Whole-Process Pollution Control for Cost-Effective and Cleaner Chemical Production A Case Study of the Tungsten Industry in China

In this research,a methodology named whole-process pollution control(WPPC)is demonstrated that improves the effectiveness of process optimization.This methodology considers waste/emission treatment as a step of the whole production process with respect to the minimization of cost and environmental impact for the whole process.The following procedures are introduced in a WPPC process optimization:①a material and energy flow investigation and optimization based on a systematic understanding of the distribution and physiochemical properties of potential pollutants;②a process optimization to increase the utilization efficiency of different elements and minimize pollutant emissions;and③an evaluation to reveal the effectiveness of the optimization strategies.The production of ammonium paratungstate was chosen for the case study.Two factors of the different optimization schemes-namely the cost-effectiveness factor and the environmental impact indicator-were evaluated and compared.This research demonstrates that by considering the nature of potential pollutants,technological innovations,economic viability,environmental impacts,and regulation requirements,WPPC can efficiently optimize a metal production process.

Distinct synergetic effects in the ozone enhanced photocatalytic degradation of phenol and oxalic acid with Fe^(3+)/TiO_2 catalyst

In this work. phenol and oxalic acid （OA） degradation in an ozone and photocatalysis integrated process was intensively conducted with Fe3 ＋/TiO2 catalyst. The ferrioxalate complex formed between Fe3＋ and oxalate accelerated the removal of OA in the ozonation, photolysis and photocatalytic ozonation process, for its high reactivity with ozone and UV. Phenol was degraded in ozonation and photolysis with limited TOC removal rates, but much higher TOC removal was achieved in photocatalytic ozonation due to the generation of-OH. The sequence of UV light and ozone in the sequential process also influences the TOC removal, and ozone is very powerful to oxidize intermediates catechol and hydroquinone to maleic acid. Fenton or photo-Fenton reactions only played a small part in Fe3＋/TiO2 catalyzed processes, because Fe＋ was greatly reduced but not regenerated in many cases. The synergetic effect was found to be highly related with the property of the target pollutants. Fe3 ＋/TiO2 catalyzed system showed the highest ability to destroy organics, but the TiO2 catalyzed system showed little higher synergy.

Continuous generation of lattice oxygen via redox engineering for boosting toluene degradation performances

Excellent performances promoted by lattice oxygen have attracted wide attention for catalytic degradation of volatile organic compounds(VOCs).However,how to control the continuous regeneration of lattice oxygen from the support is seldom reported.In this study,we selected sepiolite supported manganese-cobalt oxides(Co_(x)Mn_(100-x)O_(y))as model catalysts by tuning Co/(Co+Mn)mass ratio(x=3%,10%,15%,and 20%)to enhance toluene degradation efficiency,owing to lattice oxygen regeneration by redox cycle existing at the interface and Mn species with high valence state,initiated by cobalt catalytic performance under the role of crystal field stability phase.The results of activity test show that the sepiolite-Co_(15)Mn_(85)O_(y)catalyst exhibit outperformances at 193℃with 10,000 h^(-1)GHSV.In addition,the catalyst existed at the bottom of the"volcano"curve correlated T_(50)or T_(90)with Co/(Co+Mn)weight ratio is sepiolite-Co_(15)Mn_(85)O_(y),conforming its outperformance.Further characterized by investigating active sites structural and electronic properties,the essential of superior catalytic activity is attributed to the grands of lattice oxygen continuous formation resulted from redox engineering based on the high atomic ratio of surface lattice oxygen with continuous refilled from the support and that of Mn^(4+)/Mn^(3+)cycle initiated by cobalt catalytic behaviors.All in all,redox engineering,not only promotes grands of active species reversible regeneration,but supplies an alternative catalyst design strategy towards the terrific efficiency-to-cost ratio performance.

A Mini-Review on Metal Recycling from Spent Lithium Ion Batteries

The rapid growth of lithium ion batteries （LIBs） for portable electronic devices and electric vehicles has resulted in an increased number of spent LIBs. Spent LIBs contain not only dangerous heavy metals but also toxic chemicals that pose a serious threat to ecosystems and human health. Therefore, a great deal of attention has been paid to the development of an efficient process to recycle spent LIBs for both economic aspects and environmental protection. In this paper, we review the state-of-the-art processes for metal recycling from spent LIBs, introduce the structure of a LIB, and summarize all available technologies that are used in different recovery processes. It is notable that metal extraction and pretreatment play impor- tant roles in the whole recovery process, based on one or more of the principles of pyrometallurgy, hydrometallurgy, biometallurgy, and so forth. By further comparing different recycling methods, existing challenges are identified and suggestions for improving the recycling effectiveness can be proposed.

Laccase immobilized on magnetic nanoparticles by dopamine polymerization for 4-chlorophenol removal

In this work, a new immobilization method based on dopamine(DA) self-polymerization was developed for laccase immobilization on magnetic nanoparticles(Fe_3O_4 NPs). To optimize the immobilization condition including reaction pH, DA concentration and enzyme concentration, a central composite response surface method was applied. The optimal condition was determined as p H value of 5.92, laccase concentration of 0.25 mg mL^(-1) and DA concentration of 12.74 mg mL^(-1), under which a high enzyme activity recovery of 88.17% was obtained.By comparing with free laccase, the stabilities of immobilized laccase towards p H, thermostability, storage were enhanced significantly.Approximately 60% of relative activity for immobilized laccase was remained after being incubated for 6 h at 50℃, but the free laccase only remained 25%. After 40 days of storage at 4℃, the laccase immobilized by DA kept about 89% of its original activity, but the free laccase only retained 48%. After recycled 10 times, the relative activity of immobilized laccase still retained 70%. The immobilized laccase was then applied to catalyze the degradation of 4-chlorophenol(4-CP), 86% percentage of 4-CP was removed within 2 h. After degraded 10 times, the relative activity of immobilized laccase still remained 64% of its initial activity, which exhibits an excellent reusability and operational stability.

Comparative studies on fouling of homogeneous anion exchange membranes by different structured organics in electrodialysis

Five negatively charged organic compounds with different structures, sodium methane sulfonate(MS), sodium benzene sulfonate(BS), sodium 6-hydroxynaphthalene-2-sulfonate(NSS), sodium dodecyl sulfate(SDS), and sodium dodecyl benzene sulfonate(SDBS), were used to examine the fouling of an anion exchange membrane(AEM) in electrodialysis(ED),to explore the effect of molecular characteristics on the fouling behavior on the AEM and changes in the surface and electrochemical properties of the AEM. Results indicated that the fouling degree of the AEM by the different organics followed the order:SDBS > SDS > NSS > BS > MS. SDBS and SDS formed a dense fouling layer on the surface of the AEM, which was the main factor in the much more severe membrane fouling, and completely restricted the transmembrane ion migration. The other three organics caused fouling of the AEM by adsorption on the surface and/or accumulation in the interlayer of the AEM, and exhibited almost no influence on the transmembrane ion migration. It was also concluded that the organics with benzene rings caused more severe fouling of the AEM due to the stronger affinity interaction and steric effect between the organics and the AEM compared with organics with aliphatic chains.

Enhanced formation of trihalomethane disinfection byproducts from halobenzoquinones under combined UV/chlorine conditions

Halobenzoquinones(HBQs)are highly toxic disinfection byproducts(DBPs)and are also precursors of other DBPs such as trihalomethanes(THMs).The formation of THMs from HBQs during chlorine-only and UV/chlorine processes with or without bromide was investigated experimentally.Density functional theory(DFT)reactivity descriptors were also applied to predict the nucleophilic/electrophilic reactive sites on HBQs and intermediates.The results were combined to explain the different behaviors of 2,6-dichloro-1,4-benzoquinone(2,6-DCBQ)and tetrachloro-1,4-benzoquinone(TCBQ)and to propose mechanism for the promoting roles of UV and hydroxylation of HBQs in THMs formation.Under UV/chlorine,UV significantly enhanced THMs formation from 2,6-DCBQ compared to chlorine-only,mainly due to the production of OH-DCBQ^(*).Excited 2,6-DCBQ^(*)by UV benefited nucleophilic hydrolysis to produce OH-DCBQ^(*),which favored electrophilic attack by chlorine,thereby inducing more THMs formation.UV/chlorine modestly promoted THMs formation from TCBQ compared to chlorine-only.Hydroxylation of TCBQ and UV irradiation were both important in promoting THMs formation due to the high electrophilic property of OH-TCBQ and TCBQ^(*).Meanwhile,hydroxylation of HBQs and CHCl3 formation were enhanced at higher pH.This work suggested that enhanced formation of THMs from HBQs should be considered in the application of combined UV and chlorine processes.

Extraction of phenol from water by primary amine primene JMT

In this work,liquid-liquid extraction of phenol from aqueous solutions using primary amine Primene JMT(Primene®JM-T)was investigated.The extraction capability of Primene®JM-T with different diluents,including 3-heptanone,sulfonated kerosene,methyl isobutyl ketone,n-octanol,toluene and petroleum ether was studied.The experimental results indicated that the distribution coefficient of phenol extracted using Primene®JM-T that was diluted in 3-heptanone could reach 101.74 under the pH of 9.2.Moreover,the extraction reaction was exothermic(enthalpy change for the extraction reaction(DrHm)was21.03 kJ/mol).High temperature showed a negative effect on the extraction of phenol.The results also showed that adding mineral salt was conducive to the extraction process,and the extraction effi-ciency fell in the descending order of:(NH_(4))_(2)SO_(4)>NaCl>NH_(4)Cl.Two empirical correlations were put forward to quantitatively describe the salting effect.Furthermore,the equilibrium constants of phenol extraction using Primene®JM-T were calculated to be 78.2 L/mol.The phenol was extracted using Primene®JM-T with the possible stoichiometric formula of:[RNH_(3)^(+),PhOH]_(org),where R represents the alkyl group of the amine.