Co-Production of High-Grade Dissolving Pulp,Furfural,and Lignin from Eucalyptus via Extremely Low Acid Pretreatment and Pulping Technologies and Catalysis

Hemicellulose and lignin are not reasonably utilized during the dissolved pulp preparation process.This work aimed to propose a process for the co-production of dissolving pulp,furfural,and lignin from eucalyptus.High-grade dissolving pulp was prepared from eucalyptus using a combination of extremely low acid(ELA)pretreatment,Kraft cooking,and elementary chlorine-free(ECF)bleaching.The obtained pre-hydrolysate was catalytic conversion into furfural in a biphasic system,and lignin during Kraft cooking and ECF was recovered.The process condition was discussed as well as the mass flow direction.The results showed that ELA pretreatment could effectively remove 80.1%hemicellulose.Compared with traditional hydrothermal pretreatment,the ELA pretreatment significantly increased the xylose yield from 5.05 to 14.18 g/L at 170℃ for 2 h,which had practical significance for furfural production.The 82.7%furfural yield and 82.9%furfural selectivity were obtained from xylose-rich pre-hydrolysate using NaCl as a phase modifier in a biphasic system with 4-methyl-2-pentanone(MIBK)as an organic phase by ion exchange resin catalysts at 190℃ for 2 h.Subsequently,the pretreated eucalyptus was subjected to Kraft cooking,and the optimal alkali amount was 14%.Then,the Kraft pulp was bleached using the O-D1-EP-D_(2) sequence,and dissolving pulp was obtained with an ISO brightness of 86.0%,viscosity of 463 mL/g,andα-cellulose content of 95.4%.The Kraft lignin which has a potential application was investigated by 2D-HSQC NMR and 31P NMR.The results showed that the S/G ratio of Kraft lignin was 1.93,and the content of phenolic hydroxyl groups was 2.53 mmol/g.Moreover,based on the above proposed process,30.5 g dissolving pulp,5.5 g furfural,and 21.2 g lignin per 100 g eucalyptus chips(oven dry)were produced.This research will provide new catalysis and pulping technical routes for dissolving pulp,furfural,and Kraft lignin products,which are in great demand in the chemical industry.

Synthesis, isolation and characterization of methyl levulinate from cellulose catalyzed by extremely low concentration acid

A direct synthesis of methyl levulinate from cellulose alcoholysis in methanol medium under mild condition(180 210 C)catalyzed by extremely low concentration sulfuric acid(0.01 mol/L)and the product isolation were developed in this study.Effects of different process variables towards the catalytic performance were performed as a function of reaction time.The results indicated that sulfuric acid concentration,temperature and initial cellulose concentration had significant effects on the synthesis of methyl levulinate.An optimized yield of around 50%was achieved at 210 C for 120 min with sulfuric acid concentration of 0.01 mol/L and initial cellulose concentration below 100 g/L.The resulting product mixture was isolated by a distillation technique that combines an atmospheric distillation with a vacuum distillation where n-dodecane was added to help distill the heavy fraction.The light fraction including mainly methanol could be reused as the reaction medium without any substantial change in the yield of methyl levulinate.The chemical composition and structural of lower heavy fraction were characterized by GC/MS,FTIR,1H-NMR and13C-NMR techniques.Methyl levulinate was found to be a major ingredient of lower heavy fraction with the content over 96%.This pathway is efficient,environmentally benign and economical for the production of pure levulinate esters from cellulose.

Contrasting soil fungal communities at different habitats in a revegetated copper mine wasteland

Little is known about the responses of soil fungal communities to revegetation of mine wastelands,representing a major gap in the knowledge needed to improve the performances of revegetation schemes for mine wastelands.To shed some light on this matter,we reestablished 4000 m^(2) of vegetation on an extremely acidic(pH 2.5)copper mine tailings pond and collected soil samples from three different types of habitats:amended layer of the reclaimed tailings(ALRT),unamended layer of the reclaimed tailings(ULRT),and unreclaimed tailings(UT).Soil fungal communities in the 120 samples collected in two consecutive years were characterized via high-throughput sequencing.The fungal diversities at ALRTand ULRT were found to be significantly higher than those at UT.Ascomycota whose relative abundance ranged from 74.5% to 98.4% was the most predominant phylum across all habitats,exhibiting the lowest predominance at ALRT.Two acidophilic fungal genera,Acidomyces and Acidiella,dominated UT with relative abundances being as high as 37.8% and 15.2%,respectively.In contrast,three genera with plant growth-promoting species(Talaromyces,Trichoderma and Penicillium)were abundant at ULRT and ALRT.Remarkably,their relative abundances at ULRTcould be up to 29.0%,26.9% and 9.7%,respectively.The three types of habitats differed considerably in the overall soil fungal community composition at species level,which became more pronounced as time progressed.The abovementioned differences between habitats in soil fungal community features were related to the reduced availability of soil copper and zinc.These results improved our understanding of fungal ecology of mine wastelands.