Zhiping Jia

Adsorption of 1,2-dichlorobenzene from water to carbon nanotubes

Abstract The as-grown CNTs and graphitized CNTs were used as adsorbents to remove 1,2-dichlorobenzene from water. The experiments demonstrate that it takes only 40 min for CNTs to attain equilibrium and the adsorption capacity of as-grown and graphitized CNTs is 30.8 and 28.7 mg/g, respectively, from a 20 mg/l solution. CNTs can be used as adsorbents in a wide pH range of 3–10. Thermodynamic calculations indicate that the adsorption reaction is spontaneous with a high affinity and the adsorption is an endothermic reaction.

Effect of total aluminum concentration on the formation and transformation of nanosized Al13 and Al30 in hydrolytic polymeric aluminum aqueous solutions

Influence of total aluminum concentration (CAlT) on the generation and transformation of nanosized Al13 and Al30 in hydrolytic polyaluminum aqueous solutions was investigated using high field 27Al NMR and time-developed Al-Ferron complex colorimetry. When prepared at the optimal basicity (B) of Al13 generation and 80°C, the Al13 species in polyaluminum solution tends to further polymerize and convert to Al30 and higher polymers when CAlT>0.2 mol · L−1, but Al13 does not convert to Al30 quantificationally, as the formation of Alu from Al13 and Al30 is accelerated in the same way. The conversion rate of Al13 is accelerated by the increase in CAlT. When CAlT>0.75 mol·L−1, Al13 content decreases rapidly, and Al30 content increases continuously and becomes the dominant nanometer polynuclear aluminum species. Alm is one of prerequisites of Al13 conversion to Al30. When CAlT increases and B reduces, the polymerization rate between Al13 and Al13 increases, and at the same time, the dissociation reaction rate of Al13 and Al30 by H+ also increases. The latter becomes the dominant reaction in polyaluminum solution with low B value, so Al30 decreases with the increasing CAlT. The hydrolytic polyaluminum solution with Al13 content beyond 80% can only be prepared under the condition of CAlT<0.5 mol · L−1 and optimal B value.

Preparation and Characterization of γ-Al2O3 by Polyaluminum Chloride with High Al13 Content

In this paper a polyaluminum chloride solution with high Al-13 content was prepared and used as raw material for preparation of gamma-Al2O3. The texture and crystalline phase of the prepared alumina samples were characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction, transmission electron microscope (TEM) and nuclear magnetic resonance (NMR) analyses. The effects of alkaline solution and calcination temperature were investigated. The results showed that alkaline solution including NH3 center dot H2O and NaOH had little effect on the alumina sample formation. The impurities of NH4Cl and NaCl in solution can be removed through repeated washing by EDX analysis. Calcination temperature had a significant effect on alumina crystal phase. The alumina sample can transform completely to gamma-Al2O3 in the subsequent heating from 600 degrees C to 800 degrees C. It is very interesting that Al-13 can be existed in gamma-Al2O3 phase even after calcinations. The results indicate that polyaluminum chloride with high Al-13 content is an effective material to prepare gamma-Al2O3.

Preparation of high concentration polyaluminum chloride by chemical synthesis-membrane distillation method with self-made hollow fiber membrane

A method of direct contact membrane distillation (DCMD) with a self-made hollow polyvinylidene fluoride membrane was applied to prepare high concentration polyaluminum chloride (PACl) with high A1b content based on chemical synthesis. The permeate flux and A1 species distribution were investigated. The experimental results showed that the permeate flux decreased from 14 to 6 kg/(m2 x hr) at the end of the DCMD process, which can be mainly attributed to the formation of NaCl deposits on the membrane surface. The Alb content decreased slightly, only from 86.3% to 84.4%, when the DCMD experiment finished, correspondingly the A1c content increased slightly from 7.2% to 8.5%, and the A1a content remained at 7% during the whole DCMD process. A PACl with A1b content of 84% at total aluminum concentration 2.2 mol/L was successfully prepared by the chemical synthesis-DCMD method.