Polymers
·
2022
·Vol. 14
·期 19
·3970
·
IF 4.967
Ming Chang,Xiaomin Ma,Xianshu Dong,Yuping Fan,Ruxia Chen
It is important to identify an environmentally friendly and efficient flocculant that can replace polyacrylamide for the solid–liquid separation of coal wastewater. In this study, to explore whether chitosan can be used as an environmentally friendly and efficient flocculant for the solid–liquid separation of coal wastewater, AlCl3–chitosan was used to conduct flocculation–sedimentation and dewatering tests under different chitosan dosages and shear-strength conditions for the prepared coal wastewater. Focused beam reflectance was measured to dynamically monitor the number of refractory fine particles, and the settled flocs were photographed and analyzed with microscopy to explore the effect of AlCl3–chitosan on the flocculation settlement effect and floc characteristics. The synergistic mechanisms of AlCl3and chitosan were investigated using quartz crystal dissipative microbalance and zeta potential measurement. The results showed that the addition of chitosan can significantly improve the flocculation–sedimentation and dewatering effects of coal wastewater. A reasonable dosage under a certain shear strength is conducive to the reduction of fine slime particles, which results in a compact floc structure, increases the floc size, and improves the settling effect. The synergistic effect of AlCl3–chitosan improved the electric neutralization and adsorption bridging abilities of the chitosan, and the mixed solution of AlCl3and chitosan had stronger adsorption on the carbon surface. This study provides a new approach to the selection of flocculants for coal wastewater treatment.Keywords:coal wastewater;chitosan;solid–liquid separation;FBRM;QCM−D
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CRYSTAL GROWTH
·
2017
·
IF 1.751
Zhilong Luo,Yingdan Cui,Weibing Dong,Qipeng Xu,Gaoxing Zou,Chao Kang,Baohong Hou,Song Chen,Junbo Gong
Nitroguanidine (NQ) is a commonly used explosive, which has been widely used for both civilian and military explosive applications. However, the weak flowability and mechanical performance limit its application. In this work, mechanical performance and thermodynamic stability of NQ crystals were improved by controlling crystal morphologies in the crystallization process. Typical NQ crystals with multiple morphologies and single crystal form were obtained in the presence of additives during the cooling crystallization. The morphology controlled NQ crystals showed higher density, unimodal crystal size distribution and enhanced flowability. The additives showed the inhibitory effect on the nucleation of NQ crystals by in-situ FBRM and PVM determination, and the mechanism was analyzed by means of morphological prediction and molecular simulation. Furthermore, the morphology controlled NQ crystals suggested higher thermodynamic stability according to the calculation of entropy, enthalpy, Gibbs free energy and apparent activation energy on the basis of DSC results.
研究领域:
材料科学
·
化学
·
炸药工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Xicheng Bao,Yaowen Xing,Qinshan Liu,Jincheng Liu,Shiqi Dai,Xiahui Gui,Jihui Li,Zili Yang
Polar and compound collectors are current research hotspots in the field of low-rank coal (LRC) flotation. However, most studies only focus on the collecting ability of collectors while ignoring its selectivity. This study presents the design for a novel high-efficiency ternary compound collector (oleic acid (OA), methyl oleate (MO) and diesel) with great selectivity, strong collecting and spreading ability for Sujiagou LRC. In comparison to diesel, the clean coal yield is increased by 41.40%, and its ash content is reduced by 0.91% at optimal dosage of 2000 g/t. And we propose some new insights on the mechanism of ternary compound collector through density functional theory (DFT) calculations, focused beam reflectance measurement (FBRM), and molecular dynamics (MD) simulations. OA has the strongest collecting ability with the shortest adsorption distance and smallest frontier orbital gap, which ensures the flotation efficiency and collecting ability of ternary compound collector. The great selectivity of ternary compound collector owing to these two reasons: MO adsorbs more strongly on the LRC surface through the flat-lying adsorption at the junction of hydrophilic and hydrophobic parts; the “wasteful adsorption” on the gangue surface is prevented as the nonpolar parts of ternary compound collector attract polar collectors. Finally, a firm oil film with strong spreading ability is formed on the LRC surface, which can achieve a spread across the hydrophilic area even without the adsorption of polar collectors. The synergistic adsorption not only improves the collecting ability of the ternary compound collector but also ensures its selectivity.
研究领域:
化学工程
·
材料科学
·
环境科学
·
矿业工程
✓ 已验证
产品关联
DOI
高影响因子
Minerals
·
2023
·Vol. 13
·期 4
·582
·
IF 2.5
Bao Guo,Xinlei Zhan,Kaixi Jiang,Hongzhen Xie,Rongdong Deng
Sedimentation of ultrafine silica particles that exist in acid leaching pulp and their separation from Pregnant Leach Solution largely determines the efficiency of a hydrometallurgical process utilizing copper oxide ore. Thickener on a larger scale can allow longer sedimentation, generating low overflow turbidity but high economic input. In this paper, the flocculation behavior of quartz particles in sulfuric acid solution using nonionic flocculants polyethylene oxide (PEO) and polyacrylamide (PAM), as well as ionic cofactor montmorillonite (MMT) and nonionic cofactor tannic acid (TA), were investigated, with the dynamic size of flocs and counts of fines being monitored using an in situ particle size measurement technique, namely the focused beam reflectance measurement (FBRM), under turbulent conditions. Attention was paid to variables affecting quartz flocculation properties from both physicochemical and hydrodynamic aspects such as shear intensity. The flocculation mechanism was investigated using zeta potential and dynamic light scattering measurements. It was found that the TA promotes the bridging flocculation of PEO-quartz by forming associative complexes with larger clusters in solution, while MMT electrostatically adsorbs on the quartz surface, enhancing its bridging with PAM. Low turbidity benefited from the higher shear resistance of the compact flocs structure provided by PEO/PEO + TA/PAM + MMT. Efficient solid–liquid separation was achieved by using the synergistic flocculation of small molecule cofactors and polymer flocculants.Keywords:acid leaching;thickening;quartz;flocculation
研究领域:
湿法冶金
·
材料科学
·
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）