黏土矿物不同腐殖质组分团聚体对苯酚的封存特征

为探讨不同腐殖质组分团聚体对苯酚封存能力的影响,应用国际腐殖酸协会推荐的方法提取腐殖质,以Ca²⁺、Al³⁺、Fe³⁺为桥键离子,制备了高岭石、蒙脱石不同腐殖质组分团聚体,并采用平衡吸附/解吸试验、应用饱和吸附量与最大解吸量差减法研究了不同腐殖质组分团聚体对苯酚的封存特征.结果表明,团聚体对苯酚的吸附等温线可用Freundlich吸附/解吸方程（R²=0.991~0.998）和Langmuir吸附/解吸方程（R²=0.993~0.999）描述.高岭石不同腐殖质组分团聚体对苯酚的封存量（Q_m^irr）排序为：富里酸团聚体（（133.71±6.14）mg·kg^-1） > 胡敏酸团聚体（（49.59±8.93）mg·kg^-1） > 胡敏素团聚体（（21.68±2.95）mg·kg^-1）;封存系数（SR）排序为：富里酸团聚体（0.53±0.04） > 胡敏酸团聚体（0.27±0.05） > 胡敏素团聚体（0.18±0.03）;蒙脱石不同腐殖质组分团聚体对苯酚的封存量（Q_m^irr）排序为：富里酸团聚体（（319.44±8.95）mg·kg^-1） > 胡敏酸团聚体（（92.96±22.10）mg·kg^-1） > 胡敏素团聚体（（36.22±6.36）mg·kg^-1）;封存系数（SR）排序为：富里酸团聚体（0.76±0.02） > 胡敏酸团聚体（0.32±0.09） > 胡敏素团聚体（0.23±0.05）.考查腐殖质团聚体对苯酚的封存能力时不但要考虑腐殖质的含量,更要考虑腐殖质的赋存形态,它也是影响团聚体对苯酚封存能力的重要因素.富里酸、胡敏酸和胡敏素与黏土矿物结合形成有机矿质复合体后,对苯酚的封存能力发生了显著改变,团聚体对苯酚的封存系数与团聚体有机碳含量和内表面积呈显著正相关（p<0.01）,团聚体对苯酚的吸附/解吸分配系数（k/k_d）与团聚体有机碳含量和内表面积呈显著正相关（p<0.01）,土壤/沉积物团聚体的有机碳含量和内表面积是影响对苯酚封存特征的重要因素.研究显示,不同腐殖质组分团聚体对苯酚的封存能力排序为：富里酸团聚体 > 胡敏酸团聚体 > 胡敏素团聚体.     

高岭土铝活化法制备改性粘土及其除藻机制

以焙烧高岭土为原料,通过酸-碱组合活化、原料复配、控温熟化等连续处理步骤活化高岭土中的铝制备改性粘土(MC)。采用正交试验设计对该方法进行优化,考察了制备条件对获得改性粘土除藻效果的影响规律,探讨了不同制备条件下获得改性粘土除藻效率差异的机制。结果表明,酸-碱组合活化pH值对改性粘土的除藻效率具有显著影响(P<0.05),控制碱中和后的pH£3.6获得改性粘土的除藻效率可达90%以上。通过分析改性粘土的理化特征及絮凝除藻时的絮凝体特征发现,在最佳制备条件下,高岭土矿晶中铝大量被活化,合成改性粘土的片层致密且卷曲、微表面粗糙,分散到海水中时活化单体铝(Al_a)、多羟基铝(Al_b)含量更高,粘土表面电性由负转为正,絮凝卷扫藻细胞的作用增强,因而合成改性粘土具有更高消除赤潮生物的能力。     

Release behavior and bioefficacy of imazethapyr formulations based on biopolymeric hydrogels

Controlled release formulations of imazethapyr herbicide have been developed employing guar gum-g-cl-polyacrylate/bentonite clay hydrogel composite (GG-HG) and guar gum-g-cl-PNIPAm nano hydrogel (GG-NHG) as carriers, to assess the suitability of biopolymeric hydrogels as controlled herbicide release devices. The kinetics of imazethapyr release from the developed formulations was studied in water and it revealed that the developed formulations of imazethapyr behaved as slow release formulations as compared to commercial formulation. The calculated diffusion exponent (n) values showed that Fickian diffusion was the predominant mechanism of imazethapyr release from the developed formulations. Time for release of half of the loaded imazethapyr (t_1/2) ranged between 0.06 and 4.8 days in case of GG-NHG and 4.4 and 12.6 days for the GG-HG formulations. Weed control index (WCI) of GG-HG and GG-NHG formulations was similar to that of the commercial formulation and the herbicidal effect was observed for relatively longer period. Guar gum-based biopolymeric hydrogels in both macro and nano particle size range can serve as potential carriers in developing slow release herbicide formulations.     

Application of magnesite–bentonite clay composite as an alternative technology for removal of arsenic from industrial effluents

This study evaluated the feasibility of integrating amorphous magnesite and bentonite clay (composite) as an alternative technology for removing arsenic from industrial effluents. The removal of arsenic from industrial effluents by using magnesite–bentonite clay composite was carried out in batch mode. The effects of equilibration time, adsorbent dosage, adsorbate concentration, and pH on removal of arsenic were investigated. The experiments demonstrated that ≈100% arsenic removal is optimum at 30 minutes of agitation, 2 g of adsorbent dosage (2 g: 100 mL, S/L ratio), and 20 mg L^?1 of arsenic concentration. The adsorption data fitted well to both Langmuir and Freundlich adsorption models, hence proving monolayer and multilayer adsorption. The kinetic studies revealed that the data fitted better to a pseudo-second-order reaction than to a pseudo-first-order reaction, hence proving chemisorption. At optimized conditions, the composite was able to remove arsenic to below World Health Organization water quality guidelines, hence depicting that the composite is effective and efficient in removing arsenic from contaminated water. Based on that, this comparative study proves that the composite is a promising adsorbent with high adsorption capacity for arsenic and can be a suitable substitute for the conventional treatment methods.     

Mn-Ce/Ti-PILC催化剂低温脱硝性能研究

以钛基柱撑黏土(Ti-PILC)为载体,采用浸渍法制备了Mn-Ce/Ti-PILC催化剂,并考察了其脱硝性能。在n(Ti)∶m(黏土)为15 mmol/g、焙烧温度为400 ℃、Mn-Ce负载量(w)为12%和6%、空速为120 000 h^-1的条件下,Mn-Ce/Ti-PILC在宽温度窗口180~260 ℃的NO转化率可达90%以上,N₂选择性可达80%以上;220 ℃时NO转化率接近100%,N₂选择性达86%左右。柠檬酸和Mo的掺杂可进一步提高Mn-Ce/Ti-PILC的脱硝性能。Ti-PILC载体结构有助于活性组分分散,且Ti与Mn-Ce之间可形成强相互作用。Ce的加入可降低催化剂酸性位点强度。     

Erosion control at construction sites on red clay soils

Five single-treatment methods used to stabilize seeded areas at urban and highway construction sites (asphalt-tacked straw, jute netting, mulch blanket, wood chips, excelsior blanket) were tested for their ability to control erosion of red clay soils by comparisons with exposed sites and multiple treatments. Sediment in runoff from experimental plots was characterized during low and high intensity precipitation from natural rainfall episodes during April, May, and June. Reductions in the total sediment concentration of runoff ranged from 28 percent (asphalt-tacked straw, 50 percent slope) to 90 percent (multiple treatments, 40 percent slope), with 85 percent of the eroded material composed of particles <0.04 mm in diameter. Larger size fractions were effectively reduced by all treatments tested regardless of slope (70 percent decrease). Established grass cover exceeded 90 percent on all plots after 60 days, but sediment release remained similar, attributable to high intensity rainfall, poor establishment of root systems, and piping on plots treated with tacked straw or jute netting. Results indicate that current stabilization methods shift sediment compostion toward a smaller particle size, causing single treatments to be minimally effective for controlling erosion of the major component of red clay soils. Because small particles have the greatest direct effect on aquatic biota, certain impacts of sedimentation may not be measurably lessened by single treatments in regions where red clays predominate even though the total sediment load is reduced by as much as 75 percent. Clearly, a multiple-treatment approach offers significantly greater control of erosion on red clay soils, however, current economic and construction policy represents a substantial deterrent to implementation.     

长江三角洲顶部冰后期地层的沉积特征

钻探证实,镇江市谏壁镇长江北岸高桥镇北部埋藏硬粘土层,之上为冰后期松散沉积物.沉积物主要为粉砂、粘土质粉砂、砂泥互层,中部局部夹含细砾中细砂,顶部见淤泥质粘土;夹数十层植物炭屑层;以水平纹理为主,局部见小型交错层理、波状层理.表明冰后期以来该地处于水动力较弱的河湖环境,为多期湖沼相沉积夹汊道河流相沉积,局部有海相沉积物加入.根据碳化植物碎屑14C年龄,推测冰后期底界年龄约13 000 aBP,海侵到达该地的时间约为9 000 aBP,海侵最高位时间约为6 500 aBP.冰后期平均沉积速率约为4.9 m/ka,湖沼相3.4～6 m/ka,河流相10～15 m/ka.对全新统的底界年龄和海相层的埋藏深度进行了讨论.     

2种不同模块化填料组合的多级土壤渗滤系统的比较

以滇池入湖河流污水为对象,研究了2种不同模块化填料组合的多级土壤渗滤系统在不同运行条件下的处理效果差异.结果表明,各系统都具有较好的COD去除效果,平均去除率均在50％以上.沸石陶结系统无论曝气与否,均具有高NH⁺₄-N去除能力,出水浓度<1 mg/L.陶粒红壤MSL系统在8∶1的气水比下,具有良好的氨氮去除能力,平均去除率为84%;在非曝气条件下氨氮去除能力相对低一些,在40%以下.非曝气沸石陶结系统TN去除效果最好,平均去除率在68％以上,最高达到98％.其他3个系统在不同工况下TN去除效果差别较大.4个系统TP平均去除率在30％～90％之间,不同工况下去除效果不同.高污染负荷下,沸石陶结系统（M1、M2）的磷去除能力较强,稳定状态下平均去除率均在80％以上.通过分析系统沿程氮转化效率,探讨了各系统的氮去除机制.     

润滑油废白土的应用探索

针对炼油企业废白土排放污染环境问题,在实验室中利用溶剂进行脱油处理,其脱油率及脱油废渣活性度都较高,但再生后的脱油废渣仍难以重复利用。而利用废白土作型砂添加剂的试验研究,其工业试验结果较为理想,且能彻底解决废渣的污染问题,实现其环保利用。