The electrokinetic characteristics and coagulation behaviors of polyaluminum silicate chloride (PASiC) and polyaluminum chloride (PAC) were studied and compared by streaming current (SC) measurement and jar test metho...The electrokinetic characteristics and coagulation behaviors of polyaluminum silicate chloride (PASiC) and polyaluminum chloride (PAC) were studied and compared by streaming current (SC) measurement and jar test method. The experimental results showed that the interaction between polysilicic acid characterized negative charge and hydrolyzed aluminum species result in a decrease of the charge neutralizing ability of PASiC, compared to PAC. The decrease has a close relationship with the basicity ( B ) and Al/Si molar ratio in PASiC. The less the B value and the Al/Si molar ratio, the lower the charge neutralizing ability of PASiC is. In contrast, the preparation technique for PASiC affects the charge-neutralization of PASiC to a smaller extent. In addition, compared with PAC, PASiC may enhance aggregating efficiency and give better coagulating effects.展开更多
Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the poten...Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the potential solution of using polyaluminum chloride(PAC)in the water jet.The effects of PAC are examined through a self-designed simulation system for deep-sea polymetallic nodule collection and sediment samples from a potential deep-sea mining area.The experimental results showed that the optimal PAC dose was found to be 0.75 g/L.Compared with the test conditions without the addition of PAC,the presence of PAC leads to a reduction in volume,lower characteristic turbidity,smaller diffusion velocity,and shorter settling time of the plume.This indicates that PAC inhibits the entire development process of the plume.The addition of PAC leads to the flocculation of mm-sized particles,resulting in the formation of cm-sized flocs.The flocculation of particles decreases the rate of erosion on the seabed by around 30%.This reduction in erosion helps to decrease the formation of plumes.Additionally,when the size of suspended particles increases,it reduces the scale at which they diffuse.Furthermore,the settling velocity of flocs(around 10^(-2) m/s)is much higher that of compared to sediment particles(around 10^(-5) m/s),which effectively reduces the amount of time the plume remains in suspension.展开更多
Compared with traditional aluminum salts, polyaluminum chloride （PACI） has better coagulation-flocculation performance in turbidity removal. However, it is still inferior to organic polymers in terms of bridging fun...Compared with traditional aluminum salts, polyaluminum chloride （PACI） has better coagulation-flocculation performance in turbidity removal. However, it is still inferior to organic polymers in terms of bridging function. In order to improve the aggregating property of PACl, different composite PACl flocculants were prepared with various organic polymers. The effect of organic polymer on the distribution or Al（Ⅲ） species in composite flocculants was studied using ^27TAl NMR and Al-ferron complexation methods. The charge neutralization and surface adsorption characteristics of composite flocculants were also investigated. Jar tests were conducted to evaluate the turbidity removal efficacy of organic polymer modified composite flocculants. The study shows that cationic polymer and anionic polymer have significant influences on the coagulation-flocculation behaviors of PACl. Both cationic and anionic polymers can improve the turbidity removal performancc of PACl but the mechanisms arc much different： cationic organic polymer mainly increases the charge neutralization ability, but anionic polymer mainly enhances the bridging function.展开更多
文摘The electrokinetic characteristics and coagulation behaviors of polyaluminum silicate chloride (PASiC) and polyaluminum chloride (PAC) were studied and compared by streaming current (SC) measurement and jar test method. The experimental results showed that the interaction between polysilicic acid characterized negative charge and hydrolyzed aluminum species result in a decrease of the charge neutralizing ability of PASiC, compared to PAC. The decrease has a close relationship with the basicity ( B ) and Al/Si molar ratio in PASiC. The less the B value and the Al/Si molar ratio, the lower the charge neutralizing ability of PASiC is. In contrast, the preparation technique for PASiC affects the charge-neutralization of PASiC to a smaller extent. In addition, compared with PAC, PASiC may enhance aggregating efficiency and give better coagulating effects.
基金supported by the National Natural Science Foundation of China(Nos.52225107,U2106224,U1906234,51822904,and U1706223)the Fundamental Research Funds for the Central Universities(No.202041004)
文摘Deep-sea sediment disturbance may occur when collecting polymetallic nodules,resulting in the creation of plumes that could have a negative impact on the ecological environment.This study aims to investigate the potential solution of using polyaluminum chloride(PAC)in the water jet.The effects of PAC are examined through a self-designed simulation system for deep-sea polymetallic nodule collection and sediment samples from a potential deep-sea mining area.The experimental results showed that the optimal PAC dose was found to be 0.75 g/L.Compared with the test conditions without the addition of PAC,the presence of PAC leads to a reduction in volume,lower characteristic turbidity,smaller diffusion velocity,and shorter settling time of the plume.This indicates that PAC inhibits the entire development process of the plume.The addition of PAC leads to the flocculation of mm-sized particles,resulting in the formation of cm-sized flocs.The flocculation of particles decreases the rate of erosion on the seabed by around 30%.This reduction in erosion helps to decrease the formation of plumes.Additionally,when the size of suspended particles increases,it reduces the scale at which they diffuse.Furthermore,the settling velocity of flocs(around 10^(-2) m/s)is much higher that of compared to sediment particles(around 10^(-5) m/s),which effectively reduces the amount of time the plume remains in suspension.
文摘Compared with traditional aluminum salts, polyaluminum chloride （PACI） has better coagulation-flocculation performance in turbidity removal. However, it is still inferior to organic polymers in terms of bridging function. In order to improve the aggregating property of PACl, different composite PACl flocculants were prepared with various organic polymers. The effect of organic polymer on the distribution or Al（Ⅲ） species in composite flocculants was studied using ^27TAl NMR and Al-ferron complexation methods. The charge neutralization and surface adsorption characteristics of composite flocculants were also investigated. Jar tests were conducted to evaluate the turbidity removal efficacy of organic polymer modified composite flocculants. The study shows that cationic polymer and anionic polymer have significant influences on the coagulation-flocculation behaviors of PACl. Both cationic and anionic polymers can improve the turbidity removal performancc of PACl but the mechanisms arc much different： cationic organic polymer mainly increases the charge neutralization ability, but anionic polymer mainly enhances the bridging function.
