Desorption of Coffee Pulp Used as an Adsorbent Material for Cr(III and VI) Ions in Synthetic Wastewater: A Preliminary Study

Some of the diverse agro-industrial waste generated in primary or secondary stages have proved to be promising biomaterials for treating aqueous effluents contaminated, in this case, with heavy metals. Therefore, it is necessary to know their optimal operating conditions and the regeneration or reusability of the solid by-product, an aspect related to desorption. Considering the above, this article presents the findings of a preliminary study related to the desorption process of coffee pulp without physicochemical modification (Castilla variety), an agricultural waste used as a sorbent of Cr(III and VI) ions in synthetic wastewater. The desorption efficiency of four eluting agents at defined concentrations (0.10M)—HC1, HNO₃, H₂SO₄, and EDTA—was evaluated in a time interval of 1 to 9 days. Likewise, the proposals for the sorption and/or desorption mechanisms proposed and reported in the literature with respect to the use of biosorbents derived from the coffee crop are presented. With respect to the results, the coffee pulp used in previous studies of the adsorption of chromium species mentioned (optimal conditions in synthetic water of particle size 180 μm, dose 20 g·L⁻¹, agitation 100 RPM, room temperature, time of 90 to 105 min) showed efficiencies in the removal of Cr(III) and Cr(VI) of 93.26% and 74.80%, respectively. Regarding the extracting substances used, H₂SO₄ 0.10 M was the one that presented the highest desorption percentage in both chromic species, with a desorption of 45.75% Cr(VI) and 66.84% Cr(III) in periods of 5 and 9 days, respectively, with agitation of 100 RPM and room temperature. Finally, the dissemination of preliminary results on the desorption of coffee pulp contaminated with chromic species without physicochemical modification is novel in this study, as similar work with this specific material has not yet been reported in the literature. On the other hand, the limitations of the study and future research are related to the evaluation at different concentrations and of other extractor solutions that allow improving the efficiency of desorption of these chemical species in a shorter time from the coffee pulp (with and without modification) as well as the reuse cycles. As a result, the desorption of coffee pulp used as an adsorbent material in real water could help researchers identify the possible interfering factors that affect the process (foreign anions and cations, organic matter, environmental conditions, among others).     

纸浆卡伯值的在线测量数学模型

从Kubelka-Munk基本方程和纸浆中残留木素的光谱特性出发推导出纸浆漫反射理论模型,进而根据纸浆残余木素与纸浆卡伯值的本质关系推导出在线实时测量纸浆卡伯值的理论模型.根据纸浆中残留木素的光谱吸收特性,选择F390,F560和F840为自变量,建立了"三波长"纸浆卡伯值光谱测量简化模型.该模型结构简单,物理意义清晰,能够揭示模型自变量与卡伯值之间的线性关系.由于从机理模型变为简化模型经过了多次线性近似和简化,造成了纸浆卡伯值与反射光谱间的非线性信息缺失.为此,结合纸浆卡伯值光谱测量简化模型和自适应神经模糊推理系统(ANFIS),建立了纸浆卡伯值在线光谱测量的融合模型,经过样本训练后,融合模型预测结果稳定,精度高.     

低纤维素酶活木聚糖酶对麦草浆的辅助漂白作用

利用低纤维素酶活木聚糖酶对麦草浆进行预处理,研究木聚糖酶在氯、碱、次氯酸盐(CEH)三段漂白中对氯气用量的减少以及对漂白过程中纸浆木质纤维组分变化的影响。结果表明:经过木聚糖酶预处理,在保证纸浆漂后白度的同时,氯气用量可以减少50%;木聚糖酶预处理对纸浆中的木素有脱除作用,且能促进木素在碱抽提过程中的溶出,但木聚糖酶对戊聚糖和纤维素也有不同程度的降解作用;酶处理浆漂后的木素和半纤维素的含量略低于未经处理的对照浆,纤维素含量则略高于对照浆。     

隔膜电解法处理草浆黑液

进行了隔膜电解法处理草浆黑液的可行性实验研究．隔膜电解法实验采用铸铁作牺牲阳极,石墨作阴极,多孔性的滤过式隔膜将阳极区与阴极区分开;阳极及其附近有铁的氧化与水解反应,碱木素的取代反应;阴极有析氢反应;水分子和钠离子在势场力作用下透过隔膜从阳极区进入阴极区,碱木素分子被隔离在阳极区;阳极区不断加入黑液,取走木素沉淀,阴极区不断取走回收碱液,从而实现碱液与木素的分离．在电流为1A、电压为8V及室温条件下电解12h,阳极区黑液的色度、悬浮物及COD的去除率分别为66.4%,75.3%和94%,碱回收率达到94%以上．实验结果表明,作为一种处理黑液的碱回收技术,隔膜电解法处理草浆黑液比较容易直接嫁接到制浆工艺中,有可能成为解决草浆碱回收技术的新途径．     

耐热木聚糖酶助漂针叶木硫酸盐浆的研究

探讨了嗜热真菌耐热木聚糖酶助漂针叶木硫酸盐浆的应用前景.着重研究了应用耐热木聚糖酶进行生物助漂的酶用量、酶处理的pH值以及漂白用氯量等影响因素.结果表明,在不影响纸浆的各项性能的情况下,经酶处理的纸浆白度相比对照增加1.06%~5.11%ISO.同时,酶处理纸浆漂白时可减少漂白用氯量.另外,在偏碱性条件下进行酶处理对纸浆漂白效果的影响较为显著.纸浆纤维的扫描电镜结果显示,酶未对纤维造成损伤,而是改善了纸浆纤维的可漂性.该耐热木聚糖酶非常适宜应用于酶助漂.     

微波辅助制备甜菜渣活性炭

为了使甜菜渣得到更加充分有效的利用,本文探究了以甜菜渣为原料、氯化锌为活化剂、微波辅助制备甜菜渣活性炭的可行性。本文研究了甜菜渣和氯化锌溶液的比例(料液比)、氯化锌浓度、微波功率和辐照时间对活性炭吸附性能和产率的影响,并用氮气等温吸附、红外光谱和扫描电镜分析了最优制备条件下活性炭的比表面积、表面官能团和微观孔结构,得出其制备的最佳工艺条件为:料液比1∶6,氯化锌浓度30%,微波功率700 W和微波时间10 min。相应的活性炭的碘吸附量为1127.57 mg/g,亚甲基蓝吸附量为217.7 mg/g,产率为25.9%,BET比表面积为927.36 m2/g,总孔容为0.39 cm3/g,且表面具有含氧官能团和较好的孔结构。实验结果证实,以甜菜渣为原料、氯化锌为活化剂的微波辅助制备甜菜渣活性炭是可行的,为开发甜菜渣的高附加值产品提供了理论依据。     

蒸煮过程中纸浆卡伯值NIR法在线测量的研究

提出了蒸煮过程中纸浆卡伯值的近红外光谱（ＮＩＲ）在线测量法。通过研究,发现黑液在近红外波段８００～９００范围内的吸收主要是由黑液中木素产生的,并发现在此波段范围内,蒸煮过程中的纸浆卡伯值与对应的黑液的吸光度具有较好的线性关系。     

短周期湿地松纸浆材林的优化经营调控研究

研究确定了短周期湿地松纸浆材林的最适立地条件为16指数级以上,最佳主伐年龄为10～12 a,最适经营密度模型为n=23 360.6/d.以荻取最大树干生物量为经营调控目标,采用动态规划法进行短周期湿地松纸浆材林的优化经营调控,并依据调控结果编制了模式林分的生长过程表和优化经营调控表,以期为湿地松纸浆材林的经营管理提供科学的参考依据.     

竹浆造纸污泥蚯蚓生物处理的培养条件与重金属富集

竹浆造纸污泥产生量大,处置成本高,利用蚯蚓处理造纸污泥是一种低成本的生物处理方法,利用蚯蚓对重金属的富集作用,还可以达到无害化的处理效果。本试验采用正交设计,研究湿度、接种密度、污泥厚度和处理时间对蚯蚓生长的影响。结果表明:造纸污泥蚯蚓生物处理的最佳培养参数为湿度85%,蚯蚓接种密度10条,污泥厚度6 cm,处理天数60天,其中,污泥的湿度对蚯蚓的日增重倍数影响较大;蚯蚓能有效降低污泥中重金属Cd、Pb、Zn的含量,对Cu、Mn的影响效应不明显,处理后的造纸污泥重金属符合农用标准,可作为撑绿竹等造纸原料的有机肥源,实现造纸污泥的资源化。     

Triclosan removal by adsorption using activated carbon derived from waste biomass: Isotherms and kinetic studies

Triclosan is an antimicrobial agent that is normally used in many personal care products such as toothpastes, shampoos, deodorants, and cosmetics and is toxic to some aquatic organisms, amphibians, and the male reproductive system. In this study, activated carbon from coconut pulp waste (Cocos nuciefera) is used to remove triclosan from aqueous solutions. Activated carbon was prepared using coconut pulp waste treated with zinc chloride and burned in a horizontal furnace with nitrogen flow at 300°C for 1 hr. The parameters studied were the contact time, adsorbent dosage, agitation, initial triclosan concentration, pH, and temperature. The characterization of the adsorbent was done by field‐emission scanning electron microscopy and Fourier transform infrared spectroscopy. The activated carbon reaches equilibrium in 20 min with a percentage removal of 80.77% and adsorbent capacity (q_e) of 2.02 mg/g. From the kinetic study, it was concluded that the adsorbent followed a pseudo‐second‐order type reaction with a correlation coefficient (R²) of .999, and q_e = 2.036 mg/g. From the isotherm study, the adsorbent was found to follow the Langmuir isotherm with a higher R² value of .9249 compared to the Freundlich and Temkin isotherms. This study proved that activated carbon derived from coconut pulp waste can be a promising low‐cost adsorbent to remove dissolved triclosan from water.