【摘要】：砷及其化合物是一類具有高毒害作用的物質,對環(huán)境的危害極大,給人類的生存發(fā)展造成了嚴重的威脅。隨著高砷產業(yè)(采礦、冶金、化工)的迅速發(fā)展,砷污染的治理已成為全球的研究熱點�，F(xiàn)行的許多方法存在著除砷效果差,砷浸出高,長期穩(wěn)定性不高等弊端,砷的處置急需一種行之有效的方法。由于As0_4~(3-)與PO_4~(3-)性質相近,所以可以形成較為穩(wěn)定的砷酸鹽固溶體,利用無機砷化物的難溶性除砷將是最具潛力的一種方法。本論文通過水熱反應制備了砷羥基磷灰石及改性的砷硅羥基磷灰石,并對影響合成的主要因素進行了討論,制定出最佳合成方案。通過毒性浸出實驗,定期測定砷的浸出濃度,對固溶體的穩(wěn)定性進行了研究。研究結果如下：1、實驗采用水熱法,以Ca(NO_3)_2·4H_2O、(NH_4)_2HPO_4、Na_3AsO_4·12H_2O以及Si(OCH_2CH_3)_4為原料,成功制備出不同砷含量的砷羥基磷灰石(As-HA)和改性的砷硅羥基磷灰石(As-Si-HA),并通過研究,得到最佳反應條件：水熱反應溫度為200℃,水熱反應時間為8h,最適宜硅摻量為鈣硅摩爾比為10：1(y=1),[Ca_(10)(PO_4)_(6-x-y)(AsO_4)_x(SiO4)_y(OH)_(2-y)]。2、通過XRD、SEM、EDS、FTIR等測試手段對As-HA的晶相、化學組成和形貌等進行分析,結果表明：合成的As-HA為不規(guī)則塊狀晶體,As-HA與HA具有相似的晶體結構,砷的摻入未引入其他雜質相,As以AsO_4~(3-)的形式進入到HA晶格中,取代部分PO_4~(3-),最大砷含量為27.720%。3、通過XRD、SEM、EDS、FTIR等測試手段對As-Si-HA的晶相、化學組成和形貌等進行分析,結果表明：合成的As-Si-HA為不規(guī)則塊狀晶體,As-Si-HA與HA具有相似的晶體結構,砷和硅的摻入未引入其他雜質相,As以As0_4~(3-)的形式進入到HA晶格中,取代部分PO_4~(3-), Si以SiO_4~(4-)的形式取代部分PO_4~(3-),并造成OH-的缺失,使結晶度下降。當y=1時,最大砷含量為19.928%。4、砷的浸出濃度受pH值影響很大,在酸性溶液中砷的浸出濃度最高,在中性溶液中砷的浸出濃度最低,證明固溶體在中性環(huán)境中更為穩(wěn)定。5、通過比較As-HA和As-Si-HA在溶液中的砷的浸出濃度,得出As-Si-HA的砷浸出濃度更低,證明As-Si-HA比As-HA具有更穩(wěn)定的結構。6、砷酸鹽固溶體的砷浸出率整體較低,證明制備的固溶體具有較穩(wěn)定的晶體結構,砷能以有效鍵合的方式嵌入到羥基磷灰石晶格中。7、通過XRD、SEM、EDS、FTIR等測試手段對溶解后的樣品的晶相、化學組成和形貌等進行分析,結果表明,溶解前后固溶體的結構未發(fā)生改變。
[Abstract]:Arsenic and its compounds are a class of highly toxic substances, which have great harm to the environment and pose a serious threat to the survival and development of human beings. With the rapid development of high arsenic industry (mining, metallurgy and chemical industry), the treatment of arsenic pollution has become a global research hotspot. Many existing methods have some disadvantages such as poor arsenic removal, high arsenic leaching, low long-term stability, etc. An effective method is urgently needed to dispose arsenic. Because the properties of As0_4~ (3-) and PO_4~ (3-) are similar, a relatively stable arsenate solid solution can be formed. The insoluble removal of arsenic by inorganic arsenide will be the most promising method. In this paper, arsenic-hydroxyapatite and modified arsenic-silico-hydroxyapatite were prepared by hydrothermal reaction. The main factors affecting the synthesis were discussed and the optimum synthesis scheme was worked out. The stability of solid solution was studied by determining the leaching concentration of arsenic by toxicity leaching experiment. The results are as follows: 1. Using Ca (NO_3) _ 24H _ 2O, (NH_4) _ 2HPO _ 4H _ 2O, (NH_4) _ 2HPO _ 4N _ 3AsO _ 4 12H_2O and Si (OCH_2CH_3) _ 4 as raw materials, different arsenic hydroxyapatite (As-HA) and modified arsenic-silico-hydroxyapatite (As-Si-HA) were successfully prepared by hydrothermal method. The optimum reaction conditions were obtained as follows: hydrothermal reaction temperature was 200 鈩，

本文編號：2291645