Method of degradation	Degradation system and optimal reacting conditions	Degradation yield, time reaction	Ref.
Chemical method: Fenton's reagent	Fe(ii)/aqueous H2O2, pH = 3.4, [H2O2]o = 0.50 mM, [Fe2+] = 0.10 mM, [MG]0 = 20 mg L−1, 30 °C	99.25% (60 min)	60
Chemical method: mesoporous carbon adsorbent	Mesoporous silica (MCM-48), pH = 8.5, [silica] = 5.10−3 g/25 mL, [MG]0 = 50 mg L−1, T = 25 °C	98.2% (30 min)	61
Photocatalysis method	Using naked niobium oxide (Nb2O5) as a photocatalyst. weight of catalyst = 0.1 g, [MG]o = 5 ppm; T = 25 °C, 3 mV cm−2 light intensity, pH = 6	53.25% (60 min)	62
Photocatalysis method	Ag doped TiO2, pH = 9, [MG]0 = 5 × 10−6 M, [catalyst] = 0.12 g, 60 mW cm−2 light intensity	99.5%	63
Biodegradation method	System used: bacterium Enterobacter asburiae strain XJUHX-4TM, semi-synthetic medium having the following composition was used: MG: 0.100–1.00 g L−1, KH2PO4: 1 g L−1, KCl: 0.5 g L−1, NaNO3: 2 g L−1, MgSO4·7 H2O: 0.5 g L−1, FeSO4·7H2O: 0.01 g L−1, sucrose: 15 g L−1, and beef extract: 3 g L−1	Maximum decolorization (>98%) in semi-synthetic media	64
Biodegradation method	System used: Pseudomonas sp. strain DY1, [MGo] = 100–1000 mg L−1, pH = 6.6, T = 28–30 °C	Effective decolorization: 78.9–84.3%	65