Aging effects on chemical transformation and metal(loid) removal by entrapped nanoscale zero-valent iron for hydraulic fracturing wastewater treatment

Sun, Yuqing,Lei, Cheng,Khan, Eakalak,Chen, Season S.,Tsang, Daniel C.W.,Ok, Yong Sik,Lin, Daohui,Feng, Yujie,Li, Xiang-dong Elsevier 2018 Science of the Total Environment Vol.615 No.-

<P><B>Abstract</B></P> <P>In this study, alginate and polyvinyl alcohol (PVA)-alginate entrapped nanoscale zero-valent iron (nZVI) was tested for structural evolution, chemical transformation, and metals/metalloids removal (Cu(II), Cr(VI), Zn(II), and As(V)) after 1–2month passivation in model saline wastewaters from hydraulic fracturing. X-ray diffraction analysis confirmed successful prevention of Fe<SUP>0</SUP> corrosion by polymeric entrapment. Increasing ionic strength (<I>I</I>) from 0 to 4.10M (deionized water to Day-90 fracturing wastewater (FWW)) with prolonged aging time induced chemical instability of alginate due to dissociation of carboxyl groups and competition for hydrogen bonding with nZVI, which caused high Na (7.17%) and total organic carbon (24.6%) dissolution from PVA-alginate entrapped nZVI after 2-month immersion in Day-90 FWW. Compared to freshly-made beads, 2-month aging of PVA-alginate entrapped nZVI in Day-90 FWW promoted Cu(II) and Cr(VI) uptake in terms of the highest removal efficiency (84.2% and 70.8%), pseudo-second-order surface area-normalized rate coefficient <I>k</I> <SUB> <I>sa</I> </SUB> (2.09×10<SUP>−1</SUP> Lm<SUP>−2</SUP> h<SUP>−1</SUP> and 1.84×10<SUP>−1</SUP> Lm<SUP>−2</SUP> h<SUP>−1</SUP>), and Fe dissolution after 8-h reaction (13.9% and 8.45%). However, the same conditions inhibited Zn(II) and As(V) sequestration in terms of the lowest removal efficiency (31.2% and 39.8%) by PVA-alginate nZVI and <I>k</I> <SUB> <I>sa</I> </SUB> (4.74×10<SUP>−2</SUP> Lm<SUP>−2</SUP> h<SUP>−1</SUP> and 6.15×10<SUP>−2</SUP> Lm<SUP>−2</SUP> h<SUP>−1</SUP>) by alginate nZVI. The X-ray spectroscopic analysis and chemical speciation modelling demonstrated that the difference in metals/metalloids removal by entrapped nZVI after aging was attributed to distinctive removal mechanisms: (i) enhanced Cu(II) and Cr(VI) removal by nZVI reduction with accelerated electron transfer after pronounced dissolution of non-conductive polymeric immobilization matrix; (ii) suppressed Zn(II) and As(V) removal by nZVI adsorption due to restrained mass transfer after blockage of surface-active micropores. Entrapped nZVI was chemically fragile and should be properly stored and regularly replaced for good performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> nZVI entrapment successfully prevented Fe<SUP>0</SUP> corrosion in fracturing wastewaters. </LI> <LI> Entrapped nZVI was chemically fragile due to dissolution of Na and TOC. </LI> <LI> nZVI passivation promoted Cu(II) and Cr(VI) but inhibited Zn(II) and As(V) removal. </LI> <LI> Effects of nZVI aging on removal efficiency depended on interaction mechanisms. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Waste-derived compost and biochar amendments for stormwater treatment in bioretention column: Co-transport of heavy metals and colloids

Yuqing SUN,Daniel C.W. TSANG 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

A critical review of risks, characteristics, and treatment strategies for potentially toxic elements in wastewater from shale gas extraction

Sun, Yuqing,Wang, Di,Tsang, Daniel C.W.,Wang, Linling,Ok, Yong Sik,Feng, Yujie Pergamon 2019 Environment international Vol.125 No.-

<P><B>Abstract</B></P> <P>Shale gas extraction via horizontal drilling and hydraulic fracturing (HF) has enhanced gas production worldwide, which has altered global energy markets and reduced the prices of natural gas and oil. Water management has become the most challenging issue of HF, as it demands vast amounts of freshwater and generates high volumes of complex liquid wastes contaminated by diverse potentially toxic elements at variable rates. This critical review focuses on characterizing HF wastewater and establishing strategies to mitigate environmental impacts. High prioritization was given to the constituents with mean concentrations over 10 times greater than the maximum contamination level (MCL) guidelines for drinking water. A number of potentially harmful organic compounds in HF wastewaters were identified via the risk quotient approach to predict the associated toxicity for freshwater organisms in recipient surface waters. Currently, two options for HF wastewater treatment are preferred, i.e., disposal by deep well injection or on-site re-use as a fracturing fluid. Supplementary treatment will be enforced by increasingly rigorous regulations. Partial treatment and reuse remain the preferred method for managing HF wastewater where feasible. Otherwise, advanced technologies such as membrane separation/distillation, forward osmosis, mechanical vapor compression, electrocoagulation, advanced oxidation, and adsorption-biological treatment will be required to satisfy the sustainable requirements for reuse or surface discharge.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Shale oil and gas production via hydraulic fracturing poses risks to water quality and quantity. </LI> <LI> High risk level is related with the management of hydraulic fracturing wastewater. </LI> <LI> Wastewater quality data limitation is an obstacle for developing sustainable treatment strategies. </LI> <LI> Integration of multiple technologies is required for wastewater reuse or discharge. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Zero-valent iron for the abatement of arsenate and selenate from flowback water of hydraulic fracturing

Sun, Yuqing,Chen, Season S.,Tsang, Daniel C.W.,Graham, Nigel J.D.,Ok, Yong Sik,Feng, Yujie,Li, Xiang-Dong Elsevier 2017 CHEMOSPHERE - Vol.167 No.-

<P><B>Abstract</B></P> <P>Zero-valent iron (ZVI) was tested for the removal of 150 μg L<SUP>−1</SUP> As(V) and 350 μg L<SUP>−1</SUP> Se(VI) in high-salinity (ionic strength 0.35–4.10 M) flowback water of hydraulic fracturing. Over 90% As(V) and Se(VI) was removed by 2.5 g L<SUP>−1</SUP> ZVI in Day-14 flowback water up to 96-h reaction, with the remaining concentration below the maximum contaminant level for As(V) and criterion continuous concentration for Se(VI) recommended by US EPA. The kinetics of As(V) and Se(VI) removal followed a pseudo-second-order rate expression with the observed rates of 4.51 × 10<SUP>−2</SUP>–4.91 × 10<SUP>−1</SUP> and 3.48 × 10<SUP>−2</SUP>–6.58 × 10<SUP>−1</SUP> h<SUP>−1</SUP> (with 0.5–10 g L<SUP>−1</SUP> ZVI), respectively. The results showed that Se(VI) removal significantly decreased with increasing ionic strength, while As(V) removal showed little variation. Common competing anions (nitrate, bicarbonate, silicate, and phosphate), present in shallow groundwater and stormwater, caused marginal Se(VI) desorption (2.42 ± 0.13%) and undetectable As(V) desorption from ZVI. The competition between As(V) and Se(VI) for ZVI removal depended on the initial molar ratio and surface sites, which occurred when the Se(VI) concentration was higher than the As(V) concentration in this study. The characterization of As(V)- and Se(VI)-loaded ZVI by X-ray diffraction and Raman analysis revealed that ZVI gradually converted to magnetite/maghemite corrosion products with lepidocrocite in flowback water over 30 days. Similar corrosion compositions were confirmed in aerobic and anaerobic conditions regardless of the molar ratio of As(V) to Se(VI). The high reactivity and stability of ZVI showed its suitability for <I>in-situ</I> prevention of As(V) and Se(VI) migration due to accidental leakage, spillage, or overflow of flowback water.</P> <P><B>Highlights</B></P> <P> <UL> <LI> As(V) and Se(VI) in high-salinity flowback water was effectively removed by ZVI. </LI> <LI> As(V) removal was less susceptible to ionic strength variations than Se(V). </LI> <LI> Competing anions in groundwater and stormwater caused insignificant desorption. </LI> <LI> As(V) and Se(VI) competition depended on their molar ratio and ZVI surface sites. </LI> <LI> Surface characteristics of ZVI were unaffected by molar ratio and dissolved oxygen. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Nanoscale zero-valent iron for metal/metalloid removal from model hydraulic fracturing wastewater

Sun, Yuqing,Lei, Cheng,Khan, Eakalak,Chen, Season S.,Tsang, Daniel C.W.,Ok, Yong Sik,Lin, Daohui,Feng, Yujie,Li, Xiang-dong Elsevier 2017 CHEMOSPHERE - Vol.176 No.-

<P><B>Abstract</B></P> <P>Nanoscale zero-valent iron (nZVI) was tested for the removal of Cu(II), Zn(II), Cr(VI), and As(V) in model saline wastewaters from hydraulic fracturing. Increasing ionic strength (<I>I</I>) from 0.35 to 4.10 M (Day-1 to Day-90 wastewaters) increased Cu(II) removal (25.4–80.0%), inhibited Zn(II) removal (58.7–42.9%), slightly increased and then reduced Cr(VI) removal (65.7–44.1%), and almost unaffected As(V) removal (66.7–75.1%) by 8-h reaction with nZVI at 1–2 g L<SUP>−1</SUP>. The removal kinetics conformed to pseudo-second-order model, and increasing <I>I</I> decreased the surface area-normalized rate coefficient (<I>k</I> <SUB> <I>sa</I> </SUB>) of Cu(II) and Cr(VI), probably because agglomeration of nZVI in saline wastewaters restricted diffusion of metal(loid)s to active surface sites. Increasing <I>I</I> induced severe Fe dissolution from 0.37 to 0.77% in DIW to 4.87–13.0% in Day-90 wastewater; and Fe dissolution showed a significant positive correlation with Cu(II) removal. With surface stabilization by alginate and polyvinyl alcohol, the performance of entrapped nZVI in Day-90 wastewater was improved for Zn(II) and Cr(VI), and Fe dissolution was restrained (3.20–7.36%). The X-ray spectroscopic analysis and chemical speciation modelling demonstrated that the difference in removal trends from Day-1 to Day-90 wastewaters was attributed to: (i) distinctive removal mechanisms of Cu(II) and Cr(VI) (adsorption, (co-)precipitation, and reduction), compared to Zn(II) (adsorption) and As(V) (bidentate inner-sphere complexation); and (ii) changes in solution speciation (e.g., from Zn<SUP>2+</SUP> to ZnCl<SUB>3</SUB> <SUP>−</SUP> and ZnCl<SUB>4</SUB> <SUP>2−</SUP>; from CrO<SUB>4</SUB> <SUP>2−</SUP> to CaCrO<SUB>4</SUB> complex). Bare nZVI was susceptible to variations in wastewater chemistry while entrapped nZVI was more stable and environmentally benign, which could be used to remove metals/metalloids before subsequent treatment for reuse/disposal.</P> <P><B>Highlights</B></P> <P> <UL> <LI> nZVI could remove Cu(II), Zn(II), Cr(VI), and As(V) from fracturing wastewaters. </LI> <LI> High salinity enhanced Fe dissolution and reduced removal rates except Cu(II). </LI> <LI> nZVI entrapment mitigated Fe dissolution and improved metal(loid) removal. </LI> <LI> Removal efficiency varied with interaction mechanisms and solution speciation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Optimization of impedance boundarycontrolled casing treatment on subsonic compressors

Dakun Sun,Yuqing Wang,Jia Li,Zihan Shen,ChunWang Geng,Xu Dong,Xiaoyu Wang,Xiaofeng Sun 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5

Foam-metal casing treatment (FMCT) has the potential to enhance the stall margin while attenuating the broadband noise of compressors. An optimized structure of FMCT backed with an air gap was developed in this study with the basis of a prediction model. The eigenvalue theory with a linear perturbation assumption was employed to judge the stability of the compression system, where the casing treatment was considered as an impedance boundary condition. The effect of this kind of casing treatment on the compression system is introduced through the equivalent surface source method. The transfer element method was applied to match the relations between perturbation parameters on the surface of each section. Prediction results showed that the double-layer configuration has better stall margin improving ability, with experimental results on the steady characteristics confirming a 39.5 % stall margin improvement. The mechanism of exerting damping on the system and thus suppressing stall precursors was proved.

Crack detection in concrete slabs by graph-based anomalies calculation

Yuqing Zhou,Weifang Sun,Jiawei Xiang,Binqiang Chen,Wei Feng 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.29 No.3

Concrete slab cracks monitoring of modern high-speed railway is important for safety and reliability of train operation, to prevent catastrophic failure, and to reduce maintenance costs. This paper proposes a curvature filtering improved crack detection method in concrete slabs of high-speed railway via graph-based anomalies calculation. Firstly, large curvature information contained in the images is extracted for the crack identification based on an improved curvature filtering method. Secondly, a graph-based model is developed for the image sub-blocks anomalies calculation where the baseline of the subblocks is acquired by crack-free samples. Once the anomaly is large than the acquired baseline, the sub-block is considered as crack-contained block. The experimental results indicate that the proposed method performs better than convolutional neural network method even under different curvature structures and illumination conditions. This work therefore provides a useful tool for concrete slabs crack detection and is broadly applicable to variety of infrastructure systems.

Resource Allocation in Multi-User MIMO-OFDM Systems with Double-objective Optimization

( Chen Yuqing ),( Li Xiaoyan ),( Sun Xixia ),( Pan Su ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.5

A resource allocation algorithm is proposed in this paper to simultaneously minimize the total system power consumption and maximize the system throughput for the downlink of multi-user multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. With the Lagrange dual decomposition method, we transform the original problem to its convex dual problem and prove that the duality gap between the two problems is zero, which means the optimal solution of the original problem can be obtained by solving its dual problem. Then, we use convex optimization method to solve the dual problem and utilize bisection method to obtain the optimal dual variable. The numerical results show that the proposed algorithm is superior to traditional single-objective optimization method in both the system throughput and the system energy consumption.

An Improved Random Walk Based Community Detection Algorithm

Daxiang Ji,Yuqing Sun,Demin Li 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.5

Leaky Gut in IBD: Intestinal Barrier–Gut Microbiota Interaction

Yu Shunying,Sun Yibin,Shao Xinyu,Zhou Yuqing,Yu Yang,Kuai Xiaoyi,Zhou Chunli 한국미생물·생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.7

Inflammatory bowel disease (IBD) is a global disease that is in increasing incidence. The gut, which contains the largest amount of lymphoid tissue in the human body, as well as a wide range of nervous system components, is integral in ensuring intestinal homeostasis and function. By interacting with gut microbiota, immune cells, and the enteric nervous system, the intestinal barrier, which is a solid barrier, protects the intestinal tract from the external environment, thereby maintaining homeostasis throughout the body. Destruction of the intestinal barrier is referred to as developing a “leaky gut,” which causes a series of changes relating to the occurrence of IBD. Changes in the interactions between the intestinal barrier and gut microbiota are particularly crucial in the development of IBD. Exploring the leaky gut and its interaction with the gut microbiota, immune cells, and the neuroimmune system may help further explain the pathogenesis of IBD and provide potential therapeutic methods for future use.