董向元，張恒瑞，陳 祥，李 碩，郭淑青

水熱碳化制備榴蓮殼復(fù)合焦及其電化學(xué)性能

董向元，張恒瑞，陳 祥，李 碩，郭淑青※

（南京工程學(xué)院能源與動力工程學(xué)院，南京 211167）

為研究水熱碳化處理對榴蓮殼復(fù)合改性焦性能的影響，將榴蓮殼原料及250 ℃、10 h制備的水熱焦分別與層狀氫氧化鎂鋁（Mg/Al Layered Double Hydroxide，MgAl-LDH）復(fù)合，獲得榴蓮殼與MgAl-LDH復(fù)合焦MgAl-LDH@DP和榴蓮殼水熱焦與MgAl-LDH復(fù)合焦MgAl-LDH@HC，分析比較兩種焦的特性以及電化學(xué)性能。結(jié)果表明，同MgAl-LDH@DP相比，MgAl-LDH@HC有更強的活性含氧官能團，對LDH納米片有較好的分散性。MgAl-LDH@DP焦表面有大量針狀結(jié)構(gòu)，而MgAl-LDH@HC呈不規(guī)則片狀結(jié)構(gòu)，表面疏松多孔，BET（Brunauer-Emmett-Teller）比表面積為62.96 m2/g，平均孔徑14.81 nm，BJH（Barrett-Joyner-Halenda）累積吸附孔容積為0.24 cm3/g，均高于前者，更有利于電荷儲存和電子傳輸。在KOH溶液為電解質(zhì)、復(fù)合焦為工作電極的三電極系統(tǒng)中，循環(huán)伏安曲線和恒電流充放電曲線分別接近矩形和三角形，同MgAl-LDH@DP相比，MgAl-LDH@HC有較好的電容特性和倍率性能，低頻時交流阻抗曲線斜率更大，離子擴散阻力相對較小，有潛力作為超級電容器電極材料應(yīng)用。

生物炭；水熱焦；電化學(xué)性能；榴蓮殼；層狀雙氫氧化物

0 引 言

水熱碳化處理是利用水在亞臨界時擴散性較強、溶解性較好的特殊性質(zhì)，使生物質(zhì)組分快速發(fā)生脫水、脫羧和芳構(gòu)化等一系列化學(xué)反應(yīng)[1-3]，形成表面富含活性氧基團、具有一定孔隙結(jié)構(gòu)且含碳量較高的水熱焦[4-8]。因其特殊的性質(zhì)，水熱焦在燃燒[9-10]、污水處理[11-12]和儲能[13-14]等領(lǐng)域的應(yīng)用引起了研究者的廣泛關(guān)注。

而水熱焦作為電極材料應(yīng)用時[15-20]，為進一步提高其比表面積，改善其孔隙結(jié)構(gòu)，從而提高其電荷存儲能力，一般采取將水熱焦與KOH等堿性物質(zhì)混合，再經(jīng)高溫煅燒進行活化[19-20]，這在一定程度上增加了工藝復(fù)雜性和制備成本。

層狀雙金屬氫氧化物（Layered Double Hydroxide，LDH）是含有兩種或兩種以上金屬的無機功能材料，也可在較溫和的條件下，用水熱法合成。其具有原料易得、成本低廉、活性位點均勻分散等優(yōu)點，近年來成為了超級電容器電極材料的研究熱點[21-22]。但研究發(fā)現(xiàn)，LDH穩(wěn)定性不理想[22]，急需利用其結(jié)構(gòu)易于調(diào)整，并易于復(fù)合其他材料的特點，進行改性。

將水熱碳化法獲得的水熱焦與LDH復(fù)合，有望利用LDH材料的優(yōu)勢，改善水熱焦的電容特性；利用水熱焦的結(jié)構(gòu)特點，改善LDH的穩(wěn)定性，共同利用水熱法合成的優(yōu)勢，實現(xiàn)電極材料性能的改進。相關(guān)研究已引起了部分研究者的關(guān)注[22-27]。Zhang等[22]將柚子皮水熱焦與CoNiAl-LDH復(fù)合，探索了復(fù)合焦的電容特性，發(fā)現(xiàn)其具有較高的比電容和良好的循環(huán)穩(wěn)定性。Lai等[26]以細菌纖維素水熱焦為模板進行N摻雜后，同NiCo-LDH復(fù)合，制取的復(fù)合焦展現(xiàn)了良好的電化學(xué)性能。可見，將水熱焦與LDH復(fù)合的研究思路是可行的，且復(fù)合焦表現(xiàn)出了作為電極材料優(yōu)良的電容性能。

許多研究者針對不同來源生物質(zhì)水熱碳化做了大量研究，發(fā)現(xiàn)果殼和果皮類廢物水熱焦孔隙相對較好[28-30]，但對于殼占果質(zhì)量約70%的榴蓮殼研究相對較少，作者所在課題組研究了榴蓮殼水熱焦的特性和電化學(xué)性能[31]，并探索了氫氧化鉀催化條件下制備的榴蓮殼水熱焦與LDH復(fù)合焦的特性，但榴蓮殼及其在純水環(huán)境下制備的水熱焦與LDH復(fù)合焦特性的具體研究亟待開展，相關(guān)研究對于理解水熱碳化處理對復(fù)合焦結(jié)構(gòu)調(diào)整和性能影響有重要意義。

基于此，本研究以榴蓮殼為原料，在純水溶劑中，利用水熱碳化法將其制備成水熱焦，再將水熱焦與MgAl-LDH再次利用水熱法進行復(fù)合，獲得復(fù)合焦，為分析水熱碳化處理對復(fù)合焦特性的影響，同時將未處理的榴蓮殼與MgAl-LDH復(fù)合，研究兩種復(fù)合焦的特性和電化學(xué)性能，以期為研究水熱碳化處理對生物質(zhì)水熱焦復(fù)合改性的影響提供參考。

1 材料與方法

1.1 試驗材料和方法

試驗所用物料榴蓮殼采自南京市水果超市，清洗去除浮灰后晾干，破碎至粉末狀，粒徑不超過2 mm，其干基C質(zhì)量分數(shù)為41.22%。試驗中用水均為去離子水，所用化學(xué)試劑均為分析純，訂購于上海阿拉丁試劑有限公司。

榴蓮殼水熱碳化試驗及與層狀雙金屬氫氧化物復(fù)合試驗均在316 L反應(yīng)釜中進行。

榴蓮殼水熱碳化處理具體過程為：將榴蓮殼與去離子水按質(zhì)量比1∶10充分混合，放入釜中，密閉加熱，為使榴蓮殼水熱碳化反應(yīng)充分，結(jié)合前期研究結(jié)果，選擇反應(yīng)溫度為250 ℃，停留時間為10 h，試驗結(jié)束，通入冷卻水，冷卻至室溫和環(huán)境壓力后取出物料，過濾分離干燥，獲得榴蓮殼水熱焦記為HC（Hydrochar）。

榴蓮殼和榴蓮殼水熱焦分別與MgAl-LDH復(fù)合的試驗過程為：取固體Mg(NO3)2·6H2O和Al(NO3)3·9H2O，以Mg∶Al摩爾比為3∶1的比例加入至去離子水中溶解，取適量溶液，向其中以溶液與固體質(zhì)量比10∶1加入HC，攪拌均勻，隨后滴加NaOH與Na2CO3溶液，調(diào)理混合溶液pH值為10～11，將其放入反應(yīng)釜中，為使MgAl-LDH成功復(fù)合，結(jié)合文獻研究[22]，選擇反應(yīng)溫度為180 ℃，時間為10 h，反應(yīng)結(jié)束，冷卻、過濾、干燥獲得MgAl-LDH@HC。為探索水熱碳化處理對復(fù)合焦特性的影響，以未經(jīng)處理的榴蓮殼（Durian shell，DP）與MgAl-LDH復(fù)合作為參照，復(fù)合試驗過程同上，獲得的復(fù)合焦記為MgAl-LDH@DP。

1.2 分析方法

微晶結(jié)構(gòu)采用粉末X射線衍射儀（X-Ray Diffraction，XRD）分析，Cu 靶輻射，間隔為0.02°；微觀形貌和表面官能團分別采用掃描電子顯微鏡（Scanning Electron Microscopy，SEM）和傅里葉變換紅外光譜（Fourier Transform Infrared Spectrometry，F(xiàn)TIR）分析；比表面積采用N2吸附和脫附等溫線進行分析；表面元素組成采用X射線光電子能譜（X-ray Photoelectron Spectroscopy，XPS）進行測試。

為分析復(fù)合焦的電化學(xué)性能，將復(fù)合焦制備成工作電極，具體制備方法參見文獻[15]。在三電極體系下，采用CHI660E電化學(xué)工作站進行測試，具體條件為：以Hg/HgO作為參比電極，鉑片為對電極，自制電極為工作電極，KOH溶液（6 mol/L）為電解質(zhì)，分別進行循環(huán)伏安、恒電流充放電和電化學(xué)阻抗譜測試。

質(zhì)量比電容g依據(jù)恒電流充放電曲線計算，如公式（1）

依據(jù)黃觀音在龍州縣的生長特性，通過多年加工試驗，總結(jié)出制作花香型黃觀音的新型制茶方法：黃觀音秋季鮮葉→輕曬青(地表溫度28 ℃，空氣濕度64%，30 min)→輕搖青(1 min，2次)→室內(nèi)萎凋(空調(diào)控溫)→揉捻(40～60 min)→發(fā)酵(4～5 h，控溫控濕)→理條(針型)→烘干→提香→成品茶。

2 結(jié)果與分析

2.1 復(fù)合焦結(jié)構(gòu)特性

榴蓮殼經(jīng)水熱碳化處理后，其纖維素晶體結(jié)構(gòu)受到破壞，發(fā)生了降解碳化，其干基碳質(zhì)量分數(shù)為70.29%，與MgAl-LDH復(fù)合后獲得MgAl-LDH@HC，主要在衍射角11.23°、22.64°、33.98°和60.11°出現(xiàn)了（003）、（006）、（012）和（110）特征峰（圖1），這歸因于類水滑石LDH的相平面，說明MgAl-LDH成功復(fù)合在榴蓮殼水熱焦表面，層狀雙金屬氫氧化物獨特的類水滑石結(jié)構(gòu)也有利于離子在多層空間的快速擴散。而MgAl-LDH@DP是榴蓮殼原料與MgAl-LDH直接水熱復(fù)合而獲得，在衍射角22.37°和34.39°處可見較強的纖維素晶體結(jié)構(gòu)特征峰，與LDH特征峰同時存在。從XRD譜圖中可以看出，榴蓮殼原料及其水熱焦都成功成為了復(fù)合焦的活性組分，并分散了LDH納米片。

為進一步分析MgAl-LDH在榴蓮殼及其水熱焦上的生長情況，圖2給出了復(fù)合焦的FTIR譜圖。從圖中可以看出，MgAl-LDH@HC和MgAl-LDH@DP在3 429、2 925、1 622 cm-1處均出現(xiàn)了吸收峰，強度略有差異，分別由-OH，-CH，C=O或C=C振動引起，而且在1 383和648 cm-1均出現(xiàn)了硝酸根和Al-O的振動吸收峰。可見，兩種復(fù)合焦均有豐富的含氧官能團，因其帶有負電荷，容易使金屬離子擴散進入榴蓮殼水熱焦HC或榴蓮殼DP中，使得MgAl-LDH原位復(fù)合在HC或DP表面。

兩種復(fù)合焦紅外吸收峰明顯的不同之處在于，MgAl-LDH@DP在1 053 cm-1處存在較強的C-O-C吸收峰，而MgAl-LDH@HC只在1 111 cm-1出現(xiàn)非常弱的吸收峰，這主要是榴蓮殼經(jīng)水熱碳化處理后，半纖維素等糖苷鍵降解斷裂，并發(fā)生了脫氧反應(yīng)所致，但同時榴蓮殼組分也發(fā)生了聚合和芳香化反應(yīng)，HC碳質(zhì)量分數(shù)達70.29%，故1 622 cm-1處聚合物特征峰強，其可增加復(fù)合焦的活性和親水性。

MgAl-LDH與HC復(fù)合時，主要以榴蓮殼水熱焦HC作為碳源和框架，Mg和Al金屬離子分布在HC表面，因此MgAl-LDH@HC復(fù)合焦表面元素以C、O為主，如圖3a，C和O原子百分比分別為74.11%和22.40%，而Mg和Al原子百分比分別為2.42%和1.06%。在結(jié)合能284.80和532.14 eV處可見C 1s和O 1s強峰，而在50.31和74.71 eV處出現(xiàn)Mg 2p和Al 2p弱峰，再次證實Mg和Al金屬離子已成功復(fù)合在水熱焦表面。C 1s和O 1s的掃描譜解析如圖3b和3c，C 1s譜圖在結(jié)合能284.53、285.73、288.18 eV處出現(xiàn)3個特征峰，分別對應(yīng)C=C、C=O化學(xué)鍵，其中C=O在堿性電解液中具有電化學(xué)活性，可提供主要的贗電容；O 1s譜圖在531.08、531.93、532.78 eV處存在3個明顯的峰，分別對應(yīng)Al2O3、-OH和-O-、C=O化學(xué)鍵，其均可增加復(fù)合焦的親水性，為復(fù)合焦的潤濕性及其在電極溶液中的活性提供保證。

為深入分析復(fù)合焦的孔隙結(jié)構(gòu)，圖4給出了兩種復(fù)合焦的N2吸附和脫附等溫曲線?？梢钥闯觯谙鄬毫?0較高時，兩種復(fù)合焦的吸附等溫線接近Ⅳ類型，脫附均有回滯，而MgAl-LDH@DP脫附回滯更加明顯，這主要是兩種復(fù)合焦孔隙結(jié)構(gòu)不同所致。MgAl-LDH@HC復(fù)合焦BET比表面積為62.96 m2/g，BJH累積吸附介孔容積為0.24 cm3/g，HK微孔容積為0.03 cm3/g，平均孔徑為14.81 nm。而MgAl-LDH@DP復(fù)合焦BET比表面積和BJH累積吸附介孔容積分別為38.37 m2/g、0.11 cm3/g，HK微孔容積為0.02 cm3/g，平均孔徑為10.34 nm。可見，兩種復(fù)合焦，介孔容積均較微孔容積高一個數(shù)量級，吸附以大孔和介孔為主，這有利于吸附質(zhì)的傳輸和電荷的擴散與存儲。且MgAl-LDH@HC孔隙更為豐富，其比表面積是MgAl-LDH@DP比表面積的1.64倍，介孔容積和平均孔徑均較大。這主要是因為榴蓮殼經(jīng)水熱碳化處理后，可溶性物質(zhì)進入液相產(chǎn)物，并有少量CO2等氣相產(chǎn)物生成[2]，使得固體產(chǎn)物水熱焦形成了一定程度的孔隙結(jié)構(gòu)，其與層狀結(jié)構(gòu)的MgAl-LDH復(fù)合，促進了核殼多孔結(jié)構(gòu)的生長，復(fù)合焦孔隙得到了更好地發(fā)展，為吸附質(zhì)和電荷傳輸提供了更寬的通道。

MgAl-LDH@HC和MgAl-LDH@DP微觀形貌明顯不同，如圖5。圖5a顯示MgAl-LDH超薄的納米片以片狀堆疊的形式負載到HC焦表面，使得復(fù)合焦具有不規(guī)則片狀結(jié)構(gòu)，表面疏松多孔，有利于暴露電活性位點，可促進MgAl-LDH和OH-間氧化還原反應(yīng)，通過榴蓮殼水熱焦加速超薄納米片間的電子傳輸速率。而圖5b顯示MgAl-LDH@DP焦表面有大量針狀結(jié)構(gòu)，孔隙不如MgAl-LDH@HC豐富，所以比表面積較低，這與氮氣吸脫附等溫線分析結(jié)果相對應(yīng)。

2.2 復(fù)合焦電化學(xué)特性

為研究復(fù)合焦在超級電容器中的應(yīng)用，并確切了解復(fù)合焦的電容性能，依據(jù)參考文獻[15]和[22]，選擇了有參比電極的三電極系統(tǒng)，電解質(zhì)選擇為6 mol/L KOH。

在1 A/g的電流密度下，兩種復(fù)合焦的恒電流充放電曲線均接近三角形（圖6c），但在0.2～0.3 V存在過渡區(qū)域，這與循環(huán)伏安曲線中凸起的位置相一致，均是由雜原子所致。同MgAl-LDH@DP相比，MgAl-LDH@HC有較好的庫倫效率。文獻[22]在1～10 A/g電流密度下，研究了柚子皮水熱焦與層狀金屬氫氧化物復(fù)合焦的恒電流充放電特性。課題組擴大電流密度測試范圍，在1、5、10、20 A/g電流密度下，探索了榴蓮殼水熱焦的恒電流充放電規(guī)律[31]，發(fā)現(xiàn)榴蓮殼水熱焦均具有較好的倍率性能。為簡化測試且不影響分析結(jié)果，本研究選取1、5、20 A/g的電流密度，研究MgAl-LDH@HC復(fù)合焦的倍率性能，從圖6d中可以看出，當電流密度從1增至20 A/g時，MgAl-LDH@HC的恒電流充放電時間逐漸減小，這主要是，低的電流密度有利于MgAl-LDH@HC促進電解質(zhì)與其活性位點接觸，氧化還原反應(yīng)充分且反應(yīng)速率較高，同時MgAl-LDH@HC孔隙相對發(fā)達，為電子傳輸提供了保障，電子導(dǎo)電性較好。電流密度為1A/g時，MgAl-LDH@HC質(zhì)量比電容為1 250 F/g，當電流密度增加至20A/g時，仍有約56.32%的電容保持率，說明MgAl-LDH納米片在榴蓮殼水熱焦HC上分布較為均勻，有利于OH-離子的滲入。

兩種復(fù)合焦的電化學(xué)阻抗譜如圖6e，高頻時，兩種復(fù)合焦的電荷轉(zhuǎn)移電阻和等效串聯(lián)電阻相差不大，曲線基本重合；但在低頻時，同MgAl-LDH@DP相比，MgAl-LDH@HC阻抗譜斜率稍陡，說明榴蓮殼經(jīng)水熱碳化處理后，制得的復(fù)合焦擴散阻力較小，有利于離子擴散，電性能較好。

綜合比較分析，水熱碳化處理后制得的水熱焦經(jīng)改性后有良好的電容性能，更有潛力作為超級電容器電極材料。

3 結(jié) 論

1）將榴蓮殼原料及其經(jīng)250 ℃、10 h制備的水熱焦分別與MgAl-LDH復(fù)合，獲得復(fù)合焦MgAl-LDH@DP與MgAl-LDH@HC，兩者相比，MgAl-LDH@HC有更強的活性和親水性，且對LDH納米片有較好的分散性。

2）同MgAl-LDH@DP相比，MgAl-LDH@HC呈不規(guī)則片狀結(jié)構(gòu)，表面疏松多孔，BET比表面積為62.96 m2/g，BJH累積吸附孔容積為0.24 cm3/g，平均孔徑14.81 nm，均高于前者，更有利于電荷儲存和電子傳輸。

3）在KOH溶液為電解質(zhì)、復(fù)合焦為工作電極的三電極系統(tǒng)中，循環(huán)伏安曲線接近矩形，恒電流充放電曲線接近三角形。同MgAl-LDH@DP相比，MgAl-LDH@HC有較好的電容特性和倍率性能；在低頻時，交流阻抗曲線斜率更大，離子擴散阻力相對較小，有潛力作為超級電容器電極材料。

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Durian shell composite biochar prepared by hydrothermal carbonization and its electrochemical properties

Dong Xiangyuan, Zhang Hengrui, Chen Xiang, Li Shuo, Guo Shuqing※

(,,211167,)

Hydrothermal Carbonization (HTC) can widely be used to convert the dry/wet biomass (green and renewable materials) directly into the hydrochar with a rich oxygenated functional group (a high value-added carbonaceous material). There is a promising potential application of hydrochar in energy storage in recent years. Nevertheless, a relatively low capacitance of hydrochar has limited to serve as electrode materials. Recently, Layered Double Hydroxide (LDH) has also been considered as one of the most promising electrode materials, due to the high energy density, dispersed active sites, and cheap raw materials. However, the LDH extension has been confined to a relatively weak electrical conductivity and mechanical stability. Therefore, combing the LDH and hydrochar may be a promising trade-off to develop high-efficient electrode materials. Herein, the hydrochar (HC) was prepared through HTC using durian shell (DP) at 250℃ and 10h. Then magnesium aluminum Layer Double Hydroxides (MgAl-LDH) were decorated on the surface of HC, in order to obtain the MgAl-LDH@HC composite. MgAl-LDH was also decorated on the surface of DP raw materials to explore the effect of HTC process on the performance of the composite. The microstructure of MgAl-LDH@DP and MgAl-LDH@HC were characterized using X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and scanning electron microscopy (SEM). An electrochemical test was also carried out for the properties of the composite. The results show that the cellulose crystal structure of the durian shell was destroyed after HTC treatment, where the carbon content of HC was 70.29%. The XRD pattern of MgAl-LDH@HC presented the sharp peaks at 11.23°, 22.64°, 33.98°, and 60.11° of 2, being assigned to the (003), (006), (012), and (110) planes, respectively, indicating a typical hydrotalcite-like structure. The XRD spectra also illustrated that the MgAl-LDH was successfully decorated on the surface of HC. In MgAl-LDH@DP, there were strong peaks of cellulose crystallinity structure at 22.37° and 34.39°, in spite of the characteristic peaks of LDH in the XRD spectra. There were much stronger active oxygenated functional groups, while much higher dispersion for the LDH nanosheets in the MgAl-LDH@HC, compared with the MgAl-LDH@DP. In MgAl-LDH@HC, a strong polymer characteristic peak at 1622 cm-1contributed to the activity and hydrophilicity of the composite as electrode materials. The XPS spectra of MgAl-LDH@HC presented the strong C 1s, O 1s peaks at 284.80 and 532.14 eV, while the weak Mg 2p, Al 2p peaks at 50.31 and 74.71 eV, respectively. In the C 1s spectra, three peaks centered at 284.53, 285.73, and 288.18 eV corresponding to the C=C, C=O chemical bonding. In the O 1s spectra, three peaks centered at 531.08, 531.93, and 532.78 eV identifying as Al2O3,-OH and -O-, C=O, respectively. These functional groups significantly increased the hydrophilicity, wettability and activity of composite in the electrode solution. SEM images showed that the MgAl-LDH@DP contained a lot of needle-like structures, whereas, the MgAl-LDH@HC presented irregular lamellar structures with porous surfaces. In MgAl-LDH@HC electrochemical test, the Brunauer-Emmett-Teller (BET) surface area was 62.96m2/g, the average pore diameter was 14.81 nm, and the Barrett-Joyner-Halenda (BJH) cumulative pore volume was 0.24 cm3/g, indicating higher properties than those of MgAl-LDH@DP. It inferred that the structure of MgAl-LDH@HC was more conducive to charge storage and electron transmission. Three electrode systems were constructed, with the composite as working electrode and the KOH solution as electrolyte. They were close to rectangle and triangle in the cyclic voltammetry and galvanostatic charge-discharge curve. Higher capacitive property and rate performance were achieved in the MgAl-LDH@HC, compared with the MgAl-LDH@DP. The slope of impedance curve was much larger for the MgAl-LDH@HC at the low frequency, indicating a relatively smaller ion diffusion resistance. Therefore, the MgAl-LDH@HC can be expected to serve as potential electrode materials for supercapacitors.

biochar; hydrochar; electrochemical properties; durian shell; layered double hydroxide

董向元，張恒瑞，陳祥，等. 水熱碳化制備榴蓮殼復(fù)合焦及其電化學(xué)性能[J]. 農(nóng)業(yè)工程學(xué)報，2021，37(8)：316-322.doi：10.11975/j.issn.1002-6819.2021.08.036 http://www.tcsae.org

Dong Xiangyuan, Zhang Hengrui, Chen Xiang, et al. Durian shell composite biochar prepared by hydrothermal carbonization and its electrochemical properties[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2021, 37(8): 316-322. (in Chinese with English abstract) doi：10.11975/j.issn.1002-6819.2021.08.036 http://www.tcsae.org

2021-01-08

2021-04-07

國家自然科學(xué)基金項目（51206194）；南京工程學(xué)院引進人才科研啟動基金（YKJ201811和YKJ201812）

董向元，博士，副教授，研究方向：生物質(zhì)水熱轉(zhuǎn)化及有效利用。Email：dongxiangyuan@163.com

郭淑青，博士，教授，研究方向：生物質(zhì)熱化學(xué)轉(zhuǎn)化及有效利用。Email：shuqing.guo@163.com

10.11975/j.issn.1002-6819.2021.08.036

TK6

A

1002-6819(2021)-08-0316-07