研究論文( Articles)科技導(dǎo)報(bào)2011,29(14)導(dǎo)報(bào)不同熱解溫度生物炭改良鉛和鎘污染土壤的研究丁文川,朱慶祥,曾曉嵐,吳丹,田秀美重慶大學(xué)城市建設(shè)與環(huán)境工程學(xué)院;三峽庫(kù)區(qū)生態(tài)環(huán)境教育部重點(diǎn)實(shí)驗(yàn)室,重慶40045摘要為了探究熱解溫度對(duì)生物炭修復(fù)重金屬污染土壤的影響將300500c和700℃下制備的生物炭加入鉛(Pb)和鎘Cd污染土壤進(jìn)行培養(yǎng),檢測(cè)重金屬形態(tài)的變化。結(jié)果表明加入生物炭培養(yǎng)60d后,Pb和Cd污染土壤pH值較對(duì)照上升0350.86單位值,土壤中重金屬的酸可提取態(tài)含量下降殘?jiān)鼞B(tài)含量上升,對(duì)目標(biāo)重金屬生物有效性降低的改良效果7000>5000×30C在生物炭添加量相同的情況下,復(fù)合污染土壤中Pb的殘?jiān)鼞B(tài)含量比對(duì)應(yīng)單一污染高5060%-7279%,而復(fù)合污染土壤中Cd的酸可提取態(tài)含量較對(duì)應(yīng)單一污染高753%-129%;熱解溫度影響生物炭的表面特征和吸附重金屬機(jī)制,進(jìn)而影響生物炭改良士壤中目標(biāo)重金屬形態(tài)分布。關(guān)詞生物炭;熱解;鉿;鎘;污染土壤修復(fù)中圖分類號(hào)X53文獻(xiàn)標(biāo)識(shí)碼Ado10.381/n.100-78572011.14002Biochars From Different Pyrolytic Temperature Amending Lead andCadmium Contaminated SoilDING Wenchuan, ZHU Qingxiang, ZENG Xiaolan, wU Dan, TIAN XiumeiCollege of Urban Construction and Enrironmental Engineering Three Gorges Reservoir Area's Ecology and Enrironment KeyLaboratory of Ministry of Education, Chongg ing Unirersity, Chongying 400045, ChinaAbstract Biochar from biomass pyrolysis haw'reeeived much attention recently due to its strong affinity for organic pollutants and heavymetals. Previous stuies have revealed potential applications of biochar in the contaminated soil remediation. However, the knowledge ofpyrolysis temperature effects on biochar as a soil amendment remains lacking. In this paper, three biochars produced at 300C, 500C and700 were added into lead (Pb) and Cadmium (Cd) contained soil. variations of these two metals were analyzed before and after 60 daysincubation.The results show that soil pH value is increased by 0.35--0.86 units after biochars addition and incubation. Acid extractablform contents of Ph and Cd are reduced, whereas the residual form contents are increased. The reducing bio-availability of target heavymetals by different biochar amendments is in the following order. 700 C>500C>300T. With the same amount of biochar addition, Phresidual form contents in the combined polluted soil are inereased by 50.60%-72.79% from the single polluted soil, and Cd acidxtractable form contents in the combined polluted soil are increased by 7.53%-12.99% from the single polluted soil. Pyrolytictemperature affeets characteristics of biochar surface strueture and mechanism of heavy metal sorption on biochar, and then affects thestates of lead and Cadmium in soilsKeywords biochar: pyrolysis: Lead: Cadmium; contaminated soil remediation施加改良劑是修復(fù)重金屬污染土壤的一種較經(jīng)濟(jì)的原效,因?yàn)橐磺彝寥纏H值降低會(huì)導(dǎo)致重金屬重新釋放。磷酸鹽位處理方法。常用的改良劑包括石灰叫、磷酸鹽和工業(yè)廢物改良劑的投加量常需達(dá)到土壤中正常磷含量的20倍以上才(爐熔渣高爐礦渣粉川等。石灰對(duì)長(zhǎng)期固定重金屬井非有能生成磷氯鉛礦(難溶化合物),但土壤中磷過量可能引起周中國(guó)煤化工收稿日期:2011-02-14;修國(guó)日期:2011-04-26CNMHG作者簡(jiǎn)介:丁文川,教授,研完方向?yàn)榄h(huán)境生物技術(shù)、污染場(chǎng)地修復(fù);電子信箱; dingIn科技導(dǎo)報(bào)2011,29(14)研究論文( Article導(dǎo)報(bào)圍水體富營(yíng)養(yǎng)化。工業(yè)副產(chǎn)品本身常含有重金屬及其他化離子水給土壤補(bǔ)充水分,保持在田間持水量的70%左右,室合物施加后會(huì)對(duì)土壤造成進(jìn)一步的污染。生物炭具有很大溫下培養(yǎng)60后取樣分析。的比表面積、孔隙率和離子交換能力,可以吸附有機(jī)污染物14分析測(cè)試和重金屬。 Chimica等發(fā)現(xiàn)添加生物炭引起的土壤pH值主要分析土壤中重金屬的酸可提取態(tài)、Fe-Mn氧化結(jié)合升高可以提高CdF和N的固定效果。王漢衛(wèi)等添加5%改態(tài)、有機(jī)結(jié)合態(tài)和殘?jiān)鼞B(tài)等4種形態(tài)含量變化。土壤中PhCd性納米生物炭(碳黑)使土壤有效態(tài)Cu含量降低了809%,有總量用HC-HNO-HF-HCO2消煮法提取:土壤中PCd形效態(tài)zn含量降低了436%。生物質(zhì)在不同熱解溫度范圍發(fā)生態(tài)分級(jí)采用歐洲共同體標(biāo)準(zhǔn)物質(zhì)局提出的BCR法,酸可提取不同的熱化學(xué)過程形成的生物炭理化性質(zhì)存在差異,然而態(tài)用0lmL的醋酸提取FeMm氧化結(jié)合態(tài)用05mL的這些差異對(duì)生物炭改良重金屬污染土壤的影響目前報(bào)道不鹽酸羥胺(2 nol/L HNO酸化,pH值為15)提取,有機(jī)結(jié)合態(tài)多。本文將不同熱解溫度制備的生物炭用于Pb、Cd單一污染在30%的雙氧水水溶消化后用1mo的醋酸銨(濃HNO3酸和復(fù)合污染土壤改良,研究添加生物炭后對(duì)土壤中兩種重金化,pH值為20)提取,殘?jiān)鼞B(tài)采用差減法計(jì)算屬形態(tài)變化的影響。土壤消煮過濾后濾紙與濾渣放入馬弗爐550℃氧化2h,灰燼用 HNO-HCIO4提取并測(cè)定P和Cd在濾渣中的含量。1材料與方法兩種重金屬濃度均采用原子吸收分光光度計(jì)(TAS-990,1.1供試土壤北京普析通用儀器有限責(zé)任公司)測(cè)定。土壤pH值測(cè)定使用供試土壤取自重慶某處農(nóng)田其基本理化性質(zhì)見表1。酸度計(jì)(PHS23,上海法蘭朵科技發(fā)展有限公司),水土比(W/W)為25:1。生物炭比表面積和孔徑使用全自動(dòng)比表面積表1供試土壤理化性質(zhì)Table 1 Prmary properties of the tested soil及微孔分析儀(ASAP2020,美國(guó)麥克儀器公司)測(cè)定。一有機(jī)質(zhì)A土壤陽(yáng)離子2結(jié)果與討論交換量(CEC)/(g·kg)/(gkg"/(mg.kg")/(mg.kg")21生物炭對(duì)土壤pH值的影響添加生物炭后,重金屬污染土壤pH值均較對(duì)照升高(圖59x0032149103281484121.2添加P30030和P20的土壤p值在D單一污染中較對(duì)照分別升高了0.35059和07,在Cd單一污染中分別1.2生物炭制備升高了0360.55和086,且添加熱解溫度越高的生物炭,士壤將松木條(10m×1mx1m)置室溫下白然風(fēng)干,疊放入樣品p值也越高。由于土壤pH值升高會(huì)影響PhCd的水解托盤后置于馬弗爐內(nèi)缺氧炭化設(shè)定終溫為3005000℃,平衡使PCd通過絡(luò)合沉淀等作用被固定下來(lái),因此,達(dá)到終溫后繼續(xù)炭化2,待馬弗爐溫度降至室溫后取出黑色熱解溫度的升高可以提高生物炭對(duì)重金屬的修復(fù)效果殘?jiān)?磨碎,過20目篩得到3種生物炭,對(duì)應(yīng)標(biāo)記為P-300P-500、P-700。生物炭表面結(jié)構(gòu)特征見表2。口Pb污染C染表2生物炭的表面結(jié)構(gòu)特征Table 2 Characteristics of surface structure of biocharT比BET微孔表外表生物炭表面積面積面積總孔容平均孔(m2g)/(m2g4)/m2g4)(cm·g2)徑A8P-300320.610.00037397P-500379052923386.720.19120.10P-700453.19354.0999.100.25222.27700℃圖1生物炭對(duì)污染土壤pH值的影響13處理方法Fig. 1 Effect of biochar application on pH value in實(shí)驗(yàn)土壤風(fēng)干粉碎過20日篩,加入 PbCI CuCI2進(jìn)行污染處理,其中Pb、Cd的施加量分別為350、1mgkg,形成Pb或Cd單一污染以及P、Cd復(fù)合污染3種土壤。污染土壤穩(wěn)定、22生物炭對(duì)Pb、Cd單一污染土壤金屬形態(tài)的影響平衡2周后裝盆,每盆lkg,然后將3種生物炭按5%(W/W)的投加量加入盆中,充分混勻。設(shè)置未添加生物炭的污染土Pb的壤為對(duì)照(CK),共12個(gè)處理,每處理3個(gè)重復(fù)。每隔1d用去提H中國(guó)煤化工染士中重金屬餐604后,Pb的酸可CNMHG含量較對(duì)照分別下研究論文( Articles科技導(dǎo)報(bào)2011,29(14)導(dǎo)報(bào)降2283%-53.84%、3.90%—29.12%和2.2%-17.45%,殘?jiān)衔铩B(tài)含量則較對(duì)照上升1596%—40.10%。添加P-700后對(duì)土壤23生物炭對(duì)Pb和cd復(fù)合污染土壤金屬形態(tài)的影響中Pb的殘?jiān)鼞B(tài)(較對(duì)照上升40.10%)和酸可提取態(tài)(較對(duì)照由圖3可見,添加生物炭對(duì)Pb和Cd復(fù)合污染土壤金屬下降53.84%)影響最大,這說(shuō)明添加生物炭后土壤中Pb的生形態(tài)影響與兩種金屬單一污染趨勢(shì)一致,即酸可提取態(tài)、Fe物有效性大大降低。按此比較不同生物炭對(duì)P污染土壤的Mn氧化結(jié)合態(tài)和有機(jī)結(jié)合態(tài)含量較對(duì)照下降,而殘?jiān)鼞B(tài)含改良效果順序?yàn)?P-700>P-500P-300,表明高溫?zé)峤庵苽涞牧枯^對(duì)照上升。但是,當(dāng)存在復(fù)合污染時(shí),加入生物炭后土壤生物炭對(duì)Pb的修復(fù)效果更好。中Pb的Fe-Mn氧化結(jié)合態(tài)含量明顯低于對(duì)應(yīng)的在單一污染酸可提取態(tài)口FeMn氧化結(jié)合態(tài)口有機(jī)結(jié)合態(tài)1土壤中的含量,而有機(jī)結(jié)合態(tài)和殘?jiān)鼞B(tài)含量較單一污染的上升,酸可提取態(tài)含量變化不大,顯示Cd的存在提高了生物炭對(duì)Pb的穩(wěn)定性。與Pb的變化不同,在復(fù)合污染土壤中加入生物炭后Cd的多數(shù)形態(tài)含量與對(duì)應(yīng)在單一污染土壤中Cd的形態(tài)含量差別不大,但酸可提取態(tài)含量增加753%1299%,意味著P的存在增加了土壤中Cd的溶解性,從而提高Cd的生物活性300℃5℃口酸可提取態(tài)口FeMn氧化結(jié)合態(tài)口有機(jī)結(jié)合態(tài)口殘?jiān)鼞B(tài)口總量誓10300℃700℃處理圖2生物炭對(duì)單一污染土壤重金屬形態(tài)的影響Fig2 Effect of biochar application on the states of heavy 5metal in single target metal contaminated soil三制如己生物炭對(duì)Cd污染土壤的改良作用與Pb相類似。培養(yǎng)60d后,殘?jiān)鼞B(tài)含量較對(duì)照上升幅度達(dá)147.06%-26471%500℃700℃而酸可提取態(tài)、Fe-Mn氧化結(jié)合態(tài)和有機(jī)結(jié)合態(tài)含量較對(duì)照下降幅度分別為1765%-58.82%、9.86%—28.17%和1220%圖3生物炭對(duì)復(fù)合污染土壤重金屬形態(tài)的影響1545%。P-700生物炭對(duì)Cd污染土壤中殘?jiān)鼞B(tài)和酸可提取F1g3 Effect of biochar application on the states of heavy態(tài)影響較P更為顯著,同對(duì)照相比,殘?jiān)鼞B(tài)含量增加達(dá)到metal in two target metals contaminated soil26471%,而酸可提取態(tài)含量下降達(dá)58.82%,表明提高熱解溫由于Pb和Cd同為帶正電荷的離子,存在對(duì)生物炭吸附度更有利于生物炭降低污染土壤Cd的生物有效性點(diǎn)位的競(jìng)爭(zhēng)。但生物炭對(duì)Ph的吸附速率和吸附親和力均值得注意的是,添加P-300P-500和P-700后,土壤中大于Cd,在兩種金屬共存的體系中Pb被更快更多地吸附,優(yōu)總Pb和總Cd含量比對(duì)照均有減少。經(jīng)測(cè)定發(fā)現(xiàn),土壤消煮先占據(jù)活性點(diǎn)位,影響了生物炭對(duì)Cd的反應(yīng),導(dǎo)致Cd的酸濾渣中總P含量為8.67-5367mg/kg,總Cd含量為0.13-可提取態(tài)含量降低。0.53mgkg,表明濾渣中仍然存在被固著的重金屬,這部分重?zé)o論是復(fù)合污染還是單一污染,熱解溫度越高的生物炭金屬未被消解進(jìn)入溶液,且可能主要為殘?jiān)鼞B(tài)。因?yàn)樵谒嵝詫?duì)兩種重金屬穩(wěn)定效果也越好。低溫?zé)峤獾纳锾?P-300提取環(huán)境下,Fe-Mn氧化結(jié)合態(tài)和有機(jī)結(jié)合態(tài)能轉(zhuǎn)化為酸可比表面積和孔隙率很小,表面極性官能團(tuán)較多,吸附動(dòng)力主提取態(tài)進(jìn)入溶液。熱解溫度越高形成的生物炭,過濾殘?jiān)幸潜砻鏄O性官能團(tuán)與金屬離子之間產(chǎn)生的靜電引力;隨未被消解的總Pb和總Cd量越多。推測(cè)認(rèn)為,一方面提高熱著熱解溫度的升高,生物炭的C含量增加,0、H含量和CH解溫度,制備的生物炭表面微孔更多,且平均孔徑變小,一些均降低重金屬進(jìn)入微孔內(nèi)部難以被溶出;另一方面,高溫炭化生成積和孑H中國(guó)煤化工程度加深,比表面逆吸附量增大更多的無(wú)機(jī)鹽可能與P和Cd進(jìn)一步形成更加穩(wěn)定難溶的P500CNMHG子擴(kuò)散控制。由此科技導(dǎo)報(bào)2011,29(14研究論文( Articles)導(dǎo)報(bào)可見熱解溫度影響了生物炭化學(xué)組成結(jié)構(gòu),引起土壤性質(zhì)Wang Hanwei, Wang Yujun, Chen Jiehua, et d. China Enrirorumenun改變(如pH值),另外對(duì)重金屬的吸附機(jī)理也有差異,從而對(duì)sience.2009,294431-436生物炭修復(fù)土壤效果產(chǎn)生顯著的影響。[9] Uchimiya M, Lima I M. Klasson K T, el ad. Immobilization of heavy metalions(Cu, Cd, Ni, and Pb) by broiler litter-derived biochar in waterand soil J) Journa of Agriculture and Food Chemistry, 2010, 58(9)3結(jié)論5538-5544生物炭的加入可提高土壤p值,改變重金屬各形態(tài)的 OI Nguyen B T.hnmn. Black carbon decomposition under varying分布,降低酸可提取態(tài)含量,從而鈍化土壤重金屬,降低其生water regimes. Orgie Geochemistry. 2009. 408): 846-853[I1] Tsakou A. Roulia M. Christodoulakis N S. 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