Adsorption of Ammonium by Graphene Oxide-Based Composites Prepared by UV Irradiation and Using as Slow-Release Fertilizer

A novel sodium alginate-grafted poly(acrylic acid)/graphene oxide (NaAlg-g-PAA/GO) composite hydrogel was prepared via ultraviolet irradiation, and characterized by infrared spectroscopy spectrometer. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. It was employed to adsorb NH₄⁺ from aqueous solution and used as slow-release nitrogen fertilizers (SNFs). Result indicated that the adsorption process for NH₄⁺ reached equilibrium within 50 min, with the adsorption capacity of 6.6 mmol g^?1 even if 30 wt% GO was incorporated. The results of adsorption kinetic and isotherm were well described by the pseudo-second-order and Freundlich model. The thermodynamics analysis showed the adsorption process was spontaneous. The study indicated excellent water-holding ratio of soil with 2 wt% SNFs was 81.2%, and nitrogen release was up to 55.1% within 40 days in soil. Overall, NaAlg-g-PAA/GO could be considered as an efficient adsorbent for the recovery of nitrogen with the agronomic reuse as a fertilizer.     

用黑麦幼苗法测定土壤中污染元素的生物有效性

本文对全国污灌区１２个土样中Ｃｄ形态与生物有效性的试验表明，Ｃｄ的交换态，吸附态，有机结合态均有效，且有机结合态最为有效，对紫阳县富硒土壤的试验表明：黑麦幼苗中的总Ｓｅ量与０．１ｍｏｌ／１ＫＨ２ＰＯ４的浸提量最为相关，从而推荐该法为酸性土壤有效Ｓｅ的浸提方法，对西安污水厂污水污泥在娄土上不同施用量的试验表明：幼苗中Ｎ，Ｐ随施用量增加而增加，Ｎ，Ｐ的有效率分别为５０－７０％及１５－２８％；黑麦幼苗中     

庆大霉素和金霉素废水的处理试验研究

对庆大霉素、金霉素及其混合废水的厌氧、好氧处理进行静态试验。结果表明,对于ＣＯＤ为１９２４０ｍｇ／Ｌ的庆大霉素废水,当厌氧反应时间为３ｄ,好氧１０ｈ时,ＣＯＤ去除率为９８．４％;ＣＯＤ为７７４０ｍｇ／Ｌ的庆大霉素和金霉素混合废水（１：２）,厌氧处理２ｄ,好氧１０ｈ时,ＣＯＤ去除９５．８％;庆大霉素废水厌氧处理３ｄ,金霉素废水厌氧处理６ｈ,再将这２种废水混合进行好氧处理４ｈ,其最终出水ＣＯＤ可小于３００ｍｇ／Ｌ。     

铜(Ⅱ)-过氧化氢-溴甲酚紫-吐温80体系胶束催化动力学光度法测定铜(Ⅱ)

本研究建立了Ｃｕ（Ⅱ）Ｈ２Ｏ２溴甲酚紫Ｔｗｅｅｎ８０体系胶束催化动力学光度法,测定重金属污染物Ｃｕ（Ⅱ）。检出限２．６５×１０１１ｇ／ｍＬ,精密度１．０８％（ｎ＝１０）,线性范围０～４０ｎｇ／２５ｍＬ。选择性好,手续简便,分析速度快,无毒,价廉。可用于环境样品中微量铜的测定。     

大豆膳食纤维改性及其对阳离子染料吸附特性

对大豆膳食纤维进行了羧甲基化改性,并利用红外光谱(FT-IR)和扫描电镜(SEM)对其结构进行了表征.研究了羧甲基化大豆膳食纤维用量、吸附时间、吸附温度、溶液pH值等因素对其吸附亚甲基蓝、结晶紫和品红效果的影响.结果表明,当吸附温度为25℃、羧甲基化大豆膳食纤维浓度为20 mg/L、溶液pH值为6.8和吸附时间为60 min时,羧甲基化大豆膳食纤维对亚甲基蓝、结晶紫和品红的去除率分别达到96.4％、95.6％和94.7％.另外,此吸附过程较好地符合Langmuir和Freundlich等温吸附模型.     

三元络合物在环境监测中的应用

微量污染物的测定是环境临测的重要内容,分光光度法是测定微量污染物广泛应用的主要方法。为了提高分光光度法的灵敏度和选择性,研究新的显色体系是重要的途径。本文以生成三元络合物新体系作为研究的重点,论述了三元络合物的基本概念、类型与组成及其主要特性;阐明三元络合物在环境监测萃取分光光度法、水相分光光度法及胶束增溶分光光度法中应用的优越性。同时,简要介绍了三元络合物在环境监测中广阔的应用前景和研究方向。     

锑(Ⅲ)在合成性δ态-MnO2表面的氧化机理

研究了锑(Ⅲ)在合成性δ态-二氧化锰表面之间发生的氧化反应动力学过程，当pH=5．4时，锑(Ⅲ)的吸附和氧化速率很快．氧化产物锑(Ⅴ)释放速度也很快，但还原产物Mn(Ⅱ)速度较慢．pH对氧化作用影响很大，低pH值和离子强度有利于反应的进行。     

Investigation of adsorption/desorption behavior of Cr(Ⅵ) at the presence of inorganic and organic substance in membrane capacitive deionization(MCDI)

The adsorption and desorption behavior of Cr(Ⅵ) in membrane capacitive deionization(MCDI) was investigated systematically in the presence of bovine serum albumin(BSA) and KCl with different concentrations, respectively. Results revealed that Cr(Ⅵ) absorption was enhanced and the adsorption amount for Cr(Ⅵ) increased from 155.7 to 190.8 mg/g when KCl concentration increased from 100 to 200 mg/L in the adsorption process, which was attributed to the stronger driving force. However, the adsorption amount sharply decreased to 90.2 mg/g when KCl concentration reached up to 1000 mg/L suggesting the negative effect for Cr(Ⅵ) removal that high KCl concentration had. As for the effect of BSA on ion adsorption, the amount for Cr(Ⅵ) significantly declined to 78.3 mg/g and p H was found to be an important factor contributing to this significant reduction. Then, the desorption performance was also conducted and it was obtained that the presence of KCl had negligible effect on Cr(Ⅵ) desorption, while promoted by the addition of BSA. The incomplete desorption was obtained and the residual chromium ions onto the electrode after desorption was detected via energy-dispersive X-ray spectroscopy(EDS). Based on above analysis, the enhanced removal mechanism for Cr(Ⅵ) in MCDI was found to be consisted of ion adsorption onto electrode surface, the redox reaction of Cr(Ⅵ) into Cr(III)and precipitation, which was demonstrated by X-ray photoelectron spectroscopy(XPS) and scanning electron microscope(SEM).     

Effect of Xylanase–Laccase Synergistic Pretreatment on Physical–Mechanical Properties of Environment-Friendly Self-bonded Bamboo Particleboards

Diminishing wood supply and high formaldehyde emission from synthetic adhesive-bonded lignocellulose boards have become concerns. In this research, new adhesive-free boards made from xylanase–laccase-modified bamboo particles were developed. The bamboo particles were pretreated first with xylanase and then with laccase. The synergistic pretreatment was performed according to a Taguchi experiment that included six variables: xylanase treatment (enzyme concentration: 10, 20, 30 U/g; reaction pH: 8, 9, 10; reaction time: 30, 60, 90 min) and laccase treatment (enzyme concentration: 10, 20, 30 U/g; reaction pH: 2, 3, 4; reaction time: 30, 60, 90 min). The particles were hot-pressed to harvest the self-bonded boards, whose physical–mechanical properties were evaluated. The results showed that all six variables (except laccase reaction time) caused significant effects at 0.05 level on physical–mechanical properties of boards. The optimum pretreatment parameters were determined to be xylanase (20 U/g, pH 9, 60 min) and laccase (20 U/g, pH 4, 60 min). The optimized flexural strength, flexural modulus, internal bonding, and 2 h thickness swelling of boards met the highest requirements in Chinese national standard GB/T 4897 (2015) for particleboards. The performance of proposed boards was also better than that of reported self-bonded bamboo particleboards with only a laccase pretreatment.     

Investigation of adsorption/desorption behavior of Cr(VI) at the presence of inorganic and organic substance in membrane capacitive deionization (MCDI)

The adsorption and desorption behavior of Cr(VI) in membrane capacitive deionization (MCDI) was investigated systematically in the presence of bovine serum albumin (BSA) and KCl with different concentrations, respectively. Results revealed that Cr(VI) absorption was enhanced and the adsorption amount for Cr(VI) increased from 155.7 to 190.8?mg/g when KCl concentration increased from 100 to 200?mg/L in the adsorption process, which was attributed to the stronger driving force. However, the adsorption amount sharply decreased to 90.2?mg/g when KCl concentration reached up to 1000?mg/L suggesting the negative effect for Cr(VI) removal that high KCl concentration had. As for the effect of BSA on ion adsorption, the amount for Cr (VI) significantly declined to 78.3?mg/g and pH was found to be an important factor contributing to this significant reduction. Then, the desorption performance was also conducted and it was obtained that the presence of KCl had negligible effect on Cr(VI) desorption, while promoted by the addition of BSA. The incomplete desorption was obtained and the residual chromium ions onto the electrode after desorption was detected via energy-dispersive X-ray spectroscopy (EDS). Based on above analysis, the enhanced removal mechanism for Cr(VI) in MCDI was found to be consisted of ion adsorption onto electrode surface, the redox reaction of Cr(VI) into Cr(III) and precipitation, which was demonstrated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM).