Unveiling the potential of machine learning in cost-effective degradation of pharmaceutically active compounds: A stirred photo-reactor study

In this study, neural networks and support vector regression (SVR) were employed to predict the degradation over three pharmaceutically active compounds (PhACs): Ibuprofen (IBP), diclofenac (DCF), and caffeine (CAF) within a stirred reactor featuring a flotation cell with two non-concentric ultraviolet lamps. A total of 438 datapoints were collected from published works and distributed into 70% training and 30% test datasets while cross-validation was utilized to assess the training reliability. The models incorporated 15 input variables concerning reaction kinetics, molecular properties, hydrodynamic information, presence of radiation, and catalytic properties. It was observed that the Support Vector Regression (SVR) presented a poor performance as the ε hyperparameter ignored large error over low concentration levels. Meanwhile, the Artificial Neural Networks (ANN) model was able to provide rough estimations on the expected degradation of the pollutants without requiring information regarding reaction rate constants. The multi-objective optimization analysis suggested a leading role due to ozone kinetic for a rapid degradation of the contaminants and most of the results required intensification with hydrogen peroxide and Fenton process. Although both models were affected by accuracy limitations, this work provided a lightweight model to evaluate different Advanced Oxidation Processes (AOPs) by providing general information regarding the process operational conditions as well as know molecular and catalytic properties.

Analysis of scientific and technological trends in the incorporation of activated carbon in advanced oxidation processes-a bibliometric study

There is high interest in the development of water pollution remediation technologies. Advanced oxidation processes (AOPs) are a promising alternative for the degradation of organic compounds; however, these technologies have been limited mainly by high operating costs and, in some cases, by forming byproducts, which can be more hazardous than the original pollutants. Activated carbon (AC) is a porous material that can be combined with AOP systems in various ways, given its adsorbent and catalytic characteristics. In addition, AC is a flexible, adaptable, and low-cost material. This article presents a bibliometric analysis of AOPs incorporating CA in scientific research and patents; the Scopus database was used to obtain patents and Orbit Express for patents. The most investigated AOPs incorporating AC are photocatalysis processes, Fenton processes, persulfate-based AOP, electrochemical processes, and ozonation. However, it is the persulfate-based AOP that has seen the greatest growth in scientific publications in recent years; this great interest can be related to the synergy that the process has with AC, allowing the degradation of contaminants via radical and non-radical. According to the maturity analysis of scientific publications, photocatalysis, Fenton, electrochemistry, ozonation, and persulfate technologies are in a growth stage and will reach maturity in 2034, 2042, 2040, 2034, and 2035, respectively; these technologies coupled with AC are expected to generate a greater number of patents when they reach maturity.

Performance of a pilot-scale BDD reactor by numerical analysis of reaction rate parameters and additional numbers for mass transfers

The performance of a pilot-scale boron-doped diamond (BDD) reactor through a numerical analysis of reaction rate parameters and enhanced mass transfer has been investigated. The main objective of this research is to evaluate the efficiency of the reactor in mineralizing and degrading caffeine as an emerging contaminant. Based on the kinetic mechanisms and mass transport correlations reported in the literature, two reaction rate kinetic models for caffeine degradation are proposed and analyzed. The models consider different electrolytes (NaCl and Na2SO4) and applied current densities. The kinetic fitting process utilizes the gradient-maximal electrochemical approach, together with orthogonal placement methods, fourth-order Runge-Kutta (RK4) methods, and Nelder & Mead methods for optimization of kinetic parameters and spatial discretization of the material balance. Experimental data obtained from a factorial design with four factors and two levels (24) validate the proposed kinetic models. Caffeine degradation is achieved with NaCl and Na2SO4 electrolytes at concentrations of 60 ppm and 100 ppm, respectively. The corresponding applied loads are 1.5 AhL-1 and 3 AhL-1. Na2SO4 exhibits superior performance with a total organic carbon (TOC) removal efficiency of 99.13%, while NaCl achieves 31.47% mineralization. The behavior of caffeine degradation under the operational and scale conditions demonstrates that NaCl, as a support electrolyte, enables controlled charge transfer (current density) during the degradation process. In contrast, Na2SO4 as a support electrolyte introduces a mixed control of charge and mass transfer. The pilot-scale kinetic parameters obtained in this study provide valuable insights into the support electrolyte dynamics and current density dynamics in BDD-based Electrooxidation (EO) systems, particularly in complex matrix applications. Furthermore, the observed electrical consumption supports the potential application of EO as a viable technology for industrial-scale tertiary wastewater treatment, specifically for caffeine removal.

Morphological Electrical and Hardness Characterization of Carbon Nanotube-Reinforced Thermoplastic Polyurethane (TPU) Nanocomposite Plates

The impacts on the morphological, electrical and hardness properties of thermoplastic polyurethane (TPU) plates using multi-walled carbon nanotubes (MWCNTs) as reinforcing fillers have been investigated, using MWCNT loadings between 1 and 7 wt%. Plates of the TPU/MWCNT nanocomposites were fabricated by compression molding from extruded pellets. An X-ray diffraction analysis showed that the incorporation of MWCNTs into the TPU polymer matrix increases the ordered range of the soft and hard segments. SEM images revealed that the fabrication route used here helped to obtain TPU/MWCNT nanocomposites with a uniform dispersion of the nanotubes inside the TPU matrix and promoted the creation of a conductive network that favors the electronic conduction of the composite. The potential of the impedance spectroscopy technique has been used to determine that the TPU/MWCNT plates exhibited two conduction mechanisms, percolation and tunneling conduction of electrons, and their conductivity values increase as the MWCNT loading increases. Finally, although the fabrication route induced a hardness reduction with respect to the pure TPU, the addition of MWCNT increased the Shore A hardness behavior of the TPU plates.

Bicarbonate-Hydrogen Peroxide System for Treating Dyeing Wastewater: Degradation of Organic Pollutants and Color Removal

The textile industry is a global economic driving force; however, it is also one of the most polluting industries, with highly toxic effluents which are complex to treat due to the recalcitrant nature of some compounds present in these effluents. This research focuses on the removal of Chemical Oxygen Demand (COD), color, Total Organic Carbon (TOC), and Ammoniacal Nitrogen (N-NH₃) on tannery wastewater treatment through an advanced oxidation process (AOPs) using sodium bicarbonate (NaHCO₃), hydrogen peroxide (H₂O₂) and temperature using a central composite non-factorial design with a surface response using Statistica 7.0 software. All experiments used a 500 mL reactor with 300 mL of tannery wastewater from a company in Cúcuta, Colombia. The physicochemical characterization was done to determine the significant absorbance peaks about the color in the wavelengths between 297 and 669 nm. Statistical analysis found that the concentration of NaHCO₃ affects the removal of color and N-NH₃; however, it did not affect COD and TOC. The optimal process conditions for removing the different compounds under study were: NaHCO₃ 1 M, H₂O₂ 2 M, and 60 °C, with efficiencies of 92.35%, 31.93%, 68.85%, and 35.5% N-NH₃, COD, color, and TOC respectively. It can be concluded that AOPs using H₂O₂ and NaHCO₃ are recommended to remove color and N-NH₃.

State of microalgae-based swine manure digestate treatment: An overview

Global pork production has an annual growth of approximately 2.1%, and its economic and environmental impact are related with the treatment of waste in the production chain. There is little evidence of research advances to generate alternatives for using these wastes. The lack of research related to microalgae cultivation using digestate produced by porcine residues generates negative environmental impact, inadequate and inefficient technologies, low recovery and use of waste and loss of value and competitiveness in the market. The available literature focuses mainly on the treatment of anaerobic digestion liquid effluents for the removal of components, but not on the generation of value-added products. Therefore, there is a need to collect the available information, analyze it and propose other new methodologies. This article presents the information obtained from conducting a systematic review of the literature with a bibliometric and a comparative analysis; achieving an analysis of the temporal and geographical distribution, the main topics, the most influential players, the degree of maturity of the research and different strategies collected for microalgae-based swine manure digestate treatment. In this way, it was possible to capture an overview of the current state of the development of research focused on the use of digestate for the cultivation of microalgae, visualizing important aspects as the evolution of publications, identifying China and USA as the main players in research, biomass and wastewater as potential topics also Spirulina, Astaxanthin and beta-carotene as the main products based on microalgae. Thus, achieving an structure, organized and synthesized landscape of scientific and technological knowledge available for the proposal of investigations that allow the use of anaerobic digestion liquid effluents as cultivation medium for microalgae.

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The biometric analysis and SAN provides an overview of the evolution of technology.

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China and the USA are the main players in the use of digestate in microalgae cultivation.

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Biomass and wastewater are trending topics in the microalgal application at the near future.

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Spirulina, Astaxanthin and beta-carotene as the main products based on market worldwide forecasting.

Plastic recycling and their use as raw material for the synthesis of carbonaceous materials

Pollution by polymeric materials - in particular plastics - has a negative effect on the health of our planet. Approximately 4.9 billion tons of plastic are estimated to have been improperly disposed of, with the environment as their final destination. This scenario comes from a linear economic system, extraction-production-consumption and finally disposal. The alarming panorama has created the need to find technological solutions that generate new uses for discarded polymeric materials or turn them into part of the production process to produce new and novel materials, such as carbon nanotubes, graphene, or other carbonaceous materials of high added value, modifying the economy for a circular and sustainable production model. This review highlights the negative impact that the disposal of plastic materials has on the environment and the research needs that allow solving the pollution problems generated in the environment by these wastes. Also, the review highlights the current and future directions of recovery plastic waste research-based to promote innovations in the plastic production sector that could allow obtaining breakpoints in other industrial sectors with the technology-based companies.

Water footprint in gold extraction: A case-study in Suárez, Cauca, Colombia

This research deepens the analysis of the mineral water footprint, especially that of gold, in regions that are understudied and where mining has been an intensified extractive activity since the colonial era, as is the case in the northern part of department of Cauca in Colombia. Thus, the purpose was to estimate the water footprint indicators in gold mining in Suárez (Cauca, Colombia), to quantify the impacts generated by the non-returned water in the production process and the levels of pollutants in the wastewater, aimed to strength public policies, control strategies and mitigation that generates reductions in the impacts from mining activities on the environment. The blue water footprint was estimated in 79.91 m³ per kg of gold extracted and the gray water footprint was found to be in the range of 272,125.39 to 404,825.11 m³ per kg of gold extracted. The water footprint values obtained were compared with other mines with similar operations. These results generate a baseline for decision making, providing elements for environmental strategic planning, regulations and showing the great environmental pressure that gold activity exerts on water resources and the territories.

Engineering and modeling perspectives on photocatalytic reactors for water treatment

The debate on whether photocatalysis can reach full maturity at commercial level as an effective and economical process for treatment and purification of water and wastewater has recently intensified. Despite a bloom of scientific investigations in the last 30 years, particularly with regards to innovative photocatalytic materials, photocatalysis has so far seen a few industrial applications. Regardless of the points of view, it has been realized that research on reactor design and modeling are now equally urgent to match the extensive research carried out on innovative photocatalytic materials. In reality, the development of photocatalytic reactors has advanced steadily in terms of modeling and reactor design over the last two decades, though this topic has captured a smaller specialized audience. In this critical review, we introduce the latest developments on photocatalytic reactors for water treatment from an engineering perspective. The focus is on the modeling and design of photocatalytic reactors for water treatment at pilot- or at greater scale. Photocatalytic reactors utilizing both natural sunlight and UV irradiation sources are comprehensively discussed. The most promising photoreactor designs and models are examined giving key design guidelines. Other engineering considerations, such as operation, cost analysis, patents, and several industrial applications of photocatalytic reactors for water treatment are also presented. The dissemination of key photocatalytic reactor design principles among the scientific community and the water industry is currently one of the greatest obstacles in translating PWT research into widespread real-world application.

Advanced Oxidation Processes and Biotechnological Alternatives for the Treatment of Tannery Wastewater

The tannery industry is one of the economic sectors that contributes to the development of different countries. Globally, Europe and Asia are the main producers of this industry, although Latin America and Africa have been growing considerably in recent years. With this growth, the negative environmental impacts towards different ecosystem resources as a result of the discharges of recalcitrated pollutants, have led to different investigations to generate alternative solutions. Worldwide, different technologies have been studied to address this problem, biological and physicochemical processes have been widely studied, presenting drawbacks with some recalcitrant compounds. This review provides a context on the different existing technologies for the treatment of tannery wastewater, analyzing the physicochemical composition of this liquid waste, the impact it generates on human health and ecosystems and the advances in the different existing technologies, focusing on advanced oxidation processes and the use of microalgae. The coupling of advanced oxidation processes with biological processes, mainly microalgae, is seen as a viable biotechnological strategy, not only for the removal of pollutants, but also to obtain value-added products with potential use in the biorefining of the biomass.

New approach for the dimensionless analysis of a unidirectional flow solar reactor based on Damköhler's number profiles

A methodology for the analysis of the behavior of complex reactors based on the construction of profiles of a dimensionless number (Damköhler) for each main chemical species (Dai) was proposed. A 4-chlorophenol mineralization reaction in a heterogeneous solar reactor with suspended TiO₂ and addition of H₂O₂ with tubular geometry and radiation collectors, fluid flow and a recirculation system was selected as a complex model system in order to validate the approach. The dynamic behavior of the reactor in dimensionless variables was modeled as a function of Dai. Where Dai(z,t) is a local property and grouped the optical and surface's properties of the catalyst, catalyst load, radiation intensity, the photon absorption rate, rate of non-photochemical reactions, the H₂O₂ effect, the reaction rate of different stages like adsorption, attack of radicals, surface reactions, plus design and operation variables like reactor volume and volumetric flow.

A coupling of orthogonal collocation and Runge-Kutta methods were used to solve the PDEs and carry out the simulations to the different experimental conditions, resulting in profiles of Dai, Ci, and conversion in function of time and space. The Dai profiles proposed in the new methodology are capable of describing the disturbances in solar reactors, to indicate consumption and generation rates, instantaneous changes of reaction rate, to describe competitive reactions and quenching effects and to determine equilibrium concentrations, all of the above at each time and space. Therefore, this approach is a analysis tool of reactors which complements the concentration profile. This methodology can be extended to other reactive systems, adapting the intrinsic reaction rates.

A novel high rotation bubble reactor for the treatment of a model pollutant in ozone/goethite/H2O2 and UV/goethite coupled processes

This work proposes a novel approach for the coupling of ozonation and Fenton processes using a new prototype of a high rotation bubble reactor (HRBR), which improves utilization of the ozone and hydrogen peroxide through bubble generation and axial and radial dispersion of the flow. The HRBR integrates the rotor and the diffuser in the same device facilitating the generation and dispersion of the ozone bubbles inside the reaction tank. Thus, the mass transfer to the liquid phase is enhanced. Most of the experiments were carried out under neutral pH and 1580 rpm of agitation during the 20 min of reaction. Total ibuprofen degradation was achieved within 20 min of operation for most of the couplings and individual processes evaluated. It was successfully demonstrated that the HRBR can be used as a reactive system for heterogeneous Fenton and ozonation coupling because it presents a high synergy. For the ozonation process, the reactor also displayed a good performance because the residual ozone in the gas is lower than 0.4 mg/L, which indicates that there is a suitable ozone utilization. Ibuprofen degradation by other processes like oxidation direct by H₂O₂ and heterogeneous Fenton was 28.0% and 73.1%, respectively. It was determined that the reaction rate, synergy, OUI (ozone utilized index), and consumption of electrical energy (EE/O) of the coupled processes could be improved by using the HRBR depending on the experimental conditions.

A tube-in-tube membrane microreactor for tertiary treatment of urban wastewaters by photo-Fenton at neutral pH: A proof of concept

This work presents a disruptive approach to promote highly-efficient photo-Fenton process at neutral pH under continuous mode operation. The system consists of a tube-in-tube membrane reactor designed for continuous-flow titration of low iron doses to the annular reaction zone (ARZ). A concentrated acidic ferrous ion (Fe²⁺) solution is fed by the lumen-side of the membrane, permeating through the membrane pores (inside-out mode), being dosed and uniformly delivered to the membrane shell-side. Polluted water, containing amoxicillin (AMX) and oxidant (H₂O₂), flows continuously in the reactor annulus (space between the membrane shell-side and an outer quartz tube). The catalyst radial dispersion is enhanced by the helicoidal movement of water around the membrane shell-side, efficiently promoting its contact with H₂O₂ and UV light. The efficiency of photochemical and photocatalytic oxidation was evaluated as a function of catalyst dose, catalyst injection mode (radial permeation vs injection upstream from the reactor inlet), light source (UVA vs UVC) and aqueous solution matrix (synthetic vs real wastewater). At steady-state, photo-Fenton reaction with Fe²⁺ radial addition, driven by UVC light, showed the highest AMX removal for synthetic (∼65%, removal rate of 44 μM_AMX/min, using [Fe²⁺]_ARZ = 2 mg/L and [H₂O₂]_inlet = 10 mg/L) and real municipal wastewaters (∼45%, removal rate of 31 μM_AMX/min, with [Fe²⁺]_ARZ = 5 mg/L and [H₂O₂]_inlet = 40 mg/L), with a residence time of only 4.6 s.

Sizing of reactors by charts of Damköhler's number for solutions of dimensionless design equations

The reaction kinetic rate and mass transport play an important role in the sizing and scale-up of reactors. The Damköhler's dimensionless number ( D a ) is the quotient of these effects. A new interpretation of D a as a local property is introduced D a ( x , y , z , t ) . A new graphical methodology is proposed for the sizing and scale-up of unidirectional flow reactors and CSTRs. The partial differential equation (PDE) and algebraic that describe the continuity within these reactors transform into dimensionless variables, and the conversion at the output is expressed as a function of the conditions at the input D a 0 . The operating conditions as volumetric flow, residence time; design variables as reactor volume; and intrinsic reaction rate are involved in D a 0 . The equations are solved numerically to develop the design charts D a 0 vs X. The design volume is linear with D a 0 , and the conversion is obtained from the charts ( D a 0 vs X) or vice versa. Using these charts avoids the analytical or numerical solution of the PDE that governs the unidirectional flow reactors becoming an easy tool for scale-up. The article portrays how to use these diagrams. Reactors with D a 0 < 0.1 have a low conversion per pass, the charts also allow estimating the number of recirculations required as a function of the overall conversion. Reactors with the same conversion have the same D a 0 , both laboratory and industrial scale. Then, the D a number is presented as a fundamental parameter for design and scaling-up these reactors.

High-rate algal pond for removal of pharmaceutical compounds from urban domestic wastewater under tropical conditions. Case study: Santiago de Cali, Colombia

This study evaluated the capacity of a pilot-scale high-rate algal pond (HRAP) to remove pharmaceutical compounds (PCs) from domestic wastewater in the city of Santiago de Cali, Colombia. The compounds analyzed included antiepileptics, hypolipidemic drugs, tranquilizers and analgesics, and anti-inflammatory drugs. The HRAP operated under a continuous water flow of 0.2 m³d^-1 and a 3-day hydraulic retention time (HRT). Removal efficiencies were high (>70%) for fenofibric acid, ibuprofen, and paracetamol; medium (30-70%) for gabapentin, lamotrigine, fenofibrate, gemfibrozil, diclofenac, ketoprofen, naproxen, and pentoxifylline; and low (<30%) for carbamazepine and its metabolite 10,11-Dihidro-10,11-dihidroxicarbamazepine (CBZ-Diol). The findings herein are similar to other studies, but were obtained with a shorter HRT. These results show that tropical environmental conditions favor photodegradation and contribute to the development of microalgae and the biodegradation process. Twenty microalgae species were identified, with the phylum Chlorophyta as the most abundant, particularly due to its natural introduction. The removal of the PCs also reflected a percentage reduction (>50%) in the ecological hazard posed by most of the compounds, although it is important to note that the hazard from gemfibrozil and ibuprofen remained high even after treatment, indicating the need for complementary treatment.

Ultraviolet light-mediated activation of persulfate for the degradation of cobalt cyanocomplexes

The ultraviolet light activation of persulfate (PS) was evaluated for the degradation of cobalt cyanocomplexes, which are considered as some of the most recalcitrant compounds present in mining wastewater. The influence of the solution pH (11 and 13), initial concentration of PS (0.1, 0.3, 0.5, 0.7 and 0.9 g/L), dissolved oxygen and initial concentration of contaminant were evaluated. Photolysis results showed that [Formula: see text] is photosensitive to UVC radiation, while the activation of PS by alkaline pH does not contribute to the degradation of the cyanocomplex. There was no presence of CN^- at both solution pH values using UVC/PS. But at pH 13, the degradation of cobalt cyanocomplexes and the pseudo-first-order rate constant increased. This was attributed to the effective conversion of SO₄^•- to HO^• and to the increase in the oxidative photolysis of PS at high pH. Additional tests demonstrated better performance of UVC/PS in the absence of oxygen which may be caused by the quenching effect of O₂ to the higher energy excited state of the cyanocomplex that must be reached to initiate degradation reactions. Increasing the initial concentration of [Formula: see text] will increase the amount of Co removed but it represents the higher specific energy consumption.

Experimental dataset on preparation and characterization of black sand mineral-based as photocatalyst

Heterogeneous photocatalysis with natural minerals (geocatalysis) has been considered for a wide variety of redox processes, which require the participation of metals either as catalysts or promoters in the reactive system. Black mineral sand as raw material (RM), which is a natural composite frequently found in coastal deposits, was used for the preparation of a semiconductor potential. Due to iron content of mineral, it was applied several magnetic fields (0.0311 and 0.1645 Tesla) to obtain the fractions M1 and M2, respectively. The fraction that was not magnetically attracted was named NM. The chemical, structural and optical properties of each obtained composite were characterized by Zeta potential (ζ), X-ray fluorescence (XRF), energy-dispersive X-Ray analysis (EDX), scanning electron microscopy (SEM), BET area, thermal gravimetric analysis (TGA), X-ray diffraction (XRD) patterns, Fourier transform infrared (FT-IR) and UV-Vis spectroscopy techniques.

Wild microorganism and plankton decay in ballast water treatments by solar disinfection (SODIS) and advanced oxidation processes

Ballast water (BW) is a dead weight used by ships to provide stability in their journeys. It poses health, economic and ecological problems. Since 2017, the International Maritime Organization-IMO mandated management of BW. This research compares plankton mortality and microorganism inactivation in different BW treatments to identify possible decay models. Treatments include solar radiation (Srad), UV, H₂O₂ and advanced oxidation processes (AOPs). In the wild populations, the disinfection capacity was measured in natural seawater pumped from the Santa Marta port zone in Colombia. AOPs showed different models and effectiveness according to the treatment and microorganism. Plankton larger than 50 μm was the most resistant; therefore, it must be removed first by a previous filter. Wild microorganisms showed log-linear and log-linear tail decay models for most AOPs in E. coli. For Vibrio, the models were log-lineal tail and biphasic models.

Dataset of the efficiency of the ultraviolet light activation of persulfate ion for the degradation of cobalt cyanocomplexes in synthetic mining wastewater

In recent years, the extraction of gold has become important for the development of nations. However, mining wastewater represents an environmental problem due to its high content of free cyanide-based compounds and weak and strong cyanocomplexes for the use of sodium cyanide to obtain gold from minerals. The experimental data presented show the performance of the elimination of one of the strongest cyanocomplex that can appear in mining wastewater ([Co(CN)6]3−) by the ultraviolet C activation of persulfate (PS). The removal of total cobalt in solution was used as an indicator of the elimination of the cobalt cyanocomplexes that appear as transformation products from the degradation of [Co(CN)6]3−. The data evidence that strong cyanocomplexes can be eliminated from mining wastewater. The experimental runs were divided into two parts: as a first step, the influence of the UVC light was elucidated. Afterward, five initial concentrations of persulfate ion (0.1, 0.3, 0.5, 0.7 and 0.9 g/L of PS), two pH values (11 and 13) and two additional initial concentrations of contaminant (25 mg/L and 75 mg/L of [Co(CN)6]3− ) were examined to find the optimal parameter where the highest Co removal is obtained.

Dataset on infrared spectroscopy and X-ray diffraction patterns of Mg–Al layered double hydroxides by the electrocoagulation technique

The XRD profiles and FTIR analysis of sludge aggregates, Mg–Al layered double hydroxides, produced during electrocoagulation processes are presented. The data describes the composition of materials (LDH) produced at different operations conditions (atmospheric conditions and Mg²⁺/Al³⁺ ratio). The data show the diffraction peaks of (003), (006), (018) and (110) crystal planes for hydrotalcite structure.

Experimental data on the production and characterization of biochars derived from coconut-shell wastes obtained from the Colombian Pacific Coast at low temperature pyrolysis

Biochars are emerging eco-friendly products showing outstanding properties in areas such as carbon sequestration, soil amendment, bioremediation, biocomposites, and bioenergy. These interesting materials can be synthesized from a wide variety of waste-derived sources, including lignocellulosic biomass wastes, manure and sewage sludge. In this work, abundant data on biochars produced from coconut-shell wastes obtained from the Colombian Pacific Coast are presented. Biochar synthesis was performed varying the temperature (in the range: 280 °C–420 °C) and O₂ feeding (in the range: 0–5% v/v) in the pyrolysis reaction. Production yields and some biochar properties such as particle size, Zeta Potential, elemental content (C, N, Al, B, Ca, Cu, Fe, K, Li, Mg, Mn, Na, P, S, Ti, Zn), BET surface area, FT-IR spectrum, XRD spectrum, and SEM morphology are presented. This data set is a comprehensive resource to gain a further understanding of biochars, and is a valuable tool for addressing the strategic exploitation of the multiple benefits they have.

Experimental data on synthesis and characterization of WO3/TiO2 as catalyst

WO₃/TiO₂ is a composite photocatalyst that is being widely used in heterogeneous photocatalysis because it presents better photocatalytic properties than TiO₂. For example, the probability of recombination of the electron/hole pairs is diminished and a more range of the solar spectrum is used for its excitation. However, this depend of variables such as tungsten oxide concentration, calcination temperature and synthesis method. This work is focused in establish the effect of WO₃ on the morphological and structural characteristics of TiO₂. WO₃/TiO₂ was synthesized by sol-gel method at different calcination temperatures and at different concentrations of tungsten oxide. The surface area, the possible transition between valence band and conduction band, particle size, elemental analysis and crystallography were examined through the BET, DRS, SEM-EDS and XRD analysis.

Data on the removal of metals (Cr3+, Cr6+, Cd2+, Cu2+, Ni2+, Zn2+) from aqueous solution by adsorption using magnetite particles from electrochemical synthesis

Magnetic materials are promising adsorbents for removing heavy metals from polluted wastewaters. Magnetite particles were prepared by electrolytic synthesis (average crystallite size 37.9±1.2 nm, surface area = 17.2 m2g−1, isoelectric point = 6.3, magnetic saturation = 62 emu g⁻¹) and used as adsorbent of heavy metals in aqueous solutions. The adsorption capacity of the magnetite was highly dependent on pH value, for Cd⁺², Zn⁺², Ni⁺² and Cu⁺² the removal performance was higher that 80% at pH = 8. For Cr+6, the acid pH showed removal percentage higher that 90%.

The adsorbent was separated from the system, reactivated and reused in subsequent tests using batch adsorption. It was found that removal efficiencies were higher than 70% even during a third cycle of adsorption. Finally, the kinetic behavior of the adsorption of each adsorbate was described by a first-order. The range of values of q_e(mg/g) and k (min⁻¹) were 1.3166–1.6367 and 0.0377 to 0.0826 respectively.

Removal of indigo carmine dye by electrocoagulation using magnesium anodes with polarity change

The aim of this study was to evaluate the performance of high purity magnesium and the magnesium-aluminum-zinc alloy AZ31 as sacrificial anodes in an electrocoagulation process with polarity change for the treatment of synthetic indigo carmine solution. It was studied the effect of the main parameters such as temperature, anodic material, current density, initial dye concentration, and agitation speed on the diminishing of indigo carmine concentration and non-purgeable organic carbon. Also, image analysis was used in conjunction with zeta potential measurements to understand the mechanism of flocs formation. The best results were 80% and 96% removal for non-purgeable organic carbon and dye content respectively at room temperature, by using turbulent regime, initial dye concentration of 100 mg L^-1 and 50 A m^-2 as current density with AZ31 alloy as electrodes. Particularly, high purity magnesium reached 75% in non-purgeable organic carbon removal and 86% in dye removal at the conditions described above. Finally, an additional improvement of 43% in the diminishing of the organic carbon content was observed when polarity change was used, a phenomenon that was attributed to the distribution of the oxidation reaction between electrodes, avoiding the saturation of the surface with oxide and hydroxide layers. Major areas and major fractal dimension were obtained by using a polarity change.

Intensification of the O3/TiO2/UV advanced oxidation process using a modified flotation cell

A novel approach for the ozone and TiO₂ intensification process for wastewater treatment is presented using a modified flotation cell.

Anoxic photocatalytic treatment of synthetic mining wastewater using TiO2and scavengers for complexed cyanide recovery

A new pathway for selective photocatalytic reduction using a combination of scavengers for gold mining wastewater treatment.

Synthesis of Mg-Al layered double hydroxides by electrocoagulation

Recently, layered double hydroxides (LDHs) have attracted much consideration due to their versatility and easily manipulating properties and their potential applications such as anion exchangers, support of catalysts, flame retardants, biomedical drug delivery. A novel method for the in-situ preparation in situ of LDHs, using electrocoagulation (EC) processes was developed, the EC process was performed under two different conditions, at 5 mA m⁻², changing polarity of the electrodes to find out the composition that leads to LDHs generation. The final product was characterized using XRD, BET and FTIR techniques.

This method presented the following advantages: (1) Simultaneously LDHs synthesis and wastewater treatment by ion removal; (2) Polarity control allows to manipulate the M²⁺/M³⁺ molar ratio, LDHs properties and its potential applications; (3) The method spent less time to carry out the synthesis and; (4) it did not need complicated solid-liquid separation processes.

An approach to utilize the artificial high power LED UV-A radiation in photoreactors for the degradation of methylene blue

Two laboratory photoreactors were compared in the degradation of MB using high power UV LED and resulted in more than 98% degradation.

Radiation absorption and optimization of solar photocatalytic reactors for environmental applications

This study provides a systematic and quantitative approach to the analysis and optimization of solar photocatalytic reactors utilized in environmental applications such as pollutant remediation and conversion of biomass (waste) to hydrogen. Ray tracing technique was coupled with the six-flux absorption scattering model (SFM) to analyze the complex radiation field in solar compound parabolic collectors (CPC) and tubular photoreactors. The absorption of solar radiation represented by the spatial distribution of the local volumetric rate of photon absorption (LVRPA) depends strongly on catalyst loading and geometry. The total radiation absorbed in the reactors, the volumetric rate of absorption (VRPA), was analyzed as a function of the optical properties (scattering albedo) of the photocatalyst. The VRPA reached maxima at specific catalyst concentrations in close agreement with literature experimental studies. The CPC has on average 70% higher photon absorption efficiency than a tubular reactor and requires 39% less catalyst to operate under optimum conditions. The "apparent optical thickness" is proposed as a new dimensionless parameter for optimization of CPC and tubular reactors. It removes the dependence of the optimum catalyst concentration on tube diameter and photocatalyst scattering albedo. For titanium dioxide (TiO(2)) Degussa P25, maximum photon absorption occurs at apparent optical thicknesses of 7.78 for CPC and 12.97 for tubular reactors.

Photocatalytic mineralization of commercial herbicides in a pilot-scale solar CPC reactor: photoreactor modeling and reaction kinetics constants independent of radiation field

The six-flux absorption-scattering model (SFM) of the radiation field in the photoreactor, combined with reaction kinetics and fluid-dynamic models, has proved to be suitable to describe the degradation of water pollutants in heterogeneous photocatalytic reactors, combining simplicity and accuracy. In this study, the above approach was extended to model the photocatalytic mineralization of a commercial herbicides mixture (2,4-D, diuron, and ametryne used in Colombian sugar cane crops) in a solar, pilot-scale, compound parabolic collector (CPC) photoreactor using a slurry suspension of TiO(2). The ray-tracing technique was used jointly with the SFM to determine the direction of both the direct and diffuse solar photon fluxes and the spatial profile of the local volumetric rate of photon absorption (LVRPA) in the CPC reactor. Herbicides mineralization kinetics with explicit photon absorption effects were utilized to remove the dependence of the observed rate constants from the reactor geometry and radiation field in the photoreactor. The results showed that the overall model fitted the experimental data of herbicides mineralization in the solar CPC reactor satisfactorily for both cloudy and sunny days. Using the above approach kinetic parameters independent of the radiation field in the reactor can be estimated directly from the results of experiments carried out in a solar CPC reactor. The SFM combined with reaction kinetics and fluid-dynamic models proved to be a simple, but reliable model, for solar photocatalytic applications.