【摘要】：石膏晶須又稱硫酸鈣晶須(CSW),是一種成本較低、性價比較高而用途廣泛的新型無機材料,目前在涂料、橡膠、塑料、造紙等領(lǐng)域正獲得越來越多的應(yīng)用。已有人初步嘗試將石膏晶須用于含磷、油或染料等模擬廢水的凈化,顯示出一定效果。但是,石膏晶須在環(huán)境工程領(lǐng)域的研究應(yīng)用還相當(dāng)缺乏,尤其是石膏晶須對污染物的親和性較弱、穩(wěn)定性欠佳等方面都是需要系統(tǒng)解決的技術(shù)問題。研究硫酸鈣晶須的表面改性方法,強化其對常見污染物的去除能力,無疑對拓展石膏晶須在環(huán)境領(lǐng)域的應(yīng)用潛力具有現(xiàn)實意義。常規(guī)的硫酸鈣晶須的制備方法主要有水壓熱法和常壓酸化法兩種,但仍然存在工藝過程較復(fù)雜、生產(chǎn)成本偏高等不足。本論文采用反應(yīng)結(jié)晶法制備硫酸鈣晶須,系統(tǒng)探討了聚合物添加劑P123的濃度、溶液的過飽和度SI、溫度、溶液的pH值、反應(yīng)時間等操作條件對CSW的生長習(xí)性和形貌的影響,結(jié)果表明:實驗條件下,溶液的過飽和度、溫度、反應(yīng)時間是影響晶須形貌的關(guān)鍵因素,適量的P123有助于晶須長徑比的改善,而pH值的影響則不明顯。在30~60℃、過飽和度0.25~0.57、溶液pH=7左右、反應(yīng)時間為4~12h的條件下,可制備出長徑比大且形貌比較均勻的硫酸鈣晶須。反應(yīng)結(jié)晶法具有流程操作簡單、生產(chǎn)成本低、效率較高的優(yōu)點。為改善石膏晶須與重金屬的親和性,本文采用復(fù)合改性劑殼聚糖-己二酸對反應(yīng)結(jié)晶法制備出的硫酸鈣晶須進行表面改性,研究了改性劑用量、改性溫度、改性pH、攪拌速度等操作參數(shù)對改性產(chǎn)物用于實驗室模擬廢水中重金屬汞(Hg2+)的凈化效果的影響,結(jié)果表明:改性溫度、改性pH、攪拌速度均對改性晶須吸附汞的效果有影響,溫度升高、攪拌速度增大,改性晶須吸附汞的效率呈上升趨勢;改性溶液pH值在7.5左右時,改性晶須吸附汞的效率達95%左右;改性劑的用量,即殼聚糖與己二酸的質(zhì)量百分?jǐn)?shù)之比對改性晶須吸附汞的效率影響不明顯。為了解殼聚糖-己二酸改性石膏晶須凈化二價汞的規(guī)律和機理,論文通過間歇吸附試驗研究了改性石膏晶須凈化重金屬汞的過程,探討了吸附時間、pH值、吸附溫度、晶須用量等操作條件對除汞效果的影響,同時考察了晶須對汞的吸附動力學(xué)和吸附等溫線,并結(jié)合掃描電鏡(SEM)、紅外光譜分析以及熱重等分析手段來分析晶須除汞的機理。結(jié)果顯示:pH值是影響石膏晶須吸附汞效果的關(guān)鍵性因素,改性晶須對汞的吸附率隨pH值的增大呈現(xiàn)先增大后不變的趨勢,在pH=7.5時,晶須對二價汞的去除效果大于95%;在pH=7.5時,晶須除汞過程在2~3h左右完成。當(dāng)汞的初始濃度在1000~4000ug/L的范圍內(nèi)時,晶須對汞的吸附與Langmuir吸附等溫線模型保持很好的一致性,吸附動力學(xué)符合準(zhǔn)二級吸附動力學(xué)模型。石膏晶須與汞的作用機理為包覆到晶須表面的殼聚糖中的氨基、羥基與汞發(fā)生螯合作用形成穩(wěn)定的內(nèi)絡(luò)鹽(-N-Hg-O-)而被吸附,這個過程主要是化學(xué)吸附過程。除此之外,還有可能存在石膏晶須與汞之間的物理吸附作用。
[Abstract]:The gypsum crystal whisker, also known as calcium sulfate whisker (CSW), is a new type of inorganic material with low cost, high cost performance and wide application, and is currently getting more and more applications in the fields of coating, rubber, plastics, paper making and so on. A preliminary attempt has been made to purify the gypsum whiskers in simulated wastewater containing phosphor, oil or dye, and show the effect. However, the application of gypsum crystal whisker in the field of environmental engineering is also quite deficient, especially the weak affinity and poor stability of gypsum crystal whisker in environmental engineering. It is of great practical significance to study the surface modification method of calcium sulfate whisker and strengthen its ability to remove common pollutants. The preparation method of the conventional calcium sulfate crystal whisker is mainly composed of a water pressure thermal method and a normal pressure acidification method, but still has the defects of complex process process, high production cost and the like. The effects of operating conditions such as concentration of polymer additive P123, supersaturation SI, temperature, pH value of solution and reaction time on the growth habit and morphology of CSW were discussed. The supersaturation, temperature and reaction time of the solution are the key factors affecting whisker morphology, and a proper amount of P123 contributes to the improvement of whisker aspect ratio, and the effect of pH is not obvious. The calcium sulfate whisker with large aspect ratio and uniform morphology can be prepared under the conditions of 30 ~ 60 鈩，

本文編號：2269343