Efficiency of Coated Urea on Nutrient Uptake and Maize Production

A field experiment was conducted to study the effects of coated urea with urease inhibitor [copper (Cu) and zinc (Zn)], nitrification inhibitor (DMPP), biochar and geopolymer on ammonium, nitrate, Cu, Zn content and crop yield of maize. The treatments were composed of urea alone (control), urea coated Cu and Zn (UCuZn), urea coated with Cu, Zn, and DMPP (UCuZnDMPP), urea impregnated with biochar (Ubio) and urea coated with geopolymer (Ug2). Data showed that treatments with Cu, Zn, and DMPP produced lower ammonium (NH₄) and nitrate (NO₃) in UCuZn and UCuZnDMPP while they had the highest concentration of Cu and Zn in soil and plant tissues. Plots treated with UCuZn and UCuZnDMPP produced maximum N concentrations in grains and yield, with increases by 79.5% and 74.1%, respectively, as compared with urea (control). This finding demonstrates that by slow down the hydrolysis and nitrification process using urease and nitrification inhibitor were beneficial to increased N uptake, ultimately produced higher yield.     

秸秆土聚物保温建筑材料工艺及界面结构分析

为研究开发强度高、耐腐蚀性好的保温建筑材料,以节省建筑能源消耗,拓宽秸秆工业化利用途径,该文将秸秆掺入到土壤聚合物中制备秸秆土聚物,以抗压强度为指标,优选秸秆土聚物的较优工艺,并测定了秸秆土聚物的导热系数,确定其保温性能。用X射线衍射、傅立叶红外光谱以及扫描电镜对秸秆土聚物复合材料的晶相成分、化学键合和微观结构进行了分析。结果表明秸秆土聚物较优工艺配方如下:反应体系中Si O2与Al2O3摩尔比为3.9,Na2O与Si O2摩尔比为0.30,秸秆掺量4%,长度1 mm,水灰比0.10,制备得到的试块置于(20±2)℃、相对湿度为70%±2%的环境中养护,其7 d抗压强度可达54.58 MPa,导热系数为0.0681 W/(m·K)。X射线衍射、傅立叶红外光谱以及扫描电镜分析表明秸秆土壤聚合物为Si,O,Al组成的半晶态,无定形层状结构,与纯土聚物红外特征峰相同,无新化学键生成。秸秆土聚物界面处出现间隙和裂纹,裂纹遇秸秆后转向,产生二次裂纹,形成弱结合界面。初步判断秸秆与土聚物之间没有发生化学结合。研究结果为秸秆的工业资源化利用开辟了一条新途径,也为绿色保温建筑材料的研究提供依据。     

粉煤灰基地聚合物修补材料的组成设计与性能

以粉煤灰、矿粉两种工业废料为主要原材料,模数为1.2~1.8的水玻璃作为激发剂制备地聚合物。采用五因素四水平的正交试验组成设计方案,测试了水胶比(W)、碱激发剂掺量(S)、矿粉取代率(B)和水玻璃模数(M)在不同水平下试样的流动度、凝结时间、抗压强度和拉伸粘结强度。通过对结果进行极差分析和因素指标分析,得出这种绿色环保型修补材料的组成设计与性能指标之间的关联。综合分析得出,当水胶比为0.28,碱激发剂掺量为0.14,矿粉取代率为0.4,水玻璃模数为1.2时,制备出的地聚合物性能良好,达到绿色环保型建筑修补材料的要求。     

碱激发对砒砂岩地聚物水泥复合土强度及微观结构的影响机理

为防治水土流失,提高以砒砂岩为基础原料水泥土的力学性能,实现大量松散砒砂岩在实际工程的有效利用,通过无侧限抗压强度试验和压汞、X衍射物相分析、扫描电镜、傅里叶变换红外光谱等方法,探究碱激发对砒砂岩地聚物水泥复合土强度及微观结构的影响机理。结果表明:N-A-S-H(水化硅铝酸钠)凝胶含量是影响复合土强度的主要因素,其含量受碱激发温度及碱当量的影响。碱当量的增大及碱激发温度的提高,可促使砒砂岩中的蒙脱石、石英以及偏高岭土发生溶蚀,促进N-A-S-H凝胶的产生,但当温度超过80℃后会促进N-A-S-H凝胶向钾A型沸石晶体转化。碱当量增加使得强度增长速率先增加后减缓,在碱激发温度为80℃、碱当量为2%时,砒砂岩地聚物水泥复合土配比达到最优,此时复合土中生成N-A-S-H凝胶产物最多,10 nm孔径占比最大(11.67%),孔隙率最低(23.47%),强度最高(8.23 MPa)。该研究可为砒砂岩地聚物水泥复合土在实际工程中的应用提供理论依据。     

Experimental Analysis High calcium Fly Ash Geopolymers Solidification/Stablization of Heavy Metals

Utilization of high calcium fly ash geopolymer to solidify/stabilize heavy metals was explored. The solidification/stabilization effectiveness of heavy metals was studied using static and dynamic leaching experiments. Additionally, transferring mechanism and long term safety of heavy metals in geopolymer were also investigated. The results show that the leaching concentrations of heavy metals from the solidified/stabilized matrix were far lower than the limit values, and all the solidified/stabilized ratios of heavy metals reached 98% when the geopolymer solidified/stabilized 0.025% Pb(II), 0.025% Cr(VI), and 0.01% Hg(II), respectively. The results Dynamic leaching experiment show that real time leaching concentrations of heavy metals were lower than allowable maximum values, and the accumulated leaching concentrations became stable after 72 h. After dynamic leaching experiment, the radial distributions of heavy metals in geopolymer specimens were similar. Effective diffusion coefficient and dynamic leaching ratios of heavy metals from geopolymer were very low, and this geopolymer has a good long term safety.