Degrading Treatment Research Articles

Occurrence, removal, and risk assessment of emerging contaminants in aquatic products processing sewage treatment plants.

Emerging contaminants (ECs) in aquatic environments have attracted attention due to their wide distribution and potential ecotoxicities. Sewage treatment plants (STPs) are proven to be the major source of ECs in the aquatic environment, while there remains insufficient understanding of the removal and risk assessment of ECs in STPs. Here, we clarified the degradation and risk impact of 13 ECs in two aquatic product processing sewage treatment plants (APPSTPs) along the southeast coast of China. The concentrations of ECs followed the order: endocrine-disrupting chemicals (1877.85-15,398.02ng/L in influent, 3.37-44.47ng/L in effluent) > > sulfonamide antibiotics (SAs, 75.14-906.19ng/L in influent, 1.14-15.33ng/L in effluent) > pharmaceutical and personal care products (PPCPs, 44.47-589.93ng/L in influent, 2.54-34.16ng/L in effluent) ≈ fluoroquinolone antibiotic (54.76-434.83ng/L in influent, 10.75-32.82ng/L in effluent) > other antibiotics (16.21-51.96ng/L in influent, 0.68-6.17ng/L in effluent). Moreover, the concentrations of PPCPs (decreased by 55.33-87.65% in peak fishing season) and antibiotics (increased by 44.99% in peak fishing season) were affected by fishing activities. In particular, the sequencing batch reactor (SBR) process had a better removal effect than the anaerobic-anoxic-oxic (A2/O) process on the treatment of some contaminants (e.g., norfloxacin and nonylphenol). Risk evaluations of ECs demonstrated that nonylphenol and SAs were at high- and low-risk states, respectively. Overall, our results provide important information for the degradation treatment of ECs, which is essential for pollutant management policy formulation.

The Biosynthesis of Nickel Oxide Nanoparticles: An Eco-Friendly Approach for Azo Dye Decolorization and Industrial Wastewater Treatment

Wastewater is one of the major concerns for agriculture, and the composition of wastewater depends on its origin. Generally, industrial wastewater consists of azo dyes and heavy metals that contaminate the food chain. In this study, nickel oxide nanoparticles (NiO-NPs) were biosynthesized from Shewnella spp. and characterized by UV–visible spectroscopy (UV–vis), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Azo dye decolorization indicated that NiO-NPs decolorize methylene blue (MB) (82.36%), Congo red (CR) (93.57%), malachite green (MCG) (91.05%), reactive black 5(RB5) (55.17%), reactive red-II(RR-II) (55.45%), and direct blue-I(DB-I) (59.94%) at a dye concentration of 25 mg L−1 after 4 h of sunlight exposure. Additionally, the rate of decolorization was also examined for a 50 mg L−1 concentration of dye. In order to investigate the photocatalytic potential of NiO-NPs, different dyes were also subjected to static and shaking conditions for dye decolorization. The treatment of industrial wastewater with NiO-NPs showed a significant reduction in pH from 8.5 to 6.1, EC (48.38%), chemical oxygen demand (49.24%), total dissolved solids (67.05%), sulfates (52.5%), and phosphates (49.49%). The results of this study indicated that biosynthesized NiO-NPs are an attractive choice for azo dye degradation and industrial wastewater treatment, and they can help save the depleted natural resources of water for agricultural purposes.

A novel hybrid continuous-flow wastewater treatment for lamotrigine degradation by combining enzymatic and photo-oxidative reactions

In response to the increasing occurrence of lamotrigine (LMG) in wastewater, low removal efficiency of conventional treatments, and the need for advanced and innovative approaches, our work aimed to develop and optimize a hybrid enzymatic-photo-oxidative treatment. The coupling of immobilized homemade peroxidase and UVC/H2O2 was first studied in batch mode. The hybrid reactions resulted in 100 % removal and a first-order specific reaction rate of 0.142 min−1 at 80 mg L−1 of H2O2. Subsequently, our research focused on treatment optimization in a flat-plate reactor operated in continuous flow. Response surface methodology revealed that maintaining a UVC dose of 3240 mJ cm−2 allows >90 % removal across a wide range of H2O2 concentrations. The experiment with LMG-spiked effluent confirmed the effectiveness of the proposed treatment for removing the antiepileptic from a real matrix. The proposed degradation pathway shows that the system can oxidize lamotrigine by sequential reactions with additional dechlorination steps not yet reported. Furthermore, only the hybrid reactions showed environmental safety, as confirmed by cytotoxicity studies. Notably, our study evaluated, for the first time, the coupling of enzymatic and photo-oxidative reactions in a single reactor operated in continuous-flow mode. The operational flexibility suggests its potential application for wastewater treatment facilities.

An efficient phase-field model for fatigue fracture in viscoelastic solids using cyclic load decomposition and damage superposition

Accurate and efficient evaluations of fatigue fracture is of great importance for the design and evaluation of viscoelastic materials in critical applications subject to cyclic load. In this study, an efficiency-enhanced phase-field model for viscoelastic fatigue fracture is proposed, allowing for fast evaluations of high-cycle fatigue damage. Based on the Boltzmann superposition principle, the cyclic fatigue load is decomposed into a mean load and a zero-mean cyclic load. The response of the mean load is solved numerically, while the response of the zero-mean cyclic load is solved analytically. The phase-field driving force is obtained analytically by combining the responses of the two independent parts, and the phase-field evolution is calculated numerically. In addition, both the dissipated energy and the elastic energy are decomposed using the volumetric-deviatoric decomposition to avoid unrealistic damage under the compression portion of the cyclic load. The proposed efficiency-enhanced model satisfies the energy conservation law as it does not require the fracture toughness degradation or additional fatigue energy treatments. The computational efficiency of the overall fatigue fracture can be greatly improved by leveraging the analytical solution for the response associated with the cyclic load. Numerical investigations are performed, and comparisons with the conventional cycle-by-cycle computation method are made. The results show that the proposed method can reduce the exponential computational demand to a constant or a linear one while achieving an accuracy comparable to that of the conventional method. The effectiveness of the proposed method is further demonstrated using an actual rubber component with testing data.

The effect of surface treatment and low-temperature degradation on flexural strength of additive manufactured zirconia

This study aimed to assess the effect of low-temperature degradation (LTD) and surface treatment on the flexural strength of additive-manufactured (AM) zirconia by comparison to subtractive-manufactured (SM) zirconia. Disc-shaped zirconia specimens were fabricated using AM and SM technology, and each group was assigned to 3 subgroups according to the type of surface treatment: control, sandblasting (SB), and 9% hydrofluoric acid etching (HF). The groups were then further divided into 2 subgroups: unaged and aged. Biaxial flexural strength, crystal phase, surface topography, and surface roughness were measured to evaluate the mechanical properties. Statistical analyses were performed with 3-way ANOVA, followed by the comparison of means with Bonferroni post hoc analyses. The means and standard deviations of the biaxial flexural strength and Weibull parameters were calculated with descriptive statistics. All SM groups showed significantly greater flexural strength than the AM groups (p < .05), and LTD did not affect flexural strength except for the SMHF group (p < .05). After LTD, monoclinic phases (m-phase) were found in all groups, and SEM images showed grain pullout due to zirconia volume expansion in both control groups. Sandblasting significantly affected flexural strength (p < .05), whereas the HF group did not affect flexural strength except in the SMHF group after LTD (p < .05). No significant difference was observed in the surface roughness of AM compared to SM groups conditioned with the same surface treatment regardless of LTD. AM zirconia has comparable mechanical properties to SM zirconia, regardless of low-temperature degradation and surface treatment, which indicates the potential of the AM technique for clinical applications.

STATES OF EMERGENCY IN THE REPUBLIC OF POLAND – CONSTITUTIONAL REGULATION VERSUS CONSTITUTIONAL PRACTICE

In modern times there is a widespread conviction that every state should be prepared for extraordinary circumstances that may pose a threat to the security of the state, including the democratic system, as well as the security of its citizens. Therefore, the constitutions of democratic states define situations referred to as “states of emergency”, the occurrence of which justifies the introduction of an extraordinary legal regime1. These are states of particular danger, the removal of which is not possible by ordinary measures and therefore requires measures of an exceptional nature. Often these measures include restrictions on the exercise of certain individual rights and freedoms, as well as the conferral of specific powers on certain bodies (usually the executive branch) to combat the threat that has arisen. It is therefore important that all of these regulations are contained in constitutional norms and only developed in subordinate acts like statutes. The problem of states of emergency has also been noticed in the documents of international law. According to Art. 4 of the International Covenant on Civil and Political Rights2, “In time of public emergency which threatens the life of the nation and the existence of which is officially proclaimed, the States Parties to the present Covenant may take measures derogating from their obligations under the present Covenant to the extent strictly required by the exigencies of the situation, provided that such measures are not inconsistent with their other obligations under international law and do not involve discrimination solely on the ground of race, colour, sex, language, religion orsocial origin. No derogation from articles 6, 7, 8 (paragraphs 1 and 2), 11, 15, 16, and 18 may be made under this provision”. Provisions that cannot be limited concern, among others, the inherent right to life, freedom from torture, cruel, inhuman, or degrading treatment or punishment, and being subject to medical or scientific experimentation, slavery, being held in servitude, being imprisoned merely on the ground of inability to fulfill a contractual obligation, or the right to freedom of thought, conscience, and religion.

UV/periodate and UV/chlorine for dye degradation and real wastewater treatment: a comparative study

Abstract The discharge of synthetic dyes into the environment poses a significant threat to both human health and the ecosystem, necessitating the treatment of contaminated water. To generate free radicals for the elimination of Direct Blue 71 (DB71) dye from aqueous solutions, periodate (PI) and chlorine (Cl2) have been employed. In this study, separate activation of PI and Cl2 was achieved using ultraviolet (UV) light. The impact of various operational parameters was investigated, resulting in the complete degradation of the dye within 12 min. The presence of ferrous and copper ions had a minor enhancing effect on the degradation rate in both systems. Scavenging experiments confirmed that HO• and IO3• were the primary agents responsible for DB71 degradation in the UV/PI system, while reactive chlorine radicals played a dominant role in the UV/Cl2 process. In terms of mineralization, application for real wastewater and energy efficiency, the UV/PI system exhibited slightly superior performance compared to the UV/Cl2 system.

A Conjugated Microporous Polymer/Wood Aerogel with Physical Adsorption, Chemical Degradation and Antibacterial Self-Cleaning Triple Sewage Treatment Functions.

Conjugated microporous polymers (CMPs) have important applications in the fields of optoelectronics and sewage treatment due to their high specific surface area, broad visible absorption, processability and simple synthesis process. Biocompatibility, recycling, mass production and solar photodegradation are particularly important in wastewater treatment. Here, A CMP with a high specific surface area and a hierarchical pore structure (CPOP) was constructed based on 4,4',4″-Tris(carbazol-9-yl)-triphenylamine (3CZ-TPA). Furthermore, a CMP-loaded wood aerogel (CPOP/wood aerogel) with physical adsorption, chemical degradation, bacterial inhibition and self-cleaning properties was prepared by in situ polymerization and used for wastewater treatment. The obtained CPOP/wood aerogel is highly biocompatible and easy to recycle. In addition, the inherent broad visible light absorption property of CPOP endows it with promising photocatalytic properties. Subsequently, we investigated the photocatalytic mechanism of CPOP, and the results showed that it was mainly affected by peroxyl radicals, which implied and confirmed its microbial self-cleaning for secondary cleaning of water pollutants. The reported studies on CPOP/wood aerogel provide a new direction for water purification materials with excellent adsorption, degradation and antibacterial properties.

Compendium of Chromatographic Behavior of Post-translationally and Chemically Modified Peptides in Bottom-Up Proteomic Experiments.

We have systematically evaluated the chromatographic behavior of post-translationally/chemically modified peptides using data spanning over 70 of the most relevant modifications. These retention properties were measured for standard bottom-up proteomic settings (fully porous C18 separation media, 0.1% formic acid as ion-pairing modifier) using collections of modified/nonmodified peptide pairs. These pairs were generated by spontaneous degradation, chemical or enzymatic treatment, analysis of synthetic peptides, or the cotranslational incorporation of noncanonical proline analogues. In addition, these measurements were validated using external data acquired for synthetic peptides and enzymatically induced citrullination. Working in units of hydrophobicity index (HI, % ACN) and evaluating the average retention shifts (ΔHI) represent the simplest approach to describe the effect of modifications from a didactic point of view. Plotting HI values for modified (y-axis) vs nonmodified (x-axis) counterparts generates unique slope and intercept values for each modification defined by the chemistry of the modifying moiety: its hydrophobicity, size, pKa of ionizable groups, and position of the altered residue. These composition-dependent correlations can be used for coarse incorporation of PTMs into models for prediction of peptide retention. More accurate predictions would require the development of specific sequence-dependent algorithms to predict ΔHI values.

Study on degradation of gold-cyanide wastewater by rare-earth La doped TiO2 -MnO2 composite photocatalyst

In this study, a degradation-type catalyst consisting of rare earth element La-doped titanium dioxide nanoparticles loaded with manganese dioxide was synthesized, and photocatalysis technology was applied for the degradation treatment of gold-cyanide wastewater. The catalyst was characterized using techniques such as X-ray diffraction, transmission electron microscopy, and UV–Vis diffuse reflectance spectroscopy, and results showed that the catalyst exhibited excellent photocatalytic performance. The catalyst effectively decomposed the cyanide in the gold-containing effluent under light conditions, attaining a clearance rate of over 90%. This study explores the practicality and economic viability of its large-scale implementation while offering new concepts and techniques for effective and environmentally friendly treatment technologies in the field of wastewater treatment.

Understanding double perovskite oxides capabilities to improve photocatalytic contaminants degradation performances in water treatment processes: A review

Clean energy and environmental technologies are essential for a sustainable future. Photocatalysts are at the core of these technologies, increasing the efficiency of key chemical reactions and improving their selectivity. Metal oxides like perovskite oxides are long recognized as active photocatalysts of rather simple ionic arrangements. Double perovskites are alternatives to single perovskites, which are known as cation ordered perovskites. Double perovskite oxides such as A2B'B“O6 are emerging compounds with various optoelectronic properties that are suitable for optics, photonics, electronics, and catalysis applications. A, B', and B” are cations with varying degrees of chemical flexibility, leading to multiple combinations, which make them excellent candidates as advanced materials. Herein, we comprehensively screened stable A2B'B“O6 double perovskite metal oxides arranged based on Sr, La, K, Gd, Ba, Na, Ca, Dy, Tb, Sm, Eu, and Bi cations ordered at A sites that have been used in photocatalytic pollutant degradation and water treatment processes. Also, we examined recent developments of double perovskites oxides as photocatalysts through discussion on how their chemistries could be tailored to improve their performances. Also, photocatalytic process was explained along with its characteristics, milestones, mechanisms, modes of operation, and double perovskites materials used in this field indicating unique photocatalytic properties.

Insights into Mn loaded carbon-silica-membrane based catalytic ozonation process for efficient wastewater treatment: Performance and mechanism

Heterogeneous catalytic ozonation (HCO) is a promising technology for advanced wastewater treatment, and developing catalysts with both high catalytic activity and easy recycling capability is challenging but essential. In this work, easily separable Mn loaded carbon–silica-membrane (Mn-CSM) was synthesized by electrospinning and Mn-CSM based packed bed reactor was constructed for catalytic ozonation, achieving excellent catalytic performance for refractory organic degradation. Mn-CSM exhibited a lamellar structure with a thickness of several hundred micrometers and was centimeter-sized in the other two dimensions, which make it easy to be separated in wastewater treatment. At the microscopic scale, Mn-CSM was composed of highly connected nanofibers, which provided large specific surface area for the exposure of active sites. In oxalic acid (OA) degradation and coal gasification wastewater advanced treatment, Mn-CSM demonstrated superior catalytic ozonation performance. After 60 min, 93% of OA was degraded in Mn-CSM based HCO process, and the effluent COD of coal gasification wastewater decreased from 105 mg L−1 to 42 mg L−1. Reactive oxygen species in aqueous solution and on catalyst surface contributed to the organic degradation. The introduction of SiO2 nanoparticles in Mn-CSM can not only enhance its catalytic stability, but also improve fluid flow field distribution. Furthermore, the presence of SiO2 increased the hydrophilicity of Mn-CSM and a better removal of hydrophilic substances (HIS) was achieved in Mn-CSM based HCO. This study highlights a Mn-CSM ozone catalyst with high catalytic activity and easy recycling capability and a Mn-CSM based catalytic ozonation process, which is promising for the degradation of refractory organics in wastewater.

A Facile Aerobic Calcination Synthesis of Porous Oxygen‐Doped g‐C3N4 with High Adsorption Performance and Efficient Photocatalytic Activity

AbstractIn this study, porous oxygen‐doped graphitic carbon nitride (g‐C3N4) was successfully prepared via a facile aerobic calcination method using urea as the precursor. By adjusting the heating rate, the micro structural and the optical properties of this material were investigated. A series of characterizations indicate that the low heating rate is conducive to obtaining the g‐C3N4 possessing layered porous structure and large specific surface area. Meanwhile, it was found that narrower band gap (2.48 eV) and more effective carriers separation efficiency (2.54 ns) can be achieved by introducing oxygen dopants into the g‐C3N4, which is beneficial to the improvement of the photocatalytic performance. Additionally, the methylene blue (MB) wastewater degradation experiment was explored by using the porous oxygen‐doped g‐C3N4. It was demonstrated that the g‐C3N4 synthesized at low heating rate shows superior efficiency (99.1 %) for MB wastewater degradation treatment than the one synthesized at high heating rate (92.6 %). Thus, the porous oxygen‐doped g‐C3N4 obtains at low heating rate by aerobic calcination approach exhibits superior efficiency for dyeing wastewater treatment.

The relationship of the procedure for obtaining samples for examination in criminal proceedings with regulatory and legal acts in the field of criminal proceedings of other countries

The article draws attention to and analyzes the main regulatory legal acts that ensure international standards for the observance and protection of people’s rights and freedoms in terms of obtaining samples for examination, including in criminal proceedings, which include: The Universal Declaration of Human Rights, the International Covenant on civil and political rights, the European Convention on Human Rights, the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment and Punishment, etc.&#x0D; In the course of the research, it was found that in practice, law enforcement agencies, in a number of cases, have to face opposition from the participants in criminal proceedings regarding obtaining biological samples of a person for examination. So, as a form of counteraction, there are: 1) refusal to voluntarily provide biological samples of a person; 2) challenging the actions of law enforcement officers regarding the legitimate use of coercion to obtain biological samples of a person; 3) active resistance during the forced collection of biological samples of a person for examination (with reference to the fact that such actions degrade the honor and dignity of a person or are dangerous for his health).&#x0D; It has been proven that in the absence of normatively defined forms, methods and subjects of the use of coercion during the forced collection of biological samples of a person in criminal proceedings, as well as ignoring the issues outlined by the legislator for a considerable time, the leading role is played by the line of conduct of the subject of the investigation, his professional competence , tactical combinations, the essence of which is to influence the person from whom the samples are taken.&#x0D; As a result of a thorough analysis of the procedure for taking samples from things and documents for examination, defined in the Criminal Procedure Code of Ukraine, demonstrates, in general, its compliance with international standards for conducting similar procedural actions, including the use of coercion. However, attention is focused on the impracticality of obtaining additional court permission to conduct a search in cases of refusal to voluntarily comply with a court order regarding the provision of samples of things and documents, as provided for in Art. 166 of the Criminal Code of Ukraine in accordance with the rules of temporary access to things and documents.

Custodial Violence in India with Reference to the Prevention of Torture Bill and International Legal Framework

Torture in custody is a confession of failure to do justice. It is one of the worst crimes against humanity and a naked violation of human rights governed by the rule of law. It is the brink of disaster, specifically for the economically backward class and socially deprived section of the society. We claim ourselves as ‘Vishwa guru’ even though many instances of police savagery occur not because of individual aberration, but because of systematic compulsions. India is a member of the Convention against Torture but failed to give effects to its provisions. The cases of torture are rising at an unpredictable and unprecedented rate; it is raising so many burning questions about the quandary motive of the government to not take any appropriate steps towards protecting the rights of victims from inhuman torture. The researcher divided this paper into several parts as they attempt to study the International Convention on Torture with a detailed analysis and interpretation of the Prevention of Torture Bill 2010 and 2017 with a historical overview of torture in India in its first part, similarly, the second part focused on the infamous techniques used by the police authorities to torture the accused. A comparison study with other countries’ laws also focuses on landmark decisions by the respective Hon’ble courts. In the third part, the researcher dealt with the existing domestic legislation on inhuman and degrading treatment and ended with some short recommendations and a conclusion.

Ta'zir (Punishment) at Islamic Boarding Schools; Between Tradition, Conception, and Shadows of Human Rights Violations

This article examines the practice of Ta'zir, a form of discretionary punishment, within the context of Islamic boarding schools. Ta'zir holds a significant place in Islamic jurisprudence, allowing authorities to determine penalties for offenses not explicitly addressed in religious texts. However, the application of Ta'zir has raised concerns, particularly in the context of Islamic boarding schools, where traditional practices intersect with modern notions of human rights. Drawing upon a multi-disciplinary approach, this study delves into the historical, cultural, and religious aspects of Ta'zir, elucidating its evolution from its inception to its current manifestations within Islamic boarding schools. By analyzing primary sources, legal texts, and case studies, the article underscores the diverse interpretations of Ta'zir and its malleability in adapting to contemporary circumstances. Furthermore, the article critically evaluates the potential conflicts between the traditional practice of Ta'zir and international human rights standards. It examines instances where Ta'zir punishments might be perceived as infringing upon human dignity, bodily integrity, and freedom from cruel, inhuman, or degrading treatment. The study also explores the role of Islamic boarding schools in shaping and perpetuating these practices, considering the interplay between religious education, discipline, and the protection of children's rights. The findings of this research reveal a complex landscape where tradition clashes with modern sensibilities. The article advocates for a nuanced dialogue between religious scholars, educators, and human rights advocates to strike a balance between preserving cultural heritage and upholding universally recognized human rights. It highlights the importance of reinterpretation and contextualization of Ta'zir in line with the principles of justice, mercy, and human dignity as emphasized within Islamic teachings. In conclusion, this article contributes to the ongoing discourse on the compatibility of traditional Islamic practices with contemporary human rights frameworks. It calls for a thoughtful reevaluation of Ta'zir within Islamic boarding schools, promoting an inclusive approach that safeguards both religious heritage and fundamental human rights.

Photocatalytic evaluation of tetragonal and orthorhombic lead oxide nanoparticles in dye degradation treatment

Photocatalytic evaluation of tetragonal and orthorhombic lead oxide nanoparticles in dye degradation treatment

Human rights and the righting of ‘historical’ wrongs: the Supreme Court’s judgment in Re McQuillan, McGuigan, and McKenna

This comment examines particular aspects of the Supreme Court’s judgment in McQuillan, McGuigan and McKenna, notably its reasoning and findings in respect of the investigative obligation emanating from the right not to be subjected to torture or inhuman or degrading treatment or punishment as it related to the case of the ‘Hooded Men’. Although the Supreme Court acknowledged that the subjection of the Hooded Men to the so-called ‘five techniques’ of interrogation in 1971 would, today, be characterised as ‘torture’, and in spite of new evidence linking named members of the United Kingdom (UK) Government to the authorisation of the ‘five techniques’, the court found that there was no basis for recognising the applicability or revival of UK authorities’ obligation to investigate under article 3 of the European Convention on Human Rights. In this case commentary, I consider the court’s analysis and conclusions and reflect briefly on their significance in the context of an uninterrupted ‘history’ of British involvement in torture.

Tindak Pidana Kekerasan dalam Rumah Tangga terhadap Perempuan Korban Perkawinan Usia Dini dimasa Pandemi Covid-19

Marriage according to Law No. 1 of 1974 concerning marriage is an act that binds physically and mentally between a man and a woman as husband and wife with the aim of forming a happy family based on the Almighty God. While early marriage is a marriage in which one or both of them fall into the category under the age of 19 years, Article 1 of Law Number 23 of 2003 concerning Child Protection states that someone under 18 years is included in the category of child age. The review that will be achieved in this research is what are the factors behind the existence of violence against women victims of early marriage during the covid-19 era and how is the right legal protection for women victims of early marriage during the covid-19 period. The research method used is a qualitative research method in its implication this method is descriptive analytical. The conclusions of the research are: 1) the factors behind the violence against women victims of early marriage where covid-19 is an economic factor which is indeed in a pandemic, economic factors make everyone feel under. 2) Appropriate legal protection for women victims of early marriage during the Covid-19 period. Victims of domestic violence, most of whom are women, must receive legal protection from the state and or society in order to avoid violence or threats of violence, torture, or degrading treatment and human dignity.

Multiple laccase-mediator system treatments for carbonaceous matter degradation in double refractory gold ore

Double refractory gold ore contains a higher level of gold than general ore but has been ignored in industry due to economic reasons. To improve gold recovery from double refractory gold ore (DRGO), the sulfides must be oxidized to release gold grains and the carbonaceous matter must be degraded to minimize “preg-robbing” during cyanidation. Recently, the degradation of carbonaceous matter in DRGO by enzymatic reactions has gained extensive interest owing to its environmental friendliness. Reportedly, laccase using 1-hydroxybenzotriazole hydrate (HBT) as an electron mediator can improve gold extraction from DRGO. In the present study, multiple-divided additions of the laccase-mediator system (LMS) are performed to maintain the enzyme activity, thus resulting in an improvement of gold extraction to 86.1%, compared with performing single addition with the same final dose, which yields a gold extraction of only 67.0%. However, multiple-divided additions of a higher dose of LMS decrease the gold extraction. The total dose of laccase is optimized to 11.87 U/100 mL of 5.0 g pretreated DRGO with a C content of 5.2%. These interesting results are comprehensively interpreted by combining different characterization methods for natural carbonaceous matter, including thermogravimetry-differential thermal analysis, Raman spectroscopy, and three-dimensional fluorescence spectrometry. This LMS proposed represents a novel approach worthy of further attention, especially in understanding carbon science in hydrometallurgy.