Catalytic fast pyrolysis of walnut shell for alkylphenols production with nitrogen-doped activated carbon catalyst

Alkylphenols are a group of valuable phenolic compounds that can be derived from lignocellulosic biomass.In this study,three activated carbons(ACs)were prepared for catalytic fast pyrolysis(CFP)of walnut shell to produce alkylphenols,including nitrogen-doped walnut shell-derived activated carbon(N/WSAC),nitrogen-doped rice husk-derived activated carbon(N/RHAC)and walnut shell-derived activated carbon(WSAC).Pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS)experiments were carried out to reveal the influences of AC type,pyrolytic temperature,and AC-to-walnut shell(AC-to-WS)ratio on the product distributions.Results showed that with nitrogen doping,the N/WSAC possessed stronger capability than WSAC toward the alkylphenols production,and moreover,the N/WSAC also exhibited better effects than N/RHAC to prepare alkylphenols.Under the catalysis of N/WSAC,yields of alkylphenols were significantly increased,especially phenol,cresol and 4-ethylphenol.As the increase of pyrolytic temperature,the alkylphenols yield first increased and then decreased,while high selectivity could be obtained at low pyrolytic temperatures.Such a trend was also observed as the AC-to-WS ratio continuously increased.The alkylphenols production achieved a maximal yield of 44.19 mg/g with the corresponding selectivity of 34.7%at the pyrolytic temperature of 400℃and AC-to-WS ratio of 3,compared with those of only 4.67 mg/g and 6.1%without catalyst.In addition,the possible formation mechanism of alkylphenols was also proposed with the catalysis of N/WSAC.

Adsorption of methylene blue onto activated carbon produced from tea (Camellia sinensis L.) seed shells: kinetics, equilibrium, and thermodynamics studies

Tea (Camellia sinensis L.) seed shells, the main byproduct of the manufacture of tea seed oil, were used as precursors for the preparation of tea activated carbon (TAC) in the present study. A high yield (44.1%) of TAC was obtained from tea seed shells via a one-step chemical method using ZnCl2 as an agent. The Brunauer-Emmett-Teller (BET) surface area and the total pore volumes of the obtained TAC were found to be 1 530.67 mg2/g and 0.7826 cm3/g, respectively. The equilibrium adsorption results were complied with Langmuir isotherm model and its maximum monolayer adsorption capacity was 324.7 mg/g for methylene blue. Adsorption kinetics studies indicated that the pseudosecond-order model yielded the best fit for the kinetic data. An intraparticle diffusion model suggested that the intraparticle diffusion was not the only rate-controlling step. Thermodynamics studies revealed the spontaneous and exothermic nature of the sorption process. These results indicate that tea seed shells could be utilized as a renewable resource to develop activated carbon which is a potential adsorbent for methylene blue.

Scalable fabrication and active site identification of MOF shell-derived nitrogen-doped carbon hollow frameworks for oxygen reduction

Nitrogen-doped carbon materials as promising oxygen reduction reaction(ORR) electrocatalysts attract great interest in fuel cells and metal-air batteries because of their relatively high activity, high surface area, high conductivity and low cost. To maximize their catalytic efficiency, rational design of efficient electrocatalysts with rich exposed active sites is highly desired. Besides, due to the complexity of nitrogen species, the identification of active nitrogen sites for ORR remains challenging. Herein, we develop a facile and scalable template method to construct high-concentration nitrogen-doped carbon hollow frameworks(NC), and reveal the effect of different nitrogen species on theirORRactivity on basis of experimental analysis and theoretical calculations. The formation mechanism is clearly revealed, including low-pressure vapor superassembly of thin zeolitic imidazolate framework(ZIF-8) shell on ZnO templates,in situ carbonization and template removal. The obtained NC-800 displays better ORR activity compared with other NC-700 and NC-900 samples. Our results indicate that the superior ORR activity of NC-800 is mainly attributed to its content balance of three nitrogen species. The graphitic N and pyrrolic N sites are responsible for lowering the working function, while the pyridinic N and pyrrolic N sites as possible active sites are beneficial for increasing the density of states.

茶籽壳质活性炭的制备及其电化学性能

以茶籽壳为原料,以K2CO3作为活化剂,制备了新型活性炭。用氮气吸脱附法对活性炭的孔结构进行了分析。以活性炭为电极材料,6mol/L KOH溶液为电解液组装成超级电容器,利用恒电流充放电、循环伏安、交流阻抗等电化学测试方法研究其电化学性能。结果表明,活化后的茶籽壳炭,其比表面积高达1272m2/g,比电容高达150F/g,研究表明茶籽壳活性炭适用于超级电容器的电极活性材料。

氯化锌法制备油茶籽壳活性炭的研究

介绍了氯化锌法制备油茶籽壳活性炭的过程,并系统分析了活化温度、活化剂的浓度、活化时间、料液比等因素对活性炭脱色性能的影响。正交试验表明,用氯化锌法制备茶籽壳活性炭的最佳工艺为:料液比为1:3.0,活化液质量分数为50%,活化温度为420℃,活化时间为60min。

医用油茶籽油的脱酸脱色新工艺研究

以茶壳为原料制备氮掺杂活性炭,采用大孔树脂与氮掺杂茶壳活性炭联合使用的双重吸附工艺对油茶籽油同时进行脱酸脱色。对氮掺杂茶壳活性炭的制备条件进行了优化,并对所得油茶籽油的质量指标进行测定。结果表明:氮掺杂茶壳活性炭的最佳制备条件为以茶壳活性炭为碳源,以咪唑为氮源,咪唑浓度0.3 mol/L,活化温度850℃,活化时间60 min。在最佳工艺条件下,氮掺杂茶壳活性炭的比表面积为2 876 m^2/g,总孔容为1.55 cm^3/g,其中微孔孔容0.65 cm^3/g,中孔孔容0.55 cm^3/g,大孔孔容0.35 cm^3/g。所得油茶籽油无色透明,酸价(KOH)为0.14 mg/g,过氧化值为0.50 mmol/kg,达到了医用注射用油茶籽油的质量标准。

油茶果壳制备活性炭及其对二苯并噻吩的吸附

以氯化锌为活化剂,油茶果壳为原料,在减压条件下制备油茶果壳活性炭,探讨了体系压力、活化温度、活化时间、氯化锌质量分数等制备条件对油茶果壳活性炭吸附二苯并噻吩的影响,并通过低温N2吸-脱附表征了样品的比表面积及孔结构。结果表明,在活化剂Zn Cl2质量分数为60%,体系压力为0.03 Mpa,450℃活化1 h的条件下,油茶果壳活性炭脱硫率可达到68.94%;制备的活性炭比表面积为2 023.15 m2/g,总孔体积为2.34 cm3/g,平均孔径为4.63 nm。减压条件下制备的活性炭具有良好的吸附脱硫性能。

油茶果壳高值化利用研究进展

油茶(Camellia oleifera abel)是我国特有的木本食用油料树种,属山茶科山茶属,在南方有大面积的种植。油茶果壳是油茶果实加工后产生的副产物,随着油茶产业的兴起,每年都会产生大量的油茶果壳。过去油茶果壳的处理方式通常为填埋或直接燃烧,这不仅造成了资源的浪费,还产生了环境污染等问题。对其进行充分利用有助于解决油茶果壳的处理问题,也是提升油茶附加值的重要途径,同时为废弃生物质材料的再生利用开辟了新方向,具有广阔的市场空间和应用前景。活性炭的制备是油茶果壳最普遍的研究,由于油茶果壳复杂的成分和特殊的结构,不同工艺所制备的活性炭性能差异大,且最佳制备工艺还尚无定论。近年来,研究人员不断在活化工艺方面进行优化,并且制备出不同功能的生物质炭衍生材料。此外,根据油茶果壳的多种成分,以油茶果壳为基体的复合材料、茶皂素的提取及其中不同成分的利用已成为当前研究的焦点。油茶果壳成分中所含有的纤维素、半纤维素及木质素作为木质复合材料基体与其他材料的相容性还有待进一步研究;茶皂素、水溶性多糖及类黄酮等物质使得油茶果壳成为众多应用的理想原料,如吸附、脱色、抗癌、抗氧化等。本文从油茶果壳的各种成分及结构特征切入,介绍了油茶果壳在油茶果壳基复合材料、活性炭及茶皂素的提取及应用方面的最新研究,同时结合当今研究的热点如纳米纤维素材料、电极材料等,介绍了油茶果壳在其中积极的作用,以期为油茶果壳的高值化利用提供依据。

磁性茶籽壳活性炭固相萃取-超高效液相色谱/质谱法测定环境水样中三嗪类除草剂

以茶籽壳为原料,采用水浴法制备磁性生物质活性炭(MBAC)材料,并将其用作磁性固相吸附剂,结合超高效液相色谱/质谱法检测环境水样中西玛通、西玛津、莠去通、特丁通、草净津、异戊乙净、特丁津7种三嗪类除草剂。采用扫描电镜(SEM)和傅里叶变换红外(FT-IR)光谱技术对材料的表面形态和特征基团进行分析。考察了MBAC用量、萃取时间、解吸条件和水样pH值等因素对萃取效率的影响。研究结果表明,当MBAC用量为23.0 mg,pH=7.0,在22 min内吸附达到平衡,7种三嗪类除草剂的检出限为0.1~1.0 ng·L^-1。将该方法应用于环境水样的测定,加标回收率在79.9%~103.3%范围内,相对标准偏差为1.3%~9.6%。方法操作简单快速、准确可靠、检出限低,可用于水样中痕量三嗪类除草剂残留的检测。

微波法制备的茶籽壳基磁性生物质活性炭富集水样中的微囊藻毒素

本实验以茶籽壳为原料,Fe_(3)O_(4)为磁性添加剂和微波吸收介质,采用微波辅助法制备磁性生物质活性炭(MBAC)。实验结果表明,制备MBAC的最佳工艺条件为:50%的H_(3)PO_(4)浸渍150目茶籽壳粉末,浸渍比为5∶1(V/m),活化后茶籽壳粉末与Fe_(3)O_(4)的质量比为5∶2,微波功率为500 W。应用扫描电镜(SEM)、透射电镜(TEM)和傅立叶变换红外(FTIR)光谱等技术对该纳米材料进行表观形貌分析。采用该磁性固相吸附材料,结合超高效液相色谱-串联质谱法实现对环境水体中的微囊藻毒素(MC-LR、MC-RR)的分离分析。实验考察了MBAC用量、pH值、NaCl浓度对吸附效率的影响。实验结果表明:投加10.0 mg的MBAC,在20 min内MC-LR和MC-RR的回收率可达到80.0%以上。MC-LR和MC-RR的检出限分别为0.073μg·L^(-1)和0.016μg·L^(-1)。实际水体中MC-RR的浓度范围为51.2~56.6 ng·L^(-1),MC-LR未检测出。

茶籽壳活性炭的制备条件及表面处理效果的研究

研究了茶籽壳活性炭的制备条件及化学表面处理的方法与效果。活性炭制备条件包括二种不同活化剂的浓度、高温炭化时间和高温炭化温度。实验结果表明:选用60%的ZnCl2溶液为活化剂,低、高温炭化时间为3+3h,低、高温炭化温度为300+600℃时,所制备的茶籽壳活性炭的比表面积为:1023.5g/m2。用硝酸及氨水对所制得的活性炭进行表面处理,能有效提高其活性炭对重金属和贵金属的吸附能力。实验结果表明:用氨水处理的活性炭,对重金属铅的吸附量提高了约41%,对贵金属银的吸附量提高约27%;用硝酸处理的活性炭,对重金属铅的吸附量提高了约53%,对贵金属银的吸附量提高约41%。可用于重金属废水的处理及贵金属的吸附回收。

油茶壳中提取茶皂素及制备活性炭工艺研究

近年来,我国油茶产业的发展十分迅速,油茶壳产量更是与日俱增,不过我国并未对数量巨大的油茶壳进行充分利用。油茶壳中的茶皂素能够应用到制药、水产养殖、食品与纺织等领域,而其含有的纤维素、半纤维素及木质素,则能够用于制备活性炭。因此,油茶壳的开发价值是极高的。本文便对油茶壳中茶皂素的提取及活性炭的制备工艺进行研究,以期推动油茶壳中茶皂素提取与活性炭制备工艺的进一步发展。

茶籽壳氯化锌法制备活性炭的工艺研究

以茶籽壳为原料,通过对活化剂氯化锌影响因素活化温度、活化时间、活化剂用量等对活性炭的得率、碘吸附值、亚甲基蓝吸附值的影响的试验,结果表明用氯化锌活化法制备茶耔壳活性炭最佳工艺参数为:浸泡时液固比2.5:1,氯化锌浓度50%,活化温度400℃,活化时间60 min。