5.79% at 500 °C and further to 2.12% at 700 °C. Increasing the highest pyrolysis temperature resulted in CRSBs with higher pH values, greater surface area, and smaller pore sizes, thus providing more rapid and efficient removal of Cd from aqueous solutions. For Cd removal tests, increasing pyrolysis temperature (300–700 °C) increased the total (24.8–55.1 mg/g) and non-exchangeable (18.9–52.8 mg/g) Cd concentrations immobilized on the CRSBs and significantly decreased the exchangeable Cd fraction (23.7%–4.85%). It is suggested based on the study from aqueous solutions that CRSB700 was the most suitable for the remediation of Cd contaminated soil on site due to the lowest risks of remained Cd from feedstock, fastest and highest Cd removal, and most stable immobilization of Cd.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 41% of Cd in raw rice straw was exchangeable, posing great environmental risks. </LI> <LI> Pyrolyzing at 300 °C did not significantly alter Cd fractions remained in biochar. </LI> <LI> Exchangeable fraction of Cd dropped to 5.79% at 500 °C and to 2.12% at 700 °C. </LI> <LI> Increasing temperature decreased exchangeable Cd fraction immobilized on biochar. </LI> <LI> CRSB700 has the fastest and highest Cd removal, and most stable Cd immobilization. </LI> </UL> </P>

Multimode participation of traditional Chinese medicine in the treatment of COVID-19

Tieying Dai,Leyin Zhang,Xinyang Dai,Xinran Zhang,Beibei Lu,Yuxi Zheng,Deyi Shen,Yici Yan,Congqi Ji,Jieru Yu,Leitao Sun 한국한의학연구원 2021 Integrative Medicine Research Vol.10 No.-

Background The outbreak of COVID-19 has swiftly spread across China and all over the world, resulting in severe contagious pneumonia. However, no specific anti-COVID-19 drugs or methods are available for the treatment of this acute and fatal disease. In recent years, as the efficacy and safety of traditional Chinese medicine (TCM) have been universally acknowledged, it has been brought to a crucial status domestically and overseas for the treatment of COVID-19. Methods We searched relevant literature, electronic databases, and official statements, diagnoses and protocols to retrieve studies and applications related to traditional Chinese medicine for COVID-19 in terms of regulations and policies, clinical evidence, preclinical rationale and big data analysis and then summarized the discovery and development of potential drugs and their targets. Results Clinicians, researchers, governments, the public, colleges, institutes and companies collected and classified associated policies, regulations and actual contributions, searched clinical trials and preclinical experimental outcomes from databases, studied potential TCM drugs with possible mechanisms, retrieved numerous big data analysis method and gathered pooled results of compounds along with their effective targets to make traditional Chinese medicine vital to cover all stages of patients in the treatment and control of COVID-19. Conclusion Traditional Chinese medicine provides new evidence to support the clinical value of TCM for COVID-19. Background The outbreak of COVID-19 has swiftly spread across China and all over the world, resulting in severe contagious pneumonia. However, no specific anti-COVID-19 drugs or methods are available for the treatment of this acute and fatal disease. In recent years, as the efficacy and safety of traditional Chinese medicine (TCM) have been universally acknowledged, it has been brought to a crucial status domestically and overseas for the treatment of COVID-19. Methods We searched relevant literature, electronic databases, and official statements, diagnoses and protocols to retrieve studies and applications related to traditional Chinese medicine for COVID-19 in terms of regulations and policies, clinical evidence, preclinical rationale and big data analysis and then summarized the discovery and development of potential drugs and their targets. Results Clinicians, researchers, governments, the public, colleges, institutes and companies collected and classified associated policies, regulations and actual contributions, searched clinical trials and preclinical experimental outcomes from databases, studied potential TCM drugs with possible mechanisms, retrieved numerous big data analysis method and gathered pooled results of compounds along with their effective targets to make traditional Chinese medicine vital to cover all stages of patients in the treatment and control of COVID-19. Conclusion Traditional Chinese medicine provides new evidence to support the clinical value of TCM for COVID-19.