High-Efficiency Removal of Lead and Nickel Using Four Inert Dry Biomasses: Insights into the Adsorption Mechanisms.

In this study, inert dry bioadsorbents prepared from corn cob residues (CCR), cocoa husk (CH), plantain peels (PP), and cassava peels (CP) were used as adsorbents of heavy metal ions (Pb2+ and Ni2+) in single-batch adsorption experiments from synthetic aqueous solutions. The physicochemical properties of the bioadsorbents and the adsorption mechanisms were evaluated using different experimental techniques. The results showed that electrostatic attraction, cation exchange, and surface complexation were the main mechanisms involved in the adsorption of metals onto the evaluated bioadsorbents. The percentage removal of Pb2+ and Ni2+ increased with higher adsorbent dosage, with Pb2+ exhibiting greater biosorption capacity than Ni2+. The bioadsorbents showed promising potential for adsorbing Pb2+ with monolayer adsorption capacities of 699.267, 568.794, 101.535, and 116.820 mg/g when using PP, CCR, CH, and CP, respectively. For Ni2+, Langmuir's parameter had values of 10.402, 26.984, 18.883, and 21.615, respectively, for PP, CCR, CH, and CP. Kinetics data fitted by the pseudo-second-order model revealed that the adsorption rate follows this order: CH > CP > CCR > PP for Pb2+, and CH > CCR > PP > CP for Ni2+. The adsorption mechanism was found to be controlled by ion exchange and precipitation. These findings suggest that the dry raw biomasses of corn cob residues, cocoa husk, cassava, and plantain peels can effectively remove lead and nickel, but further research is needed to explore their application in industrial-scale and continuous systems.

Dynamic Removal of Nickel (II) on Elaeis guineensis Waste Bed: Study of the Breakage Curve and Simulation.

This research focused on the use of residual fiber from oil palm (Elaeis guineensis) for Ni (II) adsorption in a packed bed column. An analysis was conducted on the effect and statistical incidence of changes in temperature, adsorbent particle size, and bed height on the adsorption process. The results showed that particle size and bed height significantly affect the adsorption of Ni (II) ions, reaching adsorption efficiencies between 87.24 and 99.86%. A maximum adsorption capacity of 13.48 mg/g was obtained in the bed with a break time of 180 min. The Ni (II) adsorption in the dynamic system was evaluated by the analysis of the breakage curve with different theoretical models: Yoon-Nelson, dose-response, and Adams-Bohart; the dose-response model was the most appropriate to describe the behavior of the packed bed with an R2 of 84.56%. The breakthrough curve obtained from Aspen Adsorption® appropriately describes the experimental data with an R2 of 0.999. These results indicate that the evaluated bioadsorbent can be recommended for the elimination of Ni (II) in aqueous solutions in a dynamic system, and the simulation of the process can be a tool for the scalability of the process.

Adsorption Study of Continuous Heavy Metal Ions (Pb2+, Cd2+, Ni2+) Removal Using Cocoa (Theobroma cacao L.) Pod Husks.

The serious toxicological effects of heavy metal ions in aquatic ecosystems have motivated the search for alternatives to reduce contamination of water sources from industrial wastewater. In this work, continuous adsorption of nickel, cadmium, and lead was assessed using a packed bed column filled with Cocoa (Theobroma cacao L.) pod husks widely available in the northern region of Colombia. The physicochemical characterization of the agricultural biomass was performed to quantify its chemical composition by bromatological, FT-IR, and energy-dispersive X-ray spectroscopy (EDS). The breakthrough curves were constructed for all heavy metal ions with bed depth of 4 and 7.5 cm, taking aliquots at 10, 30, 60, 90, 120, 150, 180, 210, 240, and 270 min. Moreover, experimental data were fitted to adsorption models in continuous mode to predict adsorptive performance (Adams−Bohart, Thomas, and Yoon−Nelson). For the FT-IR analysis of biomass before and after adsorption, the most representative bands occur around 3200−3900 cm−1 attributed to the presence of hydroxyl groups, showing the destruction of the peaks of lignocellulosic materials. The breakthrough curves revealed that for a 7.5 cm bed, adsorption performance reported the following order of promising results: Pb2+ > Ni2+ > Cd2+; while for a 4 cm bed, Pb2+ > Ni2+. The mechanism of adsorption of the evaluated metals onto cocoa pod husk was attributed to cationic exchange and microprecipitation due to the presence of Ca, K, and Si in the structure of the bio-adsorbent. Finally, the continuous adsorption was modeled under the mathematical expressions of Adams−Bohart, Thomas, and Yoon−Nelson reporting good fitting with correlation coefficient above 0.95.

Cement-Based Solidification/Stabilization as a Pathway for Encapsulating Palm Oil Residual Biomass Post Heavy Metal Adsorption.

Heavy metal pollution is a serious issue currently affecting the environment and public health, which has been faced by applying several alternatives such as adsorption. In this work, the adsorption technique was employed to remove nickel and lead ions from an aqueous solution using palm oil residual biomass as a biosorbent. Desorption experiments were also conducted to evaluate the desorption capacity of this biomass over sorption-desorption cycles. The polluted biomass was used to prepare bricks (5 and 10% biomass content) to encapsulate heavy metal ions into the cement matrix. Both mechanical resistance and leaching testing were performed to determine the suitability of these bricks for construction applications. The experimental results revealed a good biosorbent dosage of 0.1 g/L. The highest desorption yields were calculated in 11 and 83.13% for nickel and lead, respectively. The compression resistance when 10% biomass was incorporated into the bricks was reported to be below the acceptable limit. Leaching testing suggested a successful immobilization of heavy metal ions onto the cement matrix. These results indicate that the application of this immobilization technique allows solving disposal problems of biomass loaded with heavy metal ions.

OPTIMIZACIÓN DE PARÁMETROS PARA LA CONSTRUCCIÓN DE LA CURVA DE RUPTURA EN LA ADSORCIÓN DE Cr(VI) SOBRE CÁSCARA DE CACAO / PARAMETER OPTIMIZATION FOR Cr(VI) ADSORPTION BREAKDOWN CURVES ONTO COCOA SHELL

RESUMEN El objetivo de la presente investigación fue evaluar la cáscara de la mazorca cacao (Theobroma cacao L.) para su uso en la adsorción de cromo hexavalente en solución acuosa, usando columna de lecho empacado, aplicando el método de superficie de respuesta (MSR), con el fin de determinar los valores óptimos de las variables incidentes en el proceso y, posteriormente, con estos valores, realizar los ensayos de adsorción. Se utilizó un diseño de experimentos compuesto central con puntos estrellas. La biomasa, se lavó, se secó, se disminuyó tamaño y se tamizó; los experimentos, se llevaron a cabo a 25°C, a diferentes tamaños de partícula, de caudal y de cantidad de biomasa, en columnas en sistema en continuo, obteniéndose un porcentaje de remoción de 39,16%, de Cr(VI). Al realizar los experimentos en sistema por lotes, se obtuvo que a tamaño de partícula 0,355mm, se favorece la adsorción. De los ensayos de adsorción en columna, utilizando los parámetros óptimos arrojados obtenidos por el MSR, se obtuvo un porcentaje de remoción de 62,65%, encontrando que los modelos de Yoon-Nelson y Thomas fueron los que ajustaron los datos experimentales de la curva de ruptura, con R2= 0,98. Se concluye que la cáscara de cacao es un buen precursor de bioadsorbentes y que las variables más influyentes en la adsorción de Cr(VI) en sistema por lotes y continuo son el tamaño de partícula y la altura del lecho.

SUMMARY The aim of the present investigation was to evaluate the cocoa shell (Theobroma cacao L.) for its use in the adsorption of hexavalent chromium in aqueous solution using packed bed column, applying the surface response method (SRM) in order to determine the optimum values of the variables involved in the process. The adsorption tests were carried out with these values. Was used a central composite experiment design with star points. The biomass was washed, dried, decreased size and sieved; the experiments were carried out at 25°C, at different particle sizes, flow rate and amount of biomass, in columns in continuous system; obtaining a percentage of removal of 39.16% of C (VI). Was obtained when performing the experiments in batch system that at a size of 0.355mm particle favors the adsorption. From the adsorption tests in the column using the optimum parameters obtained by the MSR, was obtained a removal percentage of 62.65%; finding that the models of Yoon-Nelson and Thomas were those that adjusted the experimental data of the rupture curve, with R2 =0.98. It's concluded that the cocoa shell is a good precursor of bioadsorbents and that the most influential variables in Cr (VI) adsorption in batch and continuous systems are particle size and bed height.

ADSORCIÓN DE NI (II) POR CÁSCARAS DE ÑAME (Dioscorea rotundata) Y BAGAZO DE PALMA (Elaeis guineensis) PRETRATADAS / ADSORPTION OF NI (II) BY PRETREATED YAM PEELS (Dioscorea rotundata) AND OIL PALM PULP (Elaeis guineensis)

El níquel es un metal pesado altamente contaminante que por sus efectos toxicológicos es materia de gran preocupación, por lo que toma importancia la búsqueda de alternativas para su remoción, siendo la adsorción una alternativa aplicable para la remoción metálica, interesante por su eficiencia y bajo costo. Se propone así la adsorción de Ni (II) usando dos materiales de desecho altamente disponibles en la región Caribe colombiana: cáscaras de ñame y bagazo de palma, ambas biomasas tratadas con ácido cítrico. Los experimentos fueron llevados a cabo en sistema batch en solución acuosa de níquel a una concentración de 100 ppm. La concentración residual de la solución fue medida mediante espectroscopia de absorción atómica, encontrando que el proceso de adsorción es altamente dependiente del pH, con un valor óptimo de 6. Por otra parte, se encontró que el Ni (II) presenta una sorción rápida los primeros 50 minutos, además el modelo de Elovich fue el de mejor ajuste. La capacidad máxima de adsorción según la isoterma de Langmuir fue de 68,14; 47,93; 103,3 y 58,7 mg/g para las cáscaras de ñame y el bagazo de palma sin modificar, y modificados químicamente respectivamente, mostrando el valor potencial del uso de estos biomateriales en la remoción de Ni (II) presente en soluciones acuosas.

Nickel is a highly polluting heavy metal which, because of its toxicological effects, is a matter of great concern and the reason why the search for alternatives for its removal, being adsoption an applicative alternative for metal removal which is considered interesting due to its efficiency and low cost. In this way, the Ni (II) adsoption is proposed using two highly available waste materials in the Colombian Caribbean region: yam peels and oil palm pulp, both biomaBes treated with citric acid. The experiments were carried out in batch system using nickel aqueous solution at a concentration of 100 ppm. The residual concentration of the solution was measured by atomic absorption spectroscopy, and it was found that the adsorption proceB is highly dependent of pH with an optimum value of 6. What is more, it was found that Ni (II) presents a quick sorption the first 50 minutes, and Elovich model showed the best fit. The maximum adsorption capacity according to Langmuir isotherm was 68.14, 47.93, 103.3 and 58.7 mg/g for unmodified chemically modified yam peels and oil palm pulp respectively showing a potential value of use of these biomaterials in the removal of Ni (II) present in aqueous solutions.

ESTUDIO DE MODIFICACIÓN QUÍMICA Y FÍSICA DE BIOMASA (Citrus sinensis Y Musa paradisiaca) PARA LA ADSORCIÓN DE METALES PESADOS EN SOLUCIÓN / STUDY OF PHYSICAL AND CHEMICAL MODIFICATION OF BIOMASS (Citrus sinensis AND Musa paradisiaca) FOR THE ADSORPTION OF HEAVY METALS IN SOLUTION

Se estudia el efecto de las modificaciones a carbón activado y recubrimiento con quitosano de biomasa lignocelulósica obtenida de cáscaras de plátano y naranja, para la adsorción de Cr (VI). La caracterización de los grupos funcionales en las biomasas aptos para la adsorción se verificó mediante un análisis elemental (CHON) y espectroscopia de infrarrojo (IR), mientras que para los carbones activados se determinó su área superficial por medio de un análisis BET. El contenido de Cr (VI) en solución se midió mediante espectrofotometría UV-vis, usando el método de la difenilcarbazida. Los resultados mostraron una remoción de los iones de Cr (VI) de 66,6 y 93 ppm para las cáscaras de naranja y plátano respectivamente, los carbones activados removieron 85 y 95 ppm, mientras que las biomasas modificadas con quitosano presentaron una adsorción 61,24 y 88,2 ppm. Se observa que la cinética de adsorción fue mejor descrita por la ecuación de Pseudo Segundo Orden, y el efecto de competitividad bimetálica se vio afectada de mayor forma por iones de níquel, y en menor proporción por iones de plomo.

The effect of changes to activated charcoal and chitosan coating of lignocellulosic biomass obtained from banana and orange peels for the absorption of Cr (VI) was studied. Characterization of the functional groups in the biomass suitable for the adsorption was monitored by elemental analysis (CHON) and infrared spectroscopy (IR), while for activated carbon surface area was determined by BET analysis. The Cr (VI) content in solution was measured by UV-vis spectrophotometer, using the diphenylcarbazide method. The results showed a removal of Cr (VI) ions of 66.6 and 93 ppm for orange peels and banana peels respectively; the activated carbons removed 85 and 95 ppm, while the modified biomasses with chitosan showed an adsorption of 61.24 and 88.2 ppm. It was observed that the adsorption kinetics was best described by the Pseudo Second Order equation, and the bimetallic competitiveness effect was affected more by nickel ions and to a lesser extent by lead ions.

Caracterización de la Opuntia ficus-indica para su uso como coagulante natural / Characterization of Opuntia ficus-indica for using as a natural coagulant

Actualmente municipios de la Costa Atlántica Colombiana no cuentan con suministro de agua potable. La aplicación artesanal de la Tuna (Opuntia ficus-indica) como coagulante es una práctica tradicional en comunidades rurales. En esta investigación se realiza la caracterización del tallo de la Tuna que crece de manera silvestre en el departamento de Bolívar, y del polvo extraído de esta planta, con el fin de identificar componentes asociados a su poder coagulante para la remoción de turbidez y de color en aguas crudas. Las pencas de la planta se sometieron a operaciones de corte, pelado, secado, molienda, tamizado y despigmentado para obtener el coagulante. El rendimiento del proceso global fue de 65g de coagulante/Kg de material vegetal. Los resultados indicaron que la penca contiene alto porcentaje de humedad y pequeñas proporciones de saponinas, flavonoides, sales minerales de calcio y hierro; lo cual permitió concluir que estos metabolitos y sales no son los responsables de su poder coagulante debido a las cantidades poco significativas en las que se encuentran. Se consideró que otras especies química tales como el ácido poligalacturónico y compuestos algínicos son realmente los que le confieran la cualidad al biomaterial. También, se evaluó el poder coagulante del material extraído, se analizó el efecto de tres dosis sobre el color, la turbidez y el pH del agua tratada. Los resultados indicaron que tiene la capacidad de remover 50% del color y 70% de turbidez de aguas crudas con alta turbidez inicial, y que no altera significativamente su pH.

Currently, municipalities in the Colombian Atlantic Coast do not have potable water supply. The implementation of the Tuna as a coagulant is a traditional practice in rural communities, but is used in craft way. In the present investigation, the characterization of the stalk of Tuna (Opuntia ficus-indica) growing in the wild in the Bolivar department, and of the powder extracted from this plant was realized with the purpose to identify components associated with its coagulant power to remove color and turbidity in raw water. The stalks of this plant were subjected to cutting, peeling, drying, grinding, sieving and depigment for obtaining the coagulant. The overall process yield was 65g of coagulant/kg of vegetal material. The results also indicated that the stalk of Tuna contains high moisture content and low amounts of saponins, flavonoids, minerals, calcium and iron. It allowed concluding that these metabolites and salts are not responsible of the coagulant power of plant due to the insignificant amounts in which they are present. Therefore, it is presumed that other chemical species such as polygalacturonic acid and alginic compounds are those that confer the quality to the biomaterial. Also, the coagulant power of extracted material was evaluated. The effect of three dosis on the color, turbidity and pH of trated water was analized. The results indicated that it has the capacity to remove 50% of color and 70% of turbity from crude water with high initial turbidity. Also, it does not affect significantly its pH.

Obtención de biodiesel a partir de diferentes tipos de grasa residual de origen animal / Extractin biodieesel from different types of animal origin residual fat

Se estudian diferentes posibilidades de obtención de biodiesel a partir de residuos grasos generados en la explotación pecuaria: grasa de pollo, cerdo, y vacuna, para ello se analizan las variables relación molar alcohol/grasa animal y cantidad de catalizador, puesto que son las que más inciden en la calidad del biodiesel, al evaluar sus características y rendimientos de la reacción de transesterificación. El rendimiento en el proceso de extracción de la grasa de material de desecho de pollo es del 70,5%, y de la grasa de cerdo del 90%, por lo que se plantean como alternativas viables desde el punto de vista técnico, permitiendo la valorización de estos desechos orgánicos y aliviando la contaminación generada en este tipo de industrias. De la caracterización realizada a la grasa de pollo y cerdo se pudo establecer que ambas materias primas son de baja acidez lo cual garantiza un alto grado de transesterificación, teniendo en cuenta que tuvo un rendimiento del 96% a partir de la grasa de pollo y del 91,2% a partir de la grasa de cerdo. Del análisis cromatográfico del biodiesel sintetizado se obtuvo que el ácido graso más común fue el del ácido oleico.

Different possibilities of extracting biodiesel from fat residues generated on farm livestock: chicken, pork, and bovine fat, were studied. To do this, the variables molar ratio alcohol/animal fat and amount of catalyst are analyzed, since those are the ones which most affect the quality of biodiesel when assessing the characteristics and efficiency of the transesterification reaction. The efficiency in the poultry waste material extraction process is 70.5%, and in pork fat is 90%, reason why they are proposed as feasible alternatives from the technical standpoint, allowing the recovery of this organic waste, thus alleviating the pollution generated by this type of industry. From the characterization performed on chicken and pork fat, it has been established that this raw material has low acidity which ensures a high degree of transesterification, taking into account that it had 96% efficiency from chicken fat and 91.2% from pork fat. From the synthesized biodiesel Chromatographic analysis it was found that the most common fatty acid was oleic acid.