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Removal of boron and silicon by a modified resin and their competitive adsorption mechanisms Full text
2020
Bai, Shuqin | Han, Jue | Du, Cong | Li, Jiaxin | Ding, Wei
Boron and silicon are essential trace elements for living organisms. However, these are undesirable in excess amounts owing to the toxic effects of boron on plants, animals, and humans, and the silica scale formation by silicon in water treatment processes. Herein, a new diol-type adsorbent (T-resin) was synthesized by grafting tiron (disodium 4,5-dihydroxy-1,3-benzenedisulfonate) onto an ion-exchange resin (grafting amount is 1.2 mmol/g dry) to separate boron and silicon from a solution. The effects of pH, initial concentration, and coexisting anions, particularly, the effect of the coexistence of silicate ion on the adsorption of boron, were investigated. T-resin showed good adsorption properties for both boron and silicon in a wide pH range (pH 2–10). The adsorption of boron and silicon was effectively described by the Langmuir isotherm, and the maximum adsorption capacities of boron and silicon were 21.25 mg/g and 8.36 mg/g, respectively. In a competitive adsorption system, boron and silicon were simultaneously adsorbed on the T-resin, but the adsorption rate of boron was faster than silicon. However, silicon could replace the boron adsorbed on the resin, indicating that the adsorption of silicon was more stable than boron. ¹¹B and ²⁹Si solid state NMR data confirmed the different adsorption mechanisms of the two elements. Boron was adsorbed via two types of complexes, a triangular complex of [LB(OH)], as well as 1:1 tetrahedral complex of [LB(OH)₂] and 1:2 tetrahedral complex of [BL₂], whereas silicon was only adsorbed via a 1:3 octahedral complex of [SiL₃]. Graphical abstract A new diol-type absorbent was synthesized by grafting tiron onto an ion-exchange resin to separate boron and silicon from a solution. Boron and silicon competitively adsorbed on the T-resin, and silicon could replace the boron adsorbed on the resin. ¹¹B and ²⁹Si solid state NMR data confirmed the different adsorption mechanisms of the two elements. Boron was adsorbed via two types of complexes, a triangular complex of [LB(OH)], as well as 1:1 tetrahedral complex of [LB(OH)₂] and 1: 2 tetrahedral complex of [BL₂], whereas silicon was only adsorbed via a 1:3 octahedral complex of [SiL₃].
Show more [+] Less [-]Development of agricultural waste/recycled plastic/waste oil bio-composite wallpaper based on two-phase dye and liquefaction filling technology Full text
2020
Xiao, Dingtian | Yu, Zhifeng | Qing, Shan | Du, Shunlin | Xiao, Huaqiang
In this paper, a complete biomass composite processing system based on agricultural waste powders, recycled plastics, and waste oil is proposed. The wood-colored wallpaper, the green wallpaper, and the blue wallpaper are produced by this processing system. These wallpapers are new products with low cost, high added value, and environmental friendliness. These wallpapers have also been systematically tested. Based on the analysis of test results, a 3D model of material formation mechanism, liquefaction filling technology, and hybrid network model construction technology are obtained. The experiment found the reasonable RLDPE and RLLDPE ratio (1:0.26), the reasonable ratio of biomass to specialty solvents (1:1.5), the reasonable dose of the solid dye (3%), and the reasonable concentration of dye solutions. Wood-colored bio-composite wallpaper products have a smooth surface, wood color (ΔE = 36.7), natural aroma, and good comprehensive mechanical properties (tensile strength 9.255 MPa; elongation at break 20.998%; Young’s modulus 2229.475 MPa). The processing system and wallpaper products in this article not only promote the plastic recycling economy and sustainable agricultural development but also provide new channels for the development of waste oil reuse and new ideas for the development of high value-added biocomposite materials.
Show more [+] Less [-]MOFs-carbon hybrid nanocomposites in environmental protection applications Full text
2020
Sule, Rasidi | Mishra, Ajay Kumar
The demand for green engineering environmentally friendly nanomaterials had made carbon nanotube a suitable material to keep metal–organic frameworks (MOFs) in the application of wastewater treatment and air pollution monitoring systems. This review summarizes many of the recent research accomplishments in the synthesis of MOFs and MOFs-carbon hybrid nanocomposites for various applications such as wastewater treatment and removal of hazardous gases (CO, SO₂, H₂S and NH₃) with emphasis on MOF/CNTs composites. This review focuses on the efficient removal of pollutants from the environment using adsorption techniques. Another important application of MOFs composite discussed in this review is sensor materials for environmental pollution.
Show more [+] Less [-]Inorganic and organic characterization of Santa Lucía salt mine peloid for quality evaluations Full text
2020
Martínez-Villegas, Nadia | Suárez Muñoz, Margaret | González-Hernández, Patricia | Melián Rodríguez, Clara | Barrios Cossio, Josiel | Hernández Díaz, Rebeca | Fagundo Castillo, Juan R. | Gelen Rudnikas, Alina | Díaz López, Cristina | Pérez-Gramatges, Aurora | Díaz Rizo, Oscar
Santa Lucía peloid is a sediment used in pelotherapy in Cuban primary health care services. Therefore, in addition to physicochemical regulated parameters, other analyses are required to complement their physicochemical characterization and understand potential element mobility, radiological risk, and toxicity as well as likely bioactive compounds present in Santa Lucía peloid. For these purposes, inorganic and organic elements and compounds were considered to evaluate Santa Lucía peloid’s quality. This was accomplished through an integral approach that included (1) determination of physicochemical parameters (pH, electrical conductivity, oxidation–reduction potential, temperature, dissolved oxygen, elemental C, H, and N analyses, organic matter, and hexane removable substances content); (2) determination of total concentration of elements with biological and toxicological importance (i.e., Na, K, Ca, Mg, Fe, Mn, Cr, Cu, Ni, Pb, and Zn), as well as their distribution in operationally defined solid phases, mineralogy, particle size distribution, and total content of radionuclides and radiological dose calculations; and (3) its organic characterization. Results from this study showed that Santa Lucía peloid was non-contaminated and showed low metal mobility and acceptable radiological dose levels, being safe for therapeutic uses. Additionally, these results contribute to the understanding of the organic composition of peloides, provide strong evidences to scientifically explain the therapeutic action of peloids in the treatment of inflammatory diseases, and set a new frame to improve peloid guidelines in Cuba and other countries.
Show more [+] Less [-]Temporal dynamics of earthworm (Eisenia fetida) microbial communities after cadmium stress based on a compound mathematical model Full text
2020
Ning, Yucui | Zhou, Haoran | Wang, Shiben | Li, Xin | Liu, Duo | Xu, Wenyue | Zhou, Dongxing
Soil cadmium (Cd) pollution has received increasing attention from scholars. In the field of Cd pollution remediation, there is an urgent need to study the combined bioremediation technology of earthworms and microbes. In this paper, a short-term stress test and a long-term stress test were conducted. Eisenia fetida were inoculated into artificial soil that was contaminated with Cd. After different Cd stress times, the regulation process between the microbial communities in the earthworms and in the soil was studied. Canonical correlation analysis and the TOPSIS method were combined to establish a mathematical model for data analysis, and the changes in the carbon source utilization intensity by microbes were analysed. The results showed that in the short-term stress tests, the regulation process could be divided into five stages. Specifically, after 1–3 days of stress, the microbial community in the earthworms regulated the soil microbial community, but on the 3rd day, the regulation was weakened. On the 4th day, the soil microbial community was affected not only by the microbes in the earthworms but also by the increasing intensity of Cd stress. After 5 days of stress, the microbial communities in the earthworms and the soil were both greatly affected by Cd poisoning, and the microbes transitioned from stable to declining. At 6–7 days, the microbes in the earthworms gained control over those in the soil once again, and the Cd-tolerant microbes began to appear and proliferate. At 8–10 days, the regulation of the soil microbes by the earthworm microbes weakened, while the Cd-tolerant population in the soil microbial communities gradually evolved at this stage to adapt to the increasing Cd stress. The long-term stress tests showed that the difference between the microbial communities in the soil and in the earthworms increased, and there was almost no regulation between them.
Show more [+] Less [-]Low-dose Roundup induces developmental toxicity in bovine preimplantation embryos in vitro Full text
2020
Cai, Wenyang | Yang, Xiao | Li, Xiangchen | Li, Hongtu | Wang, Shuo | Wu, Zhengchao | Yu, Mingxi | Ma, Shiliang | Tang, Shuang
Roundup is a widely used glyphosate-based herbicide worldwide. Roundup residues can be detected in the organs and urine of animals. However, its toxicity on mammalian preimplantation embryos has not been well investigated. Here, we show Roundup impairs the development and quality of bovine preimplantation embryos in a dose-dependent manner. Exposure to the agricultural recommended doses of Roundup caused in vitro developmental arrest and quick death of bovine embryos. Furthermore, even a very low concentration (0.9 ppm) of Roundup was harmful to bovine preimplantation development. In addition, Roundup increases intracellular calcium levels and induces oxidative stress and apoptosis in bovine embryos. Even if the embryos developed to morphologically normal blastocysts when cultured with low concentrations of Roundup, abnormal intracellular calcium and oxidative stress could be detected inside the embryos and led to an increased incidence of apoptosis in the blastocysts. These data suggest Roundup residues from the agricultural application are potentially dangerous to mammalian preimplantation embryos.
Show more [+] Less [-]Theoretical framework for the estimation of H2S concentration in biogas produced from complex sulfur-rich substrates Full text
2020
Moreno-Andrade, Iván | Moreno, Gloria | Quijano, Guillermo
A theoretical framework was developed and validated for the estimation of H₂S concentration in biogas produced from complex sulfur-rich effluents. The modeling approach was based on easy-to-obtain data such as biological biogas potential (BBP), chemical oxygen demand, and total sulfur content. Considering the few data required, the model fitted well the experimental H₂S concentrations obtained from BBP tests and continuous bioreactors reported in the literature. The model supported a correlation coefficient (R²) of 0.989 over the experimental data, obtaining average and maximum errors of ~ 25 and ~ 35%, respectively. The theoretical framework yielded good estimations for a wide range of experimental H₂S concentrations (0.2 to 4.5% in biogas). This modeling approach is, therefore, a useful tool towards anticipating the H₂S concentration in biogas produced from sulfur-rich substrates and deciding whether the installation of a desulfurization technology is required or not.
Show more [+] Less [-]Correlation between urinary chromium level and semen quality in men attending an andrology laboratory Full text
2020
Pokhrel, Gaurab | Shi, Yihao | Wang, Wangcheng | Khatiwada, Shikha Upadhyaya | Sun, Zhongyang | Yan, Jianqiao | Liu, Jihong | Zheng, Dan
Chromium is an essential element that is required for the normal physiology but can be toxic to humans above a certain level. In spite of growing interest in research on chromium exposure to human health consensus about its effect on human, semen quality has not been achieved. The aim of the present study is to evaluate the impact of chromium exposure on semen parameters. A total of 760 males attending andrology laboratory of Tongji Hospital, Wuhan, for routine semen analysis were enrolled and requested to provide semen and urine samples. The urine level of chromium was evaluated using inductively coupled plasma mass spectrometry (ICP-MS), and computer-assisted semen analysis (CASA) was applied to examine semen parameters. Associations between semen parameters and urinary chromium were analyzed by means of multivariate linear regression analysis. Multivariate analysis showed a negative association between the urinary concentrations of chromium and progressive motility (β = − 0.014, p = 0.040) and total motility (β = − 1.077, p = 0.048), while other semen parameters did not show any statistically significant changes. Urinary chromium could influence semen quality parameters and impair male fecundity.
Show more [+] Less [-]Enhanced Cr(VI) removal by waste biomass derived nitrogen/oxygen co-doped microporous biocarbon Full text
2020
Li, Panyu | Hu, Mengning | Suo, Jiao | Xie, Yi | Hu, Wanrong | Wang, Xuqian | Wang, Yabo | Zhang, Yongkui
Herein, kitchen waste hydrolysis residue (KWHR) was utilized as the precursor to fabricate nitrogen/oxygen co-doped microporous biocarbons (NOMBs) with ultrahigh specific surface area via KOH activation. Activation temperature was found to be crucial for heteroatom doping and pore structure construction. Attractively, the obtained NOMB with high surface area (2417 m²/g) and microporosity (~ 90%) displayed an outstanding capacity of Cr(VI) removal (526.1 mg/g at pH 2). The kinetics and isotherm studies showed that the adsorption of Cr(VI) onto NOMB was well described by the pseudo-second-order kinetics and Langmuir isotherm. Moreover, it was found that Cr(VI) was partly reduced to Cr(III) during the removal process as the nitrogen/oxygen functionalities and unsaturated carbon bond played crucial roles of electron-donors, which revealed the fact that the removal of Cr(VI) by NOMB was attributed to the coupling of adsorption and reduction reaction. Overall, this study has demonstrated the possibility of preparing microporous biocarbons using KWHR as a renewable material and the resultant NOMB is of great potential to detoxify Cr(VI).
Show more [+] Less [-]Factors affecting the removal of bromate and bromide in water by nanofiltration Full text
2020
Lin, Dachao | Liang, Heng | Li, Guibai
Bromide is universal in surface water influenced by salt tide and brackish water. It is harmless to human until transferring to bromate (a kind of disinfection byproducts) under certain conditions such as oxidation. Though both of them are not easily removed by conventional water treatment, nanofiltration seems to be an efficient way to solve the problems. In this study, the removal of bromate and bromide by nanofiltration membranes were systematically investigated, considering the system pressure (0.2–0.3–0.4 MPa), pH (5–7–9), ionic strength (0.005–0.05–0.1 mM), membrane type (NF270 and NF90), and the influences of organic matters (humic acid and sodium alginate). The membrane flux and the removal efficiency of anions were taken into consideration. According to the results, the membrane flux increased along with the system pressure, but slight influence on the removal of bromate and bromide was observed. Rising pH and ionic strength could not obviously deteriorate the flux. However, the removal of these anions was enhanced by increasing pH as well as decreasing ionic strength. Compared with humic acid, severer flux decline and deterioration of anion removal were achieved when sodium alginate was added in feed solution. Regardless of the operating conditions, bromate was more easily removed by nanofiltration membranes than bromide, which could result from different steric hindrance. Compared with NF270, NF90 can reject bromide and bromate more efficiently. The findings in the present study would contribute to the deep understanding of the factors affecting removal of bromate and bromide by nanofiltration and provides guidance about application of it.
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