Collector Concentration Research Articles

Modeling and optimizing the flotation of coal fines: an investigation utilizing the Box-Behnken design in conjunction with response surface methodology

ABSTRACT This study investigates a novel approach for upgrading coking coal fines by combining wet sieving with flotation. Using a Box-Behnken design and response surface methodology (RSM), we optimized the flotation parameters – collector concentration, pulp density, and frother concentration – to enhance clean coal recovery. Analysis showed that these parameters significantly impacted coal quality and yield. With a fixed pulp density of 10% and an 18% ash target, RSM identified optimal flotation conditions as 0.200 kg/T frother and 0.885 kg/T collector concentrations. The optimal conditions for an 18% ash content were a 6.645% pulp density, 0.200 kg/T frother, and 1.1869 kg/T collector. Under these conditions, clean coal with 18.00% ash content and yields of 34.27% and 39.72% were achieved, with deviations from predicted values under 2%. The study indicates that the RSM-based method is effective, with parameter selection influenced by collector cost and clean coal market price. These findings provide a basis for future research to assess the method’s industrial applicability and economic and environmental viability.

A Comparative Study of Anionic and Cationic Collector in Microbubble-Assisted Flotation for Coarse Quartz Particle: Performance and Adsorption

Recent studies have suggested that using microbubbles to assist in coarse particle flotation has some advantages. However, how the type of collector affects the recovery of coarse particles under microbubbles still needs to be clarified. This study compared the performance and adsorption characteristics of anionic (sodium oleate - NaOL) and cationic (dodecylamine - DDA) collector environments for microbubble-assisted flotation of coarse quartz particles. A two-factorial level and Box-Behnken techniques were used for statistical design for screening and characterizing the performance. The flotation process utilizing NaOL and DDA was not significantly affected by froth depth. In the presence and absence of microbubbles, the performance of DDA surpassed that of NaOL; therefore, the average recovery of the cationic collector was more than 10% higher than that of the anionic collector. Contact angle analysis revealed that NaOL measured approximately 70° while DDA measured around 90°. DDA was adsorbed more significantly than NaOL at the same collector concentration. Zeta potential was more sensitive to DDA; increasing both collector concentrations also increased the value of zeta potential. FT-IR and EDX analyses showed that DDA and NaOL were chemically adsorbed onto quartz. Overall, this study demonstrates that DDA outperformed NaOL in the presence and absence of microbubbles during the flotation of coarse quartz particles.

A novel sampling technique for monitoring atmospheric methane concentrations: A case study with livestock sources

The substantial increase in the presence of greenhouse gases (GHGs) in the atmosphere has led to the development of several sampling techniques to quantify and characterize the sources of high global warming potential gas emissions. In this context, we developed a new method to estimate the time-averaged concentration of atmospheric methane that employs a long hose to collect a sample of gas by diffusion through one of its ends. We performed numerical simulations to illustrate the basis of our method and to determine the numerical factors required to estimate the time-averaged concentration of methane. This novel technique for estimating the mean gas concentration was then validated with two sets of experiments, where the source of methane was ruminant enteric fermentation measured in a respiration chamber. We compared the time-averaged methane concentration obtained with our methodology for periods (T) ranging from 1 to 4 days with those measured using the sensor of a respiration chamber. We found that the accuracy of the estimates improved as T increased from an error of 20 % for T = 1 to an error smaller than 10 % for T ≥ 2 days. In additional tests, and as suggested by numerical simulations, we confirmed that measuring and employing the methane concentration in the furthest half of the collector leads to a more precise estimation of atmospheric concentration than when the concentration of the entire collector is considered. This work demonstrates that the new methodology for air sampling, in conjunction with numerical analysis, is a viable alternative for quantifying atmospheric methane concentrations. In addition, the simple design of the devices showed remarkable benefits in terms of both the cost and simplicity for implementing large-scale individual sampling. We discuss its potential application to other GHGs.

Study on saline-alkali water distillation system by reflection enhanced solar heating

A saline-alkali water distillation system by reflection enhanced solar heating is proposed to treat the saline-alkali soil washing water. In this system, the heat concentration collector employs heat collecting plate to receive solar radiation energy, and converges to small-area steam generating tube through efficiently heat transfer. Without expensive optical tracking equipment, the system also employs an external reflector to reflect the solar radiation to the surface of the heat concentration collector. Thereby the energy flow density is further increased, and the useful energy and vaporization intensity is promoted. The latent heat of the steam is reused by heat recovery to enhance the energy utilization efficiency. The optimal inclination angles of reflector in different seasons and system performance were theoretically calculated. In the spring equinox, summer solstice, autumn equinox, and winter solstice, the optimal inclination angles of the reflector were 30°, 45°, 30°, and 15°, respectively. The freshwater production, useful energy, and heat recovery efficiency of the system were investigated by experiments. The daily freshwater production of the system was 17.04 kg, and the maximum production rate was 3.44 kg/h. The reflector increased the useful energy and freshwater production of the system by 33.68% and 35%, respectively. With heat recovery, the initial temperature of the saline-alkali water was increased to 53.8 °C and the freshwater production was increased by 13.16%.

N1,N10-dihydroxydecanediamide: Its separation performance and action mechanism for malachite, calcite and quartz

In this study, a novel collector, N1,N10-dihydroxydecanediamide (DHH) was synthesized in our lab and introduced in flotation of malachite ore. The separation performance and action mechanism of DHH were explored and compared with octyl hydroxamic acid (OHA). The results of single mineral flotation tests indicated that DHH exhibited a stronger collecting ability to malachite and better selectivity against quartz and calcite than OHA, and floated out 94 % malachite, 8.5 % quartz and 17 % calcite at pH = 10 with a collector concentration of 60 mg/L. The FTIR spectra, zeta-potential tests and XPS tests proved that DHH could absorb onto malachite surface though a chemical mode. DFT calculation results showed that DHH anion owned a stronger affinity to malachite than DHH molecular and OHA anion/molecular, and its bis-minerophilic groups could form C(=O)NHO-Cu bond with surface Cu atom. It exhibited that DHH was an excellent candidate and capable for high efficiency flotation of malachite ore.

Influence of collector type and the glass cover cooling on the performance of the solar distiller integrated with the solar collectors

Improving the efficiency of solar distillers is essential to increasing freshwater production. One method to enhance the output of the solar distiller is to connect it with another solar collector. Previous studies did not indicate a comparison of the performance of integrated solar stills with different types of solar collectors. The current article aims to study the performance of solar distillers connected to two different types of solar collectors, study the influencing operational variables, and compare these cases. A practical model was built that included four operational cases. The first case (M1) was a solar heater with a solar concentrator collector and a solar distiller connected in series. The second case (M2): A solar concentrator collector and solar distiller connected in series. The third case (M3): A solar heater and solar distiller connected in series. The fourth case (M4): It is the same as the M1 system, but the solar distiller contains a tube to cool the glass and compare the productivity with the classical solar distiller. The results showed that the M1 case is higher than the M3 and M2 cases. In contrast, the M4 case had the highest productivity in all the cases and systems that were discussed, which is estimated at 7583 ml/ day; this means that the M4 system is the best system studied, and this is due to the glass cooling mechanism. The highest productivity recorded for the M4 system was on 28 June, and the lowest productivity recorded was on 15 July. The highest hourly productivity was reached when the glass surface temperature (4 ˚C) was 1400 ml/h at 14:00.

Investigation of calcite flotation by green natural hydrophobic talc nanoparticles as collectors, and the adverse influence of nanoparticle aggregates

Hydrophobic talc nanoparticles (T-NPs) were used as natural solid collectors to study calcite flotation in a modified Hallimond flotation tube to optimize process conditions. The results demonstrated that the calcite surface hydrophobicity and resulting floatability significantly changed with variations in the concentration of T-NPs. It was found that by increasing T-NPs amount in the range of 0.4–1.2 kg/ton, calcite flotation recovery increased. Experiments results also revealed that by increasing T-NPs concentration over 1.2 kg/ton, flotation recovery drastically decreased, which was an indication of the formation of suspended T-NPs aggregates, because of their great tendency to aggregate due to agitation. Owing to greater hydrophobicity and floatation kinetic rate of suspended aggregates than calcite surface that covered by T-NPs, they attaching to bubbles quickly and easily, thereby they will have an adverse influence on calcite floatability. Therefore, 1.2 kg/ton of T-NPs was the optimum concentration of nano collector for process recovery. The results of this study clearly showed the promising potential of natural nano particles as an environment friendly collector in froth flotation.

Development of characteristic equations of conical solar still by incorporating N identical concentrator collectors with/without photovoltaic panel: A comparative investigation

This paper focuses on the development of characteristic equations and performance analysis of a conical solar still (CSS) connected to N identical compound parabolic concentrator (CPC) collectors, with or without photovoltaic thermal (PVT) integration. The objective is to achieve sustainable solar distillation in line with the United Nations' sustainability goals. The thermal model is developed by formulating energy balance equations for each part followed by its experimental validation considering N=0and1. A fair agreement between analytical and experimental results is observed having correlation coefficients as 0.996, 0.993, 0.992, and 0.97, 0.98, 0.99 for water temperature, yield, and glass temperature for N = 0 and 1, respectively. The study considers three cases: CSS integrated with N identical partially covered PVTCPCs (case (i)), CSS integrated with N identical fully covered PVTCPCs (case (ii)), and CSS integrated with N identical CPCs (case (iii)). The performance of these cases is compared using climate conditions in New Delhi on a typical day in June. The findings indicate that the mean value of instantaneous efficiency for case (i) is higher by 67.75 % than case (ii), however lower by 22.22 % than case (iii). The study also investigates the influence of variations in mass-flow rate and N on the output of the active CSS.

Experimental study on ash reduction by classification flotation

ABSTRACT Poor endowment conditions, with abundant reserves of high-impurity and low- quality coal resources, characterize the coal resources in our country. As the primary source of carbon emissions, the coal industry faces a critical challenge in actively contributing to environmental protection and carbon reduction within the context of striving for carbon peak and carbon neutrality. With the widespread application of mechanized coal mining and the deteriorating geological conditions of coal resources, coal slurry particles have become increasingly fine. Additionally, a large amount of gangue minerals mixes with the coal slurry, resulting in an increase in ash content and a decrease in floatability. This places higher demands on the separation of high-ash, difficult-to-float coal slurry. This issue has become a core concern that needs to be addressed within the coal industry. This study employs a classification flotation technology to reduce ash content and improve the quality of low-quality coal slurry. The research primarily focuses on the flotation ash reduction effects of the grain size of −0.5 mm and classified grain-size coal slurry under various pulp concentrations, collector concentrations, and frother concentrations. It also analyzes the impact of a rougher and two cleaner flotation processes on the flotation efficiency. Experimental results indicate that the optimal reagent concentrations and process parameters differ for each particle size of the coal slurry. Under the best flotation conditions, the experimental results for the rougher and two cleaner flotation processes are as follows: For the grain size of −0.5 mm coal slurry, the clean coal yield is 48.40%, with an ash content of 11.02%. For the grain size of − 0.5 + 0.125 mm coal slurry, the clean coal yield is 50.53%, with an ash content of 10.72%. For the grain size of − 0.125 + 0.045 mm coal slurry, the clean coal yield is 49.56%, with an ash content of 9.24%. For the grain size of −0.045 mm coal slurry, the clean coal yield is 48.73%, with an ash content of 10.97%. Notably, the classified grain-size coal slurry exhibits higher clean coal yields and lower ash content than the grain size of −0.5 mm coal slurry, highlighting the significant importance of classification flotation for coal slurry.

Research on resource comprehensive utilization of granite-type sulfide mine tailings

In order to recover and utilize mica and quartz from the tailings of a granite-type sulfide ore in Jiangxi Province, the technique of separating mica and quartz from the tailings by flotation without acid was investigated. Pyrite flotation was performed on a 500 g tailing sample to remove pyrite. And the middlings were acquired by desliming of the unfloated products. Finally mica and quartz was separated from the middlings in the mechanical flotation cell. Under conditions of pH=10.3 with a pulp concentration of 35% and a collector concentration of 180 g/t, a yield of 12.89% mica and 42.73% quartz was obtained, with silica grades as high as 71.50% in the quartz. The mica and quartz products can be used in construction ceramics and construction sand, respectively. It is believed that the outcomes of this work could provide ideas for comprehensive utilization of sulfide tailings.

Dynamics of particle attachment in a model stirred cell: A new technique to characterize and quantify particle floatability

Floatability evaluation is critical to predicting flotation results and designing a flotation flowsheet. Laboratory-scale flotation cells are commonly used to study particle floatability, but differences in cell design and governing hydrodynamics make extrapolation to industrial scale operations difficult. In this work, a new experimental approach based on particle attachment dynamics is proposed to evaluate particle floatability. This method allows precise control of hydrodynamic conditions, visualization of attachment processes, and direct observation of the bubble surfaces. It is therefore ideal for studying attachment dynamics as a function of collector concentration, particle size and concentration, and propeller speed. In addition, it opens the possibility for future studies of the packing density of the particles at the interface and their selective attachment. By evaluating the time-dependent surface coverage as a function of bubble residence time, we illustrate its ability to predict flotation kinetics within a flotation cell. This innovative technique provides a faster, more versatile means of studying particle floatability and attachment dynamics with practical implications for flotation cell optimization.

Energy matrices, enviro-economic and characteristic equation-based performance analyses of photovoltaic thermal compound parabolic concentrator (PVT-CPC) coupled solar still equipped with heat exchanger using SWCNTs and MWCNTs–water nanofluids

In this paper, effect of single wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs)- water based nanofluid have been studied to examine the performance, long-term feasibility andenviro-enviro-economic analysis of partially covered series connected N- photovoltaic thermal (PVT)-compound parabolic concentrator (CPC) collectors coupled double slope solar still (DSSS) equipped with helically coiled heat exchanger (HE). Analysis have been carried out by developing thermal modelling of the proposed system. Instantaneous gain and loss efficiencies; annual thermal energy/exergy, and productivity – is investigated for optimized parameters of the proposed system in detail. Gain efficiency of the proposed system is found to be approximately 25-30% higher using CNT-NPs as compared to the system without using NPs. Annual thermal energy and exergy of CNTs, particularly SWCNTs water-based nanofluid (thermal energy- 2491.55 kWh, thermal exergy-894.67 kWh) have been found to be greater in comparison to basefluid (thermal energy -2185.76 kWh, thermal exergy-772.18 kWh). Also, results give higher value of CO2 mitigation using CNT-NPs both on the basis of energy (SWCNT-5.082t, MWCNT-4.787t) and exergy (SWCNT-1.83t, MWCNT-1.76t) respectively. SWCNT-NPs shows better performance due to their better TPPs; also PVT-CPC collector integrated DSSS equipped with HE is more viable practically.

Modeling and analysis of PCM‐encapsulated solar thermal energy storage system for space heating

AbstractIn this study, a phase change material (PCM)‐encapsulated packed‐bed thermal energy storage (PB‐TES) system is intended for Day‐round space heating in the winter. Solar concentric collectors act for day‐time heating and TES charging, while the stored energy can be used at night and intermediate time for space heating. A region‐wise techno‐economic analysis of PCM candidates is made to compare the costs and sizes of solar collectors and PB‐TES. A spherical capsule filled with sodium nitrite (NaNO2) and sodium nitrate (NaNO3) is numerically investigated during the PCM charging at constant thermal input. After complete liquefication, the charging time for NaNO2 and NaNO3 capsules is 3280 and 4300 s, respectively, holding the maximum stored energy of 733.4 KJ/kg at 285°C and 687.27 kJ/kg at 310.12°C, respectively. In addition, the stored exergy is obtained 238.78 and 234.74 kJ/kg for NaNO2 and NaNO3, respectively; however, the average exergetic effectiveness for NaNO2 and NaNO3 are 0.54 and 0.46. Despite the lower energy storage capacity (kJ/kg) of NaNO3, the PB‐TES volume is less with NaNO3 than with NaNO2 due to higher density. However, the average cost ($/tonne) of NaNO3 PCM is 50% higher than NaNO2. Subsequently, the thermal efficiency of the proposed system is estimated at 27.68% and 26.94% during day and night‐time operations.

Optical efficiency of parabolic troughs with a secondary flat reflector; effects of non-ideal primary mirrors

Secondary flat receivers enhance concentration of parabolic trough collectors with cylindrical receivers. An increase of 70 % was possible for commercial primary mirrors while allowing the optical efficiency to be less sensitive to misalignments. Including the secondary flat reflector close to a parabolic-trough receiver may, however, reduce the optical efficiency of the trough due to the shadow projected. In this work ray-tracing simulations were conducted to compare the optical efficiency and the misalignment sensitivity of the standard absorber and its secondary flat reflector variation. In some cases, the required dimensions for the secondary flat reflector would make it a non-realistic solution due to the impossibility of encapsulating it within a glass cover. To overcome this issue, a truncated version of the secondary mirror is proposed and evaluated. A truncated secondary flat reflector will decrease the deleterious effects of the shading, enhancing concentration further but changing the tolerance to misalignments of the troughs. Analysis of two benchmark primary mirrors shows a worst-case scenario of optical efficiency reductions less than 3.5 and 2 %, with concentration increases of 20 and 80 % respectively. The reduction on absorber size offsets the lower optical efficiency by the reduction of radiation losses, especially for high-temperature applications.

Effect of particle shape on bubble-particle attachment behavior: Roles of surfaces, edges, and vertexes

It has been understood through many studies that particle shape is important in terms of particle adhesion to air bubbles in flotation. However, there are many questions yet to be answered. Whether the surface of the particle or its sharp corners is effective is only one of the issues that need to be better understood. Therefore, this study aims to delve deeper into the fundamental studies on the role of particle's geometry (surface, edges, and vertex) in their flotation behavior by investigating the attachment of spherical, cylindrical, triangular prismatic, and cubic particles to air bubbles based on their attachment efficiency, settling velocity, collision efficiency, and induction time. Bubble-particle attachment test results inferred that the attachment efficiency was in the order of cubic > triangular > cylindrical > spherical. In addition, it was found that the induction time of the spherical surface decreased from 37 ms to 15 ms with increasing collector concentration, while the induction time of the edged cubic particle decreased from 8 ms to 2 ms. This was attributed to the fact that the edge facilitates the drainage, thinning, and rupture of the water film between the bubble and the particle, thereby increasing the attachment efficiency. Finally, it has also been observed that the three-phase contact line of the cube particle is larger than that of the spherical particle, which improves the attachment stability and reduces detachment efficiency. The results obtained in this study shed light on the fact that the shape of the particles fed to flotation can be produced by using a suitable mill and thus higher flotation efficiency can be achieved with lower collector concentration.

Understanding the role of water quality in separation of rare earth minerals from iron oxide minerals in a flotation circuit

In many mineral processing plants, using saline water has become necessary to improve water efficiency. However, the dissolved ions in the water such as Ca2+ and Mg2+ may have a significant negative impact on the flotation of RE (rare earth) minerals due to the chemical reaction with flotation reagents used in RE flotation. Although some researchers investigated flotation performance of pure rare earth minerals, there is no study investigating the role of water quality in the separation of rare earth minerals from iron oxide minerals in a flotation circuit. This study focused on investigating the effect of divalent cations like Ca2+ and Mg2+ on the flotation of RE minerals using a fatty acid collector and Na2SiO3 depressant. The results showed that the presence of Ca2+ and Mg2+ decreased the selectivity and recovery of RE minerals due to the formation of insoluble calcium and magnesium carboxylate, leading to the reduced residual collector concentration. Furthermore, the divalent cations acted as a bridge between the oxygen atoms of the adsorbed SiO32− and carboxylate ions, resulting in increased adsorption of fatty acid collector ions and higher recovery of FeO. Rheological measurements also revealed that the presence of Ca2+ and Mg2+ significantly increased the flotation pulp viscosity, which could be attributed to the reduced repulsive forces between particles due to the compression of electrical double layer. This study provides valuable insights into the mechanisms underlying the effects of Ca2+ and Mg2+ on RE mineral flotation.

Optimization of shape factor by the response surface method, and the effect on sphalerite flotation recovery

Various morphological parameters that affect the flotation recovery of sphalerite were modelled and optimized using the response surface method (RSM). The effects of roughness value, shape factor, and collector concentration were investigated using the central composite full design method. The results were evaluated by analysis of variance. The optimum roughening time was found to be 25 minutes, the optimum roughness value was 2.9071 um, and the optimum collector concentration was 0.001 M. Using these values, a flotation recovery of 98.01% was obtained. Similarly, in shape factor studies, the optimum grinding time was 15 seconds, the optimum roundness value 0.7421, and the optimum collector concentration 0.0009 M, which resulted in a flotation recovery of 94.30%. The average error between the optimization results and the experimental results was estimated to be less than 6%, and the R2 values were greater than 90%. The study shows that RSM can be effectively applied in finding the economic optimum condition for obtaining maximum flotation recovery with minimum reagent consumption.

Thermal performance and economic sustainability of flat plate solar collectors using MgO and ZnO nanofluids: A comparative analysis

Considering the higher outlet temperature, the present study assessed the performance of Zinc oxide (ZnO) and Magnesium oxide (MgO) nanofluid-based flat plate solar collector at a low volumetric flow rate, that is, 30 L/h. The lower solar irradiance results in a low percentage enhancement in collector efficiency; therefore, it constraints the use of the nanofluid-based collector at such conditions. The collector efficiency was nearly 67.98% and 65.22% for 1 vol% ZnO and 0.2 vol% MgO, respectively, almost 20.57% and 16.53% more than base fluid (ethylene glycol: distilled water). For 1 vol% ZnO and 0.2 vol% MgO, the heat absorption parameter intensified by 20.48% and 17.12%, respectively. The payback period at the optimum concentrations of ZnO and MgO nanofluid-based flat plate solar collector compared to electric heating was ∼2.97 and 3.69 years, respectively. In terms of present worth, the cost savings in a life span of 15 years was approximately 1918.18 and 1839.05 USD for 1 vol% ZnO and 0.2 vol% MgO, respectively. Such gains could be extended using large-sized areas of collectors. The 1 vol% ZnO at the flow rate of 30 L/h has the shortest payback period and highest cost-saving; hence, profoundly recommended in the flat plate solar collector instead of the base fluid.

Correlation of Flotation Recoveries and Bubble–Particle Attachment Time for Dodecyl Ammonium Hydrochloride/Frother/Quartz Flotation System

Recent studies in the flotation of fine particles have necessitated new techniques and analyses for developing various strategies. Particularly, the improvements in flotation chemistry including the selection of the type of frother, collector, and other reagents have become very significant. In this study, the effect of different commercial polypropylene glycol frothers (PPG200, 400, and 600) in the presence of dodecylammonium hydrochloride (DAH) was investigated for their contribution to flotation recoveries and bubble–particle attachment time values of fine quartz minerals. Zeta potential measurements with DAH were also carried out as a function of pH and reagent concentration to justify the effect of collector usage alone on the charge of particles. A linear increase in flotation recoveries against collector concentration, e.g., 7.4% recovery at 1 × 10−5 mol/L DAH and 65.4% recovery at 1 × 10−3 mol/L DAH, was obtained. In this context, the contribution of frothers was particularly important in that a recovery of 15.91% in the absence of the frother and a modest increase to 19.70% was obtained upon the addition of PPG600 at its critical coalescence concentration (CCC) of 3 ppm. Finally, a strong correlation was found between the bubble–particle attachment time and flotation recovery as a function of collector concentration (lowest attachment time vs. highest flotation recovery). The latter correlation is very promising because bubble attachment time leads to various micro-mechanisms in flotation including bubble film thinning, bubble rupture, and induction time, and consequently, frother efficiency in the presence and absence of a collector. As a result, the experimental findings were gathered to achieve a consistent base for further fundamental studies on the application of the synergistic effect of frothers and collectors in the flotation of fine particles.

Highly efficient photocatalytic removal of concentrated PEX, PAX and SIPX xanthates collectors by an immobilized nanostructured g-C3N4/ZnO low power backlighted module

This study provides a pathway to practical application of graphitic carbon nitride (g-C3N4)-based photocatalysts as a promising next-generation polymeric-based environmentally friendly two dimentional (2D) nano-photocatalyst under real conditions in a dark medium at a very high concentration of xanthates collectors. Ultra-low amounts photocatalyst loading, low-power visible LED light source and strong light-photocatalyst coupling also play important roles in practical photodegradation of pollutants. Herein, immobilized low metal-oxide loaded (LMOL) g-C3N4/ZnO backlighted photocatalytic module with 0.6 ± 0.1 g/m2 g-C3N4/ZnO loading was developed to degrade dark dyes, potassium ethyl xanthate (PEX), potassium amyl xanthate (PAX) and sodium isopropyl xanthate (SIPX) collectors. The LMOL g-C3N4/ZnO nanostructures were investigated by XRD, UV–vis, PL, FE-SEM and XPS. After an efficient decomposing of dark methylene blue and methyl orange, the photodegradation of PEX, PAX and SIPX was examined and the photodegradation mechanism of the xanthates was also investigated. The degradation efficiency of the photocatalytic module was up to 95 %, which remained unchanged after several cycles. The efficient photocatalytic removal of xanthates is due to the effective light-photocatalyst coupling in dark media and also well-established e-/h+ generation and separation in LMOL g-C3N4/ZnO heterojunction.