• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    Tailoring biochar by PHP towards the oxygenated functional groups(OFGs)-rich surface to improve adsorption performance

    2022-07-11 03:39:24XinyueXiongZhanglinLiuLiZhaoMeiHuangLihunDaiDongTianJianmeiZouYongmeiZengJinguangHuFeiShen
    Chinese Chemical Letters 2022年6期

    Xinyue Xiong,Zhanglin Liu,Li Zhao,Mei Huang,Lihun Dai,Dong Tian,Jianmei Zou,Yongmei Zeng,Jinguang Hu,Fei Shen,?

    a Institute of Ecological and Environmental Sciences,Sichuan Agricultural University,Chengdu 611130,China

    b Rural Environment Protection Engineering &Technology Center of Sichuan Province,Sichuan Agricultural University,Chengdu 611130,China

    c Key Laboratory of Development and Application of Rural Renewable Energy,Biogas Institute of Ministry of Agriculture and Rural Affairs,Chengdu 610041,China

    d Chemical and Petroleum Engineering,Schulich School of Engineering,the University of Calgary,Calgary T2N4H9,Canada

    Keywords:Biochar Oxidative modification Phosphoric acid Hydrogen peroxide Oxygenated functional groups

    ABSTRACT In this work,a modification method of H3PO4 plus H2O2 (PHP) was introduced to targetedly form abundant oxygenated functional groups (OFGs) on biochar,and methylene blue (MB) was employed as a model pollutant for adsorption to reflect the modification performance.Results indicated that parent biochars,especially derived from lower temperatures,substantially underwent oxidative modification by PHP,and OFGs were targetedly produced.Correspondingly,approximately 21.5-fold MB adsorption capacity was achieved by PHP-modified biochar comparing with its parent biochar.To evaluate the compatibility of PHP-modification,coefficient of variation (CV) based on MB adsorption capacity by the biochar from various precursors was calculated,in which the CV of PHP-modified biochars was 0.0038 comparing to 0.64 of the corresponding parent biochars.These results suggested that the PHP method displayed the excellent feedstock compatibility on biochar modification.The maximum MB adsorption capacity was 454.1 mg/g when the H3PO4 and H2O2 fraction in PHP were 65.2% and 7.0%;the modification was further intensified by promoting temperature and duration.Besides,average 94.5% H3PO4 was recovered after 10-batch modification,implying 1.0 kg H3PO4 (85%) in PHP can maximally modify 2.37 kg biochar.Overall,this work offered a novel method to tailor biochar towards OFGs-rich surface for efficient adsorption.

    Biochar,a carbon-rich solid,is producedviabiomass pyrolysis in air-free environments,which provides an effective way for waste management [1].As an adsorbent,biochar has been widely investigated in water treatment to remove the organic and inorganic contaminants [2].Substantially,the adsorption performances of biochar greatly relate to its physicochemical characteristics,such as porous structure,surface functional groups (SFGs),ion exchange capacity [3].These characteristics mainly control the adsorption of various pollutants through the mechanisms of physical holding,hydrogen bonding,electrostatic interaction,complexation [4,5],etc.

    However,it is undeniable that the prepared biochar displayed unstable properties from the precursors,the carbonization conditions,and the preparing processes [6].Consequently,various modification methods are widely employed to tailor biochar for the stable characteristics and the targeted performances [7–9].Chemical modification,mainly including acids,alkaline and oxidant,has been widely investigated,by which the surface characteristics were improved,especially,the SFGs were introduced abundantly,the adsorption performances to the pollutants thereby can be intensified[10–15].Besides,another modification method,physical modification contributed to the porous structure,the promoted adsorption performances are also closely associated with the improvement of the accessibility of SFGs [16–18].Hence,enriching SFGs on the biochar will be a powerful strategy to targetedly improve the pollutant removal in the environmental application.

    Among various SFGs on biochar,the oxygenated functional groups (OFGs,e.g.,carboxyl,hydroxyl,carbonyl and ester groups)substantially more contribute to the adsorption behaviors of biochar [19,20].As reported,the hydroxyl group,carboxyl group and carbonyl group on biochar were formed after modification by KOH [21],phosphomolybdic acid [22],O3[23]and H2O2[15,24],and these modified biochars strengthened the adsorption of phenol,methylene blue (MB) and the heavy metals through electrostatic effect,hydrogen bonding,cation exchange and complexation,respectively.Thus,it can be hypothesized that oxidative modification in acid conditions will produce more carboxyl and carbonyl groups.In previous investigations,H3PO4plus H2O2(PHP) was employed to pretreat lignocellulosic biomass,in which the recovered by-product of lignin displayed abundant OFGs and efficient MB adsorption capacity [25,26].These results inspired us that PHP can offer the oxidative modification in acid conditions,by which biochar can be targetedly tailored for abundant OFGs,and improve the adsorption capacity of pollutants.

    Fig.1.MB adsorption using PHP-modified biochars that were prepared at different pyrolysis temperatures.The modified conditions were 3.0 h and 60 °C,and the final fraction of H3PO4 and H2O2 in the employed PHP solution was 65.2% and 7.0%,respectively.

    In this context,current work aimed to check the possibility of enriching OFGs on biochar by PHP modification.MB,an organic cationic pollutant,can be typically combined with OFGs on biochar by electrostatic interaction and hydrogen bonding [22].Thereby,MB was selected for adsorption test to reflect the potentially enriched OFGs by PHP modification.The physico-chemical characteristics of biochar before/after modification were investigated to check the aforementioned hypothesis.Biochars derived from various precursors were also modified by PHP to check the technical compatibility.Besides,the main modification conditions and the recovery of H3PO4were also discussed to show the potential in application.To achieve aims,the biochars were prepared,modified,characterized and analyzed,and their detailed information was displayed in Supporting information.

    As mentioned above,PHP modification was hypothesized to oxidatively tailor biochar for more OFGs,by which the properties of biochar will be potentially stabilized,and targetedly improve the adsorption capability.To clarify this hypothesis,the harvested biochar at different pyrolysis temperatures using oak sawdust (300–700 °C) was attempted for modification.

    According to Fig.1,MB adsorption (21.1–32.4 mg/g) of the parent biochars derived from different temperatures was not in good performances,suggesting the MB adsorption was controlled by multiple mechanisms.For example,the decreased adsorption(BC5000.05).However,the MB adsorption of H2O2-modified biochar (H2O2-BC300) was better than that of H2O2-BC500 or H2O2-BC700,partially suggesting the biochar with more aliphaticity could facilitate the oxidative modification comparing the relatively higher aromatic biochar [27].When the PHPmodification (PHP-BC300) was performed on the BC300,the MB adsorption can be greatly promoted to 454.1 mg/g.By contrast,the PHP modification on the BC500 and BC700 did not display significant promotion.Besides,it was reported that the adsorption of tetracycline (TC) and Pb(II) also related to OFGs on biochar[28,29],the significant promotions (20.6 and 4.5 folds) on TC and Pb(II) adsorption were also observed (Fig.S1 in Supporting information).These results strongly support the hypothesis that PHP worked as the oxidant to efficiently modify the biochar,and the potentially enriched OFGs that targetedly promoted the adsorption performances.

    Besides,Fourier transform infrared spectroscopy (FT-IR) spectra of PHP-modified biochar before/after adsorption (Fig.S2 in Supporting information) indicated the typical peaks of MB at 885 cm?1and 1332 cm?1obviously appeared on the modified biochar after adsorption;the vibration of –C=O–O at 1704 cm?1was weakened after adsorption,suggesting the MB adsorption by the OFGs on the biochar [24].It was reported that H3PO5or H4P2O8will exist in PHP solution,which will be the strong oxidants for the modification [30].In this part,the PHP-modification was performed at 60 °C,and the thermal activation of the formed peroxy acids into free radicals,such as?OH and1O2,at this temperature [31].Besides,the persistent free radicals on the biochar will be a potential activator for the homolysis of peroxy acids to form the free radicals [32,33].These derived free radicals will trigger the oxidative modification for the biochar to generate more OFGs on the biochar[34].

    As illustrated in Table S1 (Supporting information),C content in PHP-BC300 significantly decreased to 38.06%,which meant the carbon fraction in the BC300 chemically participated in the PHP modification.Besides,the O content of PHP-BC300 was 56.46%,which was significantly higher than the other biochars.Moreover,the relatively higher O/C and H/C of PHP-BC300 suggested the polarity was promoted,while the aromaticity was reduced by PHP modification,resulting in more hydrophilic surfaces and fewer aromatic structures [11].The FT-IR spectra (Fig.S3 in Supporting information) further indicated that PHP-BC300 exhibited significant differences with the BC300 at 1704 cm?1,and the increase of peak intensity corresponded to an increase in –C=O–O stretching vibration of carboxyl and ester,which was greatly related to the produced OFGs by PHP [24].The peaks of 1603 cm?1and 1514 cm?1on BC300 were mainly attributed to aromatic and aliphatic carbon–C=C stretching vibration [35,36],but the disappearance of 1514 cm?1and weakened vibration at 1603 cm?1happened on PHPBC300,which also supported the oxidation modification by PHP.The broadened adsorption peak at 3408 cm?1of PHP-BC300,corresponding to the stretching vibration of –OH in hydroxyl groups,also partially reflected more OFGs (–OH) formation after PHP modification.According to the X-ray photoelectron spectroscopy (XPS)spectra (Fig.S4a in Supporting information),the PHP-BC300 surface displayed the lowest C content and the highest O content comparing with other biochars.These results substantially proved the formation of OFGs by PHP modification.In addition,when the C 1s spectra were further de-convoluted (Fig.S4b in Supporting information),the aromatic and aliphatic –C–C/–C=C sharply decreased from 56.43% (BC300) to 38.28% after PHP modification,while the –C–O,–C=O,and –C=O–O in C 1s were significantly increased to 44.65%,8.79%,and 8.28%,respectively,comparing with their corresponding intensity in BC300 (37.73%,3.94%,and 1.90%,respectively) [24].These results well responded to the elemental content and the FT-IR spectra (Table S1 and Fig.S3),and again directly proved the largely generated OFGs after PHP modification.Additionally,in contrast with the BC300,a very lower ash content (0.58%) of PHP-modified biochar suggested the ash function on MB adsorption can be neglected (Table S1).Besides,no significant differences on X-ray diffractometry (XRD) spectra implied the oxidative modification did not alter the chemical skeleton (the graphitized structure) (Fig.S5 in Supporting information).Moreover,specific surface area (SSA),total pore volume,pore size,and scanning electron microscopy (SEM) images (Table S1 and Fig.S6 in Supporting information) reflected that the porous structure was not developed well regardless of the modification or not.These results suggested that the physical adsorption will not dominate the MB removal by PHP-modified biochar [37].Based on these discussions,it was concluded that the oxidative modification substantially happened in PHP modification to targetedly introduce OFGs on biochar,and facilitated the OFGs-dominated adsorption.

    Fig.2.MB adsorption by the PHP-modified biochars derived from various lignocellulosic precursors.Carbonization temperature for parent biochars was 300 °C;the modified conditions were 3.0 h and 50 °C;the employed PHP solution with the final fraction of H3PO4 and H2O2 was 65.2% and 7.0%,respectively.

    To investigate PHP-modification compatibility on the biochar from various precursors,oak sawdust (OS),wheat straw (WS) and birch sawdust (BS) were employed to prepare the corresponding biochars at 300 °C.In contrast with the BC300,the significant promotion on MB absorption did not happen on the separately“modified” biochars by the H3PO4and H2O regardless of the variety of parent biochars for the modification (Fig.2),suggesting the modification function by the separated H3PO4was very weak.Although the H3PO4was reported to be a modifier to improve the biochar adsorption capacity,the different modification processes and parameters may cause the inconsistent results [38,39].The H2O2-BC300 can promote the MB adsorption by 42.9%?64.3% using these three parent biochars,this may be attributed to the oxidative modification by the H2O2to introduce OFGs [15].By contrast,the PHP modified biochars significantly promoted the MB adsorption to 450.1–453.1 mg/g,which was 5.6–21.3 folds and 3.4–14.9 folds higher than the corresponding parent biochars and the corresponding H2O2-BC300,respectively.It was obviously proved that PHP displayed a positive modification on biochar by the synergism of H3PO4and H2O2,and achieved an excellent adsorption capacity.

    Furthermore,based on the MB adsorption capacity of the biochars from these three precursors,the coefficients of variation(CV) of BC300,H2O2-BC300,H3PO4-BC300,and H2O-BC300 were calculated as 0.64,0.72,0.63 and 0.76,respectively,which suggested the distinguishable adsorption performances because of the different characteristics of precursors [40].By contrast,the CV of PHP-BC300 was only 0.0038,suggesting a relatively compatibility of the PHP-modification to the biochars derived from different lignocellulosic precursors regardless of the existing differences in biochar characteristics.Besides,according to literature comparison (Table S2 in Supporting information),MB adsorption by PHPmodified biochars from these 3 precursors were all superior to the mostly reported biochars (41.0–433.1 mg/g),although some of these reported biochars had higher SSA [22,24,41–44];this also proved that the superior MB adsorption efficiency by PHP-modified biochar was mainly attributed to the chemisorption of OFGs,rather than physical adsorption.

    Fig.3.Effects of H3PO4 and H2O2 on the adsorption performances of the PHPmodified biochars.Carbonization temperature for parent biochars was 300 °C;the modified conditions were 3.0 h and 60 °C.

    Fig.4.Effects of (a) modification time and (b) modification temperature on adsorption performances.Carbonization temperature for parent biochars was 300 °C;the employed PHP solution with the final fraction of H3PO4 and H2O2 was 65.2% and 7.0%,respectively.

    To clarify the effects of H3PO4and H2O2on the MB adsorption performances,the wide scale modulation on the concentration of H3PO4(0%?70.8%) and H2O2(0%?10%) was investigated on oak biochar modification.Fig.3 showed that increasing H2O2concentration from 0% to 10% did not improve MB adsorption significantly (P >0.05),when no H3PO4was involved in the modification;the increase of H3PO4also did not significantly promote the MB adsorption (P >0.05) without H2O2involvement.These results suggested the desired modification performances could not be successful by the sole H3PO4or H2O2.Overall,MB adsorption was obviously promoted by PHP mixture.The increase of the H3PO4fraction can significantly promote MB adsorption,especially at final H3PO4concentration ≥30%;increasing H2O2fraction in PHP solution also improved the MB adsorption.These results indicated the synergistic effect for oxidative modification was intensified by the involved H3PO4or H2O2.It can be explained that the intensity of formed peroxy acid in PHP solution will be intensified by the input H3PO4and H2O2.The highest 10% H2O2fraction was involved in PHP modification achieved 6.3 mg/g increase on MB adsorption by 1.0% promotion on H3PO4fraction.By contrast,1.0% promotion on H2O2fraction increased MB adsorption by 7.6–86.2 mg/g on average.Obviously,the effect of H2O2fraction in PHP on biochar modification was stronger than that of H3PO4.The maximum MB adsorption of 454.1 mg/g was harvested with the PHP-modified biochar at the final concentration of H3PO4and H2O2was 65.2%and 7.0% in PHP solution,respectively.

    Besides,oak biochar was PHP-modified for 1.0–5.0 h at 50 °C to clarify the effects on MB adsorption.Fig.4a indicated that adsorption capacity of PHP-BC300 arrived at 310.8 mg/g at modification time of 1.0 h;By contrast,adsorption capacity of H3PO4-BC300 and H2O2-BC300 (the modification time was 3.0 h) was only 18.7 and 33.8 mg/g,respectively (Fig.1).This result once again proved that the PHP-modification was more beneficial to the biochar adsorption of MB than that of H3PO4and H2O2alone.The adsorption capacity significantly promoted to 450.1 mg/g (P <0.05)with the removal efficiency (Re) of 90.1%,however,no significant variations were identified as longer modification were employed(>3.0 h) (P >0.05).It could be basically deduced that the chemical reaction existed in the PHP-modification,and the reaction will be equilibrated with longer reaction time.As displayed in Fig.4b,the PHP-modification temperature was promoted from 30 °C to 60 °C,MB adsorption of the modified biochar was increased significantly (P <0.05),and reached the maximum adsorption capacity of 454.1 mg/g withReof 90.8% after 60 °C modification.The improved modification effects by promoting temperature also suggested the chemical modification happened substantially,such as thermal activation of the formed peroxy acids into free radicals,which was greatly temperature-dependent in 20–60 °C [31].Besides,the very gentle modification temperature by PHP involvement exhibited the potential advantages on simplifying the modification process and reducing the energy input comparing with the reported H3PO4involved methods for biochar modification,such as H3PO4impregnation (47.5%?85%) plus pyrolysis (450 °C) [11,39].

    Although the PHP-modification targetedly generated more OFGs on the modified biochar,the large amounts of employed H3PO4triggered us to recycle the input H3PO4for the modification.As showed in Fig.S7 (Supporting information),MB adsorption of modified biochar by the PHP using the recycled H3PO4still reached 437.3–448.0 mg/g in a successive 10 batches modification (P >0.05),which was closed to the first batch (454.1 mg/g).Besides,the average 94.5% H3PO4was recovered and recycled for the next batch modification,which meant PHP solution prepared by 1.0 kg H3PO4(85%) can modify 2.37 kg biochar in total;this will greatly decrease the input cost of H3PO4.Of course,average 5.5% H3PO4will be consumed in the water washing process for the modified biochar of each batch,thereby the P valorization in wastewater should be considered.According to current experience,the calcium hydroxide and calcium oxide were suggested to introduce the wastewater for the neutralization and the recovery P by precipitation.Besides,struvite [45]and lanthanum-based nanomaterial[46]were considered as advantageous methods to recover phosphorus from wastewater.Integrating this process will potentially make the whole process cleaner and more cost-efficient.

    In summary,PHP was successfully employed to tailor biochar prepared at a low temperature (300 °C)viathe oxidative modification in acid conditions;OFGs were targetedly introduced on biochar,by which extremely high MB adsorption performances were achieved comparing with its parent biochar.PHP modification displayed wide adaptability to the biochars from various typical lignocellulosic precursors,suggesting the feedstock compatibility.The modification was significantly intensified by increasing temperature and time,and the H3PO4and H2O2fraction in PHP positively related to the modification,especially H2O2proportion.Besides,approximately 94.5% H3PO4was recovered for the next batch modification,suggesting 1.0 kg H3PO4(85%) in PHP can modify 2.37 kg biochar in total.

    Declaration of competing interest

    The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

    Acknowledgment

    This work was supported by the National Natural Science Foundation of China (No.21978183).

    Supplementary materials

    Supplementary material associated with this article can be found,in the online version,at doi:10.1016/j.cclet.2021.09.099.

    男人的好看免费观看在线视频| 国产老妇女一区| 日韩人妻高清精品专区| 亚洲国产欧美在线一区| 精品久久久久久久末码| 国产精品永久免费网站| 中文资源天堂在线| 日本免费一区二区三区高清不卡| av又黄又爽大尺度在线免费看 | 91精品国产九色| 国产日韩欧美在线精品| 国产成人a区在线观看| 成人无遮挡网站| 99久久无色码亚洲精品果冻| 大香蕉97超碰在线| 亚洲成人久久爱视频| 中文字幕精品亚洲无线码一区| 成人亚洲精品av一区二区| 啦啦啦观看免费观看视频高清| 看片在线看免费视频| 中文天堂在线官网| 国产高清视频在线观看网站| 久久久久九九精品影院| 十八禁国产超污无遮挡网站| 99视频精品全部免费 在线| 久久亚洲精品不卡| 一区二区三区免费毛片| 乱码一卡2卡4卡精品| 国语自产精品视频在线第100页| 日本色播在线视频| 一二三四中文在线观看免费高清| 亚洲美女搞黄在线观看| 人人妻人人澡人人爽人人夜夜 | 只有这里有精品99| 欧美一区二区亚洲| 成年免费大片在线观看| 天天一区二区日本电影三级| 男女下面进入的视频免费午夜| 视频中文字幕在线观看| 中文字幕亚洲精品专区| 成人高潮视频无遮挡免费网站| 亚洲精品,欧美精品| 男女国产视频网站| 99热全是精品| 国产免费男女视频| 国产精品无大码| 亚洲av电影在线观看一区二区三区 | 亚洲成人中文字幕在线播放| 欧美性感艳星| 国产精品蜜桃在线观看| 黄色日韩在线| 丰满人妻一区二区三区视频av| 午夜福利在线观看吧| 亚洲图色成人| 欧美最新免费一区二区三区| 精品久久久久久电影网 | 成人毛片a级毛片在线播放| 国产精品一区二区三区四区久久| 水蜜桃什么品种好| 久久久久免费精品人妻一区二区| 哪个播放器可以免费观看大片| 日本爱情动作片www.在线观看| 成人鲁丝片一二三区免费| 国产亚洲精品av在线| 亚洲真实伦在线观看| 国产高清国产精品国产三级 | 最新中文字幕久久久久| 日韩高清综合在线| 啦啦啦韩国在线观看视频| 精品一区二区三区人妻视频| 色综合站精品国产| 婷婷色av中文字幕| .国产精品久久| 亚洲怡红院男人天堂| 欧美成人a在线观看| 欧美成人午夜免费资源| 国产老妇女一区| 亚洲精品乱久久久久久| 熟女人妻精品中文字幕| 熟妇人妻久久中文字幕3abv| 草草在线视频免费看| 亚洲精品影视一区二区三区av| 欧美成人午夜免费资源| 亚洲电影在线观看av| 国产精品一区二区三区四区久久| 久久精品国产亚洲网站| 国产免费男女视频| 七月丁香在线播放| 久99久视频精品免费| 小蜜桃在线观看免费完整版高清| 亚洲真实伦在线观看| 日本免费a在线| 亚洲av不卡在线观看| 女人久久www免费人成看片 | 尾随美女入室| 日本午夜av视频| 丝袜美腿在线中文| 真实男女啪啪啪动态图| 亚洲精品自拍成人| 日本免费a在线| 亚洲人成网站在线播| 亚洲成色77777| 色综合亚洲欧美另类图片| 最后的刺客免费高清国语| 国产日韩欧美在线精品| 村上凉子中文字幕在线| 91精品伊人久久大香线蕉| 国产av一区在线观看免费| 高清午夜精品一区二区三区| 丰满乱子伦码专区| 内地一区二区视频在线| 中文亚洲av片在线观看爽| 五月玫瑰六月丁香| 热99re8久久精品国产| 欧美高清成人免费视频www| 亚洲自拍偷在线| 一区二区三区四区激情视频| 又黄又爽又刺激的免费视频.| 精品一区二区三区人妻视频| 视频中文字幕在线观看| 国产高清三级在线| 国产精品国产三级专区第一集| 免费大片18禁| 精品久久久久久久久久久久久| av.在线天堂| 色哟哟·www| 国产视频内射| 岛国毛片在线播放| 长腿黑丝高跟| 蜜桃亚洲精品一区二区三区| 亚洲电影在线观看av| 国产精品三级大全| 免费黄网站久久成人精品| 熟女电影av网| 中文字幕熟女人妻在线| 色尼玛亚洲综合影院| 免费观看在线日韩| 亚洲最大成人av| 成人亚洲精品av一区二区| 国产熟女欧美一区二区| 国产一区二区在线av高清观看| 日本黄色片子视频| 欧美日韩一区二区视频在线观看视频在线 | 日韩在线高清观看一区二区三区| 久久久成人免费电影| 在线免费十八禁| 91狼人影院| 亚洲欧美精品专区久久| 九色成人免费人妻av| 亚洲国产最新在线播放| 久久久久久久久久久丰满| 伊人久久精品亚洲午夜| 91av网一区二区| 亚洲高清免费不卡视频| 国产激情偷乱视频一区二区| 男女下面进入的视频免费午夜| 久久国内精品自在自线图片| 国产精品99久久久久久久久| 日韩三级伦理在线观看| 一级av片app| 欧美最新免费一区二区三区| 我要看日韩黄色一级片| 又爽又黄a免费视频| 日本免费一区二区三区高清不卡| 久久午夜福利片| 大又大粗又爽又黄少妇毛片口| 日本五十路高清| 国产成人a∨麻豆精品| 99热这里只有是精品50| 美女大奶头视频| 午夜老司机福利剧场| 欧美潮喷喷水| 国产精品av视频在线免费观看| 99久国产av精品国产电影| 人人妻人人看人人澡| 欧美日韩精品成人综合77777| 亚洲综合精品二区| av在线亚洲专区| 久久久久久伊人网av| 亚洲人与动物交配视频| 老司机影院毛片| 精品久久久久久久久av| 久久久久久久国产电影| 日韩av在线免费看完整版不卡| 99国产精品一区二区蜜桃av| 欧美变态另类bdsm刘玥| 97超视频在线观看视频| 成人鲁丝片一二三区免费| 色网站视频免费| 久久精品综合一区二区三区| 级片在线观看| 精品久久久久久久久亚洲| 久久国内精品自在自线图片| 女人久久www免费人成看片 | 看免费成人av毛片| 久久精品综合一区二区三区| 高清毛片免费看| 欧美一区二区精品小视频在线| 一夜夜www| 又黄又爽又刺激的免费视频.| 人人妻人人澡欧美一区二区| 精品欧美国产一区二区三| 亚洲性久久影院| 久久久久久伊人网av| 久久精品国产亚洲网站| 永久免费av网站大全| 午夜亚洲福利在线播放| 夜夜爽夜夜爽视频| 久久久久久久久大av| 热99re8久久精品国产| 国产精品1区2区在线观看.| 色哟哟·www| 亚洲美女搞黄在线观看| 亚洲欧美日韩无卡精品| 人妻少妇偷人精品九色| 熟女电影av网| 亚洲av熟女| 夜夜爽夜夜爽视频| 亚洲av.av天堂| 日本黄色片子视频| 国产乱人视频| 亚洲婷婷狠狠爱综合网| 国产精品99久久久久久久久| АⅤ资源中文在线天堂| 国产综合懂色| 亚洲欧洲国产日韩| 少妇熟女欧美另类| 我的老师免费观看完整版| 久久精品久久精品一区二区三区| 日韩欧美在线乱码| 五月玫瑰六月丁香| 午夜久久久久精精品| 中文欧美无线码| 中文乱码字字幕精品一区二区三区 | 精品国产露脸久久av麻豆 | 欧美xxxx黑人xx丫x性爽| 亚洲成av人片在线播放无| 美女黄网站色视频| 国产精品久久电影中文字幕| 国产真实伦视频高清在线观看| 大香蕉97超碰在线| 一个人看的www免费观看视频| 国产高清国产精品国产三级 | 欧美性感艳星| 赤兔流量卡办理| 高清日韩中文字幕在线| 亚洲精品乱码久久久v下载方式| 亚洲精品亚洲一区二区| 亚洲欧美中文字幕日韩二区| av.在线天堂| 成人午夜高清在线视频| 国产又色又爽无遮挡免| 又粗又硬又长又爽又黄的视频| 欧美成人免费av一区二区三区| 国产高潮美女av| 午夜福利在线观看吧| 欧美日韩国产亚洲二区| 国产av不卡久久| 国产精品久久电影中文字幕| www日本黄色视频网| 亚洲欧美一区二区三区国产| 天堂中文最新版在线下载 | 亚洲欧洲国产日韩| 特大巨黑吊av在线直播| 少妇人妻一区二区三区视频| 99热6这里只有精品| 亚洲中文字幕日韩| 六月丁香七月| 亚洲色图av天堂| 狂野欧美激情性xxxx在线观看| videos熟女内射| 亚洲国产精品sss在线观看| 水蜜桃什么品种好| 国产午夜福利久久久久久| 一区二区三区四区激情视频| 亚洲在久久综合| 国产精品三级大全| 成人一区二区视频在线观看| 欧美精品国产亚洲| 亚洲在线观看片| 亚洲美女视频黄频| 午夜福利成人在线免费观看| 国产av在哪里看| 国产精品久久久久久精品电影小说 | 欧美性猛交╳xxx乱大交人| 国产免费又黄又爽又色| 精品久久久久久电影网 | 亚洲国产欧美在线一区| av在线老鸭窝| 亚洲av男天堂| 高清在线视频一区二区三区 | 99热这里只有是精品在线观看| 麻豆久久精品国产亚洲av| 能在线免费看毛片的网站| 黄色配什么色好看| 两个人视频免费观看高清| 亚洲国产日韩欧美精品在线观看| 欧美一区二区国产精品久久精品| 久久这里有精品视频免费| 99热网站在线观看| 日韩欧美国产在线观看| 亚洲av.av天堂| 亚洲久久久久久中文字幕| 亚洲国产精品sss在线观看| 一级黄片播放器| 亚洲av日韩在线播放| 一级毛片我不卡| 岛国毛片在线播放| 丝袜美腿在线中文| 伦理电影大哥的女人| 在线观看美女被高潮喷水网站| 岛国毛片在线播放| 两个人视频免费观看高清| 日日摸夜夜添夜夜添av毛片| 激情 狠狠 欧美| 日韩一区二区视频免费看| 免费电影在线观看免费观看| 乱码一卡2卡4卡精品| 搡女人真爽免费视频火全软件| 啦啦啦啦在线视频资源| 91aial.com中文字幕在线观看| 国产精品美女特级片免费视频播放器| 边亲边吃奶的免费视频| 久99久视频精品免费| 麻豆久久精品国产亚洲av| 男人的好看免费观看在线视频| 国语自产精品视频在线第100页| 国产高清有码在线观看视频| 免费看光身美女| 国产精品女同一区二区软件| 熟妇人妻久久中文字幕3abv| 精品免费久久久久久久清纯| 国产亚洲精品av在线| 久久久久久大精品| 国产精品不卡视频一区二区| 一级二级三级毛片免费看| 国产精品人妻久久久久久| 久久精品综合一区二区三区| 日韩欧美在线乱码| 深爱激情五月婷婷| 伊人久久精品亚洲午夜| 99国产精品一区二区蜜桃av| 看十八女毛片水多多多| 少妇裸体淫交视频免费看高清| 日本一本二区三区精品| 91av网一区二区| 好男人在线观看高清免费视频| 久久久久免费精品人妻一区二区| 久久久成人免费电影| 最近的中文字幕免费完整| 国产黄片美女视频| 亚洲18禁久久av| 午夜激情福利司机影院| 亚洲国产精品合色在线| www.色视频.com| 亚洲av免费高清在线观看| 国产伦理片在线播放av一区| 精品一区二区免费观看| 国产亚洲精品久久久com| 国产免费男女视频| 美女黄网站色视频| 久久99热6这里只有精品| 国产黄片美女视频| 国产一区二区亚洲精品在线观看| 91精品国产九色| 色网站视频免费| 亚洲av电影在线观看一区二区三区 | 久久婷婷人人爽人人干人人爱| 中文字幕精品亚洲无线码一区| 在线天堂最新版资源| 国产黄色小视频在线观看| 麻豆一二三区av精品| 久久久午夜欧美精品| 3wmmmm亚洲av在线观看| 午夜免费激情av| 国产精品一区二区三区四区免费观看| 中文精品一卡2卡3卡4更新| 亚洲美女搞黄在线观看| 日韩一本色道免费dvd| 好男人在线观看高清免费视频| 最近中文字幕2019免费版| 成年女人永久免费观看视频| 国产乱人偷精品视频| 国产精品国产三级专区第一集| 亚洲综合精品二区| 国产精品一区二区在线观看99 | 国产精品国产三级专区第一集| 男插女下体视频免费在线播放| 国产免费男女视频| 亚洲av成人av| 99热这里只有精品一区| 91久久精品电影网| 春色校园在线视频观看| 亚洲在久久综合| 狂野欧美激情性xxxx在线观看| 日韩视频在线欧美| 精品久久久久久久久亚洲| 国模一区二区三区四区视频| 97超碰精品成人国产| 亚洲怡红院男人天堂| 美女高潮的动态| 又粗又爽又猛毛片免费看| 欧美色视频一区免费| 中文亚洲av片在线观看爽| 两个人视频免费观看高清| 国产在视频线在精品| 国产不卡一卡二| 亚洲国产色片| 亚洲成色77777| 狂野欧美激情性xxxx在线观看| 国产又色又爽无遮挡免| 最近中文字幕高清免费大全6| 国内精品一区二区在线观看| 国产精品久久久久久av不卡| 夫妻性生交免费视频一级片| 老司机影院成人| 中文天堂在线官网| 欧美丝袜亚洲另类| 神马国产精品三级电影在线观看| 啦啦啦啦在线视频资源| 久久这里只有精品中国| 丝袜喷水一区| 日本猛色少妇xxxxx猛交久久| 国产精品人妻久久久久久| 免费观看人在逋| 女人久久www免费人成看片 | 男女啪啪激烈高潮av片| 超碰97精品在线观看| 3wmmmm亚洲av在线观看| 尤物成人国产欧美一区二区三区| 国产精品人妻久久久影院| 99热精品在线国产| av在线天堂中文字幕| 一个人看视频在线观看www免费| 国产免费视频播放在线视频 | 亚洲国产欧美在线一区| 中文字幕久久专区| 亚洲欧洲国产日韩| 久久精品国产99精品国产亚洲性色| 亚洲激情五月婷婷啪啪| av国产久精品久网站免费入址| 免费av观看视频| 国产精品一区二区三区四区久久| 级片在线观看| 日本猛色少妇xxxxx猛交久久| 久久亚洲国产成人精品v| 亚洲国产最新在线播放| 熟女电影av网| 狂野欧美白嫩少妇大欣赏| 亚洲自拍偷在线| 高清毛片免费看| av又黄又爽大尺度在线免费看 | av又黄又爽大尺度在线免费看 | 亚洲国产欧洲综合997久久,| 亚洲人成网站在线观看播放| 搡老妇女老女人老熟妇| 亚洲成人av在线免费| 国产片特级美女逼逼视频| 久久欧美精品欧美久久欧美| 晚上一个人看的免费电影| 国产成人免费观看mmmm| 小蜜桃在线观看免费完整版高清| av视频在线观看入口| 高清午夜精品一区二区三区| 中文字幕精品亚洲无线码一区| av免费观看日本| 乱码一卡2卡4卡精品| 国产一区二区亚洲精品在线观看| 日韩,欧美,国产一区二区三区 | 亚洲精品日韩在线中文字幕| 中文字幕免费在线视频6| 亚洲av.av天堂| 国产激情偷乱视频一区二区| av视频在线观看入口| 日本免费在线观看一区| 麻豆精品久久久久久蜜桃| 国产 一区精品| 免费看av在线观看网站| 精品熟女少妇av免费看| 少妇丰满av| 99久国产av精品| 又粗又爽又猛毛片免费看| 春色校园在线视频观看| av天堂中文字幕网| 欧美成人a在线观看| 天堂网av新在线| 日韩欧美三级三区| 国产免费又黄又爽又色| 欧美一区二区国产精品久久精品| 国产又色又爽无遮挡免| 最近视频中文字幕2019在线8| 欧美+日韩+精品| av在线天堂中文字幕| 麻豆一二三区av精品| 一边亲一边摸免费视频| 国产av一区在线观看免费| 久久婷婷人人爽人人干人人爱| 久久久久久久久久久丰满| 最近最新中文字幕免费大全7| 亚洲三级黄色毛片| 欧美精品国产亚洲| 亚洲三级黄色毛片| 国产国拍精品亚洲av在线观看| 亚洲三级黄色毛片| 舔av片在线| 不卡视频在线观看欧美| 少妇猛男粗大的猛烈进出视频 | 人妻少妇偷人精品九色| 欧美又色又爽又黄视频| 免费在线观看成人毛片| 亚洲精品日韩av片在线观看| 精品久久久久久成人av| 久久久久久伊人网av| 一级爰片在线观看| 亚洲自偷自拍三级| 精品久久久噜噜| 精品久久久久久电影网 | 蜜臀久久99精品久久宅男| 午夜激情福利司机影院| 中文欧美无线码| 欧美另类亚洲清纯唯美| 热99在线观看视频| 天堂影院成人在线观看| 精品午夜福利在线看| 成人综合一区亚洲| 国产av不卡久久| 亚洲丝袜综合中文字幕| 有码 亚洲区| 中国美白少妇内射xxxbb| 超碰av人人做人人爽久久| 人妻制服诱惑在线中文字幕| 美女内射精品一级片tv| 国产午夜福利久久久久久| 国产精品一区www在线观看| 边亲边吃奶的免费视频| 欧美色视频一区免费| 日本免费在线观看一区| 国语对白做爰xxxⅹ性视频网站| 欧美不卡视频在线免费观看| 99九九线精品视频在线观看视频| 大又大粗又爽又黄少妇毛片口| 日韩欧美精品v在线| 蜜桃亚洲精品一区二区三区| 亚洲精品成人久久久久久| 晚上一个人看的免费电影| 日韩中字成人| 麻豆精品久久久久久蜜桃| 日日啪夜夜撸| 色视频www国产| 国产精品无大码| 特大巨黑吊av在线直播| 亚洲美女视频黄频| 国产 一区 欧美 日韩| 欧美精品国产亚洲| 成人午夜精彩视频在线观看| 18禁在线播放成人免费| 日韩,欧美,国产一区二区三区 | 麻豆成人av视频| 日日干狠狠操夜夜爽| 国产精品一区二区在线观看99 | 精品免费久久久久久久清纯| 女人久久www免费人成看片 | 你懂的网址亚洲精品在线观看 | 国产女主播在线喷水免费视频网站 | 欧美性猛交╳xxx乱大交人| 亚洲最大成人中文| 欧美成人a在线观看| 免费观看在线日韩| 久99久视频精品免费| 日本与韩国留学比较| 蜜桃亚洲精品一区二区三区| 草草在线视频免费看| 联通29元200g的流量卡| 色播亚洲综合网| 神马国产精品三级电影在线观看| 丝袜喷水一区| 一区二区三区四区激情视频| 男女啪啪激烈高潮av片| 国产综合懂色| 免费观看性生交大片5| 久久久久久九九精品二区国产| 直男gayav资源| 免费看美女性在线毛片视频| 网址你懂的国产日韩在线| 最近手机中文字幕大全| 成人综合一区亚洲| 国产一区二区在线观看日韩| 国产大屁股一区二区在线视频| 国产精品一区二区三区四区久久| 国产精品电影一区二区三区| 超碰av人人做人人爽久久| 老司机影院毛片| 人妻少妇偷人精品九色| 国产 一区精品| 尤物成人国产欧美一区二区三区| 男女边吃奶边做爰视频| 91精品一卡2卡3卡4卡| 免费大片18禁| 亚洲电影在线观看av| 一本久久精品| 日韩精品青青久久久久久| 高清毛片免费看| 国产国拍精品亚洲av在线观看| 欧美人与善性xxx| 久久午夜福利片| 两个人的视频大全免费| 韩国av在线不卡| 26uuu在线亚洲综合色| 成人美女网站在线观看视频| 91精品伊人久久大香线蕉| 亚洲欧美精品专区久久| 秋霞伦理黄片| 日本一二三区视频观看| 久久精品夜夜夜夜夜久久蜜豆| 色5月婷婷丁香|