Fluoride removal from coal mining water using novel polymeric aluminum modified activated carbon prepared through mechanochemical process

Defluoridation of coal mining water is of great significance for sustainable development of coal industry in western China.A novel one-step mechanochemical method was developed to prepare polymeric aluminum modified powder activated carbon(PAC)for effective fluoride removal from coal mining water.Aluminum was stably loaded on the PAC through facile solid-phase reaction between polymeric aluminum(polyaluminum chloride(PACl)or polyaluminum ferric chloride(PAFC))and PAC(1:15 W/W).Fluoride adsorption on PACl and PAFC modified PAC(C-PACl and C-PAFC)all reached equilibrium within 5 min,at rate of 2.56 g mg^(-1)sec^(-1)and 1.31 g mg^(-1)sec^(-1)respectively.Larger increase of binding energy of Al on C-PACl(Al–F bond:76.64 eV and Al–FOH bond:77.70 eV)relative to that of Al on C-PAFC(Al–F bond:76.52 eV)explained higher fluoride uptake capacity of C-PACl.Less chloride was released from C-PACl than that from C-PAFC due to its higher proportion of covalent chlorine and lower proportion of ionic chlorine.The elements mapping and atomic composition proved the stability of Al loaded on the PAC as well as the enrichment of fluoride on both CPACl and C-PAFC.The Bader charge,formation energy and bond length obtained from DFT computational results explained the fluoride adsorption mechanism further.The carbon emission was 7.73 kg CO_(2)-eq/kg adsorbent prepared through mechanochemical process,which was as low as 1:82.3 to 1:8.07×10^(4)compared with the ones prepared by conventional hydrothermal methods.

Chemical species distribution and transformation in polyaluminum chemical solutions

The hydrolysis polymerization precipitation process of Al(III) was studied with pH titration method, and the prepared polyaluminum solutions were characterized by various experimental methods: acid depolymerization, timed complex-colorimetric procedure, ultrafiltration, X-ray diffraction and infrared absorption spectrum. The results showed that the chemical species transformation and distribution of Al(III) in the hydrolysis-polymerization process depended on B=(OH/Al) ratio, pH and other factors. By their structures, the chemical species can be divided into three categories of monomeric (Ala), polymeric (Alb), sol or gel precipitates (Alc) and the polymeric species may be further divided into three groups such as linear low polymer (Alb1), linear high polymer (Alb2) and high polymer with cyclic structure (Alb3). The nominal molecular weight of polymeric species obtained by ultrafiltration was about 1000-50000 and most of them failed into a range around 10000. A scheme for the chemical speciation model of Al(III) solution was suggested.

Double-layer Modifi cation of Water-based Aluminum with SiO2 and Polyacrylic Acid by Solgel Process and in situ Polymerization

A double-layer aluminum consisting of an aluminum core and a shellof SiO2 and polyacrylic acid was synthesized.This modified aluminum was used to improve the corrosion resistance and dispersive property of aluminum in waterborne media.TEM,FTIR,XPS,and EDX determination showed that PAA and SiO2 were coated on the surface of aluminum.Evolved hydrogen detection showed that the corrosion resistance of composite particle had been markedly improved.Maximum corrosion inhibition efficiency of SiO2 coated aluminum（SiO2@Al）was 95.1% while that of double-layer coated aluminum（PAA/SiO2@Al）was 98.8%.Meanwhile,polyacrylic acid layer improved the agglomeration of aluminum significantly.According to the dispersibility test,the particle size of 50% volume fraction [d（0.5）] of aluminum,SiO2@Aland PAA/SiO2@Alwere 42,53,and 34 μm,respectively.

Polymeric catalyst with polymerization-enhanced Lewis acidity for CO_(2)-based copolymers

Ring-opening copolymerization of CO_(2) and epoxides is a promising way to manufacture high value-added materials.Despite a variety of catalyst systems have been reported,the reaction is still limited by low activity and polymer selectivity.Herein,a strategy of polymerization-enhanced Lewis acidity is reported to construct a series of highly efficient polymeric aluminum porphyrin catalysts(PAPCs).The characterization of the coordination equilibrium constant(K_(eq))showed significantly enhanced Lewis acidity of PAPC(K_(eg)=18.2 L/mol)compared to the monomeric counterpart(K_(eq)=6.4 L/mol),accompanied with increased turnover frequency(TOF)from 136 h^(-1) to 5500 h^(-1).Through detailed regulation of Lewis acidity,the highly Lewis acidic PAPC-OTs displayed a record high TOF of 30,200 h^(-1) with polymer selectivity of up to 99%.

The gangue preparation coagulant （PFASS） experiment research and application

In order to design a new technological process system to take the polymeric ferric aluminum silicate sulfate（PFASS） and to apply it in wastewater processing, the chemical composition analysis was carried on to the Fuxin gangue, adopted the orthogonal experiment method to obtain optimum response condition of with the acid pickling taking the aluminum in the gangue and with alkali extracting taking the silicon in the gangue, The experiments indicate that the sample chemistry content which tests elect completely conform to the preparation inorganic polymer water treatment coagulant request standard. Used the polymeric ferric aluminum silicate sulfate results in which with the system take as the coagulant of treatment wastewater, used the mercerizing degree, the wastewater pH value, the coagulation time, the coagulant throws increment factors and so on to test and verify its influence on the waste water processing. The result indicates that by using this craft production PFASS in waste water processing, after the processed waste water achieves the emission standard, the processing effect is good.